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.
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.