With the development of the industry, comprehensive and reliable machine vision technology has become an indispensable solution in various fields, and its application areas are constantly expanding. The following are some questions related to the optical fundamentals of machine vision .
1. What is the meaning of luminous intensity (photometry)?
A: Luminous intensity (luminosity, I) is defined as the luminous intensity of a point light source in a certain direction, that is, the amount of light emitted by the light source per unit time. It is also simply called luminosity. The commonly used unit is candela (cd). One international candela is defined as the luminosity emitted by a candle made of whale oil burning 120 grains per hour. One grain is equal to 0.0648 grams.
2. What is the unit of luminous intensity (photometer)?
A: The commonly used unit for luminous intensity is candela (cd). The international standard candela (lcd) is defined as 1/600,000th of the luminous intensity of an ideal blackbody at the freezing point of platinum (1769℃) in the direction perpendicular to the blackbody (with a surface area of 1m2). An ideal blackbody is an object whose emissivity is equal to 1, meaning that all the energy absorbed by the object can be emitted, keeping the temperature uniform and constant. The conversion relationship between the international standard candela and the old standard candle is 1 candela = 0.981 candle.
3. What is luminous flux? What is the unit of luminous flux?
A: The definition of luminous flux (φ) is: the energy emitted by a point light source or non-point light source per unit time. The portion of this energy that can be perceived by the eye (the radiant flux that humans can perceive) is called luminous flux. The unit of luminous flux is lumen (abbreviated lm). One lumen (lumen or lm) is defined as the luminous flux passing through a unit solid arc angle of one standard candle. Since the area of the entire sphere is 4πR², the luminous flux of one lumen is equal to 1/4π of the luminous flux emitted by one candle. In other words, the sphere has 4π. Therefore, according to the definition of lumen, a point light source of one cd will radiate 4π lumens, that is, φ (lumen) = 4πI (candle). Assuming that ΔΩ is a very small solid arc angle, the luminous flux within the solid angle ΔΩ is Δφ, then Δφ = ΔΩI.
4. What is the meaning of a foot of candlelight?
A: A foot candle refers to the illuminance on a surface perpendicular to a light source (point light source or non-point light source) one foot away from the light source. It is abbreviated as 1ftc (1lm/ft2, lumen/foot2), which is the illuminance when the luminous flux received per square foot is 1 lumen, and 1ftc = 10.76 lux.
5. What is the meaning of a meter of candlelight?
A: A one-meter candle refers to the illuminance on a surface perpendicular to the light source (point source or non-point source) one meter away. It is called lux (also written as lx), which is the illuminance (lumen/m2) when the luminous flux received per square meter is 1 lumen.
6. What does 1 lux mean?
A: Illuminance when the luminous flux received per square meter is 1 lumen.
7. What is the meaning of illuminance?
A: Illuminance (E) is defined as the luminous flux received per unit area of an illuminated object, or the luminous intensity received per unit area per unit time by an illuminated object. The unit is expressed as meter candle or foot candle (ftc).
8. What is the relationship between illuminance, luminous intensity, and distance?
A: The relationship between illuminance, luminance, and distance is: E(illuminance) = I(luminance) / r²(distance squared).
9. What factors affect the illuminance of an illuminated object?
A: The illuminance of an illuminated object is related to the luminous intensity of the light source and the distance between the illuminated object and the light source, but is not related to the color, surface properties, or surface area of the illuminated object.
