Optical Sentence Examples

The mistake, shown in all the old maps of Australia, had originated in a curious optical illusion.

His optical investigations are perhaps the subject in which he most contributed to the progress of science; and the lucidity of exposition which marks his Dioptrics stands conspicuous even amid the generally luminous style of his works.

Dark coloured micas are strongly pleochroic. Accurate determinations of the optical orientation, as well as the symmetry of the etching figures on the cleavage planes, seem to suggest that the micas, except muscovite, may be anorthic rather than monoclinic in crystallization.

His researches extended to almost every branch of physical science, but his most important work was of an optical character.

Another obvious inference from the necessary imperfection of optical images is the uselessness of attempting anything like an absolute destruction of spherical aberration.

A; and similarly the optical distance between AoBo and B is represented by f (,t+So.)ds, the integration being along Bo.

The resolving power and the width of the emergent beam fix the optical character of the instrument.

The next and most important forward step in the progress of optical glass manufacture was initiated by Ernst Abbe and carried out jointly by him and 0.

As a result a whole series of glasses of novel composition and optical properties were produced.

A certain number of the most promising of these, from the purely optical point of view, had unfortunately to be abandoned for practical use owing to their chemical instability, and the problem of Fraunhofer, viz.

The older optical glasses, now generally known as the " ordinary " crown and flint glasses, are all of the nature of pure silicates, the basic constituents being, in the case of crown glasses, lime and soda or lime and potash, or a mixture of both, and in the case of flint glasses, lead and either (or both) soda and potash.

Further, these glasses, when made from properly proportioned materials, possess a very considerable degree of chemical stability, which is amply sufficient for most optical purposes.

In practice, however, it is not found that the presence either of a decidedly greenish-yellow colour or of numerous small bubbles interferes at all seriously with the successful use of the lenses for the majority of purposes, so that it is preferable to sacrifice the perfection of the glass in order to secure valuable optical properties.

It is a further striking fact, not unconnected with those just enumerated, that the extreme range of optical properties covered even by the relatively large number of optical glasses now available is in reality very small.

The refractive indices of all glasses at present available lie between 1.46 and 1 90, whereas transparent minerals are known having refractive indices lying considerably outside these limits; at least one of these, fluorite (calcium fluoride), is actually used by opticians in the construction of certain lenses, so that probably progress is to be looked for in a considerable widening of the limits of available optical materials; possibly such progress may lie in the direction of the artificial production of large mineral crystals.

While such minute and gradual variations are harmless for most optical purposes, sudden variations which generally take the form of striae or veins are fatal defects in all optical glass.

If the glass is very badly annealed, the lenses made from it may fly to pieces during or of ter manufacture, but apart from such extreme cases the optical effects of internal strain are not readily observed except in large optical apparatus.

Very perfectly annealed optical glass is now, however, readily obtainable.

Manufacture of Optical Glass.-In its earlier stages, the process for the production of optical glass closely resembles that used in the production of any other glass of the highest quality.

The raw materials are selected with great care to assure chemical purity, but whereas in most glasses the only impurities to be dreaded are those that are either infusible or produce a colouring effect upon the glass, for optical purposes the admixture of other glass-forming bodies than those which are intended to be present must be avoided on account of their effect in modifying the optical constants of the glass.

The crucibles or pots used for the production of optical glass very closely resemble those used in the manufacture of flint glass for other purposes; they are " covered " and the molten materials are thus protected from the action of the furnace gases by the interposition of a wall of fireclay, but as crucibles for optical glass are used for only one fusion and are then broken up, they are not made so thick and heavy as those used in flint-glass making, since the latter remain in the furnace for many weeks.

The furnace used for the production of optical glass is generally constructed to take one crucible only, so that the heat of the furnace may be accurately adjusted to the requirements of the particular glass under treatment.

The annealing process is therefore carried out in a manner differing essentially from that in use for any other variety of flat glass and nearly resembling that used for optical glass.

It is true that the use of glass for windows was only gradually extending itself at the time when Roman civilization sank under the torrent of German and Hunnish barbarism, and that its employment for optical instruments was only known in a rudimentary stage; but for domestic purposes, for architectural decoration and for personal ornaments glass was unquestionably much more used than at the present day.

Projected perpendicularly against a plane boundary, the motion is determined by an equal opposite vortex ring, the optical image; the vortex ring spreads out and moves more slowly as it approaches the wall; at the same time the molecular rotation, inversely as the cross-section of the vortex, is seen to increase.

It is seen that aldoses and ketoses which differ stereochemically in only the two final carbon atoms must yield the same osazone; and since d-mannose, d-glucose, and d-fructose do form the same osazone (d-glucosazone) differences either structural or stereochemical must be placed in the two final carbon atoms.3 It may here be noticed that in the sugars there are asymmetric carbon atoms, and consequently optical isomers are to be expected.

The starting point was ordinary(d)mannite (mannitol),C 6 H 14 0 61 a naturally occurring hexahydric alcohol, which only differed from a-acritol, the alcohol obtained by reducing a-acrose, with regard to optical activity.

About the same time Francesco Maurolico, or Maurolycus, the eminent mathematician of Messina, in his Theore y nata de Lumine et Umbra, written in 1521, fully investigated the optical problems connected with vision and the passage of rays of light through small apertures with and without lenses, and made great advances in this direction over his predecessors.

The addition of optical appliances to the simple dark chamber for the purpose of seeing what was going on outside, was first described by Girolamo Cardan in his De Subtilitate (1 550), as noted by Libri.

There is a great deal of practical information on lenses in connexion with the camera and other optical instruments, and the book is valuable as a repertory of early practical optics, also for the numerous references to and extracts from previous writers.

