We are coming into a time when flash imaging is available for coherent lidar applications. Over the last 20 years we have developed various flash camera options. Each flash imaging camera option has benefits and drawbacks. Most of these detectors however were not developed for coherent imaging. Historically for coherent imaging scientists wanted a strong local oscillator. More recently the ability to measure Doppler shift, and the ability to measure the field, including phase, have been important aspects of coherent imaging. These recent applications will be significantly enabled by flash imaging. Measuring Doppler shift point by point on a bridge, or on an engine, or on the ground, could have some value, but if you measure it in a flash image then you can instantaneously see the vibration spatial modes across the object being imaged. Flash imaging will enable many important applications associated with area vibration measurements. Another important application will be multiple input, multiple output, MIMO, lidar imaging. An array of 32 ×32 format, or more, cameras behind multiple apertures could capture the field in high resolution. If for example we have a hex 19 set of receive apertures we would have 5 apertures across the largest dimension, and if we use multiple transmitters separated across approximately the width of the receive array, and use 32 × 32 format cameras, we can capture coherent images as large as about 300 × 300. Cameras we might consider include Geiger Mode APDs, GMAPDs, Linear Mode APDs, LMAPDs, pin diodes, and framing cameras. Spatial heterodyne coherent imaging can use low bandwidth framing cameras. GMAPDs, LMAPDs, and pin diodes can be used for temporal heterodyne. They have fast enough time response to measure range based upon the time it takes light to get to an object and return. Pin diodes may require a strong LO. GMAPDs will require a weak LO, and LMAPDs could require anywhere from a strong to a weak LO, depending on camera sensitivity.
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