UV (Full Spectrum) Video Capture Options - GETTING STARTED

[ylluminate]

I'm working on beginning efforts towards capturing UV level wavelength videos that are in the higher energy area of output (e.g., filming everything from high energy electrical equipment to environmental events, etc.). Does anyone have any suggestions on equipment on the lower end of the cost spectrum (if it exists)?

 

I found the following equipment on Amazon and found it quite intriguing as it is a step up from a previous modded model that they were offering:

http://a.co/e8D3FSL

 

I'm not terribly interested in the IR functionality, although that could be nice.

 

In my email exchanges with Cliff, who I suppose is the proprietor making these modifications, he notes the following to my inquiry regarding UV capture on the PREVIOUS model of their camera that I can no longer find (and seemed to be lower end):

• Our digital sensors pickup light down to 250nm (NOTE: I would like something even more sensitive if possible). This should give you the type of results you are looking for - but you’ll need to get some sort of filter to only allow light below 400nm to pass through to the camera. You’ll want to look for a UV Pass filter that is 37mm.
  
• I then sent him some information about a lens filter I found: MaxMax.com sells a lens filter called the XNite. Their XNite330 ($96) handles the UV spectrum area nicely from about 250 to 400, but their XNiteUVR ($89) is even more interesting as it allows both UV and IR in, subsequently blocking the visible light range quite well:
  

• I also noted to him (from http://www.maxmax.co...r_solutions.htm):
  
  • LDP is the only company in the world capable of removing the Color Filter Array (CFA) from the surface of a color camera sensor. The CFA blocks most of the UV light, so unless, you can remove the CFA, the camera will see very little UV. Every other company that sells a UV capable camera that has been converted from a normal color version will have very poor UV sensitivity because they do not know how to remove the CFA.
     
    When Fuji sold the Fuji S3 Pro UV/IR and IS Pro cameras, they originally marketed them as seeing to 280nnm because they were using Schott WG280 glass to replace the stock ICF/AA. In fact, Fuji contacted us about performing these modifications for them before deciding to do the modification in house. Their cameras were direct copies of our UV-VIS-IR conversions for the S3 Pro and the Fuji S9000 / S9100. Eventually, someone pointed out that just because they were using 280nm glass in front of their sensor that it didn't mean the sensor could actually see to 280nm. Unfortunately, Fuji Japan wouldn't provide Fuji USA with the spectral transmission curves, so Fuji USA couldn't really say what the UV response of the camera was. They changed their marketing to reflect that the cameras were UV capable without ever specifying exactly what the cameras could see in the UV.. Fuji has since withdrawn these cameras from the market. Because their cameras still had the CFA on the sensor, the cameras actually had very poor UV sensitivity.
     
    In addition to LDP being able to remove the CFA from camera sensors, we also have the ability to measure the spectral response of cameras. None of the big camera manufacturers such as Canon, Nikon and Sony release the spectral response curves for the consumer cameras. If you are in the market for a UV sensitive camera, it is important to know just what sort of sensitivity the camera has!
     
    Another solution to produce a UV camera is the method used by Oculus Photonic's UVCorder and UVScanner. They team a UV sensitive video camera to a camcorder or viewing device. The UV video part of the setup is a Sony XC-EU50 UV video camera which is a real UV capable camera, but, the XC-EU50 is a 0.38 megapixel camera (less than 1 megapixel) that can only take standard definition video (not HD). In contrast, our UV capable monochrome cameras can take an 18 megapixel image and shoot HD 1080P video. The LDP monochrome UV camera has over 47x the resolution on the Sony XC-EU50 for a still image. In addition, our 18 megapixel T2i UV monochrome camera that can shoot both video and stills retails for less than half the cost of the UVCorder solution. But, to the Oculus Photonics credit, at least their product can take a real UV picture without very long exposure times unlike almost everyone else marketing a UV capable camera that has been converted from a stock color camera.
    

  [*]He then came back with the following (on the older model): I am confident that our sensors can see to 280. However - after watching the videos you provided (I provided him some examples of UV videography such as the 1996 NASA tether incident) - I just don’t think our cameras will work for you. I would hate for you to but a $100 filter - and the camera not do what you wanted. We would gladly take the camera back - but I just don’t think the filter company would allow you to return the filter if it wasn’t what you were looking for.

After this he didn't really seem to have anything else to share or didn't respond to further inquiries. I obviously have reservations since I want to acquire a camera with sensors (and glass / lenses) that are capable of going as far as possible into the unseen spectrum.

 

I guess ultimately I would like to understand my options better. I would prefer to have a little more outset in investment initially if I can be certain of the results I'll get. My goal is to composite the output from the invisible spectrum into a digital composition that includes the visible spectrum via some custom software (I am a software engineer).

[Alex H]

I would like to see hard proof that his camera can record anything at 250-280nm.