He has fully discussed the optical theory of the dark chamber, with and without a lens, and its analogy to the eye.

He also made great use of the simple dark chamber for his optical experiments with prisms, &c. Joseph Priestley (1772) mentions the application of the solar microscope, both to the small and portable and the large camera obscura.

The ethnographical museum, the cabinet of coins, and the collections of fossils, minerals, and physical and optical instruments, are also worthy of mention.

There are very few substances, however, for which the optical refractive index has the same value as K for steady or slowly varying electric force, on account of the great variation of the value of K with frequency.

This can be done by placing at B an equal negative point-charge -q in the place which would be occupied by the optical image of A if PO were a mirror, that is, let -q be placed at B, so that the distance BO is equal to the distance AO, whilst AOB is at right angles to PO.

Whatever this increased illumination may be, it can be precisely imitated by removing the mirror and placing a second lighted candle at the place occupied by the optical image of the first candle in the mirror, that is, as far behind the plane as the first candle was in front.

It has manufactures of cloth, leather, chemicals and optical instruments; large quantities of beetroot sugar are produced in the neighbourhood; and there is a considerable transit trade on the Elbe.

The chief objections to the method are that, as one star is in the axis of the telescope and the other displaced from it, the images are not both in focus of the eye-piece,3 and the rays from the two stars do not make the same angle with the optical axis of each segment.

The optical centres of the segments would also remain at the same distance from the eye-piece at all angles of separation.

The optical properties of sea-water are of immediate importance in biology, as they affect the penetration of sunlight into the depths.

The results of this theory have placed the molecular conception of matter in an indisputable position, but even without this theory there is such an accumulation of electrical and optical evidence in favour of the molecular conception of matter that the tenability of this conception could not be regarded as open to question.

Many of the well-known phenomena of optical diffraction may be imitated with sound waves, especially if the waves be short.

This great advance, which is the result of the gradual focussing of a century's work in the minute exploration of the exact laws of optical and electric phenomena, clearly carries with it deeper insight into the physical nature of matter itself and its modes of inanimate interaction.

This raises the further question as to whether the transmission of gravitation can be definitely recognized among the properties of an ultimate medium; if so, we know that it must be associated with some feature, perhaps very deep-seated, or on the other hand perhaps depending simply on incompressibility, which is not sensibly implicated in the electric and optical activities.

The nature of the motion, if any, that is produced in the surrounding regions of the aether by the translation of matter through it can be investigated by optical experiment.

It has in fact been found, with the very great precision of which optical experiment is capable, that all terrestrial optical phenomenareflexion, refraction, polarization linear and circular, diffraction - are entirely unaffected by the direction of the earth's motion, while the same result has recently been extended to electrostatic forces; and this is our main experimental clue.

We shall make the natural supposition that motion of the aether, say with velocity (u,v,w) at the point (x,y,z), is simply superposed on the velocity V of the optical undulations through that medium, the latter not being intrinsically altered.

As, however, our terrestrial optical apparatus is now all in motion along with the matter, we must dealt .with the rays relative to the moving system, and to these also Fermat's principle clearly applies; thus V+ (lu'--mv'-Fnw') is here the velocity of radiation in the direction of the ray, but relative to the moving material system.

It is, however, in complete accordance with a view that would make the aether near the earth fully partake in its orbital motion - a view which the null effect of convection on all terrestrial optical and electrical phenomena also strongly suggests.

When Clerk Maxwell pointed out the way to the common origin of optical and electrical phenomena, these equations naturally came to repose on an electric basis, the connexion having been first definitely exhibited by FitzGerald in 1878; and according as the independent variable was one or other of the vectors which represent electric force, magnetic force or electric polarity, they took the form appropriate to one or other of the elastic theories above mentioned.

In this place it must suffice to indicate the gist of the more recent developments of the electro-optical theory, which involve the dynamical verification of Fresnel's hypothesis regarding optical convection and the other relations above described.

Trains of waves nearly but not quite homogeneous as regards wave-length will as usual be propagated as wave-groups travelling with the slightly different velocity d(VX-1)/dX-', the value of K occurring in V being a function of X determined by the law of optical dispersion of the medium.

The most fundamental experimental confirmation that the theory of the aether has received on the optical side in recent years has been the verification of Maxwell's proposition that radiation exerts mechanical force on a material system, on which it falls, which may be represented in all cases as the resultant of pressures operating along the rays, and of intensity equal at each point of free space to the density of radiant energy.

Wood, have been written largely on the basis of the general physics of the aether; while the Collected Papers of Lord Rayleigh should be accessible to all who desire a first-hand knowledge of the development of the optical side of the subject.

Owing to the famine and the disturbed state of the country, which demanded his attention as a large landowner and lieutenant of King's County (from 1831), the instrument remained unused for nearly three years, but since 1848 it has been in constant use, chiefly for observations of nebulae, for which it was particularly suited on account of its immense optical power, nominally 6000.

An active trade, fostered by abundant railway communications, is combined with manufactures of iron and steel wares, paper, chemicals, vinegar, physical and optical instruments, besides artistic printing and lithography.

B, The Gastrula has become a Trochosphere by the development of the ciliated ring vr (optical section).

D, Further advanced Trochosphere (optical section).

The optical effect as regards resolving power is the same as with a grating of N lines in the nth order, but, nearly all the light not absorbed by the glass may be concentrated in one or two orders.'

The limitation of power is introduced as in all optical instruments, by the finiteness of the length of a wave of light which causes the image of an indefinitely narrow slit to spread out over a finite width in the focal plane of the observing telescope.

