Absorbing filter to flatten gaussian beams

Area of Science:

• Optics and Photonics
• Materials Science

Background:

• Laser beams often exhibit a Gaussian intensity profile, which can be undesirable for certain applications.
• Uniform laser beam profiles are essential for precise laser processing and measurement.

Purpose of the Study:

• To develop an absorbing filter capable of flattening the Gaussian intensity profile of a laser beam.
• To fabricate and characterize a thin tantalum film filter for laser beam shaping.

Main Methods:

• Fabrication of a thin tantalum film using direct current (dc) magnetron sputtering.
• Utilized substrate masking and motion during sputtering to control film thickness and profile.
• Developed a predictive model for filter production, correlating process parameters with film characteristics.

Main Results:

• Achieved a filter with a flat output profile within +/-3% uniformity over a 2.2 mm diameter.
• The filter demonstrated a transmission of 60% of the peak intensity of the original Gaussian beam.
• The developed model accurately predicted the film profile and filter performance.

Conclusions:

• The developed dc magnetron sputtering technique with masking and motion is effective for creating laser beam-flattening filters.
• The fabricated tantalum filters provide a highly uniform intensity profile, suitable for advanced laser applications.
• The predictive model aids in optimizing the filter fabrication process for desired performance.