Convert lumen/square meter [lm/m^2] to watt/sq. cm (at 555 nm) Online | Free lllumination Converter

The Standard Unit of Illuminance

Lumen per square meter (lm/m²), also known as lux, is the standard unit used to measure illuminance, which is the amount of luminous flux (light) falling on a surface per unit area. One lux equals one lumen distributed over one square meter, quantifying how brightly a surface is illuminated.

Lux is widely used in lighting design, architecture, photography, and occupational health to ensure proper lighting conditions for various environments. For instance, office spaces typically require around 300-500 lux to provide comfortable and efficient lighting for work, while outdoor daylight can range from 10,000 to over 100,000 lux.

Understanding illuminance in lux helps in designing lighting systems that optimize visibility, safety, and energy consumption. It allows engineers and designers to calculate how much light a space receives and adjust fixtures or bulbs accordingly.

Lux is preferred globally because it aligns with the metric system and provides a clear, standardized measure of light intensity on surfaces, making it essential for ensuring consistent and effective lighting in both indoor and outdoor settings.

Measuring Light Intensity

Watt per square centimeter (W/cm²) is a unit that measures irradiance, the power of electromagnetic radiation received per unit area. When specified at 555 nanometers (nm), it refers to the intensity of light at the wavelength where the human eye is most sensitive—green light in the visible spectrum.

The 555 nm wavelength is significant because the eye’s photopic (daylight) vision peaks here, making it a standard reference for measuring visible light power. Measuring irradiance in W/cm² at this wavelength is essential in fields like optometry, lighting design, and vision science, where understanding how much light reaches the eye or a surface is critical.

This unit is used to evaluate the brightness of light sources, safety limits for exposure, and the efficiency of lighting devices. For example, in ophthalmology, it helps assess potential retinal exposure during laser treatments or diagnostic procedures to avoid damage.

In practical applications, light intensity at 555 nm measured in W/cm² helps engineers design lighting systems that are both effective and safe, ensuring optimal visibility and comfort.