What are the factors that affect the parallelism of light from parallel light tubes?

The parallelism of the outgoing light of the parallel optical tube is mainly affected by two aspects:

(1) Target plate defocusing amount

According to Newton's formula, when the target plate of the parallel optical tube is defocused, the image of the target plate will be at a finite distance in the object mirror space, that is, the outgoing light of the parallel optical tube is not strictly parallel, and the parallelism error is related to the aperture of the parallel optical tube. Therefore, the target plate defocusing is the main reason for the error of the parallelism of the outgoing light of the parallel optical tube.

(2) optical system residual

The theoretical aberration of the optical system design and the influence of the installation error during the installation of the optical machine will also affect the parallelism of the parallel optical tube. This part of the error can not be adjusted and compensated during the use of the parallel optical tube, and strict requirements are required in optical design, optical machine design, and optical machine installation and adjustment.

In the field of view, the output parallelism error of the target on the focal plane can be basically ignored due to the aberration of the optical tube system, and the influence outside the field of view is greater.