Extech Light Meters / Illuminance Meters
Light Meters, also called Illuminance Meters, are designed for measuring the amount of visible incident light illuminates a surface from a variety of light sources, unlike a luminance meter, which measures the light being emitted from a particular area.
Illuminance is basically another word for brightness. However, the term brightness should not be used for quantitative description. Therefore, we say illuminance. Today illuminance meters can effectively measure most types of visible light. For LED light sources, make sure the meter specifications specifically state that it is suitable for LED light sources.
Basic Light Meters are typically used to measure the illumination level in the interior of a building such as an office. The user is then able to make the best decision to either reduce or increase the output level of lighting fixtures in the building. This reduces the energy burden of the building by significantly increasing the efficiency of its lighting system. These light meters measure visible light in lux and foot-candles (fc). Many of these meters also incorporate other environmental measurement functions such as air temperature and relative humidity.
Advanced Light Meters have additional features that are designed for R&D and other applications where higher accuracy is required. In particular look for these manufacturers for higher accuracy Light Meters:
- Gigahertz-Optik
- Gossen
- Hioki
- Yokogawa
Key Features of Light Meters / Illuminance Meters
- Measuring Modes. Some meters can measure Illuminance, illuminance difference, average illuminance, illuminance ratio, integrated illuminance, and integration time. Most other meters can measure in a maximum of five modes and many often require special attachments to measure in certain modes
- Accuracy Classification. Meters are classified by DIN and JIS standards
- DIN classes: L, A, B, C
- JIN classes: Precision, AA, A, B
Class L and Precision are the highest classes in each, respectively. A higher class translates to greater accuracy. However, it will also mean a higher price.
- Illuminance Range. Most meters typically have a maximum range of 199,900 lx
- Types of Lighting. Incandescent, Fluorescent, LED, metal halide, high-pressure sodium
- Multifunction capability. Some models will measure other parameters such as temperature, humidity, and air velocity
What is Radiometry?
Radiometry is a broad field encompassing all techniques for measuring electromagnetic radiation, including the measure of visible light. These techniques measure the distribution of the radiation’s power in space. This field includes photometry, which more specifically measures attributes of electromagnetic energy that are visible to the human eye. Instruments in this category address both the broad and more specific attributes of light these fields cover.