After a long search I finally located a specifically designed beam homogenizing solution that sufficiently transmits UV and allows to generate a quite even radiation field, which is beneficial to have, especially for photography which usually requires even illumination of the target.
I have also tested it working with the newer 4 dice Nichia NC4U133 (365nm) and NC4U134 (385nm) chips, but those are not used for portable flashlights yet as far as I know.
[click on image to see a larger one]
Radiation field without homogenizing solution:
Radiation field with homogenizing solution:
Transmission of the homogenizing solution in use:
Theses simple flashlights are useful for different applications, such as stimulating visible fluorescence, reflected UV photography, forensic, dermatological and detal examinations and photographic recording, curing of UV glue / bonding, as well as leakage detection etc.
Stay tuned, more will follow on that fascinating subject...
More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos