In many cases the stand is also movable round the optic axis.
5533; the optic sign is therefore positive.
With a crossed polarizer and analyser the rings are interrupted by a dark hyperbolic brush that cuts the plane of the optic axes at right angles, if this plane be at 45° to the planes of polarization and analysation - the so-called diagonal position - and that becomes a rectangular cross with its arms parallel and perpendicular to the plane of the optic axes when this plane coincides with the plane of primitive or final polarization - the normal position.
nerv.f, Nerve fibres of the optic nerve.
This is a plate made of two equal wedges of quartz, that can be moved over one another so as to vary its thickness, and are cut so that the faces of the plate are parallel to the optic axis, which in the first wedge is perpendicular and in the second is parallel to the refracting edge.
On these principles Airy, by an elaborate mathematical investigation, successfully explained the interference patterns obtained with plates of quartz perpendicular to the optic axis.
If, by these methods, a point in the optic axis has been freed from aberration, it does not follow that a point situated only a very small distance from the optic axis can also be represented without spherical aberration.
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.
Another cartilage or ossification, the posterior sclerotic ring, occurs within the walls of the posterior portion of the cup, and surrounds, especially in the Pici and in the Passeres, the entrance of the optic nerve.
To the first class, with the optic axial plane perpendicular to the plane of symmetry, belong muscovite, lepidolite, paragonite, and a rare variety of biotite called anomite; the second class includes zinnwaldite, phlogopite, lepidomelane and most biotites.
Thus light, pressure, or mechanical stimulation acting on the retina and optic nerve invariably produces luminous impressions.
He was able to maintain his strenuous habits of study till he reached the advanced age of seventy-two, when he was, forced, by paralysis of the optic nerve, to give up work almost.
One, the quadratus or bursalis muscle, arises from the hinder surface of the eyeball, and forms with its narrow margin, which is directed towards the optic nerve, a pulley for the long tendon of the pyramidalis muscle.
Then with an uniaxal plate perpendicular to the optic axis, the black cross is replaced by two lines, on crossing which the rings are discontinuous, expansion or contraction occurring in the quadrants that contain the axis of the quarter-wave plate, according as the crystal is positive or negative.
Forwards it covers, and has driven asunder, the optic lobes; backwards it hides the much shortened medulla oblongata.
From near the entrance of the optic nerve, through the original choroidal fissure, arises the much-folded pecten, deeply pigmented and very vascular, far into the vitreous humour.
The quadrate muscle adjusts the motion, and prevents pressure upon the optic nerve; during the state of relaxation of both muscles the nictitans withdraws through its own elasticity.
The lateral eyes are in Limulus " compound eyes," that is to say, consist of many lenses placed close together; beneath each lens is a complex of protoplasmic cells, in which the optic nerve terminates.
Hickson and others, that in the bivalves Pecten and Spondylus, which also have eyes upon the mantle quite distinct from typical cephalic eyes, there is the same relationship as in Oncidiidae of the optic nerve to the retinal cells.
They are at the same time both optic nerve-end cells, that is to say, retina cells, and corneagen cells or secretors of the chitinous lens-like cornea.
The midbrain is represented chiefly by the optic lobes, the cortex of which alone is homologous with the corpora quadragemina of the mammals.
oe, Gullet; op, optic nerve; sb, sub-oesophageal ganglion; mn, mx, mx', nerves to jaws; t, tentorium.
With the .orthogonal arrangement for illuminating and observing the beam of light traverses an extremely fine slit through a well-corrected system, whose optic axis is perpendicular to the axis of the microscope; the system reduces the dimensions of the beam to about 2 to 4 in the focal plane of the objective.
When the light is circularly polarized or circularly analysed, a single plate gives two mutually enwrapping spirals, and similar spirals in circularly polarized light are obtained with plates of an active biaxal crystal perpendicular to one of the optic axes.
Wollaston, by blocking off one of the streams with a screen, sufficient lateral separation being obtained by combining two equal crystalline prisms cut differently with respect to the optic axis - an arrangement that achromatizes more or less completely the pencil that is allowed to pass.
It is essential that the objective is always brought before the lower end of the tube in such a way that the optic axis of the objective coincides with the optic axis of the rest of the system.
