Sorry guys, but it's probably not a glass prism

Started Sep 5, 2007 | Discussions thread
dkloi Senior Member • Posts: 1,952
Re: Sorry David, but it IS definately a glass prism!!

Well, there is one way of decreasing moire and not losing too much
resolution and that is by a frequency dependent optical low pass
filter. If the red and blue components can be smeared more than
green, then chroma spatial resolution is sacrificed in return for
better moire resistance but luminance resolution would be less
affected. It'll come down to actually testing the cameras to see just
how well they have designed the AA filter.

Minolta already had that patented under another use. It was used in
the Portrayer Set P, a layer-coated soft focus filter which used
selective scattering of green light to soften defects in skin tones
without losing the definition created by red and blue. A
diffraction-based, thin film deposition, portrait filter.

Neat.

Reverse the concept, leave green intact and scatter red and blue, and
you have their AA filter, I guess.

Matsushita have patented it under US5280388 unfortunately :-(. I thought I was going to make my millions.

Abstract of US5280388

A phase grating optical low-pass filter having wavelength selectivity consisting of a plurality of layers which are the same in refractive index at a certain wavelength and different from one another in refractive index dispersion, and has a configuration for generating a phase difference at a boundary of the layers.

OCLI eat yer heart out!

Optical Coating Laboratory Inc?

Cheers,
Daniel.

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