Detailed Testing of Laser Pulse Width and Repetition Rate

Pulse width and repetition rate are two core time‑related indicators for pulsed lasers. Pulse width defines how long a single laser pulse lasts, while repetition rate indicates how many pulses are emitted per second. These two parameters directly determine the application scenarios and performance limits of lasers.

Accurate measurement of these parameters has become a critical part of laser quality control for industrial processing, medical aesthetics, remote sensing and other fields.

01 What Are Pulse Width and Repetition Rate?

Pulse Width

Pulse width refers to the duration of a single laser pulse, commonly measured in nanoseconds (ns), picoseconds (ps), or femtoseconds (fs).

• Q‑switched lasers: typically deliver nanosecond‑level pulse width

• Mode‑locked lasers: generate ultrashort pulses at picosecond or even femtosecond levels

A narrower pulse width means higher temporal energy concentration and higher peak power, suitable for ultrafast‑phenomenon research and precision machining.

Repetition Rate

Repetition rate is the number of laser pulses output per unit time, expressed in Hertz (Hz) or kilohertz (kHz).

Relationship between the two parameters: Given the same average power, a higher repetition rate corresponds to lower single‑pulse energy, and vice versa.

• High repetition rate → low single‑pulse energy: ideal for high‑speed processing

• Low repetition rate → high single‑pulse energy: suitable for laser cleaning, shock peening and similar applications

02 Standard Framework for Testing

China has established a standard system for measuring time‑domain parameters of pulsed lasers:

• GB/T 41572‑2022 Measurement methods for main time‑domain parameters of pulsed lasersThe primary reference standard, implemented in February 2023. It applies to lasers with pulse widths ranging from 3 fs to 0.25 s, and specifies measurement approaches for pulse rise/fall time, pulse width (photodetector method, autocorrelation method, FROG, SPIDER), pulse repetition rate and other parameters.

• GB/T 15175 Test methods for main parameters of solid‑state lasersSets testing requirements for pulse width and repetition rate.

• GB/T 7247.1‑2024 Safety of laser products seriesCovers testing requirements for laser safety classification.

03 Main Testing Methods

Pulse Width Measurement

1. Photodetector Method: A high‑speed photodetector paired with an oscilloscope captures pulse waveforms for direct pulse‑width readout.

2. Autocorrelation Method: Used for femtosecond‑level ultrashort‑pulse characterization.

3. FROG / SPIDER: Retrieve both pulse width and phase information, applied for analysis of complex pulse behaviours.

Repetition Rate Measurement

1. Frequency Counter Method: Direct measurement of pulse repetition frequency.

2. Oscilloscope Method: Derive repetition rate by calculating time intervals between pulses from waveform traces.

04 Testing Procedure and Turnaround Time

1. Sample Preparation & Document SubmissionClients provide the laser under test together with its technical specification sheet.

2. Preliminary Evaluation & Test‑plan FormulationIdentify applicable standards and define test scope.

3. Laboratory MeasurementHigh‑speed photodetectors and oscilloscopes acquire pulse waveforms; frequency counters measure repetition rate. Autocorrelators and other instruments are deployed when ultrashort‑pulse measurement is required.

4. Data Compilation & Report IssuanceTest data is analysed, and an authoritative test report is issued.

Turnaround time: Normally 7‑15 working days, subject to project complexity.

05 Our Services

As a professional third‑party laser testing laboratory, we offer the following services for pulse width and repetition‑rate characterisation:

• Accredited competence: CNAS‑ and CMA‑recognised laboratory, delivering globally‑recognised test reports.

• Strong testing capability: Over 70 accredited laser‑related standards; pulse‑measurement resolution down to picosecond level.

• Full‑parameter coverage: Wavelength, power, divergence angle, pulse width, pulse repetition rate and other complete laser parameters.

• Compliant standards: GB/T 41572‑2022, GB/T 15175 and other applicable specifications.

• Wide product coverage: Industrial lasers, medical lasers, aesthetic lasers, consumer‑grade lasers and research‑grade lasers.

• Proven expertise: Ten‑year industry experience with more than 10 000 completed projects, serving listed companies, research institutes and SMEs.