APD

Avalanche Photodetector. The solid-state equivalent of a PMT, usually restricted to operation in the red, near-infrared and infrared part of the spectrum. For photon-counting applications, they are operated in the so-called 'Geiger Mode'. The device is noisier than a PMT but has greater quantum efficiency. Maximum quantum efficiencies are about 8...
Found on http://www.coseti.org/glossary.htm

APD

Avalanche Photo Diode. A type of detector used in fibre optic receivers.
Found on http://www.zoo.co.uk/~z0001325/Glossary.html

APD

USN designation for Fast Destroyer Transport [US]
Found on http://www.jedsite.info/index.html

APD

Australian Private Doctor [periodical, périodique]
Found on http://www.encyclo.co.uk/local/20895
No exact match found