We describe high‐performance successive approximation amplitude and phase digitizers capable of resolving 1 part in 4096 in amplitude and 0.1° in phase at a rate of 50 000 points per second. They communicate with a computer workstation by DMA over a GPIO bus. The phase digitizer exhibits negligible AM to PM conversion and an input amplitude range of 70 dB. Both digitizers reside on one thick 7×9‐in. card module. The system is currently used in an electronically scanned laser microscope. We also describe a high‐precision phase calibrator and associated calibration software.