Tuesday, April 21, 2020

Reflected UV photography in polarized light VIII - Mica

Today more about UV polarizer experiments, using a special UV capable circular polarizer in front of my multispectral camera and UV-Nikkor 105mm lens, for recording some polarized reflected UV images plus some insect and human vision ones using my XBV filters. Object used was some slices of sheet Mica. UV filter used was my classic Baader-U filter; Xenon full spectrum light was used as light source.

[click on image gets you a larger image]

Here photographic results I got today (took multiple images while moving the Mica sheet), presented as animated gif.

This is more of scientific interest, and I like the different colors one gets. If interested I refer to the famous Michel-Levy Chart which explains that well. What you see here are 2nd order colors.

Reflected UV photography in polarized light shows quite some usefulness, especially if there are (glossy) surfaces which change the polarization angle of light and which the polarizer filter makes visible. Downside is that one needs about 2 stops more exposure, due to the low approx. 25% transmission.

Some insects are able to see the polarization angle (and btw. we humans can also, but needs some traing: Haidinger's Brush) especially honeybees which navigate using the polarization angle of ultraviolet (UV) light.

I have written more about using UV polarizers HERE

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