Absorption Filter
Definition and meaning of Absorption Filter in chemistry.
An absorption filter is an optical filter that transmits a chosen band of wavelengths while absorbing the rest, using colored glass or a dyed gelatin layer. It is used to select a desired region of light in optical instruments.
In more detail
Absorption filters work because their coloring agents absorb particular wavelengths and let others pass. They are simple and inexpensive but transmit a fairly broad band of light, so they are less selective than interference filters. They are common in colorimeters and simple photometers.
Key facts
| Function | Transmits some wavelengths, absorbs others |
|---|---|
| Made of | Colored glass or dyed gelatin |
| Used in | Colorimeters, photometers |
| Field | Analytical instrumentation |
A blue absorption filter placed in front of a lamp absorbs red and green light, allowing mainly blue light to pass through to the sample.
Frequently asked questions
How does an absorption filter differ from an interference filter?
An absorption filter removes unwanted light by absorbing it and passes a fairly wide band, while an interference filter uses thin reflective layers to pass a much narrower, sharper band.