Principle and application of illuminance meter

Introduction: illuminance meter is used for measuring instrument by illumination on the illuminated surface, is one of the most used in illumination measuring instrument.

Principle of illuminance meter

Ordinary pocket electronic luminometer using photosensitive resistance as a photoelectric conversion device, comprising a DC power supply, connected in series in the DC power supply output voltage conversion circuit, a switch, a photoresistor, a test circuit, A/D converter, decoder, display driver and display device. The utility model avoids using the optical head, a DC power supply with only 3V batteries, decoder, display driver and display are integrated in an integrated circuit card, which has the advantages of simple structure, small volume, easy to move, also has the advantages of quick reaction.

Principle of illuminance measurement

Illuminance is the areal density of light flux received on the receiving plane. The illuminance meter is used for measuring instrument by illumination on the illuminated surface, is one of the most used in illumination measuring instrument.

The principle of illuminance meter

The illuminance meter is made up of two parts: the photometric head (also called the light probe, including the receiver, the V (lambda) filter, the cosine corrector) and the reading display.

An ideal pocket meter should have the following conditions:

1 small in size and light in weight

Lumeter the opportunity of using is very extensive, use time is often in different places, so the portable body of our small and light weight for the first prerequisite lumeter.

2 accuracy

The illuminance meter will, and its accuracy has absolute relationship. Of course, and it is closely related to the price, so to a reasonable price to buy a higher degree of accuracy is necessary, in general, the error is not more than 15%.

3 color compensation

The type of light source on the longer wavelengths of cover and contain everything, some of the red light or high pressure, short wavelength of blue and purple lines such as Daylight fluorescent lamp; also has an average distribution of such as incandescent lamp series, with a different wavelength of light meter may be its sensitivity is slightly different, so the compensation is necessary.

4 cosine compensation

As we all know, the incident angle of luminance and light source on the face. In the same way, as measured by the illuminance meter, sensor, Sensor, and the light incident angle meter reading will affect the control. Therefore, a good illuminance meter cosine compensation function can not be ignored.

Note of illuminance meter

Light battery application of good linearity of selenium (Se) or (Si) silicon photocell light battery; long time work can still maintain good stability, and high sensitivity; high E when used light battery with high resistance, the low sensitivity and good linearity, glare is not easy to be damaged.

There is a V (lambda) correction filter, suitable for use with the temperature of the light source, the error is small.

The addition of a cosine angle compensator (opal glass or white plastic) before the photocell is caused by the deviation of the cosine from the cosine.

The illuminance meter should work at room temperature or near room temperature (with the change of the temperature of the photocell).