Eyepiece Sentence Examples
For the eyepiece the other rule holds; the object is represented by narrow pencils, and it is hence possible to subject the relatively great object, viz.
To center the condenser close down the iris diaphragm and remove the eyepiece.
The calculation is most convenient if the micrometer is left in the position of zero and the object is moved till one of its edges corresponds to the zero mark of the eyepiece scale.
A fixed eyepiece micrometer is simpler and more popular.
This consists of a scale on a little glass plate, which, instead of a cross wire, is placed in the eyepiece.Advertisement
As fractions of intervals can only be estimated in this method, a measurement with such an eyepiece scale can of course not be as exact as with a screw micrometer ocular.
These may be diminished by using different parts of the objective micrometer for the correction of the eyepiece scale, and the calculation of the size is based on the found mean value.
A second error can arise through the inaccuracy of the eyepiece micrometer, and also in the case of a screw micrometer through periodic faults of the screw, and through dead motion.
The eyepiece micrometer allows its errors to be diminished, if one measures at different points and then fixes a mean value.
With weak systems no auxiliary microscope is necessary, the eyepiece being removed and the scale viewed directly in the tube.Advertisement
The eyepiece being removed the image of the metal plates b produced by the objective is seen.
In order to ensure for the eye a central position, there is fixed on the upper end of the tube in place of the eyepiece a disk of pasteboard or metal with an axial hole.
To determine the position of the anterior focal plane of the eyepiece, the eyepiece is placed on the stage with the eye-lens downwards.
This gives the distance of the anterior focal plane of the eyepiece from the bottom edge of the setting of the eyepiece and consequently also of the edge of the eyepiece carried by the upper end of the tube.
The same method can be used to determine the focal length of the eyepiece.Advertisement
If a drawing prism is used above the eyepiece, and an objective micrometer is inserted, then if a scale is laid on the drawing board which is 25 cm.
Bronchoscopy A tube called a bronchoscope is put into the airway and, using an eyepiece, the doctor can see into the airways.
You can rotate the eyepiece to better fit the object orientation.
Temporarily remove the eyepiece and clamp the Camera lucida to the top of the eye tube, then replace the eyepiece.
As it was when bought, very dirty and scruffy, here shown with X10 eyepiece and manual stage.Advertisement
The full field of the 20X eyepiece is used and the image quality is quite good at 20X viewing magnification.
All the above captures were taken with the camera fitted to the eyepiece tube without any eyepiece tube without any eyepiece.
The aluminum tube has an outside diameter of 1 1/4 inches to suit standard telescope eyepiece sizes.
Since there is no eyepiece, there can be no optical magnification as such.
To calibrate the eyepiece micrometer, the stage micrometer has to be focused using the objective to be used.Advertisement
The measurement of specimen size with a microscope is normally made by using an eyepiece micrometer.
Images were taken using a CCD camera attached to the eyepiece tube of a stereo microscope using a x1 paired objective with no eyepiece.
This means it can be screwed onto a standard camera eyepiece nosepiece or included in a filter wheel.
Anything you see can become a superb photomicrograph by aligning your camera to capture the image coming out of the monocular microscope's eyepiece.
Gently tipping the opened eyepiece onto a lint free cloth will remove the reticle.
I've obtained both my eyepiece reticles by this route.
The other fittings are brass and include a sliding sunshade and a pivoted eyepiece cover.
Repsolds in more recent micrometers under construction give a second motion to the eyepiece at right angles to the axis of the micrometer screw; this enables the observer to determine the zero of position-angle for his movable webs with the same accuracy as he formerly could only do for the so-called position-angle webs.
One drawback to this form of instrument is that the two webs cannot be viewed simultaneously, and therefore the observer must rely on the steadiness of rate of the clockwork and uniformity in the conditions of refraction whilst the eye is moved from one eyepiece to the other.
In more recent instruments at the observatories of the Cape of Good Hope and Paris the motion is transmitted from a separately mounted cone and clock by a light rod passing through a perforation in the pivot of the transit instrument and thence through bevel-wheels in the cube of the axis to a second rod leading to the eyepiece.
Suppose now the solar spectrogram to be viewed in the focus of Or, and the converging rays to be reflected by the prisms Pr and P, i till an image is formed in the focus of the eyepiece at the point where the axis of the eyepiece intersects From Zeitschr.
If the stellar spectrograph is viewed in the focus of 0 2 and the converging rays are reflected by the prism P2 to P4, no image would be seen in the eyepiece, for the rays would pass out directly through the parallel glass plate which is formed by the cementing together of the prisms P 3 and P 4.
