Bending Light?

[pschlosser]

I am trying to figure out if one of these mirrors is curved? Or is it just that the two mirrors are not in parallel? The beam seems to end, on the right side, suggesting its bouncing back and forth to infinity.

Any comments?

 

[Eudaimonium]

For the beam to bounce back and forth maximum number of times (permittable by divergence) the mirrors MUST be in parallel - if they were not, the beam would not bounce back three times in the same path.

I dunno, but that piece of glue holding the upper mirror shines really bright.

Where did you pull this image from? Any context?

 

[jArdi]

For the beam to bounce back and forth maximum number of times (permittable by divergence) the mirrors MUST be in parallel - if they were not, the beam would not bounce back three times in the same path.

I dunno, but that piece of glue holding the upper mirror shines really bright.

Where did you pull this image from? Any context?

google image search points here:
Argon Laser Switchmode PSU Hacking

still got me stumped though

 

[pschlosser]

For the beam to bounce back and forth maximum number of times (permittable by divergence) the mirrors MUST be in parallel - if they were not, the beam would not bounce back three times in the same path.

I dunno, but that piece of glue holding the upper mirror shines really bright.

Where did you pull this image from? Any context?

Another poster found the site, but it offers little on this image. This was an image of playing with a laser after author got it working.

I'm thinking IF the two mirrors were in parallel, then each successive bounce of the beam should not be getting closer together. If they were truly parallel, then the angle of the reflection should not be changing. That's what has me scratching my head. :thinking:

Those look like front surface mirrors, but if they're not, then maybe the refractive index of the substrate is altering the angle at each reflection.

Divergence appears small enough to not be a factor, here. The glue looks like masking tape, to me, hanging off the side of the substrate and illuminated from behind.

I don't know. The image caught my eye because it seemed to defy my understanding.

 

[Eudaimonium]

Well, for starters it most apsolutely definitely does not bounce back and forth infinite times, since somewhere around 100th time the divergence would be too great to contain the beam to the area of one mirror. So basically the moment you'd hit the sweet spot, mirrors would appear to be LED illuminated, and nothing special would happen.

Question does remain what the hell does that image represent. Maybe somebody was just simply playing around with mirrors, did that, snapped a picture, call it a day? Beam obviously goes somewhere, maybe one of the mirrors has a hole or something? Or a stop, of some kind?

 

[BShanahan14rulz]

Some fun with the laser, some oddments from my box of interesting optical bits and a can of artificial smoke

I doubt that a tinkerer of that quality would consider first surface mirrors to be "interesting optical bits."

http://www.electricstuff.co.uk/01410001.JPG < in this picture, you can see the two optics in question, still behaving strangely.

 

[pschlosser]

I doubt that a tinkerer of that quality would consider first surface mirrors to be "interesting optical bits."

http://www.electricstuff.co.uk/01410001.JPG < in this picture, you can see the two optics in question, still behaving strangely. large line-width diffraction gratings?

Hmm, I think you're right about the diffraction grating idea. That could explain the unexpected angles of reflection.

 

[cev1]

A grating would produce other modes. The mirrors are not parallel. If they are off by some small angle, each double bounce bends the light by the same angle. With minimal alignment, the beam will eventually hit a mirror at normal incidence and back-reflect out along the entrance path.

 

[Bob_Boyce]

A grating would produce other modes. The mirrors are not parallel. If they are off by some small angle, each double bounce bends the light by the same angle. With minimal alignment, the beam will eventually hit a mirror at normal incidence and back-reflect out along the entrance path.

I agree with that as well. That appears to be what the photo is of. Not difficult to do at all with proper alignment of the mirrors.

Bob