The color of stage lighting mainly comes from two ways

The color of stage lighting mainly comes from two ways: the light color of the original electro-optic and the light color caused by the additional color filter of the electric light source (or lamp).

Light color of 1. electric light source and its spectral analysis

All kinds of electric light sources in the stage lighting are full of colors, bright and colorful, and their colors are unified with the corresponding color temperature or correlated color temperature. It is a great progress to use the radiation temperature of blackbody to quantitatively and scientifically express the light color of the light source and digitally express the visual quantity of physiology and psychology.

There are two main types of electric light sources for stage lighting: thermal radiation light sources and gas discharge light sources. Belonging to the thermal radiation light source category are: halogen tungsten lamp (halogen lamp), steamed aluminum bulb, incandescent lamp, etc., belonging to the gas discharge lamp category are: xenon lamp, metal halide lamp, fluorescent lamp, etc. They have different spectral radiation relative energy distribution, and usually show different light color effects after stimulating the human eye. However, there is also the phenomenon of "metaspectrum", that is, light with different spectral relative energy will also cause the same color vision, or the same light color may also have different spectral relative energy distribution.

The spectral relative energy distribution of a fluorescent lamp (3200K) and halogen tungsten bubble (3200K), and the spectral relative energy distribution of a fluorescent lamp (5500K) and sunlight (5500K). Interpreting these four spectral lines can lead to the following insights:

1. Different light has different spectral relative energy distribution, showing different light colors, respectively marked with different color temperatures 3200KT5500K.

2. The metameric phenomenon exists objectively. The two light sources have the same color temperature, but the spectral relative energy distribution is not exactly the same.

The proportion of blue and red relative energy in the spectral distribution of 3200K light source is small, while the proportion of blue and red relative energy in the spectral distribution of 5500K light source is greatly improved.

4. The spectral relative energy distribution curve of halogen tungsten lamp and sunlight is continuous and smooth transition, while the spectral relative energy distribution curve of fluorescent lamp has several peaks, sandwiched with several strong radiation line spectra, which are the characteristic spectral lines of several fluorescent powder chemical elements.

Although the fluorescent lamp and the corresponding halogen tungsten lamp or daylight spectral communication energy distribution curve to roughly the same, but the details of the spectral distribution is still different, some band differences are still very large. Although they are marked with the same color temperature of 3200K or 5500K, there is still a difference between the two behind them:

(1) Halogen tungsten lamp, sun and blackbody are all thermal radiation light sources. Their chromaticity points are on the blackbody locus of the chromaticity diagram. Fluorescent lamp is different from blackbody and is a gas discharge lamp. Its chromaticity point deviates from the blackbody locus line. It only indicates that it is closest to 3200K or 5500K chromaticity point and is marked with color temperature 3200K or 5500K. In order to distinguish this difference between the two, the color of the gas discharge light source is called "correlated color temperature".

(2) thermal radiation light source and gas discharge light source with the same color temperature do not have the same color rendering. Since fluorescent lamps have significant line spectral distribution characteristics, their color rendering index is usually lower than that of thermal radiation sources of the same color temperature.

The spectral relative energy distribution curve of dysprosium lamp (a metal halide lamp) shows that the whole spectral range is composed of continuous spectra, with several lines with strong spectral radiation, and the relative proportion of blue and red light is relatively high. The color temperature of the dysprosium lamp is between 5000K and 600K, and its spectral distribution is similar to that of sunlight, but its color rendering is less than that of sunlight, and its color rendering index is between 80 and 90. It is a kind of gas discharge lamp with high color temperature, high color rendering and high luminous efficiency, which fully meets the technical requirements of stage and film lighting, and shows more and more broad application prospects.

Xenon lamp spectral relative energy distribution curve, its spectral distribution and sunlight is very close, the entire spectral range is a continuous spectrum, only around 480nm has a small peak, with stronger radiation energy. It is not difficult to infer that the xenon lamp is also a high color temperature electric light source, the color temperature is about 5500K, with excellent color rendering performance, and its color rendering index can be as high as 94. The excellent comprehensive performance of xenon lamp is outstanding in gas discharge lamp. Its research and development and application in high luminosity long-range tracking lamp, projection lamp and projection lamp have already borne fruit.

When the stage lighting is dimmed, the light color and color temperature of the light source will change accordingly, indicating that the relative energy distribution of its spectral radiation has changed. For example, when the halogen lamp is dimmed from the rated voltage value, the change law of the light parameters is: the brightness and color temperature gradually decrease, and the light color gradually drifts to the red direction. On the contrary, when the working voltage increases, the brightness and color temperature will both increase, and the light color will gradually change from red to yellow and white. Under the condition that the color film is configured in front of the lamp, when dimming or non-rated voltage working state is used, to consider the light source color temperature changes caused by the general trend of color changes.

2. color light and its spectral analysis

The color of the light may be converted. The simplest, most practical, and most commonly used method is to configure a special color filter in front of the light source (or lamp) to obtain a new light color.

There are two types of color filters: color temperature conversion filters (or color temperature correction filters) and color light filters. The color filter has the optical characteristics of selective absorption of light. For example, the color filter medium has different proportions of absorption of light at various wavelengths of the visible spectrum, which changes the spectral relative energy distribution of the light source, and the transmitted light stimulates the human eye to induce a different light color effect from the light source. Color filters of different chromophores have their own different spectral transmittance curves, conveying their different optical properties of selective absorption.