Holographic diffractive collimators based on recording with homocentric diverging beams for diode lasers

Area of Science:

• Optics and Photonics
• Holographic Optical Elements
• Laser Beam Shaping

Background:

• Diode lasers often exhibit beam aberrations such as astigmatism and ellipticity.
• Correcting these aberrations is crucial for applications requiring high-quality laser beams.
• Existing correction methods may be complex or less efficient.

Purpose of the Study:

• To design a single holographic diffractive element for correcting diode-laser beam ellipticity and astigmatism.
• To investigate the feasibility of using off-axis blazed surface-relief holography for aberration correction.
• To evaluate the performance of the designed element with a hypothetical diode laser.

Main Methods:

• Design of a transmissive, off-axis, blazed surface-relief holographic diffractive element.
• Recording the hologram using homocentric diverging beams with spherical wave fronts.
• Correction of asymmetry aberration due to the off-axis design.
• Reciprocal testing with a collimated He-Ne laser beam.

Main Results:

• A holographic diffractive element successfully corrected astigmatism and ellipticity.
• The element was designed for a hypothetical 633 nm diode laser with significant astigmatism.
• Testing yielded a diffraction-limited beam approximately half the size of the designed aperture.

Conclusions:

• A single holographic element can effectively correct complex diode-laser beam aberrations.
• Off-axis blazed holographic design is a viable method for aberration correction.
• The developed element demonstrates potential for improving diode-laser beam quality.