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92 Thorlabs Beam 4.0
There are no focussing elements listed because the necessary lens depends on the
given laser beam diameter. Finding the right lens is just a short calculation away.
Assuming that the beam diameter should not drop below 100 microns at the focus
point to ensure a reliable measurement the following formula gives the least focal
length of the lens:
where d
beam
is the beam diameter of the laser system and the operating
wavelength.
Round it up to the next available focal length (e.g. 50, 100, 150, 200, 300 mm).
Longer focal lengths generate waist diameters above 100 microns and relax the
measurement requirements to the Camera Beam Profiler.
In general a focussing lens with 100 mm to 150 mm (4'' - 6'') is quite common for the
desired use. This is a good choice for laser beam diameters between a few hundred
microns and a few millimeters (0.2'' to a few inches).
Be sure to order the appropriate AR-coating for your wavelength range of interest.
You can find a find a broad selection of different lenses at Thorlabs.com.