Overview
IEC 62906-5-2:2016 - "Laser display devices - Part 5-2: Optical measuring methods of speckle contrast" specifies standardized measurement conditions and methods for determining the monochromatic speckle contrast of laser display devices (LDDs). The standard covers LDDs including hybrid systems that combine laser(s) and spontaneous-emission light sources (e.g., LEDs). Note: these speckle contrast measurements are focused on optical speckle metrics and do not address general image quality.
Key technical topics and requirements
- Scope and purpose
- Defines how to measure monochromatic speckle contrast for LDDs (front and rear projection geometries).
- Applies to hybrid systems containing laser diodes (LD) and LEDs.
- Standard measurement environment
- Temperature: 25 °C ± 3 °C
- Relative humidity: 25 % to 85 %
- Atmospheric pressure: 86 kPa to 106 kPa
- Darkroom and background limits
- Background illumination reflected from the device under test (DUT) must be ≤ 1/20 of the display’s lowest black level; otherwise background subtraction is required and must be reported.
- Measurement geometry and coordinate system
- Defines projection and viewing directions using inclination (θ) and azimuth (φ) angles; includes guidance for front and rear projection setups.
- Measuring equipment and procedures
- Use of a light measuring device (LMD) to simulate the observer; recommendations on sensor pixel size and measurement conditions are provided (see informative Annex B).
- Calibration and diagnostic procedures for determining highest and lowest speckle contrast values (C).
- Safety and normative references
- Informative annexes
- Spectral behavior of laser diodes, sensor pixel-size recommendations, theoretical speckle formulation and common error sources.
Practical applications and users
Who benefits from IEC 62906-5-2:
- Display manufacturers developing laser and laser-hybrid projection systems who need repeatable speckle metrics.
- Test laboratories and QA teams performing standardized speckle characterization and certification testing.
- R&D engineers evaluating speckle mitigation techniques (e.g., spatial/temporal decorrelation).
- System integrators and product managers assessing perceived speckle risk in projection products and compliance with industry measurement practice.
Practical uses:
- Benchmarking speckle performance across prototypes and production units.
- Verifying effectiveness of speckle-reduction solutions and optical designs.
- Producing reproducible measurement reports for suppliers and customers.
Related standards
- IEC 60825-1 - Safety of laser products (equipment classification and requirements)
- IEC 62906-1-2 - Laser display devices - Vocabulary and letter symbols
Keywords: IEC 62906-5-2, laser display devices, speckle contrast, monochromatic speckle, LDD, laser diode (LD), LMD, front projection, rear projection, speckle measurement, darkroom conditions.