Revolutionizing Precision Measurement with Lux Meters

I.Measurement principle of Lux Meter:
Light photovoltaic measurement principle: LMS-6000 is a direct conversion of light energy into electrical energy of the photovoltaic components. When the light is shone on the surface of the selenium photovoltaic cell, the incident light passes through the metal film 4 to the boundary between the semiconductor selenium layer 2 and the metal film 4, creating a photovoltaic effect on the interface. The size of the generated photoelectric current is proportional to the illuminance on the surface of the photovoltaic cell. At this time, if an external circuit is connected, current will flow and the current value will be indicated on a micro-ammeter calibrated in lux (Lx). The size of the photoelectric current depends on the strength of the incident light.
Types of lux meters: 1. Visual lux meter: inconvenient to use, low accuracy, rarely used. 2. Photovoltaic lux meter: commonly used selenium photovoltaic lux meter and silicon photovoltaic lux meter.

LMS-6000 Portable CCD Spectroradiometer

II.Types:
Components and usage requirements of photovoltaic lux meter:
1. Components: microammeter, changeover knob, zero point adjustment, terminal, photovoltaic cell, V (λ) correction filter, etc.
Common selenium (Se) photovoltaic or silicon (Si) photovoltaic lux meter, also known as lux meter.
2. Usage Requirements: The probe of the Lux meter is made of glass, which is easy to break and has poor waterproof performance.
(1) Photovoltaic should use selenium (Se) or silicon (Si) photovoltaic with good linearity; long-term work can still maintain good stability and high sensitivity; when high E is selected, high internal resistance photovoltaic should be used, and its sensitivity is low and linearity is good, it is not easy to be damaged by strong light.
(2) It has V (λ) correction filter, which is suitable for illuminance of incandescent lamp, and the error is small.
(3) Add a cosine angular compensator (milky glass or white plastic) in front of the photovoltaic cell. The reason is that when the incident angle is large, the photovoltaic is deviated from the cosine rule.
(4) The lux meter should work at room temperature or near room temperature (the photovoltaic drift changes with temperature).

III.Lux calibration:
1. Calibration Principle: Using Ls to vertically illuminate the photovoltaic cell → E=I/r2, changing r can get the photoelectric current values at different illuminance, and the corresponding relationship between E and i can convert the current scale into illuminance scale.
2. Calibration Method: Use a standard light source to change the distance l between the photovoltaic cell and the standard light source at the approximate point light source working distance. Record the readings of the current meter at each distance. Calculate the illuminance E from the inverse square law of E=I/r2. From this, we can get a series of photoelectric currents i at different illuminance, and the change curve of photoelectric current i and illuminance E is the calibration curve of the Lux meter.
3. Factors affecting the calibration curve: Photovoltaic and current meter need to be re-calibrated when changing; the Lux meter should be recalibrated after using for a period of time (generally, once or twice a year); high-precision Lux meter can be tested with standard light source; the Lux meters calibration range can be expanded by changing the distance r, or different standard lights can be selected, and small range current meters can be selected.

IV.Function:
Illumination has a close relationship with people’s lives. Adequate lighting prevents people from accidental accidents. On the contrary, too dark lighting will cause physical fatigue far beyond the eyes themselves. Therefore, inadequate or poor lighting conditions are one of the main causes of accidents and fatigue. According to existing statistics, about 30% of all occupational accidents are directly or indirectly caused by inadequate lighting.
The illumination requirements for stadiums (halls) are very strict, and overexposure or insufficient lighting will affect the effectiveness of the competition.
So, what are the sanitary requirements for the illuminance of people’s living rooms? Illuminance is a very important indicator in hygiene. Light refers to electromagnetic radiation that can cause people’s eyes to experience luminous sensation. When the light enters the eyes, it can produce the perception of visual. The light seen by people refers to visible light, whose wavelength range is between 380 and 760 nm (nanometers).
Lighting can be divided into two categories: natural lighting and artificial light sources. Natural lighting refers to the natural illuminance of the indoor and regional, including direct sunlight illumination and scattered light from surrounding objects, which can be expressed in terms of lighting coefficient and natural illuminance. The general lighting coefficient of residential is between 1/5 and 1/15, and the living area ratio is between 1/8 and 1/10 (window area / indoor ground area). The natural illuminance coefficient is used to evaluate the level of natural light. It reflects the relationship between the indoor and the light coming from the outside. It also reflects the local light climate (the sum of the natural light energy and sunlight illuminance index of the climate).
In order to ensure that people live in appropriate lighting conditions, China has formulated sanitary standards for indoor (including public places) illuminance. For example, the hygienic standard of illuminance in public places such as shopping malls (stores) ≥ 100Lx; table illuminance in libraries, museums, art galleries and exhibition halls ≥ 100Lx; public bathroom illuminance hygienic standard ≥ 50Lx; bathroom (shower, pool, bathtub) ≥ 30Lx, sauna bathroom ≥ 30Lx. The foreign standards for indoor illuminance, such as Germany recommends several rated intensity, office including clerical area for 300Lx, typing, drawing work for 750Lx; in factory, visual work of production line illuminance requirements for 1000Lx; hotel, public room for 200Lx; reception point, cashier cabinet for 200Lx; shop windows for 1500~2000Lx; hospital ward for 150~200Lx, emergency treatment area for 500Lx; school, classroom for 400~700Lx; canteen, indoor gym for 300Lx, etc.

The measurement method of the degree of illuminance is generally measured by lux meter. Luxmeter can measure the intensity of different wavelengths (such as visible light bands and ultraviolet bands), providing accurate measurement results.
In short, illuminance is of great sanitary significance to human health, especially to the eye care.

V.Scope of Application
The application of lux meter has been successfully applied to many schemes, such as lighting industry, photography industry, stage lighting arrangement, etc., different models of luxmeter can meet different measurement requirements. In the factory, the requirement of lighting is relatively strict. Continuous work will cause visual fatigue, and the working efficiency will be greatly discounted. Generally, the requirement of illuminance is ≥1000Lx. For places with higher requirements of lighting, luxmeter with high sensitivity and large range can be selected to deal with strong light Illuminance measurement.
The application of luxmeter is very wide, including our daily life application, such as factory, warehouse, school, office, family, street light construction, laboratory, etc