cd/Mm²(candela per square megametre)

Candela per square megametre (cd/Mm²) is a unit of measurement for luminance in the field of optics, specifically photometry. Luminance is the measure of the brightness of a point in a given direction on a surface, which can be a screen, light source, or even an object reflecting light. Basically, it tells us how much light is emitted, transmitted, or reflected from a particular area, and it is perceived by the human eye as brightness.

Now, let's break down the unit cd/Mm²:

1. Candela (cd): It is the base unit of measurement for luminous intensity in the International System of Units (SI). It quantifies the intensity of light emitted by a light source in a particular direction.

2. Square megametre (Mm²): It is a unit of area equal to one million meters by one million meters or one trillion square meters (1 Mm² = 1,000,000 m x 1,000,000 m = 1,000,000,000,000 m²). It is a large unit typically used to measure immense areas, like regions on Earth's surface or celestial bodies.

So, when we combine these units, cd/Mm² is used to express the luminance of a light source or surface in terms of the emitted or reflected light intensity (in candelas) per unit area (in square megameters). This unit allows us to quantify and compare the brightness of different sources or surfaces on a large scale, and it is particularly useful in applications like astronomy, remote sensing, or large-scale area lighting.

cd/mm²(candela per square millimetre)

In the field of luminance, a unit called "candela per square millimetre" (cd/mm²) is used to measure the amount of luminous intensity emitted from a surface in a specific direction. Luminance represents the brightness perceived by the human eye and is a key concept in various visual applications like lighting design, display technology, and photography.

Candela (cd) is the base unit of luminous intensity in the International System of Units (SI), and it describes the amount of light emitted by a source in a specific direction. One candela relates to the luminous intensity of a light source that emits one lumen per steradian (a unit that measures the solid angle).

When we talk about luminance using the unit candela per square millimeter (cd/mm²), we are essentially measuring the concentration of light emission in a particular direction per unit area. This unit helps to quantify the brightness perceived by an observer looking at the surface of a light-emitting object, such as a display screen or illuminated sign.

In summary, the unit candela per square millimeter (cd/mm²) in the field of luminance gives us an idea of how bright a surface appears when emitting light in a specific direction. High luminance values correspond to brighter surfaces, while lower values represent dimmer ones.

sb(stilb)

In the field of luminance, the unit "stilb" (sb) measures the luminance of a surface. It is a non-SI (International System of Units) unit, meaning it is not part of the modern metric system that is widely adopted across the globe.

Luminance refers to the amount of light emitted, reflected, or transmitted by an object or surface in a particular direction, within a solid angle, per unit area. Essentially, it helps quantify the brightness or visible intensity of a light source or an illuminated object.

The stilb is defined as one candela per square centimeter (cd/cm²). A candela is the standard unit used to express the intensity of light emitted in a specific direction from a point light source, while the square centimeter refers to the bounded area.

Luminance measurements in stilb are found in applications such as display technology, lighting systems, and optical instruments. However, since it is a non-SI unit, the preferred unit for luminance measurement in modern science and engineering is the candela per square meter (cd/m²), also known as nit. To convert stilb to nit, you can use the conversion factor 1 sb = 10,000 cd/m² (1 cd/cm² = 10,000 cd/m²).