The effect of turning the pinion V is, of course, to displace the focus both of the solar and stellar spectrographs in the field of the eyepiece, but this d .a displacement is easily restored by From Zeitschr.
One prong of the fork carries a microscope objective, wart of a vibration microscope, of which the eyepiece is fixed at the back of the clock and the Lissajous figure FIG.
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 the Ramsden eyepiece (see Microscope) the focal lengths of the two piano-convex lenses are equal, and their convexities are turned towards one another.
The terrestrial eyepiece (see Telescope), which likewise ensures an upright image, but which involves an inconvenient lengthening, has also been employed in the binocular microscope.
This aberration can, however, be successfully controlled by a suitable eyepiece (see below).
The Off-Axis Guider works best with an illuminated reticle eyepiece so that very small deviations can be identified quickly and can be corrected accurately.
Spotter telescopes of between 60mm and 100mm aperture may be used to photograph the Moon simply by holding the camera lens to the eyepiece.
He would often talk about how his eyelashes would freeze to the telescope eyepiece.
Instruments have been invented by Alvan Clark and Sir Howard Grubb for measuring with the spider-line micrometer angles which are larger than the field of view of the eyepiece.
Then if the prism P4 is cemented to P3, a sharp image of such lines of the solar spectrograph as are visible in the field of view will be seen in the eyepiece.
These screens are usually embodied in the eyepiece.
The first compound miscroscope (discovered probably by the Middelburg lens-grinders, Johann and Zacharias Janssen about 1590) was a combination of a strong biconvex with a still stronger biconcave lens; it had thus, as well as the first telescope, a negative eyepiece.
In 1646 Fontana described a microscope which had a positive eyepiece.
This change is usually effected by mounting the objective and eyepiece on two telescoping tubes, so that by drawing apart or pushing in the tube length is increased or diminished at will.
If we assume that a normal eye observes the image through the eyepiece, the eyepiece must project a distant image from the real image produced by the objective.
This is the case if the image O'OI' lies in the front focal plane of the eyepiece.
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.
The image viewed through the eyepiece appears then to the observer under the angle w", and as with the single microscope tan w" = I /f 2 ' (4) where f' 2 is the image-side focal length of the eyepiece.
L i =objective, L2 L3 = eyepiece of the Ramsden type.
To obtain the magnification of the complete microscope we must combine the objective magnification M with the action of the eyepiece.
The simplest microscope which produces an upright image has a negative lens as eyepiece.
But as the object-side focus F2 lies behind the eyepiece, the real image is not produced, but the converging pencils from the objective are changed by the eyepiece into parallels; and the point 0 1 in the top of the object y appears at the top to the eye, i.e.
In all microscopes the rays are limited, not in the eyepiece, but in the objective, or before the objective when using a condenser.
Object points lying out tive eyepiece.
As it is entirely a proceeding from the eyepiece.
The eyepiece, which by means of narrow pencils represents the relatively large real image at infinity, transmits from all points of this real image parallel pencils, whereby the inclination of the principal rays becomes further increased.
The entrance window is then the real image of this diaphragm projected by the objective in the surface conjugate to the plane focused for, and the exit window is the image projected by the eyepiece; this happens with the image of the object lying at infinity.
In the case of the dispersive eyepiece, on the contrary, no sharply limited field can arise, but vignetting must occur.
The objective and eyepiece have.
The demands made upon the eyepiece, which has to represent a relatively large field by narrow cones of rays, are not very considerable.
It is therefore not very difficult to produce a usable eyepiece.
The Ramsden eyepiece is the most convenient for this because this plane lies in front of the collective lens, and the objective image has not yet been influenced by the eyepiece.
Since, however, the difference of chromatic magnification cannot be overcome in powerful objectives, this error is still further increased by the eyepiece.
The weak compensation oculars resemble a Huygenian eyepiece with achromatic eye-lens, whilst the more powerful ones are of a different construction.
One way of receiving a stereoscopic impression through a microscope is by fixing an apparatus as directly as possible above the last lens of the microscopic objective, which divides the rays passing out and directs half into each eyepiece.
By adopting right-angled reflectionprisms above the eyepiece he completely erected the image.
The tube containing the left eyepiece is a little inclined towards the right tube, which is perpendicular.
A microscope for two eyes can also be obtained by employing the Abbe stereoscopic eyepiece.
The same image can be presented to each eye by using this eyepiece also.
The tube containing the eyepiece and the objective is double.
For measuring this angle, an eyepiece with cross-threads is used.
In the lower focal plane of the eyepiece, at the spot where the real image which the objective forms of the object arises, a glass plate is introduced on which are two fine cross lines or even two very thin threads.
