Light cones and mirrors, how to do it? 1

[halfdog]

I need to model a slightly diverging cone of light and then inserting several mirrors to fold the beam around. Creating the cone by revovling is no problem, but representing the mirrors, cutting and folding (or mirroring) the rest of the cone path is.

Should it all be one part, or an assembly? How do you mirror the cone about the front surface of a mirror in an assembly?

I'm hoping someone has been through this and can share more specific tips like thread559-99293 . Thanks

 

[CorBlimeyLimey]

I use geometry in a Layout Sketch in the assy consisting of the centreline or path of the light beam.
The mirrors (or lenses) are placed at the refracted intersections of the centrelines.
Where possible I extrude profiles with the Up to surface option, selecting the mirror face as the surface, and the Draft option to create the diverging or converging cone.
The first beams profile would be from a representation of the light source.
Subsequent reflected beams would be created by using Convert Entities of the face or edges of the profile intersecting each mirror.

Constraints and equations can be used to parametrically control or adjust the Layout Sketch geometry.

 

[lumenharold]

CBL,
I want to mention that I always appreciate your responses. The approach you suggest is the one that I considered myself and so tried. The problem I ran into was extruding the oval profile from one mirror to the next and having the "beam" follow the reflected light path. If I used the beam path as the guide sketch the end profile did not terminate properly on the reflector. I'm guessing that I'm missing something in your method. I had a measure of success by placing sketch planes at the midpoints between the mirrors and using 3D sketchs to define the beam divergence from profile to profile then using the loft function from the mirror to the midplane. I then did the convert entities and extrude with draft that you suggest between the midplane and the next reflector. At least there isn't the need to trim the part to make it look correct as with the referenced post. Of coarse if the diveregence is small enough and the beam path is short enough or if this is only for illustration, I'd skip the diverging beam and make life simple.

halfdog, if you do this sort of thing much you might look into the SW Add-ins for Ray trace. Especially if you are using the ray trace for design confirmation.

Harold
SW2008 SP1.0 OPW2008 SP0.0

http://www.lumenflow.com

 

[CorBlimeyLimey]

For some reason I have yet to fathom, sometimes the beam does not terminate properly at the "Up to surface" selected. In those cases I usually use the Blind option and set the distance to beyond the mirror, then create a zero offset surface from the mirror, and then use that surface to trim the beam correctly.

The attachment below is a quick example.

 

[CorBlimeyLimey]

Ooops, sorry ... that file was screwed up. Try this one.

 

[lumenharold]

I won't get to look until Monday morning. I'm sitting at home in front of a Mac. Home office is being painted and the home PC is at the office being used for other apps until the painting is done....

It's the trim operation that I was trying to avoid. Personal preference I guess.

Several years ago at a previous employer we had tried to model an optical system error that was caused by a rotating penta prism that was decentered and tilted about the rotational axis. Modeling the beam as a part within a complex optical path was a mess. I'm really spoiled using the Raytrace software but I"ll do without a lot of other things to have it. The penta problem was the demo I had asked for at an Assembly Expo and seeing the sales engineer just drag the prism out of place rerun the raytrace sold me.

Harold
SW2008 SP1.0 OPW2008 SP0.0

http://www.lumenflow.com

 

[lumenharold]

Your tree is much cleaner than the one I generated as I rarely use surfaces. Again, personal preferences but this time one that may slow me down! I learn something new everyday (if I pay attention).

For kicks I applied optical properties to the model you posted and ran a raytrace. The results look different than your model but I realize you are demonstrating a method, not designing an optical system. jpeg attached.

Harold
SW2008 SP1.0 OPW2008 SP0.0
www.lumenflow.com

 

[lumenharold]

Just for reference, this is the quickie model I built to try my approach.

Harold
SW2008 SP1.0 OPW2008 SP0.0
www.lumenflow.com

 

[halfdog]

Wow, thanks guys for the prompt input.

I think I understand what you have both described.

Unfortunately I'm running SW2007 and can't open your sample. But I will be playing with your ideas this morning.

Mabye some more ideas will keep coming. This type of thing was so easy in 2D autocad. Much trickier in 3D solids.