Theoretical resolving power can only be obtained when the whole collimator is filled with light and further (as pointed out by Lord Rayleigh in the course of discussion during a meeting of the " Optical Convention " in London, 1905) each portion of the collimator must be illuminated by each portion of the luminous source.

This is best obtained by optical means.

This analogy is useful because the application of Fourier's analysis to the optical theory of spectroscopes has been doubted, and it may be urged in answer to the objections raised that the instrument acts in all respects like a mechanical analyser,' the applicability of which has never been called into question.

Royds made with the same rotating disk, but with improved optical appliances.

The larva is seen in optical section, and its distinguishing feature is the ciliated lobed band (vl, sl, dl), which corresponds to the pre-oral ciliated band of a trochosphere-larva..

In this case the geometrical axis is the line joining the central division of the scale to the optical centre of the lens.

Olszewski, and illustrated for the first time in public the liquefaction of oxygen and air, by means of apparatus specially designed for optical projection so that the actions taking place might be visible to the audience.

About 1892 the idea occurred to him of using vacuum-jacketed vessels for the storage of liquid gases, and so efficient did this device prove in preventing the influx of external heat that it is found possible not only to preserve the liquids for comparatively long periods, but also to keep them so free from ebullition that examination of their optical properties becomes possible.

There are iron mines and foundries and optical instrument factories.

He succeeded in liquefying several gases; he investigated the alloys of steel, and produced several new kinds of glass intended for optical purposes.

After three days he worked with common electricity, trying glass, heavy optical glass, quartz, Iceland spar, all without effect, as on former trials.

The optical phenomena produced by atmospheric water and ice may be divided into two classes, according to the relative position of the luminous ring and the source of light.

Essentially it consists in an optical system of lenses and mirrors, or mirrors alone, the upper part of which projects from cover, or from the deck of a submarine, while the observer looks into the lower end, receiving an image of the surrounding country or sea by reflection down a tube.

From the beginning of the 20th century, however, the practical introduction of submarine navigation brought about the development of new elaborate periscopes of great length and provided with an optical system of lenses, which were built into the structure of the submarine.

And in the World War, while optical instruments of this kind were elaborated and improved, the periscope as such came into use for the infantry garrisoning trenches.

The optical system is shown in fig.

Gears are provided for elevating, levelling, aligning the upper and lower optical systems, adjusting the inclination of the reflector and rotating the mast around a vertical axis so that observations may be made and azimuth angles taken in all directions.

From the large lens, E, the rays pass through the open air for a considerable distance, depending upon how much the mast has been raised, to the lower optical system.

An optical tube replaced this cupola in the "Gustave Zede," and comprised a short tube (on top of the submarine) with a lens to close the top end, which was kept just above the surface when running submerged.

This can be done in two ways, either by rotating the optical train inside the main tube, or, as is more usually the case, rotating the whole periscope.

In the majority of ant-imitating spiders the forepart of the cephalothorax is constricted on each side to resemble the neck of the insect, and in many cases the similarity is increased by the presence of a stripe of white hairs which has the optical effect of cutting out an extra piece of integument, exactly as occurs in analogous cases in insects.

In the other view the spermatia are the male sexual cells and thus A, Optical longitudinal section of the ex are rightly named; it tremity of a thin branch of the thallus should, however, be which has become transparent in pointed out that this solution of potash.

The acid has been synthesized, as has also the inactive form of methylethylacetic acid; this modification is split into its optical antipodes by crystallization of its brucine salt.

Optical examination of many chalcedonic minerals by French mineralogists has shown that they are aggregates of various fibrous crystalline bodies differing from each other in certain optical characters, whence they are distinguished as separate minerals under such names as calcedonite,pseudocalcedonite,quartzine, lutecite and lussatite.

Artificial Phenomena resembling Aurora.-At Sodankyla, the station occupied by the Finnish Arctic Expedition of 1882-1883, Selim Lemstrom and Biese (23) described and gave drawings of optical phenomena which they believed to be artificially produced aurora.

Experience, however, has shown that even when the movements of the ground are alarming the actual range of motion is so small that a satisfactory record can be obtained only by some mechanical (or optical) method of multiplication.

After fusing a panful of colored glass, it was sampled by taking pinches out with tongs; when perfectly combined it was left to cool in the pan, as with modern optical glass.

On his return he held official posts successively at Antwerp, Strassburg and Paris, and devoted himself to optical research.

The manufactures include linen fabrics, cloth, toys, buttons, optical instruments, agricultural machines, knives, mineral waters, condensed soups and condensed milk.

In 1752 he abandoned silk-weaving and joined his eldest son, Peter Dollond (1730-1820), who in 1750 had started in business as a maker of optical instruments.

The optical apparatus generally consists of a mirror mounted on an axis parallel to the axis of the earth, and rotated with the same angular velocity as the sun.

Thus Goethe had no great sympathy for the war of liberation which kindled young hearts from one end of Germany to the other; and when the national enthusiasm rose to its highest pitch he buried himself in those optical and morphological studies, which, with increasing years, occupied more and more of his time and interest.

Indeed, in its practical form the principle of the instrument has remained unchanged from the time of the Dollonds to the present day; and the history of its development may be summed up as consisting not in new optical discoveries but in utilizing new appliances for figuring and polishing, improved material for specula and lenses, more refined means of testing, and more perfect and convenient methods of mounting.

It was in vain that the French Academy of Sciences offered prizes for perfect disks of optical flint glass.

In spite of the improvements in the manufacture of optical glass practically the same crown and flint glasses as used by John Dollond in 1758 for achromatic objectives are still used for all the largest of the modern refracting telescopes.

