I. Standard Overview and Scope of Application
IEC 62471-5:2015, Photobiological Safety of Lamps and Lamp Systems - Part 5: Image Projectors, is an international standard specifically
addressing the safety of light radiation from projectors. It applies to all projectors that emit reflected visible light radiation, including traditional
light sources (UHP lamps, xenon lamps), LED projectors, and laser lighting projectors that meet the requirements of Article 4.4 of IEC 60825-1:2014.
It does not apply to scanning collimated laser beam display products, ultraviolet/infrared projectors, or general lighting projection lamp systems.
This standard evaluates only photobiological safety and does not address electrical, mechanical, or fire hazards.
II. Test core parameters
Irradiance: Radiation flux divided by unit area, expressed in W/m², used to assess the radiation energy received by the surface of the skin and eyes.
Radiance: Radiance, which is the irradiance divided by the field of view (solid angle), is a key indicator for assessing retinal hazards. The energy
received by the retina depends on the brightness of the light source rather than pure illuminance.
Apparent source angular subtense (Angular Subtense α): The apparent source angular subtense refers to the angle subtended by the apparent
source at the measurement point, determined by the exit pupil of the projection lens. The optical system of the projector alters the angular subtense
of the physical source. During continuous wave emission, the limit range for α is α_max = 0.1 rad and α_min = 0.0015 rad.
III. Test conditions and measurement conditions
Test environment: Darkroom environment, temperature ranging from 15℃ to 25℃, and relative humidity ranging from 30%RH to 70%RH. The tested
product has been used for less than 10 hours in total, and it is plugged in and set to its brightest mode during testing.
Measuring Distance: IEC 62471-5 specifies the measuring distance as 1 meter, which is closer to real-world usage scenarios. The measuring origin is
located at the exit pupil position of the projection lens, defined based on the Throw Ratio.
Image content setting: A completely white field (100% white screen) represents the most severe testing condition. Input a completely white pattern
and adjust the brightness and contrast to a state where grayscale differences can be recognized. For pulse-emitting projectors, the relationship between
peak and average power needs to be considered.
Field of View: The acceptance angle for measuring radiance is determined based on the emission type. For continuous-wave light sources, a standard
field of view is used; for pulsed light sources, the maximum angular spread α_max is determined based on the pulse duration. The field of view of the
detector needs to match the apparent angular spread of the light source.
IV. Hazard Categories and Assessment Objects
UV hazards to skin and eyes (200-400 nm): Assess the potential hazards of ultraviolet radiation to the skin and eyes, including photochemical UV hazards
and UVA hazards (315-400 nm).
Retinal blue light hazard (300-700 nm): The top priority in projector testing. The standard pays special attention to the 415nm-455nm wavelength band,
calculating the weighted radiance of blue light. Blue light can penetrate the cornea and lens directly to the retina, and excessive exposure may lead to
irreversible damage.
Retinal blue light hazard (small light source): Special assessment for high-brightness, small-sized apparent light sources. When the measured field angle
is ≥0.011 rad, the calculation is based on the large light source method; when it is <0.011 rad, the calculation is based on the small light source method.
Small light sources have higher brightness values under the same illumination, and the assessment is more stringent.
Retinal thermal hazard (visible light - 1400 nm): Assessing the risk of retinal damage due to thermal effects from high-intensity visible and near-infrared
light is particularly important for high-brightness engineering projectors.
Infrared radiation hazards to eyes (780-3000 nm): Measure thermal damage to the cornea and lens caused by infrared radiation. This assessment is
essential for projectors using traditional light sources such as UHP lamps.
Skin thermal hazard (380-3000 nm): Assess the potential thermal effects of high-intensity optical radiation on the skin.
V. Risk Level Classification
Exempt (RG0): No optical biological hazard under normal operating conditions. Ideal for household and educational projectors.
Low Risk Level (RG1 / Low Risk): No harm will be caused under normal behavior. Most compliant consumer-grade projectors should meet RG0 or
RG1 standards.
Medium Risk Level (RG2 / Moderate Risk): Strong light triggers an involuntary avoidance response (blinking, turning head), usually without causing
harm. The assessment is based on the Accessible Emission Limit (AEL) for a 0.25-second exposure time.
