This video is a demonstration of a laser positioning system.  The reference design features the OPA3S2859 trans-impedance amplifier along with the THS4541 differential amplifier.  The reference design interfaces to a variety of dual or quad ADCs.  The demonstration physically moves an IR laser diode source relative to the avalanche photo diode detectors to illustrate how the variable gain TIA is able to adjust its gain to keep the ADC within its linear region.