Thermal drift compensation in dark-frame non-uniformity correction for an InGaAs PIN 3D flash lidar camera

Abstract

This paper presents the expansion of dark-frame non-uniformity correction (DFNUC) techniques to include compensation for thermal drift in a 128×128 PIN diode 3D flash LiDAR camera. Flash LiDAR cameras are operated in various climates, which makes thermal compensation necessary in the dark NUC algorithm. The thermal excitation of electrons has a significant effect on the dark current in an InGaAs PIN photodetector and on the CMOS readout circuitry, thus impacting the output image. This is a well-known phenomenon in imaging sensors and various algorithms have been established to address thermal drift. This paper adapts a linear model for dark signal calibration used in infrared cameras for the calibration of a PIN diode flash LiDAR camera in both intensity and range return. The experimental process involves collecting dark frames in increments of the internal camera temperature from 22°C to 36°C using thermoelectric (TE) cooling modules. A linear trendline is developed for each individual pixel based on the average frame return, which suppresses the random temporal noise and isolates the dark signal return. The trendline helps form a model for the dark frame offset as a function of temperature, which is used for the dark-frame NUC process. The dark-frame NUC with thermal drift compensation is then evaluated by correcting dark frames at various operating temperatures. Finally, illuminated scenes captured by the camera with a 5.91ns, 842.4μJ pulsed laser at 5Hz are corrected at multiple operation temperatures to show the effectiveness of the dark non-uniformity correction algorithm.