21. Other important innovations include the integrated photodiode FET receiver and the engineering of GaInAs focal-plane arrays. 22. The light meter used a dual-concentric segmented silicon photodiode to provide spot or center-weighted readings. 23. The thermoreflected signal is then measured by a photodiode which is connected to a RF lock-in amplifier. 24. This combination of R and C integrates the photoresponse over time and thus lengthens the impulse response of the photodiode . 25. The scattered light is captured by a photodiode , which produces an electronic signal that is converted to a turbidity. 26. Above the main photodiode is a second photodiode that is used to sense and regulate the power of the laser. 27. Above the main photodiode is a second photodiode that is used to sense and regulate the power of the laser. 28. The towers are read out by wavelength-shifting optical fibers in a shashlik geometry coupled to an avalanche photodiode . 29. The light is channeled through the a-Si photodiode layer where it is converted to a digital output signal. 30. As a photodiode , an LED is sensitive to wavelengths equal to or shorter than the predominant wavelength it emits.
