Most modern smartwatches have laser sensors. These sensors help in health tracking like heart rate monitoring and blood oxygenation monitoring.
Smartwatch users can look at the green colored laser lights being emitted by the sensors located at the back of the smartwatch. If you have a Garmin smartwatch, you can actually look at multiple sensors emitting green laser light at the rear of the watch.
So, any smartwatch that offers health tracking features would include sensors that use laser for offering the desired functionality.
Why do Smartwatches use laser sensors?
Smartwatches use laser diodes or LEDs for photoplethysmography (PPG), which measures heart rate, blood oxygen levels, or other health metrics by detecting light absorption through the skin.
The use of laser sensors is necessitated due to various health tracking metrics. And, the laser sensors are present in regular smartwatches and solar smartwatches alike.
Are the Smartwatch Lasers safe?
Use of laser in smartwatches is governed or compliant to the IEC 60825 standards.
The IEC 60825 is the international standard governing laser safety. It defines the safety classifications, limits, and testing procedures for laser products, including those used in smartwatches. Below is a summary of the key aspects relevant to smartwatches:
Purpose of IEC 60825 Standards
- To ensure the safe use of lasers by setting guidelines for emission limits.
- Protect users from potential hazards like skin burns or eye damage.
- Provide classification systems to inform users about potential risks.
Key Laser Classifications
Smartwatches typically use Class 1 or Class 2 lasers, as these are the safest for consumer devices:
Class 1 Laser:
- Laser is safe under all conditions of use, including prolonged exposure.
- Common in health monitoring sensors (e.g., heart rate monitors).
- Typical power: <0.4 mW for continuous-wave lasers.
Class 2 Laser:
- Visible lasers safe for short-term exposure (up to 0.25 seconds) due to the natural blink reflex.
- Common in gesture recognition or environmental sensors.
- Typical power: <1 mW for continuous-wave lasers.
Class 3 and 4 Laser:
- Higher-power lasers with stricter safety requirements. Rarely used in smartwatches due to their potential to cause harm.
Most smartwatches conform to the use of Class 1 or Class 2 lasers for health tracking or optical sensors. The use of lasers is strictly regulated to ensure no harmful radiation reaches the skin or eyes.
To encourage and ensure user safety, most smartwatch manufacturers must test lasers for compliance with emission limits. On a similar note, the certification by an accredited body is often required before market release of the smartwatch.
If you would like to have more clarity about the type of laser used in your smartwatch, you may contact the customer support of your smartwatch manufacturer. Or, you could read the manual of the smartwatch to find compliance to the IEC60825 norms for laser use.
Conclusion
Use of lasers in smartwatches for health tracking and optical sensors is considered safe as long as the smartwatch conforms to the IEC 60825 standards for laser emissions.
We are essentially looking at laser power output to be well under 5 milliwatts for safe usage.
Your smartwatch manufacturer would be able to share the exact peak laser power in use by the smartwatch sensors. For most practical considerations, the use of laser sensors is deemed safe as the peak laser power is well under 5 milli Watts.