The 2151 Femtowatt Silicon Photoreceiver is ideal when you need the ultimate in low-light-level detection in the 300 to 1050 nm range. When used with a chopper and a lock-in amplifier, these receivers can easily achieve sensitivity levels in the femtowatt range. These receivers provide amazing amounts of gain and yet are easy to use, making the most difficult spectroscopy or fluorescence experiment a snap. 8-32 mounting thread. M4 metric adaptor and tool now included. Connect to a 1 MΩ oscilloscope input.