When, for instance, the axons of the ganglion cells of the retina are severed by section of the optic nerve, and thus their influence upon the nerve cells of the visual cerebral centres is set aside, the nerve cells of those centres undergo secondary atrophy (Gadden's atrophy).
The loss of an eye will be followed by atrophy of the optic nerve; the tissues in a stump of an amputated limb show atrophic changes; a paralysed limb from long disuse shows much wasting; and one finds at great depths of the sea fishes and marine animals, which have almost completely lost the organs of sight, having been cut off for long ages from the stimuli (light) essential for these organs, and so brought into an atrophic condition from disuse.
Crossed, inclined and horizontal dispersion are characterized respectively by a distribution of colour that is symmetrical with respect to the centre alone, the plane of the optic axes, and the perpendicular plane.
The angle between the optic axes varies from 70 0 -50° in muscovite and lepidolite to Io - o° in biotite and phlogopite; the latter are thus frequently practically uniaxial.
a point which divides a line, or a line which divides an angle, into two equal parts; in crystallography it denotes the bisector of the angle between the optic axes.
The optic figure seen in convergent polarized light through a section cut parallel to the plane of symmetry of a borax crystal is symmetrical only with respect to the central point.
The plane of the optic axes for red light is inclined at 2° to that for blue light, and the angle between the optic axes themselves is 3° greater for red than for blue light.
(Reference should be made to the article Crystallography for illustrations, and for applications of these phenomena to the determination of crystal form.) With an uniaxal plate perpendicular to the optic axis, the curves of constant retardation are concentric circles and the lines of like polarization are the radii: thus with polarizer and analyser regulated for extinction, the pattern consists of a series of bright and dark circles interrupted by a black cross with its arms parallel to the planes of polarization and analysation.
Curiously enough, however, they differ from the cephalic Molluscan eye in the fact that, as in the vertebrate eye, the filaments of the optic nerve penetrate the retina, and are connected with the re surfaces of the nerve-end cells nearer the lens instead of with the opposite end.
In the following year he discovered the change, produced by change of temperature, in the direction of the optic axes of selenite.
The installation of fiber optic cables around the town.
In a small commonplace book, bearing on the seventh page the date of January 1663/1664, there are several articles on angular sections, and the squaring of curves and " crooked lines that may be squared," several calculations about musical notes, geometrical propositions from Francis Vieta and Frans van Schooten, annotations out of Wallis's Arithmetic of Infinities, together with observations on refraction, on the grinding of " spherical optic glasses," on the errors of lenses and the method of rectifying them, and on the extraction of all kinds of roots, particularly those " in affected powers."
in thickness with its faces perpendicular to the optic axis is nearly opaque to light falling normally upon it, and a plate of this thickness parallel to the axis permits of the passage of a single stream polarized in a plane perpendicular to the principal section.
von Grafe, first saw the fundus of the living human eye, with its optic disc and blood-vessels, his face flushed with excitement, and he cried, "Helmholtz has unfolded to us a new world!"
In the case of a biaxal plate perpendicular to the bisector of the acute angle between the optic axes, the curves of constant retardation are approximately Cassini's ovals, and the lines of like polarization are equilateral hyperbolae passing through the points corresponding to the optic axes.
When the rings are coloured symmetrically with respect to two perpendicular lines the acute bisectrix and the plane of the optic axes are the same for all frequencies, and the colour for which the separation of the axes is the least is that on the concave side of the summit of the hyperbolic brushes.
This consists of two plates of an uniaxal crystal of equal thickness, cut at the same inclination of about 45° to the optic axis and superposed with their principal planes at right angles.
757) have shown by a few biaxal crystals, such as sugar and Rochelle salt, the rotation produced by a given thickness being in general different, and in some cases of opposite sign for the two optic axes.
If in the interference experiment with Fresnel's mirrors or biprism the slit be illuminated with white light that has passed through a polarizer and a quartz plate cut perpendicularly to the optic axis, it is found on analysing the light that in addition to the ordinary central set of coloured fringes two lateral systems are seen, one on either side of it.
