The present paper reports on the design and performance of a scanning, photon-counting laser altimeter, capable of daylight operations from aircraft cruise altitudes. In test flights, the system has successfully recorded high repetition rate returns from clouds, soils, man-made objects, vegetation, and water surfaces under full solar illumination. Following the flights, the signal was reliably extracted from the solar noise background using a Post- Detection Poisson Filtering technique. The passively Q-switched microchip Nd:YAG laser measures only 2.25 mm in length and is pumped by a single 1.2 Watt GaAs laser diode. The output is frequency-doubled to take advantage of higher detector counting efficiencies and narrower spectral filters available at 532 nm. The transmitter produces several microjoules of green energy in a subnanosecond pulse at rates approaching 10 kHz. The illuminated ground area is imaged by a 14-cm diameter, diffraction-limited, off-axis telescope onto a segmented anode photomultiplier. Each anode segment is input to one channel of fine range receiver (5-cm resolution), which records the times-of-flight of individual photons. A parallel coarse receiver provides a lower resolution (greater than 75 cm) histogram of all scatterers between the aircraft and ground and centers the fine receiver gate on the last set of returns.