I How do I stretch a laser from a beam into a sheet?

[LightningInAJar]

TL;DR

How do I stretch a laser from a beam into a sheet? Cylindrical lens?

I would like to fan out a laser pointer's beam into a sheet of light, so basically stretch it along a single axis so it creates a plain. I wasn't sure if a cylindrical lens was the right tool for the job? And I figure I might need a few laser pointers all piped into it to ensure enough light is left after it is stretched.

 

[DaveE]

TL;DR: How do I stretch a laser from a beam into a sheet? Cylindrical lens?

I wasn't sure if a cylindrical lens was the right tool for the job?

Yes, most likely. Maybe two if you want 1D collimation.

 

[sophiecentaur]

TL;DR: How do I stretch a laser from a beam into a sheet? Cylindrical lens?

And I figure I might need a few laser pointers all piped into it to ensure enough light is left after it is stretched

A very cheap laser level will have an optional end cap for the output which gives a projected straight line. I used to have one but I never actually looked at what was in that cap. (Shame on me!!!! - very unPF)

TL;DR: How do I stretch a laser from a beam into a sheet? Cylindrical lens?

stretch it along a single axis so it creates a plain.

Reading this again suggests you need a spreader with circular symmetry. A cylindrical lens would only work along one axis (as my quoted laser line source, above). A simple diffuser could work but spreading the laser power over a large area would make it very dim. OR do you mean you want to produce a 'sheet' as the light goes through a smoky medium?

 

[tech99]

I think you might use a Galilean telescope arrangement. First a concave lens to expand the beam diameter, followed by a large cylindrical lens to spread the beam in the one plane.

 

[Baluncore]

Use a cylindrical lens with a vertical axis, to convert the dot on a wall from a laser level, into a horizontal line on the wall.

 

[tech99]

The initial beam from the laser must have finite diameter for it to work I think, that is why I suggested a first, round concave lens as a spreader. The final lens need to be concave cylindrical.

 

[Ibix]

Worth asking why @LightningInAJar wants this, to put some constraints on reasonable solutions.

 

[DaveE]

The initial beam from the laser must have finite diameter for it to work I think, that is why I suggested a first, round concave lens as a spreader. The final lens need to be concave cylindrical.

It would be quite unusual for a laser to be converging away from the exit. Normally the beam waist will be near the aperture, and in expensive lasers at a specified location. It will have a predetermined diameter. Although all of this gets messy with cheap or diode lasers. in any event it's the (sort of) far field divergence in the two planes that is the real point here.

As I understand the "sheet" that the OP wants, it should have increased divergence in one plane, and minimal divergence in the other plane (normal to the sheet). So, you could add a telescope in the normal plane (for a thicker sheet), but I wouldn't add a simple lens. That would create a "wedge".

Also, this is probably a diode laser which will have a fast and slow axis (i.e. different divergence in orthogonal planes). So the orientation of the source may be worthwhile consideration.

 

[LightningInAJar]

A very cheap laser level will have an optional end cap for the output which gives a projected straight line. I used to have one but I never actually looked at what was in that cap. (Shame on me!!!! - very unPF)

Reading this again suggests you need a spreader with circular symmetry. A cylindrical lens would only work along one axis (as my quoted laser line source, above). A simple diffuser could work but spreading the laser power over a large area would make it very dim. OR do you mean you want to produce a 'sheet' as the light goes through a smoky medium?

No smoky medium. I would like to create a plain of laser light to take video of rain water or snow falling through it as a little art project.