Free optical design software?

[AHartman]

Hi all,

This is my first post in the optics area, and I'm mostly a novice, so please excuse my ignorance. I'm working on an optical system with an emitter and detector located on different sides of a plastic tube with a cross-section such that there are flat internal and external surfaces to allow TIR if the media flowing through the tube has the right refractive index. Imagine a donut, with a flat ceiling inside the ID, and a couple of roof peaks sticking out of the OD. There's a jpeg attached of the concept.

Theoretically, I can use Snell's Law, Excel, and a generous amount of pencil & paper geometry to optimize angles, dimensions, materials, etc to get the right performance out of the concept, but I was hoping some free software might be out there to help me along. I've only located one or two free software packages, and they all seem to be built on standard, defined lenses. I've got an arbitrary 2D shape and I want to trace beam paths through air, into the tube cross-section, and then back out to air again.

How can I import or parametrically draw the shape and trace the beam, accounting for refractive index? If I can just make sure the beams are going in the right places, I'd be happy. I'm not terribly concerned about power distribution, dynamics, or any other detailed effects.

Thanks in advance for any insight or advice!

-Adam

 

[drawoh]

Search the Free Software Foundation. Perhaps they have something.

JHG

 

[lumenharold]

The three or four "softwares" I have that are free downloads or that are links to websites are all as you described (standard lens profiles). If this is the one and only time you will ever do a ray trace you might set up an excel spreadsheet and do the calculations. If the project is important you should buy the software or pay someone that has the capability to run the simulation for you. I'm always a little suspect of freeware unless I have a way to confirm the results. OptisWorks ray trace or ZEMAX are capable softwares and are not that expensive (it's the lighting packages that add up).

Harold
SW2011 SP2.0 OPW2011 SP2.0 Win 7 Ultimate
BOXX 8550 Xtreme Dual Xeon 5680 @4.2Ghz
nVidia Quadro 4000

http://www.lumenflow.com

 

[imagitec]

At least at the concept stage, this looks like a straightforward geometric optics problem with collimated light. Rather than searching for a free optics program, search for a free or inexpensive parametric sketching program. Many of these will fall under the category of mechanical CAD.

If the package supports equations, it will be just as felixble and more straightforward than an Excel spreadsheet.

If it doesn't support equations, there isn't much you can't accomplish by using reference geometry (centerlines, surface normals, right triangles where the legs represent different key ratios) and a basic understanding of geometric optics.

Back in the day, I did quite a bit of this with AutoCAD 12, which did not have any parametric support. You can do much better today.

Good luck,
Rob

Rob Campbell, PE

 

[imagitec]

Actually, it looks like you have SolidWorks, which is more than capable of this. Or am I missing something?

If you just need help with geometric optics, there are no doubt good references online. In hardcopy (or ebook) Building Scientific Apparatus is an excellent resource that touches on many subjects, including basic optics. In hard copy and little more technical is John Grievenkamp's Field Guide to Geometrical Optics (even better is a set of notes from Grievenkamp's Geometric Optics course of the University of Arizona).

Rob

Rob Campbell, PE