Photonics Spectra publishes an article on camera module image quality testing. The article is quite concise and mainly talks about the advantages of collimator domes over the illuminated test chart setups:
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| Illuminated Test Chart Setup |
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| Collimator Setup |
The collimator setup advantages are:
- can be used as a “true” infinite setup, with the DUT being tested under the same conditions as in the final application. This setup is quite insensitive to the actual positioning of the collimators, as the field positions are determined only by the angles between the collimators.
- The test chamber is compact, with the outer dimensions independent of the DUT field of view, so it uses less factory floor and is easier to manage.
- less sensitive to stray light, and the reticle illumination can be better controlled, leads to better repeatability.
- By using motorized collimators that can be focused, arbitrary object distances from approximately 1 m to infinity can be generated. This makes it possible to test the focusing of fixed- and autofocus modules. It is further important for the high-precision active alignment technology.
AF modules need to be tested at 10cm (or less) to infinity. Given the hyperfocal distance of mobile lenses, 1m essentially is infinity.
ReplyDeleteThis set-up is fine for lens focus and alignment testing. It is not useful for more general image quality testing.