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Ultraviolet light with NOIR camera

Posted: Thu Mar 12, 2015 9:59 pm
by deivid
Hi
We are launching an awareness campaign for skin cancer and we'd like to show people something like this video:
https://www.youtube.com/watch?v=o9BqrSAHbTc.

I'm wondering if the noir camera can see something similar to the first video, could anyone with the camera and an UV lamp help me out?
If you can see spots (and maybe even stains) on your skin with the UV camera, then it'd be good enough.
Also, sunscreen and glass should be black (both block uv light)

This video tells me it works: https://www.youtube.com/watch?v=7gsajzhIPF8
I'm asking here instead of directly ordering a kit because with the import/customs problems we have at the moment (argentina), it could take upwards to two months to get the camera (without the pi) and cost about 100USD.

Thanks

Re: Ultraviolet light with NOIR camera

Posted: Sat Mar 14, 2015 3:01 am
by LitterBugs
My gut says yes based on how bright my UV flashlight and UV spiral bulbs are, but this is going to be tough to test correctly without a UV pass filter on the camera.

Here is a sample picture with a UV bulb in a dark room. You can see some effect on my glasses lenses and you can see how bright the UV light is reflected in my glasses. Without a UV PASS filter, you also get the visible light spectrum which does not give the effect in the video. Unfortunately I do not have a UV Pass filter.
Image

Same goes for taking IR photography. If you don't use an IR pass filter, you get ambient light which does not give the full effect. A cheap and easy IR filter is unexposed film that has been developed. Looks black but does a great job passing the IR through. Here is a sample comparing an image with no filter to an IR pass filter.
Image

Hope this helps.
LitterBugs

Re: Ultraviolet light with NOIR camera

Posted: Thu Mar 19, 2015 3:13 am
by LitterBugs
I ordered the cheapest UV pass filter I could find online. Results again look promising and you should get better results with a better filter.

Here is a sample using a Black Light, UV PASS filter, Pi NOIR camera, Glasses, and sunblock blotch on my forehead:
Image

I left the camera in full auto mode and did not try to optimize white balance, exposure or any other settings. I did convert it to black and white since the camera really had no idea what to do with the color balance. Looks like it would be worth getting a test rig of your own to make sure you will get the results you expect.

Cheers!
LitterBugs

Re: Ultraviolet light with NOIR camera

Posted: Thu Mar 19, 2015 3:16 am
by deivid
You are the best!
Where did you order the UV pass filter? I have a hard time getting them locally. I'll order a set ASAP

Re: Ultraviolet light with NOIR camera

Posted: Thu Mar 19, 2015 3:26 am
by LitterBugs
This is the one I ordered:
http://www.bhphotovideo.com/c/product/1 ... Woods.html

If you search on their site, use "UV PASS" as the search criteria and you will see many more options.

Cheers!
LitterBugs

Re: Ultraviolet light with NOIR camera

Posted: Thu Mar 19, 2015 3:35 am
by LitterBugs
FYI the glasses I was wearing in the latest picture are the same ones worn in my first post. The difference is the UV Pass filter. Again, you should probably get a better filter as you can tell this one still passes quite a bit of visible light. (You can still see my eyes through the glasses.) The better ones may be listed as "UV Black (403) filter" and the description will state that it is for UV-A reflective photography.

Cheers!
LitterBugs

Re: Ultraviolet light with NOIR camera

Posted: Thu Mar 19, 2015 7:09 am
by riklaunim
It's very very hard to make a filter that would pass UV but not IR or visual light. Astronomical filters like Baader U-Filter or Astrodon UVenus can do it, but they aren't cheap. You can Google some UV non-astronomical pictures taken with them.

A cheap alternative is to use Schott BG39 with Wratten #47 colored glass filters. 47 is a UV shortpass filter with IR leak, while Schott BG39 cuts the IR leak without cutting UV. #47 can be found in astronomical shops (violet visual filter), while BG39 in some optical shops, like uqgoptics, thorlabs, edmundoptics.

Re: Ultraviolet light with NOIR camera

Posted: Thu Mar 19, 2015 4:26 pm
by deivid
LitterBugs:
If I do get a UV Black(403) filter (such as this ), do you think I'll achieve a better result? I have to pay ~$45 for shipping anyway

Riklaunim:
I don't really care if a little IR leaks in, this'll be done indoors with a UV torch. I can get the schott bg39 on ebay a little cheaper, and the shipping is cheaper too. Will the results be similar? I'd pay USD80-90 for the bg39 instead of 135 for the other filter. (+ customs taxes). Getting the IR filter is harder because those I tried do not even ship to Argentina

Again, thanks to everyone

Re: Ultraviolet light with NOIR camera

Posted: Thu Mar 19, 2015 4:49 pm
by LitterBugs
I do not have access to other UV Pass filters to test. My assumption would be yes since they are constructed specifically for UV Reflective photography. I checked with a local resource that rents out equipment, and they do not have any either. You could contact the seller or manufacturer for more information.

