SU49374A1 - Method of centering lens glass - Google Patents

Description

When assembling an astronomical lens, it is necessary to perform a careful centering of the lenses in the frame, without which a good image quality and high resolution power cannot be obtained from the lens. Such a centering consists in the fact that three spacers between the lenses (paper leaves or rings) are folded and kneaded until the air gap between the lenses represents a strictly centered lens itself.

The calibration of the centering of glasses of such a lens can be carried out by combining images reflected from the lenses and is often used, for example, when checking the centering of photographic lenses.

In two-lens Frauenhofer lenses (and the like), as well as in many multi-lens lenses, the curvature radii of the adjacent lens surfaces are close enough to each other to observe Newton's rings (in monochromatic light with significant air gap).

When testing a centered lens, Newton's rings should be concentric with the circumference of the objective lenses. podshabrivani pads it is possible to easily achieve this condition only in that

if you have a method for evaluating such a concentric arrangement of rings.

According to the proposed method, the alignment check is performed by combining both of these techniques, i.e., the center of the Newton rings obtained is combined with the center of symmetry of the image reflected from the glasses, respectively, by changing the thickness of the gaskets between the walls having close radii of curvature.

Depending on the direction of the illuminating beams and the position of the head of the observer, the center of the rings of Newton moves along the surface of the lenses, and therefore the task of controlling the centering is actually not as simple as it can be seen at first glance.

In the schematic drawing of FIG. 1 depicts the location of parts during the inspection; FIG. 2-screen view; Figs 3-5 are different points of calibration of the centering of lens glasses.

A simple fixture proposed for carrying out this method makes it possible to bring the lens centering process to a very quick and simple operation with proper accuracy, and the fixture itself can be made of a piece of Whatman paper on which is drawn

mascara cross and made a puncture needle in the center of the cross.

To check the centering, the lens A under study and the illuminator B as a source of monochromatic light (for example, a mercury arc) are separated by a screen G, shielding the lens from the direct rays of the source. The bela or colored plate D for diffuse reflection of light with a hole in the center and with cross-shaped black strokes (crosshairs) that intersects the center of the hole serves as a screen (Fig. 2). Through an opening of a correspondingly inclined plate, an observer's eye E, armed or not armed with a filter, looks and sees lens A illuminated by the rays reflected by plate D.

In the case of, for example, a two-lens objective, in which usually the radii of curvature of G2 and Gd are close enough to each other, the eye sees three images of plate D obtained from the three surfaces of the lens (from the r and z images are almost merged), and, in addition, Newton's rings (Fig. 3).

By moving the eye with the plate D, one can find such a position where the intersection of images is merged together, and this is a sign that the eye is observing, and the rays illuminate the lens in the direction of its optical axis.

The mismatch of the center of Newton's rings with a crosshair (Fig. 4) gives an indication to the master which of the three shims and to what degree should be chased or flattened.

The position of the rings in a properly centered lens is shown in FIG. five.

Since the eye well feels very small displacements of the center of the circle from the cross, and since the occurrence of each Newton's ring is due to a change in the thickness of the air gap by Vi micron, hence the height of the accuracy of the centering is clear.

The plate-screen D described above can be mounted in a spectacle or other frame, which frees both hands of the observer for the necessary manipulations.

The subject matter of the invention.

Claims (2)

I 1. A method of centering the lens glass, in which images reflected from the surface of the glasses forming the lens are combined, characterized in that by changing the thickness of the gaskets between glasses having close radii of curvature, the center of the resulting Newton rings is aligned with the center of symmetry of the image reflected from the glasses. 2. When implementing the method according to claim 1, use to obtain a reflected image of the illuminator, placed in front of the observer's eye and illuminated from the side with a white screen with a crosshair and a hole at the intersection of the cross lines. Fip1 Fig.Z Fip2 Fight Fip5