Editorial Feature

What is a Collimator?

A collimator may be described as a device that focuses or narrows a light beam or a stream of particles to be aligned in a different direction or reduce its cross section. The collimator focuses a beam of light and aligns it to a different direction, making it parallel or collimated. Collimators can also be used for reducing the spatial cross section of a light beams, thereby, making it narrower.

Collimators that are used to converge light beams are referred to as optical collimators, while those that are used to collimate energy particles are called neutron, gamma or X-ray collimators. This datasheet will elaborate on the working principle, construction and applications of collimators.

Working Principle

The incident beam of light or stream of particles fall on the curved lens or mirror of the collimator and emerge as parallel rays or aligned particles on the other side of the lens. The change in orientation of the light or particles depends on the curvature of the lens and the type of collimator used.

Construction and Types of collimators

Collimators are usually made of a curved mirror or lens with the light source placed at its focus. The different types of collimators are listed below:

  • Pin hole collimator – consist of thick conical collimators having a hole in the bottom
  • Parallel (multi-) hole collimator – consists of an array of parallel holes that are perpendicular to the crystal surface
  • Convergent collimator – consists of an array of tapered holes that focus at a point
  • Divergent collimator – it is an inverted converging collimator.


Typical applications of collimators are listed below:

  • Planar scintigraphy for electronic detection medical imaging
  • Radionuclide imaging
  • Scintillation imaging
  • Nuclear power stations
  • Calibration of optical devices.

Sources and Further Reading


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