1. Overview of Laser Applications
Known as “the fastest knife”, “the most accurate ruler” and “the brightest light”, lasers are widely deployed in industrial manufacturing, medical surgery, communication sensing, scientific research and military sectors. Ranging from signal transmission in optical‑fiber communication, cutting and welding for precision machining, to refractive correction in ophthalmic surgery, the output characteristics of a laser directly determine application performance and operational safety. Laser wavelength and laser power are the two fundamental core parameters used to evaluate laser output performance.
2. Definitions of Laser Wavelength and Power
Laser wavelength refers to the specific spectral position of laser radiation, representing its “colour” or frequency property. Typical laser wavelengths include 1064 nm (Nd:YAG solid‑state laser), 10.6 μm (CO₂ gas laser), and 532 nm (green‑light laser). According to national standards, key spectral‑characteristic parameters cover peak wavelength, central wavelength, mean wavelength and spectral bandwidth.
Laser power indicates the magnitude of laser output energy. For continuous‑wave lasers, output power is measured directly with a laser power meter. For pulsed lasers, single‑pulse energy or instantaneous power is measured, from which peak power and average power can be calculated.
3. Importance of Laser Wavelength and Power
Wavelength and power are core metrics for verifying whether laser products meet performance specifications. Excessive wavelength deviation may reduce machining accuracy or cause therapeutic failure for medical laser devices. Unstable power or excessive power decay can degrade processing quality and even create safety hazards. Especially in laser safety practice, different wavelengths and power levels correspond to distinct laser hazard classes, which directly govern product classification and protection requirements under IEC 60825‑1.
4. Standard System for Laser Wavelength and Power Testing
Wavelength and power measurements shall be performed in accordance with authoritative international and domestic standards:
International Standards
ISO 13695: Methods for measuring laser spectral characteristics
ISO 11554: Test methods for laser power measurement
IEC 60825‑1: Safety of laser products
Chinese National Standards
FDA Regulation
ISO 13695 categorises lasers into three accuracy classes: broad‑band lasers, mode‑stable multimode lasers and single‑frequency lasers, and specifies corresponding measurement approaches and parameter requirements for each category.
5. Test Methods and Instrumentation for Laser Wavelength and Power
Wavelength testing is primarily carried out using optical spectrum analysers, interferometers or wavemeters, achieving measurement precision up to ±0.001 Å. Under ISO 13695, measurements shall be conducted under defined ambient conditions (temperature: 25±1 °C; relative humidity: 40‑60 %). Recorded parameters include spectral radiant power distribution, spectral bandwidth and wavelength stability.
Laser power is measured with laser power meters featuring two main receiver types: photoelectric and thermal. Photoelectric sensors deliver high sensitivity and fast response, suited for low‑power measurement. Thermal sensors offer flat spectral response and excellent stability, ideal for high‑power applications. Water‑cooled calorimeters are widely adopted for high‑power laser testing, covering measurement ranges from the picowatt level up to several kilowatts.
6. Standard Test Procedure for Laser Wavelength and Power
The standard testing workflow is as follows:
Pre‑inspection and calibration: Power meters and spectrum analysers shall be calibrated against traceable reference light sources (e.g. NIST‑traceable standards) prior to use to guarantee metrological accuracy.
Ambient conditioning: Adjust test‑lab conditions to meet specified temperature, humidity and cleanliness requirements.
Laser warm‑up: Operate the laser until it reaches stable working status.
Parameter acquisition: Perform wavelength and power measurements and record raw data.
Data analysis: Calculate metrics such as wavelength deviation and power stability, and judge compliance against relevant standards.
7. Recommended Testing Intervals for Laser Products
Recommended test frequencies vary by application scenario and regulatory obligations. Export‑oriented laser products must complete FDA registration or IEC/CB certification testing before market launch. Industrial laser equipment is recommended for annual performance verification. Medical laser devices shall undergo periodic testing as mandated by regulations to guarantee clinical safety.
