Multimode laser Fizeau interferometer for measuring the surface of a thin transparent plate

Area of Science:

• Optical Physics
• Metrology
• Materials Science

Background:

• Fizeau interferometers are crucial for optical metrology.
• Multimode lasers present unique interference characteristics.
• Testing thin transparent plates requires precise optical path control.

Purpose of the Study:

• To investigate interference fringe formation using a multimode laser in a Fizeau interferometer.
• To analyze the conditions for obtaining interference fringes with thin transparent plate samples.
• To propose methods for managing interference in systems with multiple reflective surfaces.

Main Methods:

• Utilized a Fizeau interferometer with a multimode laser.
• Examined interference fringe generation based on optical path difference.
• Investigated the role of laser effective cavity length in fringe formation.

Main Results:

• Interference fringes are observed only when the optical path difference is twice a multiple of the laser's effective cavity length.
• This condition is specific to the multimode linear laser operation.
• For three parallel surfaces, fringe control is achieved by adjusting surface separations or selecting an appropriate laser.

Conclusions:

• The effective cavity length of a multimode laser dictates interference fringe visibility in Fizeau interferometry.
• Precise control over optical path differences is essential for accurate testing of transparent plates.
• Methods exist to manage multi-surface interference, enhancing the applicability of Fizeau interferometry.