Optics: Reversing a Nuetral Density Filter

AI Thread Summary
The discussion centers on the impact of reversing a neutral density (ND) filter on light transmissivity. When the ND filter is flipped, the transmissivity may change depending on the coating on the uncoated side, potentially resulting in either the same or reduced transmissivity due to surface reflection and transmission effects. For heat transfer analysis, the total energy transmitted remains unchanged regardless of the filter's orientation. However, in photographic applications, the placement of anti-reflection coatings can affect image quality by increasing flare from multiple reflections. Resources such as optical engineering textbooks are recommended for further understanding of light and energy transmission through layered optical mediums.
coucher630
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I'm conducting a heat transfer analysis on an instrument, but must first overcome my apparent lack of knowledge of optics.

Light is incident on a neutral density filter. The ND filter consists of 0.050" thick quartz with a a negligibly thin metal coating with emissivity of 0.065 on the surface that is exposed to the light. In this configuration, the transmissivity of filter is 0.01. However, I need to know what happens when the filter is flipped. That is, when the quartz is the surface that is exposed to the light, and the metal coating is on the bottom of the filter, what happens to the transmissivity?
 
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It will depend on the coating on the uncoated side, I could see it being either the same or less depending on surface reflection/transmission...
 
For this sort of use, there would be no difference in total energy transmitted. However, for photographic use, the effect on a final image could be that the amount of flare (due to multiple reflections) could be worse with anti reflection surface in the 'wrong' place.
 
Are there sample problems or instructional texts somewhere that go over light/energy transmission through layered optical mediums?
 
coucher630 said:
Are there sample problems or instructional texts somewhere that go over light/energy transmission through layered optical mediums?

Sure, any optical engineering textbook.
 
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