The 1623 InGaAs Nanosecond Optical Detector is similar to 800-1700 nm photodetectors with moderate gain and large bandwidth that many of us have built from scratch over and over again. It is ideal for use as a general purpose detector with Q-switched or CW lasers, and it's large diameter and DC response make alignment easy. The user-switchable load resistor (50Ω or 10 kΩ) lets you optimize for response time or sensitivity. Choose a nanosecond response time with 50-V/A sensitivity, or a slower response time with a higher (10,000 V/A) sensitivity. The nanosecond rise time at the 50Ω load setting is fast enough to see your Q-switched pulses. Or use the 10-kΩ resistor setting for alignment purposes and for detecting lower-power pulses and cow light. We've even included an open-circuit setting so you can choose the best gain-bandwidth combination for your application. 8-32 mounting thread. M4 metric adaptor and tool now included.