# Beam Divergence from non-circular laser beam

nordmoon

## Homework Statement

The laser beam is not a point source. It is known that it has a rectangular shape with a divergence of 30 mrad x 1 mrad. I would like to know how large my laser lobe will be at a distance of 250 mm from the laser source.

## Homework Equations

I think you can use trigonometri for a triangle. tan(A) = opposite/adjacent

## The Attempt at a Solution

The angle of the rectangle will be half of angle of the divergence spread since the divergence is linear.

opposite = adjacent * tan(A), thus

opposite_height = 250 mm * tan(15mrad) = 3.75 mm
opposite_width = 250 mm * tan(15mrad) = 0.125 mm

Thus, the laser beam or lobe should have the size of 2*3.75 mm x 2*0.125 mm = 7.5 mm x 0.25 mm at a distance of 250 mm from laser source.

Correct?

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