[Andy Perrin]

Trying to get lower than 320nm or so is something many people here have been interested in for a long time, but there is no way (that I know of) to do it at LOW COST. David Prutchi posted this awhile ago, but I never heard whether he got it working or not:

 

http://www.ultravioletphotography.com/content/index.php/topic/1888-shortwave-uv-imaging-for-sbuv-and-ruvis/

 

One needs a lens that passes all the way out there, and probably a sensor without a Bayer array or microlenses? I know Klaus (who is no longer on this site) says he has done this. Filters are probably less of a problem because you can't use sunshine anyway (there is little UVB in sunshine and no UVC), so you can filter your light source.

 

I have had some thoughts on the subject, mainly whether I could rig up something with a pinhole (no lens), an Omega filter, and a fluorescent down-converting screen, like with my shortwave infrared setup.

[Andrea B.]

Klaus is using an industrial UV camera, some of which reach below 300nm. But, as always, the problem is -- what are you going to use for illumination below 300nm? And the closer you get to 250nm, the more dangerous the UV becomes.

 

[[OP link is to a ghost hunting camera???]]

 

The industrial UV cameras, whether video or still, are typically used in machine vision for testing surfaces for scratches, nicks, dents and so forth. But once you go below about 300-320 nm, then you are going to need a more specialized sensor for which the silicon is thinner and perhaps coated for somewave-shifting trickery. I can't remember right now about the backlighting, but I think you need that too? All in all, shortwave UV cameras become very much more expensive because of all these special requirements. They also need to have lens elements made from quartz or fluorite in order to pass the shorter UV.

[enricosavazzi]

I remember reading that some UVC videocams used in the semiconductor industry have naked sensors, i.e. an open chip carrier with no window covering the sensor chip (and of course no microlenses and no Bayer filters on the sensor). The manufacturer recommended never removing the lens from the camera, and there were a number of other warnings about the expected lifetime of the sensor being quite short.

 

Given that fused silica is transparent down to 180 nm, this would seem to suggest that these UVC cameras are able to record at least down to these wavelengths, and perhaps further down - else there would be no need to skip the window.

 

Another possible factor suggesting that skipping the window may have some advantage is that ordinary fused silica solarizes (i.e. becomes less transparent to UV) quickly when exposed to high-intensity short-wave UV. This is primarily important in fiberoptics, where the length of the optical path through the material is substantial, but might also affect fused-silica chip-carrier windows.

 

Also, the spectroscope I am using is based on a Toshiba linear CCD, and is specified for use between 200 and 1200 nm. It very clearly records the 253.7 nm Hg line (see my post from yesterday with the spectrum of a UVC lamp). I have no available 200 nm source available for testing, but this sensor may well record down to 200 nm as specified. So I don't really see why CCD or CMOS sensors should be intrinsically insensitive below 280-300 nm. It would seem more likely that the sensors in our cameras are designed, optimized and packaged for use in VIS color imaging, and all these factors combine together to restrict the intrinsically wider range of the sensor.

[Andrea B.]

It would seem more likely that the sensors in our cameras are designed, optimized and packaged for use in VIS color imaging, and all these factors combine together to restrict the intrinsically wider range of the sensor.

 

From my reading, I agree that the likely cause for the typical interchangeable lens DSLR/mirrorless camera is exactly this. And would also be the case for any consumer video camera.

 

The Sony ICX407BLA sensor is mentioned on several industrial camera websites as having been specificially designed for increased UV sensitivity for machine-vision industrial cameras. So that designation might be something to search on.

 

I haven't really seen any specific video cameras for UV. Only these industrial cameras with typically a low pixel count and no video -- although some have a very fast frame rate.

 

Thanks, Enrico, for the warning that shortwave UV can solarize fused silica (quartz, in some cases).

Do you know if UV is also harmful long-term to calcium fluorite lenses?

[enricosavazzi]

Thanks, Enrico, for the warning that shortwave UV can solarize fused silica (quartz, in some cases).

Do you know if UV is also harmful long-term to calcium fluorite lenses?

Yes, depending on its impurities (this is also the case with quartz and fused silica, b.t.w.).

See e.g. https://books.google...ization&f=false

 

Edit: see also https://www.google.com/patents/US20030158028

[ylluminate]

Really appreciate your input on this topic so far... Been thinking about this and trying to digest things a bit. Have not really settled on any solution so far. I wish there were some way to validate the CCD capabilities without having to essentially set up a lab first in order to go into this with some higher levels of confidence. I'm surprised that UV imaging (especially videography) is not more easily accessible given what should be some pretty rapid progress over the past 20 years.

