Laser rangefinder Laser rangefinder

Laser rangefinder

A laser rangefinder is a rangefinder which uses a laser beam to determine the distance to an object. The most common method of distance measurement is the time-of-flight (TOF) principle, which measures the time it takes for a laser pulse sent towards an object to return to the sender.


Pulsed laser diodes and detectors (PIN-PD, APD, MPPC) from Hamamatsu have been used in laser rangefinders.

Parameter MPPC® APD PIN photodiode
Range Long Middle Short
Accuracy High High High
Readout circuit Simple Complex Complex
Operation voltage to several tens of V 100 to 200 V to 10 V
Gain 105 10 to 100 1
Temperature sensitivity Middle High Low
Response time Fast Medium Medium
Ambient light immunity Medium Medium High
Array Suitable Suitable Suitable
Gap Narrow Wide Wide
Uniformity Good Depends on the size Good

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Si photodiode

Basic detectors for rangefinders, photodiodes are suitable for short range measurement under high ambient light conditions. Their lower cost and lower voltage operation are advantageous for rangefinders. The S13773 is sensitive from the visible region to 1100 nm, and has a high-speed response of 500 MHz. Its JEDEC level is 2a. 


An APD can measure longer distances than a PIN-PD, and has high sensitivity at 900 nm.

Also available is an APD series with a bandpass filter that blocks background light, which improves the accuracy of distance measurements.


An MPPC is a device having multiple APD pixels operating in Geiger mode.

Its excellent sensitivity, which can detect extremely weak light at the photon counting level, is suitable for long range measurement.


These LDs feature high peak power at 905 nm pulsed operation.

Various types are available with different peak output power and emission widths. 

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