The figures given are the partial dispersions for ordinary crown and ordinary extra dense flint glasses, styled in Messrs Schott's catalogue of optical glasses as o 60 and 0.102 respectively, having refractive indices of 1 5179 and 1.6489 for the D ray respectively, and (µ D -I)/(l F -µc) =60 2 and 33.8 respectively to indicate their dispersive powers (inverted), = v.

The surface of the large mirror should be a paraboloid of revolution, that of the small mirror a true optical plane.

The proper mounting of a telescope is hardly of less importance than its optical perfection.

Where accurate differential observations or photographs involving other than instantaneous exposures have to be made, the additional condition is required that the optical axis of the telescope shall accurately and automatically follow the object under observation in spite of the apparent diurnal motion of the heavens, or in some cases even of the apparent motion of the object relative to neighbouring fixed stars.

There must be a certain loss of light from two, additional reflections; but that could be tolerated for the sake of other advantages, provided that the mirrors could be made sufficiently perfect \ optical planes.

He has never seen more perfect optical definition in any of the many telescopes he has employed, and certainly never measured a celestial object in such favourable conditions of physical comfort.

In those of type E the eye-piece has a fixed position and the observer may even occupy a room maintained at uniform temperature, but he must submit to a certain loss of light from one or more reflecting surfaces, and from possible loss of definition from optical imperfection or flexure of the mirror or mirrors.

Up to 1908 neither the optical qualities of the images given by the object-glasses and reflecting plane nor the practical working of the instrument, have, so far as we know, been submitted to any severe test.

Undoubtedly a large number of these are only optical pairs, but mere considerations of probability show that the majority must be physically connected.

The optical instruments of Jena and the scientific instruments of Ilmenau are well known.

The only refractive indices which had been measured were the optical refractive indices of a number of transparent substances.

Maxwell made a comparison between the optical refractive index and the dielectric constant of paraffin wax, and the approximation between the numerical values of the square of the first and that of the last was sufficient to show that there was a basis for further work.

Experimental methods were devised for the further exact measurements of the electromagnetic velocity and numerous determinations of the dielectric constants of various solids, liquids and gases, and comparisons of these with the corresponding optical refractive indices were conducted.

On the other hand, the divergence in some cases between the square of the optical refractive index and the dielectric constant was very marked.

He investigated the optical constants of the eye, measured by his invention, the ophthalmometer, the radii of curvature of the crystalline lens for near and far vision, explained the mechanism of accommodation by which the eye can focus within certain limits, discussed the phenomena of colour vision, and gave a luminous account of the movements of the eyeballs so as to secure single vision with two eyes.

Like every Jew, Spinoza had learned a handicraft; he was a grinder of lenses for optical instruments, and was thus enabled to earn an income sufficient for his modest wants.

It was as an optician that he was first brought into connexion with Huygens and Leibnitz; and an optical Treatise on the .Rainbow, written by him and long supposed to be lost, was discovered and reprinted by Dr Van Vloten in 1862.

The Gaussian theory, however, is only true so long as the angles made by all rays with the optical axis (the symmetrical axis of the system) are infinitely small, i.e.

These authors proved, however, that no optical system can justify these suppositions, since they are contradictory to the fundamental laws of reflexion and refraction.

If S (fig.5) be any optical system, rays proceeding from an axis point 0 under an angle u l will unite in the axis point O'1; and those under an angle 24 2 in the axis point 0'2.

The origins of these four plane co-ordinate systems may be collinear with the axis of the optical system; and the corresponding axes may be parallel.

It is readily seen that if the optical system be symmetrical, the origins of the co-ordinate systems collinear with the optical axis Object J Barrel shaped Cushion shaped Distorted image FIG.

The existence of an optical system, which reproduces absolutely a finite plane on another with pencils of finite aperture, is doubtful; but practical systems solve this problem with an accuracy which mostly suffices for the special purpose of each species of instrument.

The absence of this error is termed achromatism, and an optical system so corrected is termed achromatic.

On this account the lines D and G' are united for ordinary photographic objectives; the optical as well as the actinic image is chromatically inferior, but both lie in the same place; and consequently the best correction lies in F (this is known as the " actinic correction " or " freedom from chemical focus ").

Optical correction f c = fF = 100 mm.

The sodium ammonium salt is not capable of decomposition into its optical antipodes, as is sodium ammonium racemate.

The optical characters are interesting, because of the striking crossed dispersion of the optic axes, of which phenomenon borax affords the best example.

This substance, which has been found to be a purely siliceous concretion, is possessed of peculiar optical properties.

Furth is the seat of several important industries; particularly, the production of chromolithographs and picture-books, the manufacture of mirrors and mirror-frames, bronze and gold-leaf wares, pencils, toys, haberdashery, optical instruments, silver work, turnery, chicory, machinery, fancy boxes and cases, and an extensive trade is carried on in these goods as also in hops, metals, wool, groceries and coal.

By adding an alcoholic solution of iodine to a solution of the sulphate in acetic acid a compound known as herapathite, 4Qu 3H 2 SO 4.2HI Ie6H 2 O, is obtained, which possesses optical properties similar to those of tourmaline; it is soluble in Iwo parts of boiling water; and its sparing solubility in cold alcohol has been utilized for estimating quinine quantitatively.

Clear transparent rock-crystal is used for optical purposes and spectacle lenses.

In its optical characters, quartz is also of interest, since it is one of the two minerals (cinnabar being the other) which are circularly polarizing.

The undulatory theory of light, first founded upon experimental demonstration by Thomas Young, was extended to a large class of optical phenomena, and permanently established by his brilliant discoveries and mathematical deductions.

