Illuminometer test principle and method 1. The illuminance test principle Illuminance is the areal density of the received luminous flux in the illuminated plane. The illuminometer is an instrument for measuring the illuminance of the surface of illumination, and is one of the most widely used instruments for illumination measurement. Tenor Ukulele,Kala Tenor Ukulele,Best Tenor Ukulele,Electric Tenor Ukulele Shandong Changyun Musical Instruments Co., Ltd. , https://www.cyukulele.com
2. The principle of the illuminance meter illuminance meter consists of two parts, the luminosity head (also called the light receiving probe, including the receiver, V(λ) pair of filters, the cosine corrector) and the reading indicator.
IV. Measurement Procedures and Methods In the working room, the illuminance should be measured at each work site (such as a desk or work table) and then averaged. For empty rooms or non-working rooms where the working place is not determined, if single lighting is used, usually
The illuminance is measured at a level of 0.8m. The measurement area is divided into equal-sized squares (or close to a square). The illuminance Ei of the center of each square is measured. The average illuminance is equal to the average value of the illuminance at each point, that is, Eav, the average illuminance of the measurement area, lx ;
Ei - the illuminance at the center of each measurement grid, lx;
N - number of measuring points.
The illuminance uniformity refers to the ratio of the minimum illuminance to the average illuminance on the specified surface, ie:
In the formula Emin - refers to the minimum illuminance on the measured surface, lx.
In this experiment, the measuring point surface of the room can be designated as the surface, and the minimum illuminance can be considered as the minimum illuminance value of the measured point.
Measure the side length of each square in the room is lm, the large room can be in the middle Eav - the average illumination of the measurement area, lx;
Ei - the illuminance at the center of each measurement grid, lx;
N - number of measuring points.
The illuminance uniformity refers to the ratio of the minimum illuminance to the average illuminance on the specified surface, ie:
In the formula Emin - refers to the minimum illuminance on the measured surface, lx.
In this experiment, the measuring point surface of the room can be designated as the surface, and the minimum illuminance can be considered as the minimum illuminance value of the measured point.
Measure the side length of each square in the room is lm, large room can take 2 - 4 m. Measured points along the longitudinal centerline of a narrow traffic section such as aisles and stairs, spacing 1 -2 m
The measurement plane is ground plane or 150mm above ground level.
The more number of measuring points, the more accurate the average illuminance value obtained, but it also takes more time and effort. If the allowable measurement error of Eav is ±10%, the workload can be reduced by selecting the minimum measurement point based on the chamber index. The relationship between the two is shown in Table 1. If the number of fixtures is exactly the same as the number of measurement points given in the table, the measurement point must be increased.
Chamber Index Kr Least Measured Points Loudness Index Kr Least Measured Points <1 4 2 ~ 3 16
1 to 2 9 ≥ 3 25
Where L, W is the length and width of the room, hr is the height from the lamp to the measurement plane.
When supplementing general lighting with local lighting, the illuminance of the operating point is measured in accordance with the normal working position of the person, and the photocell of the illuminometer is placed on the working surface or on the operation surface of the visual work.
An ideal illuminometer should have the following conditions:
â— Small size and light weight (Compact Size, Light Weight)
Illuminators have a wide range of opportunities to use, and the timing of their use is often in different locations. Therefore, the portable system (18) can be used to burn oysters. â— Accuracy zAccuracy {
The goodness of the light meter is absolutely related to its accuracy. Of course, it is also closely related to its price. Therefore, it is necessary to buy a high-accuracy illuminance meter at a reasonable price. Generally, an error of no more than ±15% is appropriate.
â— Color compensation zColor Compensation{
The types of light sources are all-inclusive. Some high-pressure red lights with longer wavelengths, or shorter blue-violet lines such as Daylight fluorescent lamps, and others with relatively even distribution, such as incandescent light bulbs, may have slight sensitivity to different wavelengths. Different, so appropriate compensation is necessary.
Cosine Compensation zCosine Compensation{
As we all know, the brightness of the illuminated surface is related to the incident angle of the light source. In the same way, when measuring with an illuminometer, the sensor zSensor {with the incident angle of the light source naturally affects the reading of the illuminometer. Therefore, whether a good illumination meter has the cosine compensation function cannot be ignored.