Development of a spatially dispersed short-coherence interferometry sensor using diffraction grating orders.

Area of Science:

• Optical Engineering
• Metrology
• Manufacturing Technology

Background:

• Modern manufacturing demands rapid, high-precision quality control for increased throughput.
• Existing metrology systems face challenges in achieving both speed and accuracy for process feedback.

Purpose of the Study:

• To present a novel, compact sensor configuration for high-speed surface profile measurement.
• To enhance process-oriented precision metrology for manufacturing applications.

Main Methods:

• A spatially dispersed short-coherence interferometry sensor was developed.
• A diffraction grating was utilized as a beam splitter/combiner, employing zeroth and first-order diffractions for reference and measurement arms.
• The system was configured as a compact Michelson interferometer with reduced optical path length.

Main Results:

• The sensor effectively measures surface profiles with high repeatability.
• Step-height repeatability was determined to be within the range of 27 nm to 22 nm across tested specimens.
• The innovative design demonstrated its efficacy in precision metrology.

Conclusions:

• The developed sensor offers a compact and efficient solution for rapid surface profile measurement.
• This technology supports advanced quality control in manufacturing by providing faster inspection and valuable feedback.
• The use of diffraction orders in a Michelson interferometer configuration represents a significant advancement in precision metrology.