His labours in the cause of optical science received during his lifetime only scant public recognition, and some of his papers were not printed by the Academie des Sciences till many years.

In spite of its somewhat sleepy appearance, Potsdam has manufactures of silk goods, chemicals, furniture, chocolate, tobacco and optical instruments.

As the incandescent bodies of the universe are visible by their own light, the problem of ascertaining their existence and position is mainly one of seeing, and our facilities for attacking it have constantly increased with the improvement of our optical appliances.

Optical complications fatally impeded sharpness of vision, and the phenomena took place in a debateable borderland of uncertainty.

An appeal then lay to the 19th century pair of transits in 1874 and 1882; but no peremptory decision ensued; observations were marred by the same optical evils as before.

Between 1 774 and 1789 he built scores of of ft ., the optical excellence of which approved itself W illiam by a crowd of discoveries.

The determination of the curves of constant retardation depends upon expressing the retardation in terms of the optical constants of the crystal, the angle of incidence and the azimuth of the plane of incidence.

This state of things may, however, be considerably departed from if the axes of optical symmetry of the crystal are different for the various colours.

Fresnel obtained his formulae by assuming that the optical difference of media is due to a change in the effective density of the ether, the elasticity being the same - an assumption inconsistent with his theory of double refraction - and was led to the result that the vibrations are perpendicular to the plane of polarization.

The optical constants (refractive index and co-efficient of extinction) of the metal may then be obtained from observations of the principal incidence and the elliptic polarization then produced.

This refractive index should be equal to the greatest index of the plate, and with a biaxal plate the mean axis of optical symmetry should be parallel to its faces and in the normal section of the prisms, while with an uniaxal plate the optic axis should be in a plane perpendicular to this normal section.

If measurements be required, the plate must have a motion round an axis perpendicular to that of the optical systems, and also about an axis normal to its faces; the polarizer and analyser must also be capable of adjustment.

In using optical instruments the eye in general is moved just as in free vision; that is to say, the attention is fixed upon the individual parts of the image one after another, the eye being turned in its cavity.

The diamond has the requisite optical properties, its index of refraction being about i 6 times as large as that of ordinary glass.

Let O01=y, O'01' =y', the focal distance of the image F I 'O' =A, and the image-side focal length f l ', then the magnification M =y /y=o/,/1' (3) The distance A is called the " optical tube length."

In this case the optical tube length may be altered within fixed limits without spoiling the image; at the same time the objective magnification M is also altered.

For strong objectives there is, however, only one optical tube length in which it is possible to obtain a good image by means of wide pencils, any alteration of the tube length involving a considerable spoiling of the image.

When forming an image by a microscope objective it often happens that the transparent media bounding the system have different optical properties.

In this case the optical tube length equals the distance of the adjacent focal planes of the two systems, which equals the distance of the image-side focus of the objective F 1 ' from the object-side focus of the eyepiece F2.

In this optical way it is possible to show thin sections even in liquid preparations.

The new glasses produced at Schott's glass works, Jena, possessed in part optical qualities which differed considerably from those of the older kinds of glass.

By using these glasses and employing minerals with special optical properties, it is possible to correct objectives so that three colours can be combined, leaving only a quite slight tertiary spectrum, and removing the spherical aberration for two colours.

In German and French microscopes the optical length of the tube, when apochromats and compensation-eyepieces are used, is 180 mm.

Illuminating Systems Most microscopic observations are made with transmitted light; an illuminating arrangement is therefore necessary, and as the plane of the object is nearly always horizontal or only slightly inclined, the illuminating rays must be directed along the optical axis of the microscope.

This concentration is most easily produced by sliding or revolving diaphragms. A series of holes of different sizes perforate a revolving disk below the stage plate at an equal radial distance from the axis of the disk, so that the holes can be brought under the preparation in turn, the centre of the diaphragms always being a continuation of the optical axis of the microscope.

A changeable diaphragm is placed at the upper end of a short tube which can be moved in a case below the stage in the direction of the optical axis.

If the objects have a low reflecting power, or if a slightly higher magnification is needed, the lighting can be improved by optical system.

Mechanical Arrangements Although the optical system is the first consideration in a microscope, the system is valueless if the fittings do not allow its correct use.

The optical system must be kept at a certain distance and well centred, and a correct position for the object in relation to the system must be assured.

An essential in all rough and fine adjustments is that the motion must always be parallel to the optical axis of the microscope, so that the same point in the object remains in the centre of the field.

To obviate mistakes the optical axis of the microscope must coincide with the revolving axis of the plate, and the revolving plate has a central position C to keep this condition fulfilled.

The magnification of a microscope is determined from the focal lengths of the two optical systems and the optical tube length, for N = 250 A/fi'f2 To determine the optical tube length 0, it is necessary to know the position of the focal planes of the objective and of the ocular.

The process is analogous to the optical experiment of looking at a quickly rotating wheel or engine through slits in a disk, rotating slightly faster or slower than the object observed.

In this way an optical representation is obtained of the oscillatory discharge of the condenser.

Finally, purely optical methods have been employed.

If this patch is also given a displacement in the direction of right angles by examining it in a steadily vibrating mirror, we see a wavy or oscillatory line of light which is an optical representation of the wave form of a current in the coils embracing the Braun tube.

The pejorative connotation of an optical illusion is a visual malfunction.

The theoretical resolution is never obtained due to lens aberrations which are difficult to fully compensate for in electron optical systems.

Through water communication using acoustic, electromagnetic and optical devices is continuing to be an active research area for us.

The UVOT detected afterglows from these two bursts in optical light, but not significantly in ultraviolet.