Theoretically the best construction for prisms of this class is the following: a rectangular block of Iceland spar, of length about four times the width and having its end and two of its side faces parallel to the optic axis, is cut in half by a plane parallel to the optic axis and making an angle of about 14° with the sides; the two halves are then reunited with a cement whose refractive index is between the ordinary and extraordinary indices of the spar and as nearly as possible equal to the latter.
Soda light, first sifted by passage through a plate of potassium bichromate, traverses in succession a lens, a Nicol's prism, and a glass plate half covered with a half-wave plate of quartz, that is cut parallel to the optic axis and has its principal section inclined at a small angle to that of the prism.
The former consists of two semicircular plates of quartz, perpendicular to the optic axis and of opposite rotations, placed so as to have a common diameter and having such a thickness that each rotates the plane of polarization of mean yellow light through the same multiple of 90°.
This is made of two plates of quartz, cut normally to the optic axis and of opposite rotations, placed the one in front of the other: the thickness of the one plate is fixed, while that of the other can be varied, as it is formed of two equal prisms that can be moved over one another along their common face.
The plane of the optic axes may be either perpendicular or parallel to the plane of symmetry of the crystal, and according to its position two classes of mica are distinguished.
William Molyneux, in his Dioptrica Nova (1692), p. 256, declares his opinion that Roger Bacon (who died c. 12 9 4) "did perfectly well understand all kinds of optic glasses, and knew likewise the method of combining them so as to compose some such instrument as our telescope."
One of the most puzzling features in its structure, and, at the same time, one of the greatest obstacles to the view that it is essentially primitive and not merely a degenerate creature, is the entire absence of the paired organs of special sense, olfactory, optic and auditory, which are so characteristic of the higher vertebrates.
The optical characters are interesting, because of the striking crossed dispersion of the optic axes, of which phenomenon borax affords the best example.
In the Phyllopoda it consists mainly of two pairs of ganglionic centres, giving origin respectively to the optic and antennular nerves.
With a biaxal plate perpendicular to the optic axis in the diagonal position, the hyperbolic brush becomes an hyperbolic line and the rings are expanded or contracted on its concave side, with a positive plate, according as the plane of the optic axes is parallel or perpendicular to the axis of the quarter-wave plate, the reverse being the case with a negative plate.
Airy extended Fresnel's hypothesis to directions inclined to the axis of uniaxal crystals by assuming that in any such direction the two waves, that can be propagated without alteration of their state of polarization, are oppositely elliptically polarized with their planes of maximum polarization parallel and perpendicular to the principal plane of the wave, these becoming practically plane polarized at a small inclination to the optic axis.
To examine crystals, especially in converging light, a condenser, movable in the optic axis, is needed above the polarizer.
Foramina by which the optic, trigeminal and portio dura, and abducens nerves leave the skull.
He has bilateral optic nerve atrophy, which affects the visual information passing from the eye to the brain.
The fiber optic servo bus allows the system's " almost dumb " servo amplifiers to be up to 100m apart.
H, Of the optic. Ep, Epiotic process.
Another key factor of modern fiber optic systems that we have not touched on is optical amplifiers.
anisotropic etching of silicon enables the accurate fabrication of V-shaped grooves to locate optic fibers.
Whatever the working environment we can deliver structured cabling (Cat5e & Cat6 copper ), fiber optic backbone cabling.
In an area called the Optic chiasm, the nerves join and then separate.
At the optic chiasm about half of the visual information in each optic nerve swaps over to the opposite nerve.
ciliary arteries resulting in ischaemic optic neuropathy.
Glaucoma was diagnosed if matching visual field and optic disk cupping were present, without reference to intraocular pressure (IOP) level.
Toxicities included transient periorbital edema in four eyes and optic atrophy in one eye that also received laser photocoagulation and cryotherapy.
Liquid anisotropic etching of silicon enables the accurate fabrication of V-shaped grooves to locate optic fibers.
fibre installation of fiber optic cables around the town.
fibre optic nerve is made up of thousands of nerve fibers.
ganglion cells form the optic nerve.
ganglion cell axon guidance in the mouse optic chiasm: expression and function of Robos and Slits.
More commonly it is also called an optic chiasm glioma.
