SU65652A1 - Device for comparing focal lengths of lenses - Google Patents

Description

The subject of the invention is a device for comparative and focal lengths of the studied and this.;: 11 lenses, based on a comparison of the image scales of identical test scales introduced into the field of view of the device using a plane-parallel plate.

The device is intended for rejection and selection of lenses with the same distance and the same last segments for the control and shop laboratories of the plants of the optical-mechanical industry.

An exemplary optical circuit is shown in FIG. I. On (rig. 2, 3, and 4, types of zero vision are given when igglyzvanii in the device of various test scales.

In the focal plane of the reference lens Oi (Fig. 1), the scale nil is set, updated through the c; i to the condenser mode Ki "drain: .g light C |. In front of the lens, a translucent mirror or a plane-parallel plate 3 is mounted at an angle of 45 ° to its optical axis. At an angle of 90 ° to the axis of the first lens, a second lens is set — the lens under investigation is 0–2, in the focal n: o: the bones of which have the ZZ / 2 scale, are identical with the Z or several scales,) enenna. The I / O scale through the condenser system / Ca is refreshed by the lamp C 2. The lens O 2 can within a small range (iO, 05 /) re; ; run along its optical axis. The amount of mixing can be measured according to the line L. Perech Z: p; -; scar 3 installed a telescope (for example, tube 6 binoculars) through which observation is made. If both scales Zffj and I / O. and are forks, then with equal focus, the first distances of the lenses are Oi i; 62 the observer, with the appropriate orientation of the mirror NW, sees two equal scales in the field of view of the pipe. Vrash, and mirror 5, the observer can set the corresponding strokes of both scales one against the other, as indicated in FIG. 2. As is well known, with such an installation, the accuracy of combining the strokes of both scales will be very high (about 10 after the eyelets of the telescope). If a

Since the focal lengths of the lenses Oi and 0-2 are unequal between themselves, then when the lower extreme edges coincide, the upper strokes. p ;; the convergence of the psychiozihalia-difference of the focal distances of both objects. L l stbor object on nkale w ,, except for irrpixa shpgygo. iiaoy i cpxu-ix luTpiixoiii, pi is the distance between which is defined by specified donations.

Matching the lower strokes of the -Z // 1 and Sh2 scales, the observer determined the position of the top bar / 1/2 of the compared lens relative to the allowable strokes in the IHi scales of the reference (Fig. 3).

For the selection of lenses, but groups with focal distances lying within the set limits of many limits, the scale nJi has a number of strokes with intervals determined by the tolerance inside the soil (fi-g. 4). Having combined the lower strokes of the e-scale, the observer — the limit — against which the upper grades of the scale I / I are against, thus determines which group the target lens should be assigned to.

Below, the calculation of the scale for an objective lens of f 120 mm is provided as Nilger, provided that the maximum distance from the nominal focal distance from the nominal is -0.05 /; Lenses should be broken up into edges. Within each group the focal length should be constant within + 0.01 /.

Let us assume an increase in the telescope equal to 6. The apparent angular distance between the strokes of the reference scale, corresponding to a change in the distance by 0.0if, is taken equal to 5 after the eyelets of the telescope (at a distance of clear vision, this corresponds to approximately 0.4 Mm) .

Denoting the length of the scale by Y, we have (fng. 4):

pi

T.

A + A / where. fa is the focal length of the Etalon lens (fa 120 mm), gA f is the same test length,

 ., telescope lens, foK- „eyepiece of the telescope,

.foK -,: increase in umbrella TDVcv, apparent angular distance between two adjacent :: strokes in the upper group of strokes of the reference scale; by condition; and 5 - 15.

L f HMeeMF - G la

10 or 15 10-1

1 g

Af

but condition Af: / 0,01;

substituting numerical values, we get:

Y 3 mm.

Thus, the distances of the individual strokes in the e; the d by the group to the bottom are equal

Г „m

0.95

2.86 2188 0.96 0.97 2.91 0.98 2.94 0.99 2.97 1.00 3, CO 1.01 3.03 1.02 3.06 1.08 3.09 1.34 3.12 1.05 3.15

L - the serial number of the stroke

Scales Sh.

The angular value of l - the maximum length of the scale {Y 3.15 mm) is equal to

o. 120

To compare the last segments, the observer shifts the Oa volume along its axis and achieves the absence of a parallax between the strokes of both ShKal, and then reads along the ruler L. by myself. By installing interchangeable test tables of worlds or point diaphragms instead of scales I / i and W., it is possible to produce a simultaneous comparison of the image quality and resolution of the lenses. In this case, it is necessary to pre-select the density of the mirror layer of the mirror 3 so that the luminances of both are depicted to be the same. This device for controlling lenses and has several advantages over the device, based on: P1 on measuring the last segments, for example, the Beck bench. It is necessary to determine deviations from the standard of both the focal length and the last segment from a single installation and to divide the lenses into different groups according to

2

.

FIG. four

FIG. 3

i -

i: xird magnitude of their focal length. In addition, this device allows you to make a simultaneous comparison of the quality of the image given by the test lens and the zonalo. P re m ate and c ode and the Device for the device; and fuchnyh segments object11; C) in the way-; compare the scale with the footer; - :; test scale room; The test plane with the reference point is so that it is i-lonno; scales in the plane of the device) ;; a plane-parallel image of the test-scale is entered. It is identical to the first one, given by the reference object Om. ;.