[Raytrace] Where To Start?

[Michael Peck]

At 18:46 12/6/2001 -0600, John D. Upton wrote:

>     For starters, do all programs use the same conventions for data entry?
>
>     OSLO uses a "spreadsheet" format.  If you draw out a design on paper 
> with light starting from the left, the following rules apply.  Are these 
> basic rules the same for all other programs we might be interested in using?

I don't *know* the answer to this, but I think professional level design 
programs are generally consistent in surface numbering and sign conventions 
as long as you stick to centered systems. I don't think that's necessarily 
the case with some of the atm oriented software out there. There seem to be 
no generally accepted standards for specifying tilts & rotations. 
Documenting differences among programs that atm's are likely to use might 
be a worthwhile FAQ item.

>Perhaps a couple of text prescriptions from OSLO will help illustrate the 
>(typical?) data entry formats.
>This is the text printout of an OSLO design for a simple double convex 
>lens made of Schott BK7 glass.

I'd like to make a modest administrative suggestion here. OSLO .len files 
are just text files, and they're usually quite short. Embedding the 
complete file in your posts separated from the text by asterisks or 
something won't waste a lot of bandwidth -- interested readers can cut, 
paste, and save using notepad or any other text editor.

I'd also suggest - if the site owner and list administrators are willing - 
maintaining a file upload/download area for list members (maybe the public 
too). I think Peter Smith is right that the best way to learn this stuff is 
to play around with existing designs. I learned what little I know by 
entering published designs from any source I could find into OSLO, and 
gradually learned new capabilities of the program by trying to extend and 
optimize existing designs. I've never gotten beyond capabilities that can 
be accessed with spreadsheet entries, menu selections, or taskbar clicks, 
but you can do quite a lot without ever mastering the programming language 
that's part of OSLO.

Somewhere on atmsite there are a couple dozen OSLO files that I uploaded a 
year or so ago. Most of them were entered directly from R&vanV or other 
published designs. A few months ago Steve Fejes sent me some optimized, 
flat field APO designs that he built starting from an unoptimized 3 element 
design that I had swiped from some source (I've forgotten where). If 
Steve's on the list maybe he can explain how he got from my simple APO to 
his optimized field corrected version. He really did an amazing design job.

The last bit of advice I'd offer is obvious to anyone who's done any kind 
of design work on a computer. Save files often. If your design goes 
hopelessly astray just give up and go back to your last working layout. 
OSLO LT seems to be pretty stable (at least version 5.4 was), and I've 
rarely crashed it just by doing stupid lens design tricks. I don't think 
I've ever caused my machine to crash with OSLO.

Mike Peck

_________________

Michael Peck
email mpeck1@ix.netcom.com
Wildlife photography page http://home.netcom.com/~mpeck1/index.html
Amateur telescope making http://home.netcom.com/~mpeck1/astro/astro.html