Prisms

A wedge prism is an optical element consisting of a transparent body with two refracting surfaces forming a small angle (the wedge). Such a prism deflects a light beam toward the thicker part of the wedge, providing precise control of light direction with minimal distortion.

Operating principle
When passing through a wedge prism, light is refracted at the wedge surfaces, causing the beam to deviate at a certain angle, which depends on the wedge’s apex angle and the refractive index of the material. Due to the small wedge angle, the prism enables precise and stable light control while preserving beam quality and minimizing optical aberrations.

Applications

• Laser systems for precise beam steering and deviation.
• Interferometry and optical calibration.
• Medical equipment and microscopy.
• Optical measurements and metrology.
• Telescopes, projectors, and photolithography.
• Geodesy and other scientific and industrial instruments requiring precision light control.

An equilateral prism is an optical element in the shape of a triangular prism, in which all three angles are 60°, and the sides of the triangular cross-section are of equal length. This shape provides symmetrical light refraction and allows effective control of beam direction.

Operating principle
When light passes through an equilateral prism, it is refracted at two faces, changing its direction. Due to dispersion — the dependence of the refractive index on wavelength — the prism separates white light into a spectrum of colors, deflecting rays of different wavelengths at different angles. This phenomenon is widely used for spectral analysis of light. At the minimum deviation angle, rays pass through the prism with minimal losses and distortions.

Where is an equilateral prism used?

• In spectrometers and spectroscopes for analyzing the spectral composition of light.
• In optical research and laboratory experiments for demonstrating dispersion.
• In laser systems for controlling and splitting light beams.
• In telecommunications and photonics for processing optical signals.
• In education for clearly illustrating optical phenomena.

A rectangular prism is an optical element that is a transparent body with two parallel rectangular bases and lateral faces in the form of rectangles. In geometric terms, it is a right parallelepiped in which all lateral edges are perpendicular to the planes of the bases.

Operating principle
A rectangular prism changes the direction of a light beam through refraction and total internal reflection. It is often used to rotate or reflect a beam by 90° or 180° while preserving image quality and light direction. Thanks to the precision of its angles and surfaces, the prism ensures minimal distortion and high reflection efficiency.

Main functions and applications

• Rotation and reflection of light beams in optical devices (e.g., binoculars, cameras, projectors).
• Image inversion and correction (flipping or mirror reflection).
• Use as a reflecting element with high angular accuracy for stable light direction.
• Application in laser systems, measuring instruments, and visualization.

A Dove prism is a reflective optical prism designed to invert an image while maintaining the direction of the light beam. In its main cross-section, it is an isosceles trapezoid with slanted faces at a 45° angle to the base.

Operating principle

Light enters the prism through one of the slanted faces. It reflects off the long face of the prism (the hypotenuse) due to total internal reflection. The reflected light then exits through the opposite slanted face, remaining parallel to the incoming light beam. As a result of total internal reflection, the image is mirrored.

Features and advantages

• The light exits the prism in the same direction as it entered.
• Mirrors the image.
• Works with parallel beams.
• In some applications, a Dove prism can rotate the image by an angle twice as large as the rotation of the prism itself.

Applications

• Optical instruments requiring image rotation or inversion (e.g., spectroscopes, laser systems, telescopes).
• Laser technology and photonics for precise beam direction and orientation control.
• Scientific research and measurements where it is important to preserve the beam direction while changing image orientation.
• Systems requiring image stabilization or rotation without shifting the optical axis.

A pentaprism is a reflective optical prism with a pentagonal cross-section, featuring two reflective surfaces positioned at a 45° angle to each other. It is designed to deflect a light beam by exactly 90° without altering the image orientation — the image remains upright, without mirror inversion or rotation.

Operating principle
Light passing through the objective and reflected from a mirror enters the pentaprism. Inside the prism, the beam is reflected twice from the reflective-coated faces set at 45°, ensuring precise 90° deflection. Thanks to the even number of reflections, the image retains its correct orientation and is not inverted. This is especially important in optical systems where a direct and continuous view of the scene is required.

Features and advantages

• Constant 90° light deflection angle, independent of the incident beam angle.
• Preservation of a direct, non-mirrored image, improving perception through the optical device.
• Compact optical system design due to efficient beam turning without increasing dimensions.
• High light transmission thanks to solid glass construction and anti-reflective coatings on input and output surfaces.
• Reliability and durability provided by reinforced reflective coatings (aluminum, dielectric coatings) on reflective faces.

Applications

• Viewfinders of single-lens reflex (SLR) cameras, where the pentaprism converts the inverted mirror image into a direct one for convenient composition.
• Optical devices and observation systems requiring precise beam turning and image stabilization.
• Laser and measurement systems where beam direction and image orientation stability are crucial.
• Industrial and scientific optical assemblies where compactness and image quality are critical.

A roof prism is a special type of reflective optical prism in which one of the reflecting faces is formed by two planes at a 90° angle, resembling the shape of a roof. This design not only deflects the light beam by 90°, but also mirrors the image in one plane, providing unique optical effects.

Operating principle
A light beam enters the prism and is reflected twice inside it: first from one roof face and then from the other. These two reflections cause the image to be mirrored along one axis (usually horizontal), while the beam direction changes by 90°. Importantly, the reflections occur due to total internal reflection or high-quality reflective coatings, minimizing light loss.

A roof prism creates an optical illusion effect, making the reflected light appear to originate from the opposite direction — similar to a mirror, but with high stability and without distortion.

Features and advantages

• Provides 90° beam deflection with image mirroring along one axis.
• Minimal light loss thanks to total internal reflection and high-quality coatings.
• High angular and surface accuracy ensures no distortion and image stability.
• Reduction in optical system size due to compact beam control.
• Reliable performance with high-intensity laser beams, where mirrors degrade quickly but prisms withstand heavy loads.

Applications

• Prism binoculars and optical instruments for enhancing image depth and correction.
• Laser technology where reliable reflection is required at high energy densities.
• Optical systems requiring mirrored image inversion along one axis.
• Scientific and measuring instruments where precision and optical stability are crucial.
• Projectors and cameras requiring compact and high-quality light management.