Optical Slits
Author: the photonics expert Dr. Rüdiger Paschotta
Definition: narrow openings through which light can be transmitted
DOI: 10.61835/4lg Cite the article: BibTex plain textHTML Link to this page LinkedIn
Optical slits are narrow openings through which light can be transmitted. They are usually made with high precision, often with laser material processing in some resistant metal such stainless steel, molybdenum or tungsten. In some cases, such a slit is made in a thin metallic coating on a glass piece.
Typical slit widths are some tens or a few hundreds of micrometers, but slits with a width of only a few micrometers are also available. The width tolerance can be of the order of 1 μm. The length may be a few millimeters or more.
There are also adjustable mechanical slits, where the slit width can be tuned with a micrometer screw.
Applications of Optical Slits
Optical slits are used in various optical instruments:
- At the entrance and exit of a monochromator, e.g. of Czerny–Turner type, or an optical spectrograph, there is usually a narrow slit. It prevents the propagation of light on paths which would be possible for light outside the wanted range of transmission wavelengths.
- Some beam profilers work with a rotating disc with one or more optical slits, where one measures the transmitted optical power as a function of the slit position. Two such discs can be used for obtaining two-dimensional beam profiles.
- Thin optical slits have been used in interference experiments, for example in the famous double-slit experiment of Thomas Young.
More to Learn
Encyclopedia articles:
Suppliers
The RP Photonics Buyer's Guide contains five suppliers for slits. Among them:
Geola
The MID14-24 is precise motorized iris diaphragm, which is adjustable either mechanically or on a PC with an intuitive graphical user interface. Our unique design has aluminum blades forming a square diaphragm, always remaining centered to an internal SM1–threaded hole during size tuning. The adjustment step size is ≈10 µm.
The square Iris diaphragm is also designed to be compatible for either stand-alone (MID14-24) or 60 mm standard (for example Thorlabs) Cage System (MID14-24C).
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