PI camera lens...

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lfishel
 
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PI camera lens...

Post by lfishel »

I have two related questions for a project I'm working on:
1) Can anyone give me the Refractive index of the lens used in the Raspberry PI camera?
2) Is there any chance of my purchasing a camera without the lens adjustment glued in place (either so I can ajdust the lens easily if the RI is in a range that will work for my project, or so that can easilly replace it)?

If the camera is manufactured by another company, a pointer to them would suffice (unless that is confidential, which would be understandable).

I realize the question is rather cryptic. Adafruit is all about "open ideas", and I'm not ready to show my cards just yet...because I want to be the first to do this (I can't find any hint that anyone else has), but then I will be putting up a page explaining it, and anyone else who wan't to try can do it, hopefully for less than $100, but the cost may depend on what I find about the lens.

Oh, I guess I can give a little information in case it helps. The reason I need the RI and/or ajdistment is because I want to operate the camera, submerged in mineral oil, and it looks like the RI of minerl oil is close enough to the RI of the camera lens that I get a grossly out of focus image (until the oil disolved the glue holding the camer parts together, but I can fix that.)

Thanks.

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adafruit_support_bill
 
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Re: PI camera lens...

Post by adafruit_support_bill »

We do not manufacture these. The people at RaspberryPi.org might have that information, although I'm sure that they purchase the camera modules from yet another source.

Most camera lenses have multiple elements of differing refractive indices. From what you describe, you would be interested in the RI of just the front element. The focus issue can be dealt with by putting a flat filter in front of the lens. That doesn't address the other issues of mineral oil immersion, but it sounds like you have handled.

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lfishel
 
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Re: PI camera lens...

Post by lfishel »

Thanks for the info. I'll try PR.org. I haven't taken th camera apart yet (because of the glue and the fact that I've already mangled it a bit trying to get it out, but it's tiny and fixed-focus, so I supect it's a single lens and maybe a fixed aperture.

I'm certainly no optical guru, but I'm missing what you mean with the flat filter...

Someone on another board gave me a brillient idea (though possibly to expensive for now). A parabolic mirror lens bypasses all my Ri problems.

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adafruit_support_bill
 
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Re: PI camera lens...

Post by adafruit_support_bill »

The flat filter means that the interface between the oil and glass is a flat surface. That means that the front surface of the lens is still a glass/air interface and the ability to focus is not impaired. It is basically the same principle as wearing swim goggles or a diving mask so that your eyes can focus underwater.

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lfishel
 
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Re: PI camera lens...

Post by lfishel »

Understood. One of the many details I left out was that the system will be under tremendous (and variable and unpecified) pressure, so any air spaces are out. Thanks.

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adafruit_support_mike
 
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Re: PI camera lens...

Post by adafruit_support_mike »

Deep-sea robot?

You may want to do a crush test on a plain RasPi before going too much farther. There are some electrolytic capacitors on the board and I'm not sure how much external pressure those can stand.

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lfishel
 
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Re: PI camera lens...

Post by lfishel »

Thanks. Part of the problem with this project is that I'm not sure ther's an affordable way to SAFELY build a pressure chmber to pre-test it to the pressures I'm hoping to eventually see, and since I'm only out $100 or so if it fails (I fully expect it to at some point, but whether that will be at 100 feet or 10,000 will be interesting to see), it's probably easier to just "try it and see".

Also, my admittedly limited knowledge of electolytic capacitors suggests that they mighr be the last things to fail.(already filled with fluid.) Dry capacitors would concern me more. Add them to my my list of unknowns though...

(And for now I would call it more of a "probe" than a robot.)

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