When observing with such an eyepiece, care must be taken that the real image of the object lies in the plane of the crossthreads, i.e.
If the eye is moved to and fro over the eyepiece and the image makes apparently similar movements in relation to the cross threads, then the image does not yet lie in the plane of the threads.
This measurement can also be made with a goniometer eyepiece, in which a row of parallel double-marks are used instead of the cross threads.
The fitting of the eyepiece at the upper end of the tube is provided with a graduated circle.
The eyepiece proper with the parallel strokes can be revolved, and the rotation be read from the graduated circle.
The placing of the analyser near the objective has the advantage that the field of view is not restricted, as is the case if the analyser .is used above the eyepiece.
This small plate can also be laid above the polarizer in the illuminating apparatus or in the eyepiece.
The use of an eyepiece with a cross thread is essential to this measurement.
Then the object is moved by the micrometer till the image of the other edge is covered by the thread in the eyepiece, and the micrometer is again read.
The second and most widely used method employs a micrometer eyepiece.
People have even snapped pictures of crystals right through the eyepiece using camera phones and the results are quite presentable.
In the case of the negative eyepiece, on the other hand, the divergence of the principal rays through the eyepiece is also further augmented, but their point of intersection is not accessible to the eye.
This property shows the superiority of the collective eyepiece over the dispersive.
Light from an extended source passes after polarization through two convex systems of lenses, between which the crystalline plate is placed, and is then received in an eyepiece furnished with an analyser.
It is on this latter plane that the eyepiece must be focussed, and here the measuring web must be placed.
The eyepiece slides into the tube cd, which screws into the brass ring ef, through two openings in which the oblong frame, containing the micrometer slides, passes.
It should be mentioned that an essential feature of the travelling wire micrometer is that the eyepiece as well as the wire shall be moved by the micrometer-screw.
The eyepiece is removed and the photographic plate (k) placed in position.
Of polarimeters for the study of rotary polarization there are three principal forms. In Wild's polaristrobometer, light from a soda flame, rendered parallel by a lens, is polarized by a Nicol's prism, and after traversing the space into which the active substance is to be inserted, falls on a Savart's plate placed in front of an astronomical telescope of low power, that contains in its eyepiece a Nicol's prism, which with the plate forms a Savart's analyser.
This is known as Ramsden's eyepiece, having been made originally by him.
Through the eyepiece of the bent 1 telescope E' another hour circle attached to the lower end of the polar axis can be seen; thus an assistant is able to direct the telescope by a handle at H to any desired hour angle.
The eyepiece ab consists of two plano-convex lenses a, b, of nearly the same focal length, and with the two convex sides facing each other.
In its simplest form it consists of a direct-vision spectroscope, having an adjustable slit (called "camera slit"), instead of an eyepiece, in the focal plane of the observing telescope.
The compound microscope generally consists of two positive lens systems, so arranged that the system nearer the object (termed the objective) projects a real enlarged image, which occupies the same place relatively to the second system (the eyepiece or ocular) as does the real object in the simple microscope.
The scales of the images formed in the focus of the eyepiece common to both microscopes shall be identical.
Immediately above this plane surface and almost touching it is a system of wires which enables angular distances from the centre of the field to be read at the eyepiece below.
The top is closed by a pressure-tight window, inside of which is a prism which reflects the light rays vertically down the tube to a prism at the bottom end, where they are reflected in a horizontal direction and focussed in an eyepiece attached to the bottom of the tube.
They determined to reinvestigate the motion of y Draconis; the telescope, constructed by George Graham (1675-1751), a celebrated instrument-maker, was affixed to a vertical chimneystack, in such manner as to permit a small oscillation of the eyepiece, the amount of which, i.e.
By moving the lens G up and down the image can be formed in the correct position for the eyepiece at all extensions of the mast.
Instead of a mirror, the objective of a microscope is attached to one prong of the first fork and the eyepiece of the microscope is fixed behind the fork.
A cross-hair, in the focal plane of an eyepiece, is then moved horizontally until it coincides with the line in question.
Huygens contrived some ingenious arrangements for directing such telescopes towards any object visible in the heavens - the focal adjustment and centring of the eyepiece being preserved by a braced rod connecting the objectglass and eye-piece.
In polarized light they show a weak grey colour with a black cross, the arms of which are parallel to the cobwebs in the eyepiece of the microscope and remain stationary when the section is rotated.
In order to correct this, the light after analysation is passed through another plate of quartz and then the sensitive tint may be more or less restored by cutting off some colour, the same for the whole field, by a Nicol's prism placed in the eyepiece of the telescope.
The convenient and rapid change in the magnification obtained by changing the eyepiece or the objective is also a special advantage of the compound form.