Thanks again,

Ken

 

[drawoh]

halfdog,

I answered on the original thread. Try out my suggestion. It works.

I attach non-functional blobs to assemblies. On an optical system, I attach a Field Of View (FOV). I add the mechanical parts around the field of view. I can verify that I am not blocking light anywhere. I can test the geometry of complex mirror scanners. On SW2007, you can specify that a given part in your assembly should not show up on the BOM.

Take the case that you have a lens aimed at a mirror. The light entering or leaving the lens has some divergence angle. I model the FOV by drawing a section view and revolving. As noted in the other post, you can extrude with a draft angle, but I find this less convenient.

Next, I select the mirror face, and I create a plane at it. Now, I can mirror my FOV about the mirror plane. I will have to trim the beams that are on the opposite sides of the mirror.

At the assembly level, I can change the mirror angle and observe the new position of the output beam. For any mirror position, I can see the FOV pattern on the mirror.

JHG

 

[APPENG]

Dog,

I do this alot actually sorry i didnt see your post earlier.. what I do when I need to create this is create the cone of light straight however long it needs to be, then i create a plane where the first mirror is located at the precise angle it will be. I will use the split part command to split the cone of light into two pcs. the reorient the cut peice so that its coincident to mirror face, create the next plane, cut the light cone again.. etc etc.. i have a nice example if you can tell me where to send it.

Regards,
Jon
jgbena@yahoo.com

 

[CorBlimeyLimey]

APPENG ... Any chance you can post it here for others to benefit from?

 

[APPENG]

Sure.. where should i put it? its been a while since I've been here and forgot the procedure.


Regards,
Jon
jgbena@yahoo.com

 

[APPENG]

Oh I found where to upload it.. here is the file

hope that helps

Regards,
Jon
jgbena@yahoo.com

 

[APPENG]

Ok, now that I have the file uploaded i suppose a little explaination is in order.

I created a sample here simulating a projector shooting a rectangular light cone at a divergence of 5 degrees. I created a sketch outlining where the mirrors are going to be located and used those to define center of the mirror and subsequently to define axes, and planes that represent the mirror faces.

Next I used the first plane to cut the solid. INSERT/FEATURES/SPLIT. Select the "Cut Part" button then click on both peices of the solid so that they both remain when the command is complete.

use the INSERT/FEATURES/MOVE command to relocate the light cone so that its edges match the first piece.

use the second plane to cut the solid again in the same fashion. and repeate the procedure for moving it into position.

As an added touch you can change the color properties to show the bodies transparently.


Regards,
Jon
jgbena@yahoo.com

 

[APPENG]

OK LOL!

I have received some comments on this and what i was trying to do was to just show the method, i wasnt trying to be "optically correct" with the angles of reflection, however, someone asked that I provide the model in 2007 format so I went ahead decided to create one that was corrected for the reflection angles! lol. Here is the model for your review.

This model shows two methods for doing this.

1 splitting with a plane and moving the light cone into position.

2. splitting with a sketched line and moving the light cone.



Regards,
Jon
jgbena@yahoo.com

 

[lumenharold]

No kidding? I used OptisWorks Add-In to apply optical properties to your original model and light comes out where it is supposed to....

Harold
SW2008 SP2.0 OPW2008 SP0.1
www.lumenflow.com

 

[halfdog]

Thanks so much. This seems to work, and work well. I knew there had to be a better way! Ken

 

[APPENG]

Thanks for the star.. you mean to tell me that it was right the first time? This guy emailed me and told me that i had to change how it works from the original model so if its wrong.. let me know!!!



Regards,
Jon
jgbena@yahoo.com

 

[lumenharold]

I suppose if a person wanted to get really picky, not every edge lined up properly but who cares? As you said, the thread is about demonstrating a method. If accuracy is everything, buy an optical modeling add-in. Our business here is photonics so buying the package saves us a great deal of time. Of coarse we use it for more than tracing the light path so the cost is well justified.

I've attached a jpeg of the most recent model you did.

Harold
SW2008 SP2.0 OPW2008 SP0.1
www.lumenflow.com