Factors Affecting the Output Parallelism of Collimators?

The parallelism of the output light from a collimator is mainly affected by two aspects:

1. Target plate defocus amount

According to Newton's formula, when the collimator's target plate is defocused, the image of the target plate will be at a finite distance in the object-image space, meaning the collimator's output light is not strictly parallel. The parallelism error is related to the aperture of the collimator. Therefore, target plate defocus is the main cause of errors in the parallelism of the collimator's output light.

2. Optical system residual errors

The theoretical aberrations in the optical system design and the alignment errors during opto-mechanical assembly will also affect the collimator's parallelism. This part of the error cannot be adjusted or compensated for during the use of the collimator, requiring strict demands in optical design, opto-mechanical design, and opto-mechanical assembly.

Within the field of view, the output parallelism error of the target on the focal plane due to system aberrations is generally negligible, while the impact outside the field of view is more significant.