The lobes of the cerebral hemisphere, optic nerves, arachnoid granulations and blood vessels are all identified.
His interests in the fiber optic sensors field include fiber optic chemical sensors, and, in particular, fiber grating sensors.
Precision Acoustics are funding the development of a fiber optic hydrophone.
Some people may know the visual side alone as optic nerve hypoplasia.
Fiber optic illuminator with focusing lens, brackets and trolley.
There is a private 28 ft pool with fiber optic colored lighting, extended deck and covered lanai.
Further development of this device to make it commercially marketable is possible, and research into similar fiber optic devices is envisaged.
The anatomy of the visual pathway The optic nerves carry visual signals from each eye into the head.
The optic nerve is made up of thousands of nerve fibers.
Despite the large number of the optic nerve fibers their capacity of plasticity for to achieve recovery is rather limited.
optic neuritis, or inflammation of the optic nerve, is often the first symptom of MS for many people.
A randomized trial of intravenous immunoglobulin in inflammatory demyelinating optic neuritis.
However, in eyes with established glaucomatous optic neuropathy at diagnosis, iridotomy failed in 47% .
Sometimes children with optic neuropathy find spectacles improve vision.
AB - OBJECTIVE: Radiation optic neuropathy usually occurs months to years after exposure of the anterior visual pathways to ionizing radiation.
The joined up path that signals travel down from retina to optic nerve then optic chiasm then occipital lobe is called the visual pathway.
optic nerves carry visual signals from each eye into the head.
optic neuritis has been taking place.
At the optic chiasm about half of the visual information in each optic chiasm about half of the visual information in each optic nerve swaps over to the opposite nerve.
optic nerve atrophy, which affects the visual information passing from the eye to the brain.
optic neuropathy find spectacles improve vision.
optic nerve coloboma in my right eye.
A thin fiber optic cable is needed to connect the two.
There are three types of fiber optic cable commonly used: single mode, multimode and plastic optical fiber (POF ).
This axis of symmetry is called the optic axis.
The wires joining each eye to the brain are called the optic nerves.
A really high pressure will damage the optic nerve immediately.
In the visual pathway the fibers of the retinal ganglion cells form the optic nerve.
The left optic nerve also enhanced (not shown ).
Fiber optic devices for cross section converters The complete range of fiber optics can be connected to amplifiers with analog outputs.
The Mr Fantastic Deluxe playsuit is a one piece polyester playsuit with fiber optic flashing badge.
Endoscopic orbital decompression may be used to treat disfiguring proptosis or sight threatening optic nerve compression in patients with thyroid eye disease.
puppetry artists, Faulty Optic.
rosin factory Showcases Industry's First 20 Gbps Parallel Fiber Optic Module for InfiniBand DDR Standard at OFC (Booth #3349 ).
That's fiber optic cables, by the way: Presumably, you're talking about storm sewers, and not sanitary sewers.
They are also compatible with fiber composite hosts and there is a potential of embedding the fiber optic sensor relatively unobtrusively within the host.
Their experience in selling fiber optic based spectrometers makes them ideally placed to promote the nkd in the Japanese market.
Cavefish have evolved regressive characters such as a degenerate eye, small optic tectum, and less pigment.
The Optic System is a 300mm Acrylic lens with a 250 watt tungsten lamp controlled by an electronic flasher.
3 If the beasts can properly be said to see at all, " they see as we do when our mind is distracted and keenly applied elsewhere; the images of outward objects paint themselves on the retina, and possibly even the impressions made in the optic nerves determine our limbs to different movements, but we feel nothing of it all, and move as if we were automata."
Their transverse dorsal connexion is the posterior commissure; otherwise the whole roof portion of the midbrain is reduced to a thin membrane, continuous with that which covers the Sylvian aqueduct, and this ventricle sends a lateral cavity into each optic lobe, as is the case in reptiles.
Apteryx, which since Owen has generally been stated to be devoid of such an organ, likewise possesses a pecten; its base is, however, trumpet-shaped, covers almost the whole of the optic disk, and extends nearly to the lens in the shape of a thick, densely pigmented cone, without any plications, resembling in these respects the pecten of many Lacertilia (see G.
