This issue was very fully explored under the thread “Sunglasses” originated by vaqueroaero on 28 Nov 2002 in the Non-Airlines Forums - Rotorheads forum. To return to the original request, I presume Fullforward has long since bought some sunglasses but for anyone else interested Hidalgos, Inc of Wimberly, TX has some useful technical data on their website. This gives the pros and cons of various lenses, how to select sunglasses for various uses, and a Lens Light Transmission Chart. They state:
“For the technical folks, we use a Hoya ULT-2000 Universal Light Transmittance meter to make our measurements. This instrument measures visible light levels in the 400-760nm wavelength range, the ultraviolet light in the 310-400nm range, and the infrared light in the 760-1200nm range. The wavelength of the light is measured in nanometers (nm).”
Having mentioned Hidalgos, Inc, does anyone know their current status? I recall that a few years ago the owner was considering retiring because of ill health. However, the website seems to have been updated since then so perhaps they are still as active as ever. I have since early March emailed them four times to ask for a paper catalogue. I have not received any response or a catalogue. It will be appreciated if someone would confirm whether or not they are still in business. I hope they are. Thanks.