Spot centroid sensitivity to angle of intensity on image detector with lenslet array

Area of Science:

• Optical engineering
• Image sensor technology

Background:

• Lenslet arrays enhance image detector sensitivity but can introduce angular dependency.
• Accurate subpixel measurements are crucial for optical testing, where angular deviations pose challenges.

Purpose of the Study:

• To investigate the impact of incident angle on spot centroid position in Kodak KAI-16000 image detectors with lenslet arrays.
• To quantify the resulting spherical aberration errors and assess calibration effectiveness.

Main Methods:

• Experimental analysis of spot centroid position as a function of incident angle.
• Integration of angular dependency data to correct spherical aberration measurements.
• Comparison of scanning pentaprism test with principal test before and after calibration.

Main Results:

• A cubic dependency of spot centroid position on incident angle was identified.
• A 48 nm rms spherical aberration was found at 14° incident angle (F/2).
• Calibration reduced the discrepancy in spherical aberration between two tests from 56 nm to 8 nm rms.

Conclusions:

• The lenslet array introduces a significant, angle-dependent error in image detectors.
• Calibration based on the observed cubic dependency effectively corrects spherical aberration errors.
• This work is crucial for accurate optical metrology using lenslet-equipped detectors.