The angle between the optic axes varies from 70 0 -50Ã‚° in muscovite and lepidolite to Io - oÃ‚° in biotite and phlogopite; the latter are thus frequently practically uniaxial.
The acute bisectrix of the optic axes never deviates from the normal to the basal plane by more than a degree or two, hence a cleavage flake of mica will always show an optic figure in convergent light when placed on the stage of a polarizing microscope.
They agree with the dorsal eyes of Oncidium (Pulmonata) in the curious fact that the optic nerve penetrates the capsule of the eye and passes in front of the retinal body (fig.
The plane of the optic axes for red light is inclined at 2Ã‚° to that for blue light, and the angle between the optic axes themselves is 3Ã‚° greater for red than for blue light.
The ectoderm continued over the optic vesicle forms a transparent cornea (fig.
8, c) (better perhaps termed a conjunctiva), below which the spherical lens projects into the optic vesicle, imbedded in the vitreous humour (v.b) which fills it; the retina (r) consists of visual cells with long cones (fig.
With a crossed polarizer and analyser the rings are interrupted by a dark hyperbolic brush that cuts the plane of the optic axes at right angles, if this plane be at 45Ã‚° to the planes of polarization and analysation - the so-called diagonal position - and that becomes a rectangular cross with its arms parallel and perpendicular to the plane of the optic axes when this plane coincides with the plane of primitive or final polarization - the normal position.
The examination of dispersion of the optic axes in biaxal crystals (see Refraction, § Double) may be conveniently made with a plate perpendicular to the acute bisectrix placed in the diagonal position for light of mean period between a crossed polarizer and analyser.
This consists of two plates of an uniaxal crystal of equal thickness, cut at the same inclination of about 45Ã‚° to the optic axis and superposed with their principal planes at right angles.
Theoretically the best construction for prisms of this class is the following: a rectangular block of Iceland spar, of length about four times the width and having its end and two of its side faces parallel to the optic axis, is cut in half by a plane parallel to the optic axis and making an angle of about 14Ã‚° with the sides; the two halves are then reunited with a cement whose refractive index is between the ordinary and extraordinary indices of the spar and as nearly as possible equal to the latter.
The former consists of two semicircular plates of quartz, perpendicular to the optic axis and of opposite rotations, placed so as to have a common diameter and having such a thickness that each rotates the plane of polarization of mean yellow light through the same multiple of 90Ã‚°.
Children over 3 will love this colorful collaboration by York Theater Royal, tutti frutti and international puppetry artists, Faulty Optic.
Zarlink polymerized rosin factory Showcases Industry 's First 20 Gbps Parallel Fiber Optic Module for InfiniBand DDR Standard at OFC (Booth #3349).
That 's fiber optic cables, by the way: Presumably, you 're talking about storm sewers, and not sanitary sewers.
One of the leading causes of vision loss among senior citizens is the progressive, irreversible damage caused to the optic nerve by glaucoma.
A naso-pharyngeal exam using a fiber optic camera that fits into the nasal cavity to explore possible structural problems or obstructions.
The examination may include an x-ray of the skull or a small fiber optic camera used to evaluate the nasal cavity and throat.
Go Optic: At Go Optic, you'll find an outstanding selection of eyeglasses from the Bellagio line.
Go Optic: At Go Optic you can find the Roberta as well as the Kensley, Audrina, Paulina and Lyric models.
Go Optic: Go Optic is a good site to visit because they carry an extensive collection of Pulitzer looks, and perhaps most importantly, styles that are not currently available on the company's official website.
Go Optic sells various styles of Saki eyewear in addition to the Saki 710 frame.
Go Optic: Go Optic is the first online site on our list with good reason; they offer a wide array of Silhouette looks!
Specially speaking, the Silhouette 8067 offered at Go Optic comes in two different styles.
Go Optic: Out of all of these shopping sites Go Optic has the least amount of styles to choose from.
Based in San Diego County, California, Spy Optic is in a perfect location for sports enthusiasts of all kinds.
Spy Optic has developed a number of advancements in sun protection.
Eyeglasses Go Optic: Here, you can find Takumi eyewear and take advantage of a 30-day return and exchange policy.
