Safety
Safety is the top priority for me – but ultimately, responsibility for safe usage lies with the user.
I do not accept liability for damage from use or misuse of the hardware.
Key Safety Information
Infrared radiation comprises approximately 50% of sunlight naturally. The hardware includes multiple safety mechanisms ensuring IR emissions remain far below internationally recognized safety limits. Calculations, testing, measurements, and expert consultations confirm compliance with a safety margin of approximately 70 times lower than standard requirements.
User Responsibilities
Users must:
- Never attempt to replace, disable, or modify safety-related components
- Monitor eye comfort during use
- Stop immediately if noticing unusual warmth or discomfort
- Discontinue use if experiencing dark spots in vision, dry eyes, or excessive eye strain
Slight warmth may occur from cameras, but eyes should feel normal with proper cooling fan operation.
Scientific Foundations
Infrared Radiation Basics
IR is commonly used in eye-tracking systems. While natural, prolonged excessive exposure can harm sensitive areas like eyes. Safety guidelines establish exposure limits based on affected body parts, wavelength, and duration.
Safety assessment relies on:
- ICNIRP (International Commission on Non-Ionizing Radiation Protection): Independent organization providing scientifically-backed non-ionizing radiation guidelines
- EN 62471: European standard evaluating photobiological safety of lamps and lamp systems covering UV, visible, and infrared radiation (200–3000 nm range)
EN 62471 Standards
Infrared Radiation Hazard Exposure Limits for Eyes
For exposure longer than 1000 seconds, ocular exposure to IR radiation (780–3000 nm wavelength) shall not exceed:
Retinal Thermal Hazard - Weak Visual Stimulus
For near-infrared (780–1400 nm) exposure longer than 10 seconds:
Where α is angular subtense in radians.
Thermal Hazard for Skin
For exposures exceeding 10 seconds over larger areas, skin pain occurs before tissue damage, so individuals naturally limit exposure. Specific limits not provided for skin exposure longer than 10 seconds.
Technical Specifications
LED Datasheet Parameters (CSL1501RW1)
- Radiation Intensity: Maximum 3.4 mW/sr at 30 mA
- Horizontal Emission Angle: 140°
- Vertical Emission Angle: 160°
- Operating Current: Limited to 2.4 mA (board design)
- Adjusted Radiation Intensity: 0.273 mW/sr
Calculations
Solid Angle
Illuminated Area (at 1 cm distance)
Total Power
Irradiance (7 LEDs)
Radiance
Angular Subtense (0402 LED)
Radiance Limit
Compliance Check
- Irradiance: 1.4 W/m² is approximately 70 times lower than the safety limit of 100 W/m²
- Radiance: 545 W/(m²·sr) is roughly 110 times lower than the safety threshold of 60,000 W/(m²·sr)
Both values are far below EN 62471 safety limits. Measured LED values similarly showed low irradiance.
Hardware Safety Mechanisms
Host Device Protection
EMC (Electromagnetic Compatibility)
Hardware successfully passed EN55022 AV/QP measurements. A two-stage EMC filter reduces high-frequency noise using inductors and capacitors.
Polyfuse Protection
Integrated polyfuse limits current to 1 A in case of short circuit or excessive current draw, automatically resetting when fault conditions resolve.
Eye Safety Protections
Three independent current-limiting mechanisms:
- Software-Based Current Limiting: LED current adjustable via software with maximum firmware limits
- Hardware LED Driver (AW9967DNR): Built-in current limiter sets hard cap per output channel
- Polyfuse Protection (10 mA per IR Ring): Each LED ring has dedicated polyfuse protecting against current exceeding safe values
These operate independently with hardware-based limiting ensuring software failure cannot exceed safe levels.
Excessive IR output would immediately appear in practice as washed-out or unusable eye-tracking images, indicating malfunction requiring immediate correction.
Contact & Support
For safety-related questions or concerns about calculations, circuits, or specifications, please contact me through Discord.