An optical or image analysis system should be used wherever possible to interpret the results of tests performed using microplate or column agglutination methods.

Another key factor of modern fiber optic systems that we have not touched on is optical amplifiers.

Abstract Jones matrices describe the polarization, or spin angular momentum, of a light beam as it passes through an optical system.

The instrument uses 400 optical fibers, which a robotic arm takes about one hour to position with incredible accuracy.

A " best fit " between the detections and the optical background is used to precisely fix the astrometry of each field.

Careful calibration of the relative positioning and nonlinear optical distortion is required in order to do astrometry using WFC data.

Accurate optical astrometry would locate these peaks relative to the nucleus as defined by the radio core, and so resolve this ambiguity.

Key technologies include airborne radar systems avionics and mission systems, electronic warfare systems, electro optical systems, military...

This means that layers of ATM and SDH systems sit between devices and the optical backbone.

The self-alignment of crystallites manifests itself as patterns of optical birefringence when the liquids are viewed between crossed polars.

An optical telescope is used with a special detector called a bolometer placed at its focus.

Name ` Name ` is the source name from cross-correlations with optical catalogs.

Today, we are reviewing their latest low profile keyboard and optical mouse combo.

No optical counterpart can be seen on the 2nd generation red Digital Sky Survey.

Headings include crystallography, chemical composition, physical and optical properties, as well as an alphabetical listing of mineral species.

He experiences himself, his thoughts and feelings as something separated from the rest, a kind of optical delusion of his consciousness.

Factors to be considered when selecting an appropriate scanner include optical resolution, optical density, bit depth and scanning time.

They also facilitate the use of optical diagnostics which are often impractical in explosives environments.

Hirofumi Ogawa rewrote chunks of the FAT (DOS/Windows fs) code base and made the larger magneto optical disks work.

The velocity dispersion of the cluster galaxies can be measured from optical spectra.

Describes the installation and configuration of optical disk drives for Linux.

The tablet's exaggerated entasis is vulgar, it should be hardly visible but nonetheless correct to eliminate optical illusions The tablet is brutal.

By combining ergonomics and cutting edge design Perific is a wireless optical mouse that you easily can adapt to your workplace.

Fiber Optics - Also called optical fiber Optics - Also called optical fibers or optical fiber bundles.

Annual layers in polar firn detected by Borehole Optical Stratigraphy.

Meade Optical Coatings Aluminum Coatings with magnesium fluoride over coat provides bright images full of detail.

Its newly designed optical system consists of 17 elements in 13 groups, including one fluorite and two UD lenses.

The directionality of place-memory ghosts suggests that they are possibly emotional equivalents of optical holograms.

These can be measured by holographic methods, similar to the process used to produce optical holograms.

A second research interest since 1988 has been in Optical Information Processing, specifically real-time holography using photorefractive materials.

While optical data are best for land cover mapping, radar imagery is a good replacement in very cloudy areas.

This is known as a racemic mixture and it is optically inactive due to one isomer canceling out the optical effect of the other.

Spatially inhomogeneous optical excitation may provide a means of movement control of the molecular motors.

For Terrestrial Planet Finder, five spacecraft, flying in formation about one kilometer apart, will function as an optical interferometer.

Such radio interferometers can resolve details far sharper than anything current optical telescopes can see.

In contrast to other optical methods of the detection of Shear force interactions the fiber interferometer enables to measure the tip amplitude oscillation.

Not only is the product a stereospecific optical isomer, the reactant is it self a stereospecific geometrical isomer!

The active site of an enzyme will only be able to operate on one type of optical isomer.

At the moment, such archives are created on tape, or huge, expensive optical jukeboxes.

Synthesis of a flat optical lens was investigated by using short pulsed laser induced surface graphitisation of CVD diamond in air.

The optical lens of the video camera focuses the image on the chip mounted behind the lens.

The lens part of the DMC-FX01 comprises of seven elements in six groups, incorporating four aspherical lenses to generate high optical performance.

Do some kind of optical lithography - like how you make PCBs?

This technique, optical stimulated luminescence dating (OSL ), can show how long soil has been hidden from sunlight.

Since there is no eyepiece, there can be no optical magnification as such.

The representation of the visual world in the primary visual cortex of the common marmoset revealed by optical imaging.

The design was created through an integrated approach involving mechanical, electronic and optical constraints and optimization.

The General Engineering Research Institute The Institute conducts research in a variety of areas in the fields of advanced manufacturing technology and optical metrology.

There is a full range of electronic and optical characterisation techniques available for thin films and an extensive surface microanalysis suite.

A computer enhanced optical micrograph of a liquid crystal.

Using an optical microscope Wembley Stadium would look like a blurred blob.

Unlike optical microscopy SEM does not suffer from a severely limited depth of field.

Abstract Permanent 3D microstructures are created within a gel using holographic optical tweezers.

It is not intended to replace a lecture course on the principles of optical mineralogy.

This " optical molasses " can slow millions of atoms to temperatures just millionths of a degree above absolute zero.

My research is looking at the use of modulated retro-reflector to provide reliable optical networking for micro-machines within an environment such as a room.

Figure 4 shows an optical image of a silicon nitride block which has been damaged on the right side.

The optical data allows a study of the dust obscuration.

His work in theoretical quantum optics recently predicted the existence of the optical analog of " black holes " .

Digital audio cross conversion - coax to optical and optical to coax.

Optical illusion - John Langdon, 1999 Can you see why this painting is called optical illusion - John Langdon, 1999 Can you see why this painting is called optical illusion?

The optical fiber An optical fiber is a solid rod of glass, finer than a strand of human hair.

