1、 The relationship between two standards and detection positioning
GB/T 41265-2022 "Safety Requirements for Optical Radiation of Wearable Devices" is a safety requirement standard that solves the problem of "what is the qualification criterion", specifies the optical radiation limits, hazard level classification, and management requirements for various wearable devices; GB/T 42750-2023 "Measurement Methods for Optical Radiation Safety of Wearable Devices" is a measurement method standard that solves the problem of "how to measure", specifies testing equipment, layout, conditions, and data processing procedures. In actual testing, the two must be used together - the measurement is completed according to the method of 42750, and then judged based on the limit value of 41265.
AR glasses belong to the category of "eye wearing devices" in these two standards, and are a key controlled object due to their display surface being closely attached to the human eye, long single wearing time, and light source directly reaching the retina through the waveguide system. The detection object covers the display screen (Micro LED/OLED/LCoS, etc.), waveguide lens exit end, as well as auxiliary light sources such as eye tracking infrared fill light and camera fill light.
2、 Main testing items
Retinal blue light hazard: wavelength range of 300-700 nm, measure spectral radiance and calculate according to the blue light weighting function. This is the most core and easily exceeded project of AR glasses, which directly determines the retinal blue light hazard level (exemption or 1-3 categories).
Retinal thermal hazard: wavelength range of 380-1400 nm, measure spectral radiance and synchronously determine apparent light source size (opposite angle). The virtual images of AR glasses are often collimated or imaged from a distance, and the calculation of apparent size directly affects the judgment results.
Infrared radiation hazards to the eyes: measuring irradiance at the eye position within the wavelength range of 780-1400 nm to assess the risk of thermal damage from near-infrared radiation.
Corneal/Conjunctival UV Hazards: Measure spectral irradiance at the ocular surface within the wavelength range of 200-400 nm.
Near ultraviolet harm to the crystalline lens: wavelength range of 315-400 nm, measure spectral irradiance, and evaluate the cumulative risk of long-term wear.
3、 Hazard level and judgment criteria
According to GB/T 41265, the equipment is classified into exemption category (no harm) and categories 1, 2, and 3 (risk gradually increases) based on the measurement results. Eye worn devices typically require exemption or Class 1 status; If the limit is exceeded, the standard also specifies corresponding management requirements, such as warning signs, instructions on usage duration restrictions, etc. The judgment requires comprehensive consideration of wavelength weighting, exposure time (usually taken in daily continuous wearing scenarios), and correction of apparent light source size.
4、 Measurement condition requirements
Environmental conditions: The experiment is conducted in a dark room with an ambient light intensity of less than 0.1 lx, and the reflection ratio between the measuring surface and the equipment surface is not greater than 10%; The atmospheric conditions are temperature of 25 ℃± 3 ℃, relative humidity not exceeding 65%, and atmospheric pressure of 86-106 kPa.
Equipment working status: The deviation between the power supply current or voltage and the rated value shall not exceed 0.2%; The equipment must be set to the maximum light radiation output state (maximum brightness, white full screen image, and other most unfavorable working conditions), and if it has dimming function, it should cover all gears and take the maximum value; Use the posture fixing device as expected.
Measure distance and position: Use the minimum distance corresponding to the expected usage state specified in the product manual as the evaluation distance; The irradiance measurement receiver is set at the vertex of the cornea, and the radiance measurement corresponds to the conjugate position of the retina.
5、 Testing process
The process is as follows: product technical data review (light source type, display parameters, auxiliary light source list, usage instructions) → determination of the worst working condition and pre adjustment of equipment → installation of fiber optic spectrometer, radiance receiver, imaging brightness meter and other measurement systems in the darkroom → scanning and measuring according to each hazard item → calculation of weighted values based on the size of the apparent light source and exposure time → determination of hazard category according to GB/T 41265 → issuance of a CMA/CNAS qualified testing report.
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