Spectral stripe-based large-range chromatic confocal displacement system with nanometer uncertainty

Area of Science:

• Optics and Photonics
• Metrology and Measurement Science
• Instrumentation Engineering

Background:

• Chromatic confocal displacement systems (CCDS) are crucial for high-precision measurements.
• Existing CCDS designs face limitations in range and noise suppression.
• Developing advanced displacement measurement techniques is essential for various scientific and industrial applications.

Purpose of the Study:

• To present a novel design for a chromatic confocal displacement system (CCDS) utilizing a spectral stripe.
• To enhance measurement accuracy and range compared to existing CCDS technologies.
• To investigate the performance and feasibility of the spectral stripe approach in displacement metrology.

Main Methods:

• A novel CCDS design based on spectral stripe generation is proposed.
• Confocal light is collected, dispersed, shaped by a Powell lens, and diffracted into a spectral stripe on a detector.
• Displacement is measured by analyzing changes in the spectral stripe's position on the detector.

Main Results:

• The spectral stripe method significantly increases the pixel count for analysis, effectively suppressing random noise.
• Positional uncertainty of the spectral stripe was reduced to less than 1‰ pixel.
• Measurement uncertainty of less than 14.3 nm was achieved across a 4 mm measuring range.

Conclusions:

• The spectral stripe approach offers a new method for developing large-range CCDS with nanometer uncertainty.
• This design demonstrates superior noise suppression and positional accuracy compared to spectral profile or diffractive spot methods.
• The developed system provides a promising solution for high-precision displacement measurements in demanding applications.