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:
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
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.