Question: Is there a way to make a cheaper "UV Hound"?

oh ok! yes, in this section of the book, looks like Gwen is using a UV Hound that was in fact rented from Hilton Kelly's organization Community In-Power and Development Association. Can the world get any smaller...

Id love to hear of how the "hound" data has been used effectively in communities. After the data was collected, what did they do with it...Are there examples in Gwen's book?

I also want to know about this type.

Deep UV or DUV is pretty hard to detect. This article talks about it: https://www.vision-systems.com/non-factory/life-sciences/article/16736672/uv-imaging-opens-new-applications

(These are some cameras that can do it, but I'm not sure if it's necessary for them to be cryogenically cooled or if these are that for a different reason: https://www.horiba.com/en_en/products/detail/action/show/Product/1487/)

One idea that the article explores is using a fluorescent coating that will glow, so the camera doesn't have to detect DUV, but can photograph the coating:

Another method involves coating the substrate with a wave-shifting coating such as Metachrome II or various phosphors. These coatings fluoresce in the visible portion of the spectrum. The fluorescence signal can traverse the substrate more easily than short-wavelength UV and, therefore, is detected. The disadvantage is that half the light generated by the fluorescence process radiates away from the sensor and is never detected. The coatings also degrade the MTF of the camera system and can introduce image-retention issues if the camera is running at a high frame rate.

And the lenses have to be made of quartz:

Standard glass lenses will not work well in the deep-UV band, since the typical lens glass absorbs strongly below 300 nm. Special lenses made with quartz (fused silica) or calcium fluorite are required. There are few off-the-shelf sources for these lenses, and the cost is quite high compared to visible-light optics. Microscope objectives are available for confocal microscopes operating in the DUV band.

Big thanks for unpacking all this @warren

Sure!

I think the takeaway is that searching for a price for the OPSIS, or pricing for a different UV-DOAS device that could substitute for the UV-Hound, could get you a moderately lower price, BUT the need for an expensive Deep UV (DUV) camera sensor and lenses makes this device reasonably expensive to start with.

BUT, for those interested in DIY spectrometry for UV, there are some experiments at #uv-imaging, but this hobby imagery website also has a good overview, saying some off the shelf cameras can actually photograph down to 200 nanometers:

http://www.astrosurf.com/luxorion/photo-ir-uv4.htm

LifePixel offers some UV conversion cameras for ~$475, but it's not clear that they'd go much below 300 nanometers, according to this chart from http://www.astrosurf.com/luxorion/Physique/spectral-response-ccd.jpg

This USB microscope camera goes down to 200nm, but i can't find a price: http://www.m-shot.com/index.php?a=show&m=Product&id=126

OK, this is weird and interesting. Maybe it relates to the above suggestion of a fluorescent coating, but this product seems to 'convert' UV from the 193 - 360nm range into visible light for a CCD camera: https://www.ophiropt.com/laser--measurement/beam-profilers/products/Accessories/Reimaging-UV-Lasers/1-1-UV-Image-Converter

Yes: "The UV image converters are fluorescent plates that convert UV radiation that is poorly imaged by silicon cameras into visible light that is then imaged onto the CCD of the camera. " -- more at https://www.ophiropt.com/laser--measurement/knowledge-center/article/9184

Huh. https://www.dataray.com/collections/accessories/products/uv-converter

Here's one which converts 193-360nm light to visible, and it costs $3,272

So i guess the modified camera approach might be cheaper; especially since we don't need a lens.

I wonder if any CMOS sensor could work, like a cheap webcam, as long as our diffraction grating was reflective in the UV range. Those seem to be available for about $100: https://www.edmundoptics.com/f/Reflective-Ruled-Diffraction-Gratings/12220/

Or maybe a scanning UV sensor like this: https://www.amazon.com/200nm-370nm-Wavelength-UV-Sensor-Ultraviolet/dp/B00NL9XNN8/

For all this to work together, it'd be something like:

• a really really powerful Xenon spotlight, aimed across a thousand feet of open air
• reflected back with a first-surface mirror
• bounced off of a reflective diffraction grating in a dark box like one of our spectrometers
• aimed at a CMOS camera OR a spinning mirror plus a UV sensor
• wait a long time to get a long exposure
• then do it again when there is suspected benzine and other PAHs, kind of like in this post (image below)

I think it's a pretty tough challenge, and you'd have to try to separate out just the benzene detection from any other things you detected, just like we struggled to ID fluorescence spectra in a mixed sample of liquid.