Dove prism

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The Dove prism , seldom also called Harting Dove prism, is an optical prism that is counted among the reversing reflection prisms . Since the light is refracted on both the entrance and the exit surface , it can only be used to invert the image with monochromatic light . Its use is also limited to parallel bundles of rays, since astigmatism would occur due to the refraction on the inclined side surfaces .

The prism was named after Heinrich Wilhelm Dove .

Structure and functionality

Beam path in a Dove prism
Dove prism

A Dove prism is a prism with the base of a trapezoid with sides inclined by 45 °; Often it is also described as an isosceles, right-angled prism in which the optically ineffective area is cut off. The length of the prism is usually four to five times (in the case of glass as the prism material) the diameter of the light beam that is to be transmitted.

If a collimated light beam running along the longitudinal axis of the prism hits one of the inclined incident surfaces, it is first refracted into the prism and directed to the longest side of the prism. There the light beam experiences a total reflection and is refracted again in the inclined exit surface. The incoming and outgoing beam are aligned with each other, but the one-time reflection in the prism causes an image to be reflected around a straight line across the direction of the beam.

Properties and application

Rotation around the longitudinal axis

If a Dove prism is rotated around its longitudinal axis, a transmitted image is rotated by twice the angle. If the prism is rotated by 180 °, for example, the image rotates 360 °, and the speed of rotation of the image around the optical axis is twice as great as the speed of rotation of the prism. This property can be used to rotate a beam by an arbitrarily chosen angle. This results in the use of Dove prisms as "beam rotators", which are used in areas such as interferometry , astronomy and pattern recognition . A special field of application are multi-channel fiber optic rotary transmitters for coupling optical fibers from stationary to rotating parts, such as B. in industrial robots . The Dove prism is rotated by a special gear at half the speed as the movable fiber part, and thus the permanent imaging of the collimated light beams from the input to the output fibers is realized.

polarization

Lesso and Padgett (1999) and Moreno et al. (2003, 2004) found that the polarization state of a light beam changes when it passes through a Dove prism. These properties of the Dove prisms are of particular interest as they can influence the signal measurement of scientific instruments.

variants

Double dove prism

If two Dove prisms are joined together on their longest side (after being mirrored by a metal coating), the so-called double Dove prism is created . It behaves essentially like a simple Dove prism, but the center of the beam is in the middle of the overall prism. As a result, the light beam is split into two partial beams running differently in the prism and the length of the prism can be halved (compared to the simple Dove prism) at twice the height. Due to the splitting into two partial beams, the double Dove prism must be manufactured very precisely in order, for example, to prevent the two halves of the image from drifting apart.

Dove prism with roof edges

In this prism, the large, reflective surface has been replaced by two roof-edge surfaces . It essentially corresponds to an Amici prism , in which the light beam passes the entry and exit surfaces vertically. When reflecting on the roof edge surfaces, the image is split in the middle, and the fields are reflected twice each separately before they unite again. The double reflection means that an image is not reversed. In the Dove prism with roof edges, an image is rotated 180 ° around the optical axis.

Individual evidence

  1. ↑ Michael Bass (Ed.): Handbook of optics. Vol. 1 - Geometrical and physical optics, polarized light, components and instruments . 3. Edition. McGraw Hill Professional, ISBN 978-0-07-149889-0 , pp. 19.9 .
  2. ↑ Dietrich Kühlke: Optics - Basics and Applications , Harri Deutsch, Frankfurt / Main, 2011, ISBN 978-3-8171-1878-6 , p. 133
  3. ↑ H. W Dove: The reversion prism and its application as a terrestrial ocular and for measuring angles . In: Annals of Physics . tape 159 , no. 5 , 1851, pp. 189–194 , doi : 10.1002 / andp.18511590515 ( digitized on Gallica ).
  4. ↑ O. Ziemann, J. Krauser, PE Zamzow, W. Daum: POF manual: Optical short-range transmission systems . 2nd Edition. Springer, 2007, ISBN 978-3-540-49093-7 , pp. 285–288 ( limited preview in Google Book search).
  5. ^ Miles Padgett, J. Paul Lesso: Dove prisms and polarized light . In: Journal of Modern Optics . tape 46 , no. 2 , 1999, p. 175-179 , doi : 10.1080 / 09500349908231263 .
  6. ↑ Ivan Moreno, Gonzalo Paez, Marija Strojnik: Polarization transforming properties of Dove prisms . In: Optics Communications . tape 220 , no. 4-6 , 2003, ISSN  0030-4018 , pp. 257-268 , doi : 10.1016 / S0030-4018 (03) 01423-8 .
  7. ↑ Ivan Moreno: Jones Matrix for Image-Rotation Prisms . In: Applied Optics . tape 43 , no. 17 , 2004, ISSN  0003-6935 , p. 3373–3381 , doi : 10.1364 / AO.43.003373 ( reduaz.mx [PDF; accessed on August 24, 2011]). Jones Matrix for Image-Rotation Prisms ( Memento of the original from December 27, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / planck.reduaz.mx
  8. ^ Warren J. Smith: Modern Optical Engineering: The Design of Optical Systems . 3. Edition. Mcgraw-Hill Professional, 2000, ISBN 0-07-136360-2 , pp. 107 .
  9. ↑ Heinz Haferkorn: Optics: Physical-technical basics and applications . 4th edition. Wiley-VCH Verlag GmbH & Co. KGaA, 2002, ISBN 3-527-40372-8 , p. 483 .