Collomating through a sheet of perspex

[reggio68]

Hi everyone,

 

I'm working on a project where I need to project a sheet of light across a 14cm gap. I had an idea to use a line generator (fresnel lens) on a laser, and project the line onto the edge of a piece of acrylic so that the front (receiving) edge of the acrylic collimates the beam and the output side just presents a flat sheet of light.

 

My problem is calculating the curve required on the receiving edge (I guess it's a parabola) to make the light "straighten". I have various laser lenses on the way of different angles so I can experiment with the source, but have no idea how to calculate the angles required to refract the diverging beam from the laser back into straight light.

 

Further info, the sheet is intended to project onto 48 photodiodes. I hope to detect a break in the sheet on a particular diode (or two) hence the need for a straight beam.

 

Any help would be appreciated!