Cheers!
LitterBug

Re: Ultraviolet light with NOIR camera

Posted: Thu Mar 19, 2015 5:41 pm
by riklaunim
deivid wrote:LitterBugs:
I don't really care if a little IR leaks in, this'll be done indoors with a UV torch.
If you will cut out other light sources then IR leak isn't a problem.

DSLR UV filters at low prices will also be one of Schott/Hoya/Wratten color glass filters and will have IR leaks unless stacked with blockers like BG39.

Re: Ultraviolet light with NOIR camera

Posted: Thu Mar 19, 2015 7:50 pm
by thegnnu
Hi I have just taken some pictures using a NOIR camera in motionpie software snap a picture. The picture are taken in a room with a 10W LED and total darkness except for the Laptoptop screen.
I used a UV torch 5 LED onto my hand and back of the hand.
I can email you the 2 files one is 2.3Mb the other is 9.5Mb if you would like

TerryR

Re: Ultraviolet light with NOIR camera

Posted: Sun Mar 22, 2015 4:35 pm
by Mark_T
Firstly UV covers a whole wide patch of the spectrum, so its key to know which wavelength
is important. It may be hard UV (the fact glass absorbs 100% suggests this).
Image

You can buy optical filters to any specification you like, but typically expensive.

The PiCam may have a glass lens which may be no good. An alternate UV lens might
be needed - again expensive (look at scientific optical supplier websites to see what's
readily available).

Re: Ultraviolet light with NOIR camera

Posted: Tue Mar 31, 2015 11:34 pm
by insanitycheck
Hi All-

This is very exciting, I have been trying to find a test setup for something like this for awhile, but have been stuck in limbo with various technical resources always ending up with some really expensive solution.

I have found small lens assemblies and such for UV photography, but it appears that the Noir board has a fixed lens (i.e., can not remove it easily and attach something new) nor can one "easily" attach a filter (like the ones mentioned above).

Has anyone found a way to either modify the Noir to a new lens/filter structure or, if not, how have filters been attached to the camera module?

Thanks in advance for the help!

ic

Re: Ultraviolet light with NOIR camera

Posted: Wed Apr 01, 2015 6:33 am
by riklaunim
You can place a filter on top of the lens. You could also check ebay if there are some cheap simple mono USB2 machine vision cameras that are supported on ARM Linux. That would give a more versatile solution.

Re: Ultraviolet light with NOIR camera

Posted: Wed Apr 01, 2015 6:52 am
by PiGraham
insanitycheck wrote:Hi All-

This is very exciting, I have been trying to find a test setup for something like this for awhile, but have been stuck in limbo with various technical resources always ending up with some really expensive solution.

I have found small lens assemblies and such for UV photography, but it appears that the Noir board has a fixed lens (i.e., can not remove it easily and attach something new) nor can one "easily" attach a filter (like the ones mentioned above).

Has anyone found a way to either modify the Noir to a new lens/filter structure or, if not, how have filters been attached to the camera module?

Thanks in advance for the help!

ic

You can unscrew the lens and use another lens to focus onto the sensor.
Here's a fairly elaborate DIY version http://letsmakerobots.com/content/upgra ... ks-edition.

Re: Ultraviolet light with NOIR camera

Posted: Tue Apr 07, 2015 11:52 pm
by insanitycheck
Thanks.
I also found a US$1 M12 mount that fits the Pi camera for mount M12 lenses (that I assume I get to mach the ¼" format of the sensor.

One last question - I wanted to repeat the experiment above, but I am at a bit of a loss as to how to mount the Woods glass filter on the original lens of the PI Noir? Did you just hold it there, rig something up or find an effective mechanical solution to keeping the filter against the lens?

Thanks again!

Re: Ultraviolet light with NOIR camera

Posted: Fri Jun 22, 2018 8:33 am
by duelly2003
LitterBugs wrote:
Thu Mar 19, 2015 3:13 am
I ordered the cheapest UV pass filter I could find online. Results again look promising and you should get better results with a better filter.

Here is a sample using a Black Light, UV PASS filter, Pi NOIR camera, Glasses, and sunblock blotch on my forehead:
Image

I left the camera in full auto mode and did not try to optimize white balance, exposure or any other settings. I did convert it to black and white since the camera really had no idea what to do with the color balance. Looks like it would be worth getting a test rig of your own to make sure you will get the results you expect.

Cheers!
LitterBugs
Hi, I know I'm late to the party, but I am on a similar mission as the original poster. I noticed, in your description, you said youi're using a blacklight to see the sunscreen on your forehead. Is the black light necessary? What does it look like with no blacklight on? I figured it would work without the blacklight considering that you're using a UV filter, and no other examples of pictures I've seen show photographers using black lights. I want to make something similar to the sunscreenr camera (https://sunscreenr.com/)

Re: Ultraviolet light with NOIR camera

Posted: Fri Jun 22, 2018 10:21 am
by Gavinmc42
People have dissolved the bayer pattern and microlens from a Pi camera.
With a filter to block visible light they got down to 300nm.
They had to use a better lens.

http://www.volcano-blog.com/blog/low-co ... spberry-pi