Optical Filter and Laser Ranging|Maxoptics in China

Optical Filter and Laser Ranging

Products

Principle of Laser Rangefinding
1. Pulsed laser ranging: The laser emits extremely narrow light pulses to the target → the reflected light returns, and a timer measures the time of flight (TOF). Formula: Distance = 2c × t, where c is the speed of light and t is the round-trip time. Features: long-range measurement: from a few meters to several kilometers or tens of kilometers, fast speed. Suitable for: rangefinders, surveying, security, drones, and autonomous driving.
2. Phase-based laser ranging: emits modulated continuous light and measures the phase difference between emission and reception. It has high accuracy but is for short distances (tens to a few hundred meters) and is mostly used in: total stations, precision ranging.
3. Flight Time Camera TOF: Area array imaging, simultaneously measuring the distance of the entire image. Mostly used for: obstacle avoidance, 3D perception.
Typical optical path design and filters
Emission optical path: pulsed laser → collimating lens → emitted light → target; Laser: 905nm / 1064nm / 1550nm; Lens: compresses the light into a narrow beam to increase range; Receiving optical path (core): target reflected light → receiving lens → filter → photodetector (APD).
The main type of optical filter used in laser ranging is a narrow bandpass filter NBPF (or bandpass BPF). Its function is to only allow the laser wavelength to pass through, blocking sunlight, lamp light, and stray light, thereby improving the signal-to-noise ratio → measuring farther, more stably, and resisting strong light; common filter wavelength bands are 905 nm, 1064 nm, and 1550 nm.
Core Technical Parameters of the Optical Filter:
1. Central wavelength CWL: 905nm, 1064nm, 1550nm.
2. Bandwidth FWHM: standard ranging: 10~20nm, long distance / strong light resistance: 5~10nm.
3. Transmittance Tmax and Blocking OD.
Maxoptics.cn uses ion beam assisted deposition technology and ion beam sputtering deposition technology to research and produce optical filters for laser ranging. The core wavelengths are 905nm, 1064nm, and 1550nm; the transmittance is greater than 90%, and the bandwidth can be adjusted from 5nm to 30nm according to customer requirements; the film structure is dense, and the center wavelength is confirmed to have no drift during operation, making it capable of withstanding harsh working environments.