High Risk Level (RG3 / High Risk): Even instantaneous exposure may cause harm. For professional use only, not for sale as consumer goods. Hazard
Distance (HD) must be determined.
VI. Manufacturer Requirements and Identification
Hazard Distance (HD) determination: The manufacturer must determine the distance from the nearest accessible point of the projector to the point
where the luminance/irradiance of the light beam exceeds the Exposure Limit (EL). HD is determined based on EL for an exposure time of 0.25 seconds.
Safety feature requirements: Projectors of grade RG2 and above should have a Soft Start function, which gradually brings the light source to full power
to avoid sudden glare that may cause dazzling. Optional features include projecting warning messages and automatic power reduction by sensors.
Product identification requirements:
RG0: No special warning sign required
RG1: Optional identifier
RG2: Warning signs and instructions such as "Do not stare at the beam" must be labeled
RG3: The "Non-Household Use" label, optical radiation warning symbol, and detailed hazard distance information must be indicated
User information requirements: The user manual must include risk level classification, safe use distance, warnings against direct viewing of the light beam,
instructions on changes in risk level for replaceable lenses, and safety information for maintenance personnel.
VII. Accessible Emission Limit (AEL)
Continuous Wave (CW) emitted AEL: Determined based on risk level and hazard type, including retinal blue light hazard AEL (based on weighted
radiance of blue light), retinal thermal hazard AEL (based on weighted radiance of thermal radiation), ultraviolet hazard AEL, and infrared hazard AEL.
AEL for pulse emission: It is necessary to consider the relationship between pulse duration, peak value, and average power. The dependent values of
α_max for pulse duration are determined based on the pulse characteristics, and it is required to analyze whether the pulse waveform has multiple
peaks.
Spectral Weighting Function: The standard provides a blue light hazard spectral weighting function B(λ) and a retinal thermal hazard spectral weighting
function R(λ) for converting spectral data into biologically effective dose.
VIII. Requirements for testing equipment
Spectroradiometer: It should scan within the range of 200nm-3000nm, possess high resolution (such as 0.075nm), low stray light (up to 10⁻⁸ for dual
monochromators), and be traceable to national metrological standards (such as PTB in Germany).
Measurement accessories:
Irradiance measurement: Precise transmission of diffuser coupled with fiber
Radiance measurement: Using a direct-view telescope, measurements can be taken at distances ranging from 200mm to 10m within fields of view of
1.7, 5, and 11mrad
Beam profiler: Determine the apparent source size and position
Virtual illuminometer: Measure threshold illuminance (Ethr) and threshold distance (dthr)
Measurement software: The PSL Wizard application software is used for measurement guidance, calculation, and report generation, automatically
completing risk level classification.
IX. Content of Test Report
The complete report should include: basic product information, testing standards, testing conditions (temperature, humidity, measurement distance,
projection ratio, image content), radiation measurement data for each wavelength band, apparent light source position and size, hazard weighting
value calculation results, risk level determination (RG0-RG3), hazard distance (HD), threshold illuminance (Ethr) and threshold distance (dthr), labeling
requirements, user information suggestions, and compliance conclusions.
X. Special considerations
Laser illumination projectors: They must meet both IEC 60825-1 (laser module safety) and IEC 62471-5 (projection light bio-safety). If the visible light
emission of a laser illumination projector has been excluded from the classification of IEC 60825-1, then IEC 62471-5 applies.
Interchangeable lens system: Different lenses may alter the apparent source angle and brightness distribution, thereby changing the risk level.
Manufacturers must evaluate all possible lens combinations and label the corresponding risk level information on both the product and the lens.
Small light source evaluation: When the apparent light source angle is less than 0.011 rad, the small light source evaluation method is employed. Based
on irradiance rather than radiance, it typically only yields the threshold illuminance (Ethr) and threshold distance (dthr) for RG2, without obtaining the
unrestricted classification of RG0/RG1.
Pulse emission evaluation: When the peak radiation power does not exceed 1.5 times the average power and the output duration is >0.25 seconds, it can
be considered as continuous wave emission; otherwise, it shall be evaluated according to the special requirements for pulse emission.
