Position and displacement sensing with shack-hartmann wave-front sensors.

Area of Science:

• Optical Metrology
• Wave-front Sensing
• Precision Measurement

Background:

• Traditional position-sensing devices have limitations in accuracy and complexity.
• Wave-front sensing offers potential for high-resolution spatial measurements.
• Shack-Hartmann sensors are typically used for optical system characterization.

Purpose of the Study:

• To propose and demonstrate the Shack-Hartmann wave-front sensor as a viable position-sensing device.
• To determine object coordinates using Zernike coefficients from detected wave fronts.
• To measure the position of both point-like and moderately extended objects.

Main Methods:

• Utilized a Shack-Hartmann wave-front sensor to detect emitted wave fronts.
• Calculated object coordinates from modal Zernike coefficients.
• Employed off-the-shelf CCD cameras, relay optics, and diffractive microlens arrays for experimentation.

Main Results:

• Successfully determined coordinates of point-like objects via Zernike coefficients.
• Measured the position of the luminous centroid for extended incoherent objects.
• Achieved axial positioning accuracy of 74 micrometers root mean square (rms) at 300 mm.
• Attained angular accuracy of 4.3 microradians rms.

Conclusions:

• The Shack-Hartmann wave-front sensor is effective for precise position sensing.
• The method allows for accurate measurement of both axial and angular positions.
• Inexpensive components enable high-accuracy measurements, making the technique broadly applicable.