How does a Lumen (Lux) Meter work?

How does a Lumen (Lux) Meter work?


A light meter is used to measure the amount of light distributed over a particular area at a specified distance from the light source. The units that a light meter will measures in are either Lux, lumens and/or foot candle. The amount of light will vary between light source such as a well-lit office having a reading of 500 Lux to an overcast sky of 5000 Lux.

To measure the light intensity, light meters use a sensor called a photodiode. A photodiode is a semiconductor that converts the incoming light to electrical current. The sensor conducts electrical current directly proportional to the amount of light that it measures. Filters and built in lenses make up the photodiode. A photodiode will also differ in surface.

There are many applications to use a light meter to measure light intensity. Office lighting is an important part of occupational health and safety. Proper lighting can reduce eye fatigue and headaches for people that work in an office for long periods. Proper lighting will also prevent workplace accidents by increasing the visibilities of dangers and reducing momentary blindness.

Councils will use a light meter to check if street lights are performing at optimal levels during night time. A light meter will ensure street lights are emitting the right light levels to improve road and pedestrian safety. It will also help councils to reduce energy bills by ensuring the street lights aren’t producing too much light.

Optimizing light levels in museums and art galleries is very important. The optical light levels will ensure the intricate details and colour work of a piece of artwork won’t be missed by the viewer. It ensures the artwork is properly displayed as intended. The wrong light intensity can potentially harm light sensitivity artworks. Measuring the light intensity ensures the preservation of light sensitive artworks.

The Light Intensity Meter with Protective Cap - 0560-0540 is a light meter that has a sensor designed to the spectral sensitivity of the eye. This makes the 0560-0540 the ideal meter to be used to measure light intensity in a workplace. The unit has a quick read out, hold function, max/min features and a protective cap making it perfect to be used as a portable meter to be measure multiple light sources at a workplace quickly and with ease.



Figure 1: Testo 0560-0540 Light Intensity Meter

The Visible Light Meter SD Card Logger - IC850007 is a light meter that measures in lux and foot candle. The IC850007 has a detachable colour probe that meets C.I.E photopic spectrum. The unit is extremely accurate and has a fast response time. A Type K or J thermocouple probe can be connected to the IC850007, turning it into a thermometer. The IC850007 can act as a data logger and records onto a SD card. The data is uploaded onto a pre-formatted Excel spreadsheet can be accessed without the need of cables of special software. With the probe being on a cable and the logging capabilities, this makes it an ideal unit the measure and record light intensity over an extended period of time in difficult to reach areas.


Figure 2: Sper IC850007 Visible Light Meter with SD Card Logger

If you’re still unsure about which Lumen (Lux) meter is right for you, contact one of our scientists on 1300 737 871 or at [email protected]

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