They offer something called an "Optic Control System" which allows for interchangeable protection for both court and off-court activities.
Go Optic has a selection of Wrangler frames, too.
If you plan to shop online, check out Vizio Optic and Optical Effects.
If you prefer to shop online, sites such as Frames Direct, Go Optic and Eyeglass Direct sell a range of magnetic eyeglass frames as well.
Tumors along the optic nerve, causing vision disturbances in about 20 percent of those affected.
Leber hereditary optic neuropathy (LHON).
Other photo-therapy methods-such as a fiber optic bilirubin blanket-incorporate the light into a blanket so that the child can be breastfed during treatment or treated at home.
The retina transforms the image it receives into electrical signals that are sent to the brain via the optic nerve.
Small surgical openings are made in the uterus, and a tiny fiber optic fetoscope is inserted to guide the operation.
Fetoscope-A fiber optic instrument for viewing the fetus inside the uterus.
The job of the retina is to transform the light into information that can be transmitted to the optic nerve, which will transmit this information to the brain.
Some centers may use chemotherapy in place of radiation therapy when the tumors are too large to be treated by local therapies or are found over the optic nerve of the eye.
Optic nerve-A bundle of nerve fibers that carries visual messages from the retina in the form of electrical signals to the brain.
Incomplete development of the optic (sight) and olfactory (smell) nerves often accompany the brain defects described above.
Sometimes a lighted, flexible fiber optic instrument (sigmoidoscope) may be inserted rectally in conjunction with a barium enema to visualize the bowel.
Glaucoma-A common eye disease characterized by increased fluid pressure in the eye that damages the optic nerve, which carries visual impulses to the brain.
In a laryngoscopy, a slender, flexible tube containing a fiber optic camera is inserted through the nose and down the throat to the larynx.
Hemianopsia (loss of half of the field of vision): Angiomas can affect the optic nerve, causing blindness in half of the eye.
This leads to increased pressure within the eye and eventual damage to the optic nerve.
However, children with Lyme disease frequently complain of chest pain and have papilledema (swelling of the optic nerve).
The physician may perform a bronchoscopy, a visual examination in which the airways and lungs are seen through a fiber optic tube inserted down the person's windpipe (trachea).
You should also avoid B12 if you suffer from Leber's disease as supplementation could lead to serious damage to the optic nerve including blindness.
If the tutu isn't your kid's style, there are also the Prestige version and the Magic Lights version, with fiber optic touches.
They are available in small and large and in pebbled leather, jacquard, or optic fabric.
The Optic Signature Diaper Bag is currently the only available style, but this bag can do it all, while looking completely gorgeous.
Add this is the fact that DSL isn't available everywhere, won't work with fiber optic cables and its Caveat Emptor.
These dorsal eyes are very perfect in elaboration, possessing lens, retinal nerve-end cells, retinal pigment and optic nerve.
But they also receive the nerve fibres of the optic nerve.
The black represents the cuticular product of the epidermal cells of the ocular area, taking the form either of))...,r,, f lens, cl, of crystalline body, cry, or of rhabdom, rhab; hy, hypodermis or epidermal cells; corn', laterallyplaced cells in the simpler stage, A, which like the nerve-end cells, vit' and ret', are corneagens or lens-producing; corn, specialized corneagen or lens-producing cells; vie, potential vitrella cells with cry', potential crystalline body now indistinguishable from retinula cells and rhabdomeres; vit, vitrella cell with cry, its contained cuticular product, the crystalline cone or body; ret', rhab', retinula cells and rhabdom of scorpion undifferentiated from adjacent cells, vit'; ret, retinula cell; rhab, rhabdom; nf, optic nerve-fibres.
To the same degree of accuracy as that employed in obtaining the expression for the intensity, the form of the lines of like polarization is given by the section, parallel to the plate, of a cone, whose generating lines are the directions of propagation of waves that have their planes of polarization parallel and perpendicular to a given plane: the cone is in general of the third degree and passes through the optic axes of the crystal.
The word usage examples above have been gathered from various sources to reflect current and historial usage. They do not represent the opinions of YourDictionary.com.