Industrial optical length measurement is known to deliver fast and reliable measurement results with ultra-high precision over long and short distances. Encoders, LIDAR systems, laser scanners and laser rangefinders are examples of optical distance measuring devices. First Sensor develops and manufactures advanced detector solutions for these optical distance measuring devices. The company optimizes its photodiodes to meet customers’ unique requirements, for instance, with reference to capacitance, rise time, amplification and sensitivity.
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Sensitive Avalanche Photodiodes for Laser Rangefinders. Image Credit: First Sensor
Laser Rangefinders
Laser rangefinders are used in a wide range of applications; for instance they are used to measure buildings and rooms in the construction sector as well as for distance measurement in industry. In majority of cases, laser rangefinders employ a continuous laser beam with a modulated intensity and determine the phase shift of the laser beam reflected by the object as opposed to the output beam (phase measurement process). In addition, these devices use sensitive avalanche photodiodes that allow them to cover ranges of up to 200 meters.
Sensor Solutions for Laser Rangefinders
First Sensor’s avalanche photodiodes (APDs) are optimized for different wavelengths ranging from blue (400 nm) to infrared (1064 nm). Series 8 and 9 are employed in many laser rangefinders and have their highest sensitivity at 650 to 850 nm or 905 nm. In particular, Series 10 is ideal for all applications where Nd:YAG laser beam sources at 1064 nm are used. Series 12 is optimized for the red wavelength range and can be operated with low bias voltages. It provides very fast response times.
Laser Scanners and LIDAR Systems
In LIDAR systems and laser scanners, the environment is often scanned with a pulsed laser beam and the time taken for the signal to reflect from the object and back to the detector is determined. The Time-of-Flight (TOF) reflection time measurement can be employed over distances ranging from one meter up to several kilometers.
In order to increase the systems’ range, very short laser pulses in the invisible NIR range are employed. These allow for a higher laser power when compared to continuous wave lasers and at the same time complies with eye safety requirements. During the scanning process, individual distance points within an aggregate of points are collected by the systems and based on these points three-dimensional images of the environment can be calculated. The laser scanners use deflecting mirrors to deflect the laser beam, enabling them to attain very wide fields of vision.
There are some LIDAR systems that even rotate around their own axis and provide 360° all-round visibility. Modern devices are capable of achieving very high data rates with more than one million distance points per second.
Our Sensor Solutions for Laser Scanners and LIDAR Systems
Measuring systems are based on the reflection time process using light pulses of different intensity in the nanosecond range. For such systems, First Sensor provides highly sensitive APDs with internal amplification across wide bandwidths and a wide dynamic range. In order to attain the high spatial resolutions needed in optical LIDAR systems, First Sensor develops APD arrays that contain multiple sensor elements using, for instance, 8, 16, 5 x 5 or 8 x 8 pixels. Development modules that ease the process of detector testing are also available for the matrix arrays.
Products include:
- Series 11: APDs with enhanced blue sensitivity
- Series 12: APDs with enhanced red sensitivity
- Series 8r: APDs with enhanced red/green sensitivity – 650 nm
- Series 8: APDs optimized for high cut-off frequencies – 650-850 nm
- Series 9: APDs with enhanced NIR sensitivity – 900 nm
- Series 9.5: APDs with enhanced NIR sensitivity – 950 nm
- Series 10: APDs with improved NIR sensitivity – 1064 nm
- Customized sensors, modules and arrays
This information has been sourced, reviewed and adapted from materials provided by First Sensor AG.
For more information on this source, please visit First Sensor AG.