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Affordable Fast UV sensitive Sensor!

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#1 dabateman

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Posted 08 November 2020 - 06:59

Warning UV-C should never be taken lightly. Wear protective gear and cover up your skin. You will damage your skin and can get seriously hurt yourself.

I was able to convince Dan at MaxMax (LDP) to convert a Raspberry Pi HQ camera to Monochrome. Its an exciting camera and he now has them for sale. You can see them here:
https://maxmax.com/m...erry-pi-hq-12mp

Mine arrived today and the first thing I tested was my 254nm light with 25mm single fused silica element with the 254.3bp25 filter on front. This sensor is very sensitive to UV-C!!!!!

Direct from camera Jpeg, resized for posting. ISO equivalent 320, F4 (cut a 6mm disc behind the lens), 1/16 second shutter speed!
Attached Image: 20201108_012650_ag8.jpg

Direct from camera Jpeg, resized for posting. ISO equivalent 320, F4 (cut a 6mm disc behind the lens), 1/16 second shutter speed!
Attached Image: 20201108_012535_ag8.jpg

Using DCraw for Raspberry Pi HQ camera with -d -6 -T switches and resizing for here ISO 160, 1/16, F2 (cut 1/2 inch hole behind lens):
Attached Image: 20201108_005350_ag4.jpg

I just missed the focus on where I want for that one.

This sensor is fast and can capture movies.

So for under $1000, UV-C imaging at 12 Mpixels is in our hands (my hands). This should be fun. Its only Monochrome but still, great.

#2 colinbm

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Posted 08 November 2020 - 07:26

Good on you Dave...have fun....& get focus sometimes too.... :tongue:

#3 enricosavazzi

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Posted 08 November 2020 - 11:38

Edit: I originally asked about the type of conversion, but got my answer from the Maxmax page.

Most likely a better alternative to a converted GoPro, although some coding is probably required. It might be a good idea to make an open-source basic imaging software available for those who do not code (unless it already is available).

Edited by enricosavazzi, 08 November 2020 - 11:52.

-- Enrico Savazzi

#4 JMC

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Posted 08 November 2020 - 11:48

Very interesting David. Thanks for sharing.
Jonathan M. Crowther

http://jmcscientificconsulting.com

#5 Stefano

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Posted 08 November 2020 - 12:50

Yes, very interesting. Try stopping down the lens, you will gain sharpness. Sensitivity seems not to be a problem.

In the future, if I will ever do UVC, I will definitely consider this.

#6 WiSi-Testpilot

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Posted 08 November 2020 - 13:11

Thank you for the information. That's very interesting.
Best regards,
Wilhelm

Edited by WiSi-Testpilot, 08 November 2020 - 13:20.


#7 dabateman

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Posted 08 November 2020 - 14:43

The camera has been monochrome converted with the coverglass, microlenses and color filter array removed. Its a naked back side illuminated sensor, so you can't touch it. Its also tinny, so my 25mm lens is effectively a 140mm focal length.
Dan does have a M12 board quartz lens that is 6mm that fully covers the sensor. That would be roughly 35mm equivalent. But focusing would be screwing it in and out.

The Raspberry pi thread has the code I use and images. Not too hard to code in the pi to get a fully working camera. But may be a steep learning curve for some. Main problem was during the time I was learning and trying to get the software to work, the pi software got broken twice by the development team. So I would say once you get it working and doing what you want, don't ever update it. Something might get broken that you use in your code, within an update. Just look at the current Windows 10. The same keeps happening. One of the Windows 10 updates killed one of my old laptops. If this continues in Windows I might just lock down into a specific Linux build.

So I have pi 4B 8GB board, but I would recommend the 4Gb. Fewer problems and if your not doing image editing on the camera, you don't need 8Gb.

A UPS HAT that takes two 18650 batteries to power it.

A 4.3 inch HDMI touch screen. Don't get a DSI screen as they will conflict with the camera port. You must get a HDMI screen or cable to run into a standard monitor.

I use the CSI to HDMI adapter, as the camera cable is fragile and like to just swap HDMI cables to switch between camera modules. There are 2 in a pack. One goes on the main board. The other on your camera module, then use easy removable HDMI cables for connecting.

I have my full spectrum module on my microscope, so just use long HDMI Cable to connect to the board.

This will be fun, but will have to carefully use compressed air to blow off that dust on the sensor.



#8 dabateman

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Posted 08 November 2020 - 14:49

All above images taken with single 15W germicidal 254nm bulb.
I still need to try the candle test and compare it to my KSS imager.

