Patent ID: 9071744
Filing Date: 2015-06-30
Classification: G03B,H04N

Abstract:
1. A method, comprising: exposing each photo detector in an array of photo detectors to light from a calibration light source (CLS) having one or more of a known luminous intensity, a known geometric location with respect to the array of photo detectors, and a known correlated color temperature; measuring, for each photo detector, at a location proximate to the photo detector, a characteristic of light received at the location, the characteristic including one or both of luminous intensity and chromaticity; sampling an output signal generated by each of the photo detectors to generate a sampled calibration signal for each of the photo detectors; determining, for each photo detector, a corresponding calibration coefficient based on a comparison of the measured characteristic with an average indicated light characteristic determined from the corresponding sampled calibration signal, wherein each calibration coefficient is further based on the sampled calibration signal of the corresponding photo detector and the sampled calibration signals of one or more neighboring photo detectors near the corresponding photo detector; pulsing, through duration of a duty cycle, a light-emitting diode (LED) to expose the array of photo detectors to light output by the LED; sampling a respective analog output signal generated by each of the photo detectors in response to the light output by the LED, wherein sampling the respective analog output signal includes performing analog to digital conversion on each respective analog output signal to generate a respective sampled signal data set for each of the photo detectors; generating a corrected sampled signal data set for each of the photo detectors by using the calibration coefficients for each of the photo detectors to correct the sampled signal data set for errors, the errors relating to one or more of angular misalignment of the photo detectors, tolerance uncertainties in the performance of a photo transistor circuit, and errors induced in sampling the respective analog output signal, or in color filtering of the photo detector; and determining a spatial uniformity measure for the light output by the LED using the corrected sampled signal data set.