OE here. Did you get the index from the patent? At that wavelength, the index will vary with glass manufacturer. Also, different glass manufacturers publish relative to air, N2, or vacuum so it can be tricky. Oh, and they publish at different temperatures too. It can be a real pain to decide what index to use in the deep UV, especially below 248. A lens like this will also have several compensators - elements that are adjusted after assembly to reduce aberrations. At the very least, there will be one element adjusted in x,y to reduce coma, and one adjusted in z to reduce spherical. Maybe a third to adjust the mag to exactly the right value. Deciding which elements to use is a complex process usually determined by singular value decomposition, which CodeV can do, but not Zemax.

@stephenremillard1

Жыл бұрын

I used the value of refractive index that was included in the patent. The patent was in Japanese along with a translated Word file of the text in English posted by the Japanese patent office. The translation didn't mention if the refractive indices were relative to air or vacuum. Of course, patent embodiments usually aren't the best optimized design. Thank you for bringing up compensators. Now that you mention it, surely the inventors had some compensation methods. I'm curious to know what. Of course, I won't be able to investigate that with my homemade code.

Thankyou for the video. I can't see Lambda and not think, λ = (h/p), I like their version: λ /NA, just use 193nm/1.55. That made me giggle.

Hi, I am newbie and got interested in optical design while building small refractors.I wanted to build a Petzval lens with for a small F ratio with 2 doublets for deep sky observation. Recently discovered your channel and seems to have very good information related to Optics. Looks like you have used Matlab. Would love to see how to write raytracing code without fancy software and would appreciate if you could make a video on this. Thanks for this video.

@stephenremillard1

Жыл бұрын

Most certainly! Stay tuned. I will post it in a week or two. And thanks for using my channel.

@stephenremillard1

Жыл бұрын

Done. Here's the link. kzread.info/dash/bejne/Z21qlMagprPAc84.html

Hello Stephen. It seems to me that such a large number of glass-air-glass transitions will change all theoretical calculations to Zero due to re-reflections of glass surfaces. I'm a photographer, but I'm interested in microphotography. Eduard.

@stephenremillard1

Ай бұрын

It is a lot of surfaces isn't it. With 58 surfaces each having a 1% AR coating the back-of-the-envelope transmission is at best 0.99^58=56%. Not zero, but still a lot of loss. I'm not really sure if anything else is typically done to reduce loss with so many elements. The stray light from these reflections is probably no trivial matter either.

@Fujik1966

Ай бұрын

@@stephenremillard1 Yes, scattered internal light will also lead to a significant decrease in contrast, halos and blur at the borders. And this is the most necessary thing in lithography, a clear/sharp separation from dark to light. It would be interesting to see an image from this lens on a matrix camera. Creating one copy of a lens is an expensive pleasure. Only an enthusiast who risks time and expense will be able to do this.

@Fujik1966

Ай бұрын

​@@stephenremillard1 Maybe look at this with lens blocks immersion glued on. You may end up with universally changeable options.

Hello Stephen! Nice to see the video that you shed insight on the UV lithography lens design. I was thinking last night in this bulk lens ray trace as the ray angles can be larger with the strong + and - ve lens groups, do you use tan(u) instead of u in the YNU ray trace propagation?

@stephenremillard1

Жыл бұрын

Good question. Yes, I do use tan(u). When larger angles are involved, I find that the benchmarking against my Zemax-analyzed projects is noticeably closer when using tan(u).