Calibration standard for laser beam profilers: method for absolute accuracy measurement with a Fresnel diffraction...

Area of Science:

• Optical Metrology
• Laser Beam Characterization

Background:

• Accurate measurement of laser beam parameters is crucial for various applications.
• Existing calibration methods for laser beam profilers may lack sufficient precision.
• International Standards Organization (ISO) is developing standards for laser beam measurements.

Purpose of the Study:

• To establish an absolute accuracy calibration standard for clip-level laser beam profilers.
• To validate a novel test method using Fresnel diffraction patterns.
• To assess the profiler's accuracy to the 0.3% level.

Main Methods:

• Utilized a Fresnel diffraction test pattern generated by opposed knife edges.
• Measured the pattern width using the 50% cut points of a scanning knife edge pair.
• Modeled the convolution of the scanning aperture with the diffraction pattern to correct for aperture size.

Main Results:

• Achieved an absolute accuracy measurement of the laser beam profiler to the 0.3% level.
• Demonstrated that the Fresnel diffraction pattern method is a viable calibration standard.
• Developed a method to determine the scanning aperture width.

Conclusions:

• The described test method is an acceptable calibration standard for optical profilers.
• This method supports the development of ISO standards for laser beam parameter measurements.
• The validated profiler accuracy meets stringent metrology requirements.