Laser divergence angle and beam profile quality are core parameters for evaluating beam characteristics, directly determining the suitability of lasers in ranging, optical communication, precision machining and other applications. For laser manufacturers, research institutes and export traders, a divergence angle and beam quality test report endorsed by CMA/CNAS accreditation serves as a critical technical document for factory acceptance, research project closure and export certification.
1. Why Lasers Require Divergence Angle & Beam Profile Quality Test Reports
The divergence angle defines beam collimation and far-field energy density. A smaller divergence angle limits beam spot expansion after long-distance transmission, making such lasers suitable for LiDAR ranging, free-space optical communication, precision machining and similar applications. Semiconductor lasers with larger divergence angles are commonly used in optical read/write heads or short-range sensing.
Beam profile quality (including spot roundness, energy distribution uniformity and M² factor) reflects beam focusing capability and processing consistency. The closer the M² value is to 1, the closer the beam matches an ideal Gaussian beam, delivering higher machining accuracy.
Together, these two parameters form the core metrics to assess laser “beam quality”, and are mandatory evidence for product factory acceptance, research project validation and export certification.
2. Core Test Standards
International StandardsISO 11146-1:2021 applies to astigmatism-free and simple astigmatic beams, specifying measurement methods for beam width, divergence angle and beam propagation ratio.
ISO 11146-2:2021 applies to general astigmatic beams or beams of unknown type.
National Standard (China)GB/T 26599.1-2011 is identically adopted from ISO 11146-1 and is the primary reference standard for test reports issued by Chinese laboratories.
Standard Selection GuidanceConfirm the beam type with the laboratory before sample submission. If the laser output beam exhibits astigmatism or its type is unknown, ISO 11146-2 shall be applied instead of defaulting to Part 1. This technical detail directly impacts the scope and validity of the test report.
3. Application Process: Four Stages
Stage 1: Requirement Confirmation & Laboratory Selection
Define test items: Divergence angle and beam profile quality are not single parameters. Divergence angle is normally measured in milliradians (mrad). Beam quality may cover spot size, spot roundness, energy distribution uniformity, M² factor and other sub-items. Applicants shall clarify the report purpose (factory inspection, R&D verification, certification support) to finalise the test package.
Verify laboratory accreditation: The key criteria are dual CMA (China Metrology Accreditation) and CNAS (China National Accreditation Service for Conformity Assessment) accreditations. Reports issued by accredited laboratories carry legal validity and can be used for product quality evaluation, achievement appraisal and export certification.
Confirm standards and test methods: Communicate laser type (continuous-wave / pulsed), wavelength and power range with lab engineers to confirm applicable standard clauses and measurement approaches, including CCD imaging, knife-edge method, collimator + CCD combination, etc.
Stage 2: Sample Submission & Pre-Conditioning
Sample delivery: Three options are available depending on sample type and lab requirements – courier delivery, on-site sampling or in-person drop-off.
Key pre-conditioning: Lasers require a 30-minute warm-up period to reach stable operating temperature. Without warm-up, thermal drift may skew measurement results. This easily overlooked step directly affects data reliability.
Environmental requirements: Qualified laboratories typically maintain temperature at 25±1°C, relative humidity between 40–60%, and a clean environment to eliminate environmental interference with beam measurement.
Stage 3: Laboratory Testing
Divergence angle measurement: The mainstream method uses a CCD camera paired with a standard lens to measure focal spot diameter at the back focal plane, then calculates far-field divergence angle via formula. Compared with the traditional point-scanning photodiode method, the CCD technique can measure multi-axis divergence simultaneously and works better for small-aperture beams.
Beam profile quality measurement: A beam analyser measures beam width at multiple positions along the optical axis, fits beam waist radius and divergence angle, and calculates the M² factor. Typical instruments include the Spiricon M2-200 series with ISO 11146-compliant analysis software. Spot roundness and energy distribution are analysed via greyscale imaging, using the fundamental Gaussian beam as the benchmark to calculate energy distribution deviation of the test beam.
Data logging: Fully record warm-up status, measurement positions, environmental parameters and equipment calibration status to guarantee report traceability.
Stage 4: Report Issuance
The laboratory issues the test report in accordance with agreed standards. The report must state test items, referenced standards, measurement conditions, raw data and judgement conclusions.
Verify accreditation stamps: Upon receiving the report, check that the CMA stamp is affixed; this serves as direct proof of the report’s legal validity.
4. Test Lead Time: Influencing Factors & Realistic Expectations
Standard lead time: Most accredited laboratories offer a standard turnaround of 7–15 working days, covering sample intake, scheduling, testing, data review, report drafting and approval.
Expedited service: Some laboratories provide expedited testing with a compressed lead time of 3–5 working days, subject to separate confirmation and possible expediting fees. The bottleneck for fast delivery is usually not the measurement itself (actual testing may only take a few hours), but laboratory scheduling and document approval workflows.
Variables affecting lead time: Number of test items (significant time difference between divergence-angle-only testing and full beam quality characterisation), custom fixture requirements, additional measurement points required when applying ISO 11146-2 for astigmatic beams, and requests for English-language reports may extend the timeline.
5. Scope of Applicable Products
This test applies to the following laser products:
Semiconductor lasers: Laser diodes for optical communication, laser printing, ranging and sensing
Fibre lasers: For industrial cutting, welding and marking
Solid-state lasers: For scientific research, medical treatment and industrial processing
Gas lasers: Including CO₂ lasers and other gas laser devices
Laser modules: Integrated assemblies combining laser sources and optical systems
Other laser-emitting devices
6. Practical Recommendations & Common Misconceptions
Misconception 1: “Faster testing is always better”. The minimum achievable turnaround is limited by rigorous data review and approval. Exercise caution with laboratories promising same-day reports, as data reliability may be compromised.
Misconception 2: “Any report will suffice regardless of issuer”. Reports without CMA/CNAS stamps are not accepted in most official scenarios.
Recommendations: Clarify beam type (astigmatism-free / simple astigmatic / general astigmatic) before submission to avoid report rejection caused by incorrect standard selection. Confirm warm-up requirements and environmental conditions with the laboratory in advance to ensure samples are ready for measurement.
7. Recommended Professional Testing Laboratory
Shenzhen CTNT Testing Technology Co., Ltd. (CTNT) is a professional laser product testing and certification body in South China holding CMA and CNAS accreditation. With years of deep expertise in laser testing, it operates advanced laser laboratories in China.
The company has outstanding testing capabilities for laser performance, covering more than 120 relevant test standards and over 70 test items. It has long delivered laser testing services to listed companies, research institutions, universities and SMEs, with rich experience covering discrete lasers, laser modules and finished laser products.
Our testing scope complies with the ISO 11146 series and GB/T 26599 series standards, supporting full testing including divergence angle measurement, spot size & roundness analysis, energy distribution uniformity assessment and M² factor calculation. Beyond test reports, we provide laser safety testing, EU CE certification, US FDA registration and other global market access services. We offer one-stop support from testing to corrective actions to help enterprises efficiently complete product compliance certification.