 

Perhaps I should lower my bar a little in terms of expectations in order to just get at an entry level UV capture point to start work on integration into the visual spectrum algorithm I'm developing. My goal is to create a realtime presentation of both UV and VIS (and IR) so that the observer can dynamically expand and manipulate the spectrum in a VR environment. IT seems doable, but this initial stab into the UV spectrum is indeed daunting as far as price points go since initially I just need to play around vs getting into some seriously hefty UV imagery costs. The trick, for me, is to develop the algorithm with some multiplexed test inputs at first before I can really get into multi thousand dollar investments on the UV hardware.

[OlDoinyo]

UViRCO sells "solar blind" cameras at

 

https://www.uvirco.com/products/corocam-solar-blind-cameras/

 

which have some video acquisition capability that extends to the UVc channel. Needless to say, this is not cheap hardware; but the technology to make it possible does exist. I do not know the details of sensors, lenses, or filters used in the UVc channels of these cameras; but they are clearly something beyond what most of us here have at our disposal.

[Andy Perrin]

I think you should start on the other end of the spectrum, actually. Start by trying to do in infrared, which is MUCH easier. For starters, IR light is more plentiful (something like 55% of sunlight is IR, versus 5% UV altogether, and no UVC at all!). And camera sensitivity is much higher for IR, and most lenses transmit a lot more of the IR. Then you could start trying to expand into UVA a bit.

[JCDowdy]

OlDoinyo!

What a cool website you linked! Lets see, 1 beamsplitter, 2 lenses, 3 cameras and you're off to the races. ;-)

 

ylluminate,

For some additional ideas on how multispectral video may be implemented you might also check out the multispectral sensors and filter wheel cameras from Pixelteq, and the multispectral prism 3CCD based system from FluxData.

[ylluminate]

Some more great information there guys as far as where to look. I did see something concerning: it appears that Sony is out of the CCD mfg business? Who is innovating? Where can one get cutting edge and innovative CCDs at this point? It appears that Sony will make their CCDs available for 10 more years, from that point (until 2026; but have stopped wafer production as of this year, 2017), BUT that makes me think that I wouldn't really want to count on Sony for anything that would be pressing the envelope at this point... there must be others...?

 

EDIT: from what I'm seeing there are indeed perhaps more innovative CCDs from Toshiba and maybe even Panasonic.

 

Have dug about quite a bit more and finding a number of other options as far as CCD and CMOS mfgs go. Quite interested in the high frame rate Chronos build out (not to mention it's going to be open sourced). Seems like some solid information strewn about different sites from what I'm seeing and may serve as an interesting base. Frankly I'm getting to the point where I think I'm going to take some old digital cameras apart and see what makes these things tick.

[enricosavazzi]

(...) I did see something concerning: it appears that Sony is out of the CCD mfg business? (...)

It seems Sony only intends to concentrate on CMOS sensors, which is where most of the development is going on anyway, rather than getting out of the imaging sensor business altogether. The Olympus E-M1 Mark II uses the new Sony IMX270 CMOS sensor, for example.

[Andrea B.]

Perhaps I should lower my bar a little in terms of expectations in order to just get at an entry level UV capture point to start work on integration into the visual spectrum algorithm I'm developing.

 

Why not just convert a used Panasonic Lumix camera of the G line to full spectrum? Panasonic is known for its good video.

[nfoto]

I second that. Panasonic G-xx/GH-xx additionally have the very useful property of being able to set almost perfect UV w/b in camera.

[enricosavazzi]

I second that. Panasonic G-xx/GH-xx additionally have the very useful property of being able to set almost perfect UV w/b in camera.

This is a good-quality setup, not just entry level but likely to remain satisfactory for quite some time, depending on the G or GH model.

 

Another alternative that may be more cost-effective than a converted GH* model for HD video (but not for still-image quality) is a modified Gopro Hero action camera with an added C/D lens mount and a legacy C lens capable of decent UV performance. The modification is iffy but not impossible for a home project. Finding a decent lens for UV with a sufficiently long thread to mount in the unmodified camera (the sensor is quite deep within the camera) would not require modifying the camera but just swapping out the original lens and adding a UV-pass filter. Universe Kogaku even makes a few UV quartz lenses in M12 mount that should be a direct replacement (although the inner lens mount might need replacement). The GoPro Hero does not go very deep into the UV, but around 365-375 nm is not a problem. The GoPro 4 Silver has been discussed in a thread on this site: http://www.ultraviol...__fromsearch__1

[Shane]

It would seem more likely that the sensors in our cameras are designed, optimized and packaged for use in VIS color imaging, and all these factors combine together to restrict the intrinsically wider range of the sensor.

The junction depth for consumer digital cameras (except Foveon sensors) is optimized for green wavelengths around 540nm. That and the overlying insulating & protective layers tend to reduce UV sensitivity significantly. Backside thinned sensors can be advantageous in that respect.

[Andrea B.]

[Testing a reply to yilluminate.]