Flat-field correction (FFC) is essential for addressing relative illuminance roll-off in optical imaging systems, a calibration process that requires capturing an image of a uniform light source. In imaging systems capable of mimicking or measuring SPH, CYL, AXIS, such as those used for eye prescriptions, the number of images required to collect for FFC increases with each lens adjustment. We propose a numerical method that uses a few core images to synthesize FFC images for various configurations, reducing data requirements substantially. This method was validated on two imaging systems with differing optical alignment quality, achieving relative illuminance falloff of less than 2% with only 5% the amount of the original data.
White balance calibration ensures colorimeter measurement accuracy on a display, but changing of display luminance can cause spectral drift, leading to the need of recalibration. Mimicking a micro-LED or OLED panel and using a colorimeter, we compare color error sources, finding spectral drifts to be a major contributor to the error. This finding highlights the need for high-speed recalibration in mass production.
A single optical system with features of both automatic calibration and multiple configurations has been developed for high-resolution wavefront measurements. With the configuration of fine measurements, the tester can scan a large area to obtain mapping data with detailed local wavefront information of the sample. The tester can also take a fast snapshot of wavefront measurement by using the configuration of coarse measurements.
Existing position sensors have limitations such as single function, limited range, slow speed, and low resolution. Emerging applications need sensors that work in variable and unpredictable environments with multiple dimensions. The proposed system offers advantages that outweigh these existing sensors. It has a unique design that combines optical imaging and laser techniques to provide a full capability of 6-dimensional sensing with only one sensor system, covering a wide range for both near and far fields with both high spatial and angular resolutions. The sensor can also easily extend its capability by modifying optics and laser or exploiting new optical components. In addition to the above six degrees of freedom, the sensor has potential to detect additional information such as the speed and acceleration of the target for both linear translation and rotation, by simply record the time lapse between events. Therefore, our technique has broad potential applications. It can also facilitate technical advances in metrology, biomedicine, and scientific research.
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