Comprehend such basic concept concepts of optical engineering

The first and most important concept was Luminous flux & light-illuminance and light- lightness .The basic concept and definition of optical engineering are presented in this paper. We are walk way too much: about concept before . Perhaps I can give you a brief explanation, outlining The main points today.

In ordinary language：

Luminous flux as how many light had been granted（Add up all the light）

light-illuminance refers to how much light was reverberation of object ‘average surface.

light- lightness means: If light is not completely absorbed by the object, some light is said to be reflected. returns a specified part of light — We called them light- lightness.

The unit of Luminous flux is Lm , the unit of light-illuminanc is Lux. the conversion relation of them is: 1 lm illumination in 1 square meter of a surface. its 1 lux at this point. The unit of light- lightness is candela. highlight intensity of candela in a solid angle,within this range the total highlight intensity —- we take it as 1 lm.