Browse Prior Art Database

Zoom Lens Effect Using Rotational or Radial Shear in Incoherent Holography

IP.com Disclosure Number: IPCOM000091775D
Original Publication Date: 1968-May-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 3 page(s) / 29K

Publishing Venue

IBM

Related People

Bryngdahl, O: AUTHOR [+2]

Abstract

A zoom effect, that is, a continuous change of magnification, can be achieved using holographic recording techniques. This device records a hologram of spatially incoherent object 10. The latter consists of three points 10A, 10B, and 10C. The mechanism for generating the hologram includes collimating lens 12, beam splitter 14, mirror 16, and recording plate 18. Image rotating device 20 is positioned in one leg of the holographic recording mechanism. Device 20 rotates the image passing along that leg of the recording apparatus. However, the light entering device 20 is collimated and, likewise, the light leaving such device is collimated. Device 20 can, for example, be a dove prism, or a telecentric system of cylindrical lenses.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 52% of the total text.

Page 1 of 3

Zoom Lens Effect Using Rotational or Radial Shear in Incoherent Holography

A zoom effect, that is, a continuous change of magnification, can be achieved using holographic recording techniques. This device records a hologram of spatially incoherent object 10. The latter consists of three points 10A, 10B, and 10C. The mechanism for generating the hologram includes collimating lens 12, beam splitter 14, mirror 16, and recording plate 18. Image rotating device 20 is positioned in one leg of the holographic recording mechanism. Device 20 rotates the image passing along that leg of the recording apparatus. However, the light entering device 20 is collimated and, likewise, the light leaving such device is collimated. Device 20 can, for example, be a dove prism, or a telecentric system of cylindrical lenses.

The distance between object 10 and lens 12 is equal to the focal length of lens 12. The distance from lens 12 to plane 18 along either path 14A or 14B is approximately equal to the focal length of lens 12. The difference in length between paths 14A and 14B is less than the temporal coherence length of the light used. These path lengths can be made exactly equal by inserting a series of mirrors in path 14A.

The light from each point 10A, 10B, and 10C does not interact, that is, interfere, with the light from any other point. This is because the light from each point is incoherent with the light from all other points. However, at plane 18, part of the light from each point arrives via path 14A and part of the light arrives via path 14B. The two wavefronts from each point interact to create a series of interference fringes. The orientation and spatial frequency of these fringes is determined by the amount of rotation introduced by device 20. The rotation of the light passing along path 14B introduces a tilt between the wavefronts which come from each point, that is, the wavefronts traveling along paths 14A and 14B. The amount of tilt is dependent upon the amount of rotation. The spatial frequency of the fringes created in plane 18 is dependent upon the tilt between the wavefron...