Focal length test device

Abstract

The invention provides a focal length test device. The light beam emitted by an LED light source illuminates a reticle; a parallel tube objective lens projects the line pair on the reticle into firstparallel light; the first parallel light is incident to the measured optical lens and forms an image of the line pair; the image of the line pair is projected into second parallel light after passingthrough a standard lens; a focus lens receives the second parallel light and focuses the image of the line pair on a detector; the detector receives the image of the line pair and transmits the imageof the line pair to an external computer for processing and calculation so as to obtain the focal length of the measured optical lens. According to the focal length test device, the microscope objective lens is replaced by the standard lens and the focusing lens, and a parallel light path is formed between the two lenses so that the small distance change between the standard lens and the focusinglens has no influence on the test, the standard lens can be conveniently replaced and the requirement of a wide-range focal length test is met.

Description

technical field [0001] The invention relates to the field of optical testing devices, in particular to a focal length testing device. Background technique [0002] Focal length is an important parameter of optical lens. The focal length of the optical lens determines the size of the image and the size of the field of view. In order to grasp the performance of the optical lens and use the optical lens correctly, the focal length of the optical lens must be tested. [0003] The focal length test methods of optical lenses include magnification method and precision angle measurement method. The precision goniometric method requires that the reticle must be precisely focused on the focal plane of the optical lens to be tested. This condition is very inconvenient to realize, so the precision goniometric method is rarely used. Compared with the precision angle measurement method, the magnification method is relatively more convenient to use, so it is used more often. [0004] I...

AI Technical Summary

Problems solved by technology

In the focal length test device, replacing the light source has no effect on expanding the focal length range, and the process of replacing the detector or reticle is also very cumbersome

The distance between the collimator objective lens and the reticle is inconvenient to adjust during the measurement process, so the collimator objective lens should not be replaced

In this way, only the microscope objective lens is left, but if the microscope objective lens is replaced directly, the distance between the microscope objective lens and the detector needs to be adjusted, which is also very inconvenient

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