@TDer
'Softener' seems the word you look for.
My experience on this subject comes from professional application of optronics in open air (maritime environment).
Home application in my garden certainly is a different class, considering the trade-off between cost & quality; but the experience counts.
The sheets found by Grumpf surely are for application for sensing far-UV:
he only must invent a holder keeping such sheet in front of the sensor, covering the whole field of view of the sensor.
Would be useful if the transfer characteristics of the sheets could be mentioned [= range bracket of wavelength and related attenuation]
My (home) aim is to apply easily available materials, simple & sturdy and easily replacable.
Main concern is compatibility in wavelength and life-cycle.
Plastic sheet covers for home application should be thin and uniform:
the thinner, the better for transfer of light of all types, but on the other hand the sheet should be thick enough to survive for some time.
(Dutch) bags for bread are nicely thin, but e.g. document holder front covers seem a better compromise, lasting longer in dutch weather.
A crack or split causes disruption of the light transmission, and dictates replacement.
Discoloring may occur when heated or long subject to UV.
Coverage by some salt usually is not a real problem, but a unequal layer of dust is 'not good'.
Plastic gaze cover of white/transparant variety is better transparent for all kinds of light.
By it's structure it
usually fends off raindrops etc. (=> the grid must be very small)
Cleaning of sheet or gaze is not trivial: replacement usually is easier and more effective.
Both materials deteriorate under the influence of UV & temperature and become brittle (due to those 'softeners' loosing their characteristics).
The
white-glass and clear-plastic bowl lampholders were a pleasant surprise, in practise having good transmissien for light and for UV.
On the other hand the lack of ventilation inside the bowls is 'killing' during sunny periods:
the electronics do not like the resulting very high temperatures and ultimately will 'strike'.
Demonstration that configuration matters is also by the plastic dome coming with my zenith scanning BH1750:
as construction it looks nice, but very clear attenuation for incoming light, when comparing with performance of another 'naked' BH1750.
The experiments with that domed BH1750 also demonstrated another aspect:
the location at the top of the hood of a ventilation exhaust as housing was excellent spot for measurement, well protecting against falling rain, but the air circulating in the housing & head induced condensation at the underside of the hood, which was killing for the electronics of that BH1750.
Lessons learned by practise .....
- Ventilation exhaust aka Lighthouse
- Lichtmeethuis.jpg (79.53 KiB) Viewed 14815 times
- Domed BH1750
- bh1750dome.jpg (43.83 KiB) Viewed 14815 times