It is found that in between Talbot images of the same order,produced by the said illumination,exist focal-like phenomena similar to those with the thin lens images.

Precision measuring system of focus to aerial cameras with CCD;

New focus measuring method of camera zoom lens;

This article introduces the theory and design methods of a zoom lens controller for zooming focus,focussing,and focus feedback in the incorporate zoom lens CCD camera based on 89C2051 microchip and MAX187 A/D switch.

Explanation of calibration specification for IR optical focal length measuring equipment;

The autocollimating telescope method for determination of the radius of curvature and focal length of thin lens;

Further study on thin-lens focal length measurement experiment;

Comparing to see the objects with glasses,with seeing them directly will become bigger,equal or small all depends on focal distance between glasses and eyes.

It shows that Intensity distribution depends on such parameters as focal distance,wavelength and distance between two apertures.

Beginning with the talk about the basic factors of TV camera shooting-shooting distance and focal distance,the paper approaches the effect of appearance of picture in order to improve the quality of camera shooting.

In this paper, a measuring method of convex lens foci in collimator is given.