Eventually, the Biogon was the only optical product in the world that still required it.

This all optical computing, or ` light controlling light ' has remained a dream of technologists for some time.

Those include optical, scanning and transmission electron microscopes.

Fiber Optics - Also called optical fibers or optical fiber bundles.

As the particle passes through the beam, a secondary " pulse " signal is generated by a single optical fiber.

The report explained how Professor Schyns could understand why people were fooled by optical illusions by using advanced brain imaging technology.

Vital Signs by Robin Blackledge assisted by Gerrard Martin 24 installations, including mirrors and flames creating optical illusions.

It is impossible for temperature inversions to produce optical illusions or reflections of lights over the horizon under these conditions.

Topics cover physics, chemistry and biology, including optical illusions and the psychology of science.

This is often the same with many optical illusions or " trick " pictures.

If you are like most people, when you look at this amazing optical illusion, you will be sure there is a mistake.

It illustrates a well-known optical illusion; the crater looks like a hill when the photo is upside-down.

Currently, fiber optics networks are not completely optical.

Optical Express awarded a scholarship to first year optometry student, Sam Chiu pictured above.

His dissertation research was involved with the application of optical parametric oscillator (OPO) in laser spectroscopy.

He will be investigating the optical properties of aerosol particles by cavity ringdown spectroscopy.

In transparent materials with anisotropic dielectric permittivity, important optical effects can be observed.

Conventional systems rely on measuring Raman scattering by optical phonons.

The consequent modulation in optical power reflected by the film is detected using a photodiode at the proximal end of the fiber.

The animation allows the user to select from a number of fluorescence photomicrographs and vary the amount of astigmatism in the optical system.

Other methods of sampling plankton are being developed which include optical plankton counters, video and acoustic systems.

The site is part of an optical microscopy primer from the Molecular Expressions site.

This definition also makes optical depth proportional to the amount of obscuring stuff along the line of sight.

Then there are dark-field stops, and colored filters for optical staining of the transparent protists I like to observe.

The tipo piu comune is the optical microscope, nel quale l'esame of the object viene fatto in luce visibile... .

It is a suggestive coincidence that the space density of bright optical quasars also reached a peak sometime around z = 2-3.

This article has been scanned and may contained errors due to the process of scanning and optical character recognition.

Using an optical technique for displacement measurement enables remote sensing of vibration.

The optical filter - which stops infrared light from reaching the camera sensor - is in place during the day for correct color rendition.

A brief history of nonlinear bistable optical resonators is discussed and the simple fiber ring resonator is analyzed in particular.

In a parallel with the development of ocean color sensors there have been major innovations in situ optical sensors.

The NV7 has built-in OPS, an optical anti-shake technology, to minimize camera shake technology, to minimize camera shake and to deliver clearer resolution.

This camera also has optical image stabilization to help combat blur caused by camera shake.

An internal thread at their beam exits may be used for installing mechanical shutters or various types of optical components.

At every stage of manufacture each test sieve is individually inspected by optical projection including the very latest computer based optical measuring equipment.

I doped silicon with several different group I and II impurities and measured their influence on the electrical and optical properties.

The research experiments have shown that ionization type smoke detectors reacted faster for all research fires than optical type smoke detectors.

It is a wide field optical integral field spectrograph aimed at performing deep field science.

The buttons carry light collecting prisms attached to optical fibers in a 10m cable that directly feeds a spectrograph on the dome floor.

However, the size of the retinal image depends upon the optical angle subtended at the eye by the tree.

The hardware of the digital superhighway -- optical fiber -- isn't due to arrive in many poorer parts of the country for years.

We are planning to use infrared observations of type Ia supernovae to improve the accuracy of the results obtained at optical wavelengths.

One important ingredient in optical telecommunication is the need for good sources of optical pulses.

The HET is one of the world's largest optical telescopes, with a primary mirror some 11 meters in diameter.

Long life optical components mean that, for the most part, you only ever need to replace toner.

An optical trackball and a scroll wheel are the key to precise navigation through all of your documents.

Reflective This system uses optical transceivers located near to devices that transmit the data to a common location for redirection to a receiving device.

Further progress has been made in the development of high speed optical transceivers for in-building free space data networks.

Integrated optical wireless transceivers Research Group home page To demonstrate compact potentially low cost optical transceivers for in-building free space networks.

A new optical device was developed for continuously measuring the rate of sediment transport in the system.

To achieve this, negative feedback is applied to the optical tweezer to compensate for bead movements measured by the position detector.

Machines that use this technique are called optical tweezers.

At such low stiffness the bead held in the optical tweezers necessarily exhibits large amounts of thermal motion.

Abstract Within inverted optical tweezers we measure both the lateral and axial trapping efficiency obtained with Gaussian and high-order Laguerre-Gaussian beams.

The group also leads several programs in novel optical traps (laser tweezers and spanners) and active holographic devices.

What makes matters worse is that like many camera manufacturers, HP has opted not to include an optical viewfinder.

For lining up shots there is an optical viewfinder or a large 2.5 " LCD screen.

Above the lcd is the large optical viewfinder, which covers 95% of the frame.

Visor rated as optical class 1. High clear 3 anti-fog visor rated as optical class 1. High clear 3 anti-fog visor coating.

The Bill is intended to strengthen the protection of public funds through improved controls over who may redeem optical vouchers.

Embedded optical waveguides can be created using the material.

In QinetiQâs unique approach, hollow waveguides are used to guide light through a circuit of optical components located in a common substrate.

The above image pair shows the core of NGC 1705 in both optical as well as near-infrared wavelengths taken with Hubble.

