Introduction to Scanning-Slit Profilers0 pages

3.3 Introduction to Scanning-Slit Profilers
The scanning slit beam profiler moves two narrow orthogonal slits in front of a linear photo-detector
through the beam under analysis. Light passing through the slit induces a current in the detector.
Thus, as the slit scans through the beam, the detector signal is linearly proportional to the spatial beam
irradiance profile integrated along the slit. A digital encoder provides accurate slit position. The photoinduced current signal is digitized and analyzed to obtain the beam profile in both X and Y from the two
orthogonal slits.
The slit apertures act as physical attenuators, preventing detector saturation for most beam applications.
High dynamic range amplification allows operation over many orders of magnitude in beam power.
From these profiles, important spatial information such as beam width, beam position, beam quality, and
other characteristics are determined. This technique can accommodate a wide variety of test conditions.
Because slit scanners measure beams at high powers with little or no attenuation, they are ideal to profile
beams used in material processing.
3.3 Beam Profile
Carbon dioxide (CO2) lasers are widely used in materials processing, and have a 10.6 micron wavelength
that cannot be profiled with most cameras. Slit scanners, therefore, provide an convenient means of
measuring high-resolution CO2 lasers with powers up to and exceeding 1000 watts.
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