[zitoune]

Hello,

I initially built an enclosure for the UV/solar sensors with no specific protection: all sensors fully exposed to the elements.
The UV sensor was glued with Araldite glue but it did not happen to work properly. Somehow I had no signal for days until one day the UV sensor decided to throw funny values. IT was time to change it and redesign it.

So I did a bit a research like some of you did and decided to cover my UV sensor for a better protection (of course )
Borosilicate and silicon based materials tend to offer the best transmission range (source); typically UV-C to near-IR.
This encompasses the full spectre of UV light. But given the UV-C are mostly absorbed by the atmosphere layers, we are left with mainly UV-B and UV-A at the surface of the globe.

JGS1 being a source of interest in this thread and is equivalent to Suprasil 1 and 2 (Heraeus), Spectrosil A and B (Saint-Gobain) and Coming 7940 (Coming), Dynasil 1100 and 4100 (Dynast).
I decided to hunt for the Spectrosil® that is a synthetic fused silica. It has excellent optical transmission from 180 nm in the deep UV through to 2000 nm in the IR.

(a bit of history) Heraeus Quarzglass acquired back in 2008 the Saint-Gobain Semiconductor Materials and Optical Products lines, which includes the Spectrosil products.
There are several manufacturers on the market for such products, and eventually I selected this one.

The transmission for a 3mm thickness is given by:



Around 93% transmission in UV-B and UV-A range. This rather good as the EPA defines the UV index (or strength of UV radiation) is calculated for several wavelengths between 280 and 400 nm:

Wavelength Strength Weight Result
290nm | 4 | 15 | 60
320nm | 26 | 5 | 130
400nm | 30 | 3 | 90

I opted for the coated version, of a 25mm, 3mm thick piece which I mounted on my enclosure.



Mounted on my enclosure: the UV sensor is maintained just underneath.





It's sealed with Epoxy.

It should behave properly now

Thanks,
Zitoune