Laser rangefinders have numerous applications and are used, for example, to measure rooms and buildings in the construction sector and for distance measurement in industry. In most cases, the devices use a continuous laser beam with a modulated intensity and measure the phase shift of the laser beam reflected by the object in comparison to the output beam (phase measurement process). Laser rangefinders use sensitive avalanche photodiodes that enable them to cover ranges of up to 200 meters.
For measuring the phase shift, avalanche photodiodes enable the reflected signal from the measuring object to be mixed with the modulation frequency. The ability to trace the operating point of the APD synchronously with the modulated laser signal means that the detected and sent signals can be multiplied directly in the APD.
First Sensor's avalanche photodiodes (APD) are optimized for various wavelengths from blue (400 nm) to infrared (1064 nm). Series 8 and Series 9 have their highest sensitivity at 650 to 850 nm or 905 nm and are used in many laser rangefinders. Series 10 is particularly suitable for all applications using Nd:YAG laser beam sources at 1064 nm. If particularly high amplifications are required, there are also hybrid solutions available that further amplify the APD signal. In this case, the integrated amplifier is optimized for the photodiode and enables compact structures as well as very high signal-to-noise ratios.