What is lumen per square metre?
Lumen per square metre is a unit of illuminance numerically equivalent to lux. It expresses the amount of light falling on a surface and is used in lighting engineering and photometry to quantify light intensity at a specific location.
What is phot?
A phot is a CGS system illuminance unit equal to 10,000 lux. It is now largely obsolete but may be encountered in older scientific literature and historical photometric measurements.