Light-Mediated Biological Effects and Blue Light Radiation Assessment: Research and Application of Retinal Blue Light Hazard Tester

Light-mediated biological effects refer to the physiological changes in the human body caused by exposure to light radiation. The mechanism of light-mediated biological effects varies depending on different pathways.

Firstly, light can directly act on the human eye, transmitting visual information and inducing visual effects. Secondly, light can regulate the body’s physiological rhythms by acting on the body’s physiological regulatory system, transmitting non-visual information and triggering non-visual effects. Lastly, light can directly impact the human skin, causing radiation damage and forming radiation effects.

Based on light-mediated biological effects, attention has been drawn to photobiological safety, particularly the effects of visible light wavelengths used for illumination on human health. With the development and widespread use of LED light sources, traditional light sources have gradually lost market competitiveness. LED light sources offer many advantages, such as rich color, compact size, durability, environmental friendliness, and wide applicability, making them the preferred light source in the field of illumination.

White LED light sources mainly generate high-brightness white light by exciting yellow phosphors with blue light chips, hence containing a significant amount of blue light. However, excessive blue light radiation can not only damage the eyes, retina, and skin but also adversely affect the body’s physiological rhythms, making blue light hazard one of the most concerning photobiological safety issues today.

Blue light radiation, categorized as electromagnetic radiation, has a shorter wavelength, typically ranging between 400 to 500 nm, within the visible light spectrum. The phenomenon of shifting towards shorter wavelengths is known as “blue shift” in optics. Additionally, blue light is a crucial component in current LED white light illumination sources.

The retina, located at the back of the eye, is at risk from light radiation within the wavelength range of 380 to 1400 nm. However, blue light radiation poses the highest risk to the retina, as the human retina is highly sensitive to blue light stimulation.

Currently, the photobiological safety level of LED products is determined by evaluating their blue light hazard values. Blue light-weighted radiant exposure and blue light hazard efficiency are physical quantities used to quantify the degree of blue light hazard.

• Radiant exposure: Represents the intensity of radiation passing through a unit area. Spectral radiant exposure can be divided based on wavelength distribution, reflecting exposure at different wavelengths.

• Blue light-weighted radiant exposure: This value reflects the extent of blue light’s harm to the human body, calculated as the integral of spectral radiant exposure multiplied by the blue light hazard weighting function.

• Blue light hazard level: The final blue light hazard level is determined based on blue light-weighted radiant exposure. By integrating spectral radiant exposure with the blue light hazard weighting function, LED product blue light hazard levels can be assessed.

During light source measurements, general provisions are made based on the type of light source and measurement requirements:

For ordinary lighting sources:

• Measurement distance: Measurement should be conducted at a distance that produces 500 lx illuminance.

• Minimum distance: Controlled within 200 mm.

Other types of light sources: Measurement distance: Generally controlled within 200 mm.

Blue light-weighted irradiance (Es): Used to characterize the potential damage of blue light radiation to the retina, reflecting blue light’s impact on eye health.

The damage from blue light radiation to the eyes mainly affects eye structure, particularly influencing diseases like cataracts and macular degeneration. Human lenses are ineffective at blocking blue light radiation, allowing it to penetrate directly to the retina. Retinal pigment epithelial cells are highly sensitive to blue light radiation, leading to cell shrinkage and potential apoptosis under radiation stimulation.

This cell shrinkage and apoptosis can cause vision impairment, with severe cases potentially resulting in irreversible macular degeneration and ultimately blindness. Therefore, reducing prolonged exposure to blue light radiation is crucial, especially when using light sources with high blue light radiation like LEDs, to protect the retina and eye structure from damage.

Photobiological safety testers are devices used to evaluate the photobiological safety of lamps and lighting systems on human bodies (mainly eyes and skin). According to IEC TR62471-2 (2009) guidelines on non-laser optical radiation safety, these testing instruments aim to address potential harm caused by light sources, particularly focusing on non-laser light sources (e.g., LED products, UV radiation in general lighting products).

The Retinal Blue Light Hazard Tester developed by Shanghai Lisun is a portable photobiological safety assessment device based on laboratory photobiological safety testing systems, offering the following advantages:

• Portability: The device is compact and lightweight, making it easy to carry and move for testing in various locations.

• User-friendly: It features a simple and intuitive operation interface, facilitating easy testing and evaluation for users.

• Wide application coverage: The tester is designed to meet the requirements of most current light source applications, providing comprehensive evaluations of light source biological safety for eyes and skin.

EN62471-P_Portable Retinal Blue Light Hazard Tester

Key features of the Retinal Blue Light Hazard Tester by Shanghai LISUN include:

• Simulated human eye optical design: Utilizes a 7mm pupil diameter simulation, employing dual-path testing to ensure accurate measurement results of radiant exposure distribution and spectral radiant exposure.
• Wide wavelength range spectrum measurement: Offers a wide range of 300nm to 1050nm spectrum measurements, fully covering the requirements for retinal blue light hazard (300nm-700nm) measurements and partially covering retinal thermal hazard (380nm-1400nm) band measurements.
• Ultra-wide and ultra-fast spectral measurements: High-speed USB communication, with a minimum integration time of 11.4us, capable of measuring over 1000k cd/m^2.
• Built-in electric light shutter: Facilitates zeroing operations to improve measurement accuracy.
• Programmable measurement distance adjustment: Enhances measurement operation convenience.

The main functions of the Retinal Blue Light Hazard Tester by Shanghai LISUN include measurements based on IEC/EN62471:2008 and IEC62471-7:2023 (replaces IEC62778), assessing parameters such as retinal blue light hazard effective radiant exposure, blue light hazard level, retinal blue light hazard coefficient KB, V, spectral radiant exposure distribution curve, blue light-weighted radiant exposure ratio BR, retinal thermal hazard effective radiant exposure, apparent source angles, evaluating light source safety levels, and featuring spectral analysis processing capabilities.