Laser optics puzzle

[dgoulian]

I am trying to construct an inexpensive laser flatness detector to bring on my trip to Egypt.

Because of their optics, lasers all tend to be round, so the beam will never exit at the surface that it rests on (yes, you can aim the laser below the edge of the surface, but that won’t work for inner surfaces).

Is there a way to refract the beam so that it skims the surface of and object? Attached diagram illustrates my question.

 

[FireMyLaser]

I don't know how you intend for this device to detect flatness, but whatever.

 

[dgoulian]

Seems reasonable, but I suspect details on the the mirror design you propose would be complex. Care to show zoomed in detail on that mirror?

 

[Encap]

Google "laser flatness measurement" and see how it is done in the real world and the equipment and techniques of doing.
No need to attempt to "reinvent the wheel".

 

[FireMyLaser]

Not complicated at all. Just a front surface mirror with the edge ground to a sharp 45 degree angle.
Or you can get the exact mirror from a dvd optical assembly.

 

[dgoulian]

OK, a contemptuous in tone but useful. Thanks.

 

[gazer101]

If you can make a sturdy rig off the edge of the material whose flatness you are trying to measure and make a laser mount on it that's parallel to the laser, you could just mount your laser normally and at a lower height

 

[dgoulian]

If I'm understanding your answer correctly, that would not work for interior surfaces (see original attached diagram).