Introduction

Laser rangefinding systems rely on pulsed lasers to measure distances with extreme precision. While most users focus on output energy or wavelength, one crucial—but often overlooked—parameter is pulse width. Pulse width directly impacts range resolution, timing accuracy, and signal detection performance—all of which determine how accurately a system can measure the distance to a target.

In this article, we explore what laser pulse width is, how it works, and why it matters for UAV navigation, target acquisition, LiDAR, and other laser-based measurement applications.

What Is Laser Pulse Width?

Laser pulse width, often measured in ns, refers to the duration of a single laser pulse, typically defined at Full Width at Half Maximum (FWHM). It describes how long the laser stays "on" during each pulse.

For example:

• The ERDI's ER900-03 has a pulse width of 7 ns, meaning each pulse lasts 7 billionths of a second.

• A narrower pulse width (e.g., 4–6 ns; ERDI's ER100-03 features a 6ns pulse width, while the MINI-100-03 boasts an even narrower 3.5ns) enables the generation of shorter, more concentrated energy pulses.

Why Pulse Width Matters for Measurement Accuracy

1. Time-of-Flight (ToF) Precision

Most laser rangefinders work by measuring the time it takes for a laser pulse to travel to a target and back (Time of Flight). A shorter pulse allows the system to detect the return signal with higher time resolution.

Shorter Pulse Width = Better Distance Resolution

• A 1 ns difference in timing corresponds to ~15 cm in distance (since light travels ~30 cm in 1 ns round-trip).

• Systems with shorter pulses can distinguish objects that are closer together, which is critical in obstacle detection and topographic scanning.

2. Reduced Range Uncertainty

A shorter pulse generates a sharper return signal, making it easier to pinpoint the leading edge of the pulse when it reflects off the target. This improves timing accuracy and reduces jitter, leading to more reliable distance data.

3. Better Target Discrimination

When multiple surfaces or objects are close together (e.g., in a cluttered or urban environment), a shorter pulse helps separate returns, allowing the system to differentiate between foreground and background targets.

Trade-Offs of Pulse Width

While shorter pulse widths improve accuracy, they also introduce design challenges:

• Lower Pulse Energy: Concentrating energy into a shorter time frame can require higher peak currents or more advanced driver circuits.

• Higher Cost: Short-pulse DPSS lasers may require more precise components and alignment.

• Detection Challenges: Very short pulses can be harder to detect over long ranges, especially in fog, dust, or rain.

That’s why systems like the ER400-03 (6 ns) or ER900-03 (7 ns) are designed to balance pulse width, energy output, and eye safety to optimize performance for practical applications.

Applications Where Pulse Width Makes a Difference

• UAV Obstacle Avoidance: Short pulses improve real-time detection and response.

• Laser Target Designation: Better timing precision ensures accurate locking on small or moving targets.

• Topographic Mapping: Enhanced resolution allows more detailed elevation profiles.

• Autonomous Vehicles: Faster, sharper range returns mean better situational awareness.

Conclusion

In laser ranging systems, pulse width is more than just a technical spec—it directly affects measurement accuracy, system responsiveness, and application success. Choosing the right pulse width depends on your application’s requirements for resolution, range, and environmental conditions.

If you're building or integrating a laser system, especially for UAVs, autonomous robotics, or defense applications, understanding pulse width can help you choose the right laser module—like the ER-series lasers from ERDI TECH LTD—that balances energy, speed, and precision.

Learn more about our laser products with different pulse widths: yeva@erdimail.com