[Tig] camera dynamic range quotes are getting silly!

Kevin Wheatley hxpro at cinesite.co.uk
Tue Feb 22 10:05:11 GMT 2011


Bob Friesenhahn wrote:
> There is an alternative to this approach that you might not have
> considered.  For example, the Foveon X3 sensor
> (http://en.wikipedia.org/wiki/Foveon_X3_sensor) senses light at
> different depths in the chip.  Using different principles, it seems that
> a sensor could be tapped at different depths, with deeper depths
> corresponding to higher light levels.  Of course one would want to avoid
> the spectral effect that the Foveon X3 is counting on.  As long as the
> sensing elements are semi-transparent and don't alter the passed
> spectrum, then it should be possible to simultaneously sense light at
> several dramatically different levels.
>

If I remember correctly, wavelength absorption in silicon based
sensors is a function of depth anyway, longer wavelengths penetrate
further which is why sensors are more red/infrared sensitive to start
with (photons are more likely to generate an electron). Something like
0.19 microns for 400nm, 16microns for 750nm from here:

http://www.olympusmicro.com/primer/java/digitalimaging/ccd/quantum/index.html

If you are going to try this don't forget to focus the wavelengths
separately to avoid chromatic aberrations :-)

Kevin

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