The device used to measure the brightness of light falling on an object is a lux meter.
The meter is held close to the object, facing the light source. It measures the number of lumens, that is, the quantity of light of all wavelengths per square metre.
When setting up your exhibitions, it is handy to have a lux meter. By moving it to different distances from the light source, you can determine a suitable position for the object in relation to the light.
Measuring microwatts per lumen
The amount of energy in the ultraviolet band can be measured using a UV meter/monitor.
This device measures the amount of ultraviolet light energy in each lumen of light.
Measuring the UV content of light can be useful in determining whether or not you have a problem. For example, a conservator taking UV readings in an art centre in the far north of South Australia expected very high UV content. The building is not in a sheltered position and the principle light source is sunlight. The readings, however, were low, because the building has Perspex windows instead of glass. Perspex does not allow as much UV radiation to pass through it as glass. Because the Perspex develops static electricity, it attracts the red dust which surrounds the building. This also helps to reduce UV radiation passing through the windows. In this case, a problem was expected, but did not in fact exist.
Measuring infrared energy
Infrared energy can be measured using a simple thermometer. Infrared light causes objects to heat up. So by measuring the rise in temperature with a thermometer placed near the object and directly exposed to the light, we can get an indication of the quantity of infrared energy.
For more information see Damage and decay.