Yes, I checked cosine sensitivity but the results showed that UV sensor did
not calibrated by cosine law. I have two UV sensors made by different maker,
but both showed almost same responses to incident angle. I am going to ask
the maker on this problem and I think the UV sensors might not cosine
calibarated with UV.
http://iga.iis.u-tokyo.ac.jp/tmp/test05.gif Fraction of value in 0 degree
http://iga.iis.u-tokyo.ac.jp/tmp/test06.gif Fraction divided by cosine
I think UV sensors would be calibarated to reponse according to cosine
law. It can be controlled with geometry of sensor body and diffuser plate
attached on the receptor and I think it shoud be as shown in figure
test06.gif (FL, illuminance sensors). I used UV sensor body sending electric
signal to datalogger and the datalogger convert the signal to UV intensity
according to calibration curve as usual photosensors.