# What is spectral power distribution curve?

## What is spectral power distribution curve?

A spectral power distribution (SPD) is a graph of the energy levels of a light source through a range of wavelengths of light. The spectral power distribution is the true “fingerprint” of a light source, as it is the key to how the light source renders colors.

### What is spectral light distribution?

The spectral distribution chart is a visual representation of the light spectrum produced by a lamp. It is a graph showing the relative intensities of a light source at each wavelength. These charts can be used to compare the energy levels of various light sources.

#### Why is spectral power distribution important?

Light may be precisely characterized by giving the power of the light at each wavelength in the visible spectrum. The resulting spectral power distribution (SPD) contains all the basic physical data about the light and serves as the starting point for quantitative analyses of color.

What is spectral illumination?

A spectral color is a color that is evoked in a typical human by a single wavelength of light in the visible spectrum, or by a relatively narrow band of wavelengths, also known as monochromatic light.

How is the spectral power distribution related to color?

The resulting spectral power distribution (SPD) contains all the basic physical data about the light and serves as the starting point for quantitative analyses of color. The SPD can be measured by a spectrophotometer. From the SPD both the luminanceand the chromaticityof a color may be derived to precisely describe the color in the CIEsystem.

## How is the SPD curve of light measured?

SPD curves are measured using a Spectroradiometer, which are designed to measure the spectral density of an illuminant. They measure the relative intensity of a light source at a number of defined steps across the visible region of the electromagnetic spectrum, generally 380-780nm.

### How to understand the relative power distribution of light?

Relative Spectral Power Distribution To understand an illuminant it is necessary to first understand how we describe light. Light is described for our purposes by what is called a spectral power distribution curve. A specific type of light will emit different amounts of energy at each part of the visual spectrum.

#### What kind of power distribution does a led have?

Left: Daylight model, characterized by smooth SPD with small blips that come from filtering in the atmosphere.Center: HPS, characterized by almost all energy in the medium \\(yellow\\) wavelengths.Right: Color-mixed LED, characterized by a combinati\\ on of three or more individual peaks. 17 Phosphor-Coated LEDs Direct LED