[UVC SAFETY WARNING] UV-C light sources & filters

[lukaszgryglicki]

[UV SAFETY] UV-C Light Is Dangerous

 

NEVER look at a UV-C light.

NEVER let UV-C light hit your skin or eyes directly or by reflection.

UV-C light can cause:

• severe burns of the eyes and the skin, and
• DNA damage from broken chromosomes.

When working with UV-C illumination, you MUST:

• cover up completely, 
• wear head & eye protection, and
• have strong ventilation.

---

 

 

Hi, I know this was asked in other threads, but can we make some kind of summary about available UV-C options?

To be honest, I can't even find one best light source & filter for this, so I think such kind of topic is needed.

I know that there are UV-C light sources like:

- low pressure Hg lamps (but are they enough to photograph with, can we have a summary about a distance they are able to lighten so any picture can be made?).

- excimer lamps (like 222nm) - aren't they too weak to do any photo with them - I see only input powers but not actual UV-C output when shining at anything from, say, 50cm away?

- others?

Regarding filters or stacks - I literally find no option. Every filter I see is either just a band-pass filter that only passes 20nm width around some UV-C frequency and then has IR leaks that would make it useless, and if you want to block IR with S8612 then no way - S8612 and similar block UV-C). So I can't find any usable filter, not even speaking about having it in 52mm thread or any similar, they are usually tiny, specific for some laser etc.

 

So can we list possible, most powerful UV-C light sources and possible (if any) filters?

 

[dabateman]

I use two 15W E26/E27 base germacidal bulb that are not ozone, they most likely have been dopped to avoid deeper than 230nm wavelengths of light.

They work with my Olympus full-spectrum converted Em5mk2 camera, about 6 to 8 inches away from my subject for UVC reflectance imaging.

 

The MaxMax monochrome raspberry pi sensor is much more sensitive to UVC and I can use a handheld 4W portable light (rock shortwave uv lamp) to illuminate subjects about 2 to 4 inches away.

I haven't tried the small 3W uVC bulb yet for reflectance imaging.

A single 25W uvc bulb can work,  but many produce ozone.

 

For UVC fluorescence imaging, the 4W hand held light is nice.

[lukaszgryglicki]

Thanks, how about filters? How do you filter out IR, visible, UV-A and UV-B?

[dabateman]

I bought a used Sirchie crime scene imaging device,  with a KSS quartz 60mm f4 macro lens and 253.75bp25 filter, which is 25mm in diameter.  The filter is excellent at blocking most UVB, all UVA, visible and IR. The filter alone is worth the price of what I paid.

I have mounted the filter into a 25mm ring to use on any lens. 

 

If you buy a band pass 254nm filter, you may need to get 2, to block the unwanted wavelengths. My filter only lets in 20-25% at 254nm. So a nice germacidal bulb with nice low pressure Mercury 254nm line is needed.

 

[Andy Perrin]

I think the KSS is still available on ebay if he wants one for the filter. 

[Andrea B.]

I still think I should ban discussion of UV-C.

But I don't because it is probably better to try to get people to learn about the dangers.

 

You all above promised to help out by providing warnings whenever UV-C topics are posted.

So.....??? Hmmmmm.........

 

 

 

 

[Andy Perrin]

It has the warning at the top? I mean, I think one warning per thread, in the first post of the topic and the title, is probably okay. 

 

Also, we would be missing out on a lot of interesting work (like Jonathan's microscope!) if we banned it altogether. 

[Andrea B.]

agreed....

 

[colinbm]

I am trying to educate people about UVC dangers & also trying to introduce people to the safer Far UVC 222nm Excimer lights.

[lukaszgryglicki]

UV-C light is dangerous

I'm really interested in this 222nm excimers, need to get my setup complete first. Germicidal bulbs woudl be a lot cheaper probably... filtering remains the biggest issue right now... there are some options to try, I just want to get some knowledge to avoid as much as possible doing mistakes and buying stuff that won't work.