Also just found I need to code in:
-awb greyworld
So that my jpeg's will be monochromatic. That should also help.

Dan said the DNG that gets output from PyDNG works in the DNG2monochrome software for Windows computers. I still have to test the output DNG in RawTherapee.

Edited by dabateman, 08 November 2020 - 15:23.


#9 Stefano

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Posted 08 November 2020 - 16:23

David, I think you have a quartz or fused silica lens, not the plano-convex, but a complete lens made for UV photography. I know it isn't easy, but can you attach it, in some way, to the camera? It will probably crop a lot, since the sensor is small, but at least it is corrected.

#10 dabateman

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Posted 08 November 2020 - 19:09

Yes I have a 60mm macrol, which is really 75mm focal length and an 85mm.
However, with 5.6x crop of the Pi HQ camera that makes them both extreme telephoto lenses.
I have 25mm, 39mm, 50mm biconvex single lens elements. And planoconvex lens elements. Still trying to work out what will be best for this.
A 12mm quartz lenses would be nice.

#11 Andy Perrin

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Posted 08 November 2020 - 19:24

David, edmund lenses on eBay are very common...

#12 dabateman

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Posted 13 November 2020 - 07:01

For Stefano, here are some of the fast movie shots. I was able to screen grab something from the fast video.

No explanation needed, but fast read out is possible with the HQ sensor:
Attached Image: Video_A.jpg
Attached Image: Video_B.jpg
Attached Image: Video_Bb.jpg
Attached Image: Video_C.jpg
Attached Image: Video_D.jpg

#13 Andy Perrin

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Posted 13 November 2020 - 08:13

Is that your finger in UVC? It looks as dark as in SWIR!

#14 Stefano

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Posted 13 November 2020 - 08:46

Yes, it really does! That's what I would have expected, UVC is well absorbed by most materials.

David, thanks. Although I don't really advice trying this, those images are interesting and rare. I would take a UVC selfie, eyes open, if I had the equipment AND UVC wasn't so bad... I guess even my sclera (the white of the eye) would turn dark, just like in SWIR. My hair would not turn white though, I am sure of that.

#15 dabateman

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Posted 13 November 2020 - 08:52

All I will say is for safety, make sure you have turned off your lights before you make minor focus adjustments. Make sure they are off with a switch, definitely don't look at them.

I had forgotten to turn off my light for one adjustment. Fortunately, I hit movie record, instead of focus adjustments in my application. So I got a 30 seconds video. These are the best frame grabs using VLC from that video. The light is mostly behind. The frame rate is about 1/30 seconds shutter, maybe even a little faster. The aperture was about f4 and I have only anolog gain set to 4, roughly ISO 320. Impressive, grabs. But will not be repeated.

We got more Nitrile gloves, so will be protected incase I forget again to hit my kill switch.

I still need to program in monochrome capture. Colors go all over the place with a CFA removed sensor. It doesn't know not to mess with color. I think best test will be coolor effects switch with 128:128 for monochrome. Need to compare that to greyworld switch in white balance.

#16 Stefano

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Posted 13 November 2020 - 09:21

If you want to be sure your UVC lights are turned off when you don't want them to be on, you may use something like a dead man's switch, that will be closed only if you are "alive" (vigilant). If you let it go, it will open. If you want to turn on your lights for a long time or simply leave the room while they do their nasty things, it wouldn't be a good solution, but if you use them for quick experiments you may consider this.

#17 ori333

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Posted 03 December 2020 - 07:13

Hey,

I got the same camera from Dan.

https://youtu.be/reH0vDb4Pdo

#18 dabateman

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Posted 03 December 2020 - 12:49

For your raspivid code you can add the switch:
-cfx 128:128

This will give you a monochrome (grey scale image) rather than seeing everything in magenta like the USA.

Its an amazing canera.

#19 ori333

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Posted 04 December 2020 - 03:38

Thanks. My next step is trying this camera outside with natural sunlight. I'm not using a quartz lens (yet).

#20 ori333

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Posted 08 December 2020 - 23:23

I'm very excited about this camera too. It's a first step to many possibilities. Especially if you have a solid programming background (or if we create enough tools for others). Currently just shooting first and asking questions later, but at some point I would like to do the math on frequency response on camera sensitivity, sunlight light intensity, all the lenses and filters to have an engineered result.

For now just having access to the RAW data in real time is good enough.