Okay so for positive meniscus lenses for a custom projection lens I assume an anti reflective coating is beneficial and would like to know what sort of anti reflective coating I need.
I assume it needs to be coated on both sides but what wavelength does it need to be for, and what % etc.
Thanks for your help 🙂
I assume it needs to be coated on both sides but what wavelength does it need to be for, and what % etc.
Thanks for your help 🙂
AR coating
It doesn't really need to have AR coating on the surface that faces the screen, but I don't know if you can save any money by only having one side coated. The side that faces the LCD should be AR coated so you don't have light bouncing back to the LCD and then back as a bright defect in the center of the image.
You need a "visible light band" AR coating.
BTW: I think you can do better than a single positive mensicus by getting two positive meniscus or PCX that are around twice the EFL you want for projection. Then space them 20 - 80 mm apart in a flat-black tube with the convex surfaces facing away from each other. This gives you a symmetrical duplet that works pretty well out to around a 40 degree field angle. If you do this, use coated lenses. Here is a link to a calculator for these lenses:
http://www.lightshow.cc/explorer/Calculators/Lens_Designer/lens_designer.html
You can also make the same lens using a pair of achromatic doublets to get a color-corrected lens. But that might cost you more than getting an optimised projection triplet.
It doesn't really need to have AR coating on the surface that faces the screen, but I don't know if you can save any money by only having one side coated. The side that faces the LCD should be AR coated so you don't have light bouncing back to the LCD and then back as a bright defect in the center of the image.
You need a "visible light band" AR coating.
BTW: I think you can do better than a single positive mensicus by getting two positive meniscus or PCX that are around twice the EFL you want for projection. Then space them 20 - 80 mm apart in a flat-black tube with the convex surfaces facing away from each other. This gives you a symmetrical duplet that works pretty well out to around a 40 degree field angle. If you do this, use coated lenses. Here is a link to a calculator for these lenses:
http://www.lightshow.cc/explorer/Calculators/Lens_Designer/lens_designer.html
You can also make the same lens using a pair of achromatic doublets to get a color-corrected lens. But that might cost you more than getting an optimised projection triplet.
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