Principles of Optical Rangefinders

Optical rangefinders are instruments based on optical principles, widely used in measurement, surveying, and engineering. This article explains three common optical ranging methods: triangulation, phase measurement, and time-of-flight, and discusses their pros and cons.

1. Triangulation

Triangulation uses geometric relationships: measure two angles and a baseline to compute distance with trigonometry. Suitable for medium to long ranges and multi-point measurements.

2. Phase measurement

Phase measurement uses phase shifts of coherent light to measure distance with very high resolution, suitable for short-range precision but sensitive to environmental disturbances.

3. Time-of-flight

Time-of-flight measures the round-trip time of light pulses; distance = time × speed of light / 2. It offers long-range capability and high accuracy but requires fast timing systems.

Applications include autonomous driving, virtual and augmented reality, smart cities, and surveying. Future directions include integrated, remote-capable devices and multimodal sensor fusion for improved robustness.