This is the principle of the kaleidoscope, an optical toy which received its present form at the hands of Sir David Brewster about the year 1815, and which at once became exceedingly popular owing to the beauty and variety of the images and the sudden and unexpected changes from one graceful form to another.

One of his great aims was optical illusion, carried out by a mastery of perspective which, though not always impeccably correct, nor absolutely superior in principle to the highest contemporary point of attainment, was worked out by himself with strenuous labour, and an effect of actuality astonishing in those times.

With Reichenbach and Utzschneider, Fraunhofer established in 1809 an optical institute at Benedictbeuern, near Munich, of which he in 1818 became sole manager.

If, however, two compounds only differ with regard to the spatial arrangement of the atoms, the physical properties may be (I) for the most part identical, differences, however, being apparent with regard to the action of the molecules on polarized light, as is the case when the configuration is due to the presence of an asymmetric atom (optical isomerism); or (2) both chemical and physical properties may be different when the configuration is determined by the disposition of the atoms or groups attached to a pair of doubly-linked atoms, or to two members of a ring system (geometrical isomerism or allo-isomerism).

The d modification is of the commonest occurrence, the other forms being only known as synthetic products; for this reason it is usually termed glucose, simply; alternative names are dextrose, grape sugar and diabetic sugar, in allusion to its right-handed optical rotation, its occurrence in large quantity in grapes, and in the urine of diabetic patients respectively.

Faraday independently recognized the necessity for mechanical agitation of the molten glass in order to ensure homogeneity, and to facilitate his manipulations he worked with dense lead borate glasses which are very fusible, but have proved too unstable for ordinary optical purposes.

Later Maes of Clichy (France) exhibited some " zinc crown " glass in small plates of optical quality at the London Exhibition of 1851; and another French glass-maker, Lamy, produced a dense thallium glass in 1867.

The manufacture of the new varieties of glass, originally known as " Jena " glasses, is now carried out extensively and with a considerable degree of commercial success in France, and also to a less extent in England, but none of the other makers of optical glass has as yet contributed to the progress of the industry to anything like the same extent as the Jena firm.

Mannite on oxidation yields an aldose, mannose, C6H12061 which 3 To distinguish the isomerides of opposite optical activity, it is usual to prefix the letters d- and 1-, but these are used only to indicate the genetic relationship, and not the character of the optical activity; ordinary fructose, for example, being represented as d-fructosealthough it exercises a laevorotatory power - because it is derived from d-glucose.

There are, however, very few allusions to these phenomena in the later classical Greek and Roman writers, and we find the first scientific investigation of them in the great optical treatise of the Arabian philosopher Alhazen, who died at Cairo in A.D.

It acquired considerable application in platinum works, this metal being only fusible in the oxyhydrogen flame and the electric furnace; and also for the production of limelight, as in optical (magic) lanterns.

As already mentioned, all efforts to assimilate optical propagation to transmission of waves in an ordinary solid medium have failed; and though the idea of regions of intrinsic strain, as for example in unannealed glass, is familiar in physics, yet on account of the absence of mobility of the strain no attempt had been made to employ them to illustrate the electric fields of atomic charges.

In his optical researches, Optiska Undersiikningar, presented to the Stockholm Academy in 1853, he not only pointed out that the electric spark yields two superposed spectra, one from the metal of the electrode and the other from the gas in which it passes, but deduced from Euler's theory of resonance that an incandescent gas emits luminous rays of the same refrangibility as those which it can absorb.

Magnusson, is to introduce a thin film of the dye into one of the optical paths of a Michelson interferometer, and to determine the consequent displacement of the fringes.

At the same time, on land, the new necessities imposed on field artillery by the growing use of covered positions led to the development of scissors-telescopes (see Rangefinders) and panorama-telescopic sights (see Sights), in which the optical system was arranged with the tube of the telescope vertical and the object-glass and eyepiece systems at right angles to the axis of the tube.

In 1794 he was elected a member of the Manchester Literary and Philosophical Society, and a few weeks after election he communicated his first paper on "Extraordinary facts relating to the vision of colours," in which he gave the earliest account of the optical peculiarity known as Daltonism or colour-blindness, and summed up its characteristics as observed in himself and others.

In spite of the improvements in themanufacture of optical glass (see Glass) practically the same crown and flint glasses as used by John Dollond in 1758 for achromatic objectives are still used for all the largest of the modern refracting telescopes.

Upon an axis concentric with the declination axis is carried a plane mirror, which is geared so as always to bisect the angle between the polar axis and the optical axis of the telescope.

In optical systems composed of lenses, the position, magnitude and errors of the image depend upon the refractive indices of the glass employed (see Lens, and above, " Monochromatic Aberration ").

The discovery by improved optical means, and especially by photography, of new bodies of our system so small that they evaded all scrutiny in former times, is still going on, but does not at present promise any important generalization, unless we regard as such the conclusion that our solar system is a more complex organism than was formerly supposed.

According to Huygens's principle (see Diffraction) each aether particle, set vibrating by an incident wave, can itself act as a new centre of excitement, emitting a spherical wave; and similarly each particle on this wave itself produces wave systems. All systems which are emitted from a single source can by a suitable optical device be directed that they simultaneously influence one and the same aether particle.

Adulteration of expensive oil with cheaper oils is now more extensively practised, and such tests as the determination of the saponification value (see above) and of the optical rotation, and in special cases the isolation and quantitative determination of characteristic substances, leads in very many cases to reliable results.

The tipo piu comune is the optical microscope, nel quale l'esame of the object viene fatto in luce visibile....

These glazing types are capable of changing their optical properties in order to control solar radiant heat flux into the building.