 

 

[rfcurry]

I recently returned to an early love of mine, CuSO4. See https://uvroptics.com/index.php?CuRB. I wonder if this filter would be useful for UV-C, in killing the NIR, but not trampling the UV. 
Just a thought.

[JCDowdy]

28 minutes ago, rfcurry said:

I recently returned to an early love of mine, CuSO4. See https://uvroptics.com/index.php?CuRB. I wonder if this filter would be useful for UV-C, in killing the NIR, but not trampling the UV. 
Just a thought.

Show a semi-log plot and we might see.

[photoni]

moved

[rfcurry]

• 4 hours ago, JCDowdy said:

  Show a semi-log plot and we might see.

  John,

• My spectrophotometer is officially dead, so I only have the old data from 2016. However, CuSO4 is the standard for spectroscopy calibration, so plenty of curves should be on the net. I use 4mm of 80% CuSO4 (pentahydrate) between two 1mm JGS1 fused silica windows.
  Here is a graph from the old data:
  

[dabateman]

1 hour ago, rfcurry said:

• John,

• My spectrophotometer is officially dead, so I only have the old data from 2016. However, CuSO4 is the standard for spectroscopy calibration, so plenty of curves should be on the net. I use 4mm of 80% CuSO4 (pentahydrate) between two 1mm JGS1 fused silica windows.
  Here is a graph from the old data:
  

Reed, has anyone compared the spectrum directly between your copper sulfate filter and 2mm thick S8612?

Do you get optical homogeneity with the liquid filter? Or can you see spherical artifacts?

I wonder if it could correct for some simple fused silica lenses.

[JCDowdy]

Thanks Reed, that looks like quite high blocking above 680nm.

80% solution?  

[rfcurry]

John,

I spent a long time working with Beers on this. :)

I tried to go for more than 3.5-4.0mm, but the image quality quickly suffered; so I upped the concentration instead. Otoh, if you go too high in concentration, crystallization is possible. 
Dave,

How about this graph:

 

Here are two shots. Both with natural light, overcast skies, Panasonic GF1 full-spectrum, Schneider-Kreuznach 4/35 Radiogon lens, f11, in-camera wb on subject, single click WB post-processing, reduced to 1000px width. UV photo used the CopperU filter which is 4.0mm CuSO4 and a 2mm ionic UV bandpass. How is the IQ?
P.S. - Focus was done for the visible shot, but no re-focusing for the UV shot.

Regards,

Reed

[colinbm]

Looks fantastic Reed

I liked the one I bought off you a few years ago.

 

[dabateman]

@rfcurry,

That looks great. Thank you. 

[colinbm]

@rfcurry can CuSO4 be melted into JGS1 fused silica ?  Ed, I can see that that won't work as when heated the blue turns to white !

 

[lukaszgryglicki]

That CuSO4 looks amazing, blocks IR good and allows UV-C in. Definitelly something very usefull - I think I'll buy it once I have my camera from maxmax.com.

Thanks for this - this is the real thing after discarding S8612 for deep UV.

EDIT: there is also a "ready to go" stack: https://uvroptics.com/index.php?CopperU - looks really good for UV-B/UV-A mixture...

 

 

[lukaszgryglicki]

Ordered CuRB & CopperU from UVR optics - I'm happy with their AndreaU and SEU, this CURB transmission (even around 220nm) and OD5+ blocking of IR is exactly something I need.

CopperU also seems to be good for UV-B.

[rfcurry]

Colin,

Yes, the CuSO4 needs to retain some H₂O to remain blue. Some astronomers use blue crystals grown from CuSO4 -  an easy crystal to grow - as camera filters. (See https://crystalverse.com/best-way-to-grow-copper-sulfate-crystals/) I do not do that because the crystals are difficult to maintain in their proper humidity, but you might like to try it. 

Regards,

Reed

[colinbm]

Thanks Reed

 

[lukaszgryglicki]

Simple question:

What is the most powerful UV-C light source?