lm/am²(lumen per square attometre)

In the field of illuminance, a lumen per square attometre (lm/am²) is a unit used to describe the luminous flux per unit area. It is a metric unit of illuminance or the amount of visible light illuminating a specific area.

In lm/am², the lumen (lm) is the unit of luminous flux, which represents the amount of visible light emitted by a source in a given direction. The square attometre (am²) is the unit of area, where 1 attometre (am) is equal to 10^-18 meters. A square attometer is an extremely small area, typically appearing in more theoretical aspects or specialized scientific contexts.

So, the unit lm/am² indicates how much of this emitted light (lumens) falls upon each square attometre of the surface being illuminated. In practical terms, it quantifies the brightness of light—how effectively an area is lit by a given light source—on an extremely small scale. However, for most practical applications, illuminance is generally measured in lumens per square meter (lux or lm/m²), since square attometres are too small for most everyday scenarios.

µph(microphot)

A microphot (µph) is a unit used to measure illuminance, which is the amount of light that falls on a surface. Illuminance is an important concept in various fields, such as photography, film, architecture, and interior design, as it helps to determine optimal lighting conditions for visibility and aesthetics.

One microphot is equal to 1x10^-6 phot or 10 lux. A phot is another unit of illuminance and is equal to 10,000 lux. Lux (lx) is the SI unit for illuminance and is widely used today, making the use of microphot less common.

To put it in perspective, a lux represents the amount of light that falls on one square meter of the surface when the light source emits one lumen (the unit of luminous flux) uniformly across that one square meter. To convert microphot to lux, you can simply multiply the value in microphot by 10.