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Optics / Lenses / Filters Questions

Question Asked:

I was testing a telecentric lens that allowed a fiber optic light source to be inserted in its side. When testing the lens with the fiber optic light source my image got washed out with a grey color, adjusting gain and offset did not help. When I used an external light source with the same lens and camera I got a normal image. The supplier was unable to tell me why my image turned grey with this light. They were able to tell me the lens, camera, fiber optic cable and light source are compatible. Has anyone else experienced this issue and have information on what caused it/how to correct it?

3 Answers

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  • = Answered Questions

David Dechow - Principal Vision Systems Architect
Integro Technologies
ddechow [at] integro-tech [dot] com
(704) 636-9666

The description of the image as turning "grey" is hard to visualize. The components you describe are standard imaging and lighting products and this illumination technique is common. Can you provide more information? Knowing the camera model, light source color and the object(s) being illuminated would help our understanding. Feel free to respond here or to my email address.

Yoshigi Nakata - President CEO
Nacacue Corporation
yoshigi_nakata [at] nacacue [dot] co.jp
81 759 344 178

What is your target object to be detected? If it is the plane mirror surface, it might happen. Illumination inserted in the lens side become parallel ray to the object. If the object surface is plane and mirror under the parallel ray illumination, object image has 100% illumination intensity to the camera sensor. You can change the angle of object against the camera axis as a trial if it's possibel. then if you see some difference, it might be the part of the cause.

Andrea Iniquez - Vice President, Business Development
Theia Technologies
ainiguez [at] theiatech [dot] com
(503) 570-3296

Hello Nicholas, We are not experts in telecentric lenses specifically, however as optics engineers we would say this is what we would expect with your setup. We can perhaps provide a theory on how this is happening. If your subject is reflective (glossy, under glass, etc.) then you could be getting a reflection directly from the subject directly back into the lens. Your solution of using off-axis lighting solves this issue. We hope this is somewhat helpful. Finally, our apology for such a delayed response - we didn't receive notice of your question until this week. best regards, Andrea

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