The remainder, called the reference beam, shines directly on a piece of film. Light scattered from the object interferes with the reference beam, producing constructive and destructive interference. As a result, the exposed film looks foggy, but close examination reveals a complicated interference pattern stored on it.
Where the interference was constructive, the film a negative actually is darkened. Holography is sometimes called lens-less photography, because it uses the wave characteristics of light, as contrasted to normal photography, which uses geometric optics and requires lenses. Light falling on a hologram can form a three-dimensional image of the original object. The process is complicated in detail, but the basics can be understood, as shown in Figure , in which a laser of the same type that exposed the film is now used to illuminate it.
The myriad tiny exposed regions of the film are dark and block the light, whereas less exposed regions allow light to pass. The film thus acts much like a collection of diffraction gratings with various spacing patterns. Light passing through the hologram is diffracted in various directions, producing both real and virtual images of the object used to expose the film.
The interference pattern is the same as that produced by the object. Moving your eye to various places in the interference pattern gives you different perspectives, just as looking directly at the object would. The image thus looks like the object and is three dimensional like the object. The hologram illustrated in Figure is a transmission hologram. Holograms that are viewed with reflected light, such as the white light holograms on credit cards, are reflection holograms and are more common.
White light holograms often appear a little blurry with rainbow edges, because the diffraction patterns of various colors of light are at slightly different locations due to their different wavelengths. Further uses of holography include all types of three-dimensional information storage, such as of statues in museums, engineering studies of structures, and images of human organs.
Invented in the late s by Dennis Gabor — , who won the Nobel Prize in Physics for his work, holography became far more practical with the development of the laser. Since lasers produce coherent single-wavelength light, their interference patterns are more pronounced.
The precision is so great that it is even possible to record numerous holograms on a single piece of film by just changing the angle of the film for each successive image.
This is how the holograms that move as you walk by them are produced—a kind of lens-less movie. In a similar way, in the medical field, holograms have allowed complete three-dimensional holographic displays of objects from a stack of images. Storing these images for future use is relatively easy. With the use of an endoscope, high-resolution, three-dimensional holographic images of internal organs and tissues can be made.
How can you tell that a hologram is a true three-dimensional image and that those in three-dimensional movies are not? If a hologram is recorded using monochromatic light at one wavelength but its image is viewed at another wavelength, say shorter, what will you see? What if it is viewed using light of exactly half the original wavelength? What image will one see if a hologram is recorded using monochromatic light but its image is viewed in white light?
White light falls on two narrow slits separated by 0. The interference pattern is observed on a screen 3. Identify the order for each maximum. Microwaves of wavelength Quasars , or quasi-stellar radio sources , are astronomical objects discovered in They are distant but strong emitters of radio waves with angular size so small, they were originally unresolved, the same as stars.
The quasar 3C is actually two discrete radio sources that subtend an angle of 82 arcsec. If this object is studied using radio emissions at a frequency of MHz, what is the minimum diameter of a radio telescope that can resolve the two sources? JOSA 56 6 , — Georgiou, A. Aspects of hologram calculation for video frames. A-Pure Appl. Deng, Y. Effect of masking phase-only holograms on the quality of reconstructed images. Optics 55 , — Filling factor characteristics of masking phase-only hologram on the quality of reconstructed images.
SPIE , M Zhang, Z. Fundamentals of phase-only liquid crystal on silicon LCOS devices. Light Sci. Goodman, J. Introduction to Fourier Optics. Roberts and Company Publishers Thibeault, B. Enhanced light extraction through the use of micro-LED arrays. Patent No. Choi, H. GaN micro-light-emitting diode arrays with monolithically integrated sapphire microlenses. McKendry, J. High-speed visible light communications using individual pixels in a micro light-emitting diode array. IEEE Photonic.
Lebby, M. Superluminescent edge emitting device with apparent vertical light emission and method of making. High-power quantum-dot superluminescent LED with broadband drive current insensitive emission spectra using a tapered active region.
Ray, S. Broad-band superluminescent light emitting diodes incorporating quantum dots in compositionally modulated quantum wells. Integrated Optoelectronic Devices. Sun, T. An accuracy measurement method for star trackers based on direct astronomic observation.
Sensors 13 4 , — Download references. Dandan Zhu for providing the mLEDs used in this work. You can also search for this author in PubMed Google Scholar. Correspondence to Daping Chu. Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Reprints and Permissions. Coherence properties of different light sources and their effect on the image sharpness and speckle of holographic displays. Sci Rep 7, Download citation.
Received : 23 January Accepted : 08 June Published : 19 July Anyone you share the following link with will be able to read this content:. Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative. Scientific Reports Optical and Quantum Electronics Analytical and Bioanalytical Chemistry By submitting a comment you agree to abide by our Terms and Community Guidelines.
If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate. Advanced search. Skip to main content Thank you for visiting nature. Download PDF. Abstract Coherence properties of different light sources and how they affect the image quality of holographic display are investigated. Introduction Holographic displays can reconstruct three-dimensional 3D images with full wavefront information 1 , 2 , 3 , 4 , 5 , 6 , which is free from issues such as lack of accommodation depth cue, discontinuous motion parallax and crosstalk 7 , 8 , 9 , 10 , Results Temporal Coherence and spatial coherence Theoretically a holographic display is based on the use of an ideal coherent light source.
Figure 1. Full size image. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Figure Table 1 Normalized spatial and temporal coherence and speckle contrast and image sharpness. Full size table.
Conclusions Coherence property of a light source can be characterized by its temporal coherence and spatial coherence values, respectively. References 1. Article Google Scholar 3. Article Google Scholar 5. Article Google Scholar View author publications.
Ethics declarations Competing Interests The authors declare that they have no competing interests. Additional information Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. About this article. Cite this article Deng, Y. Copy to clipboard. Olarte-Carrillo , A. Comments By submitting a comment you agree to abide by our Terms and Community Guidelines.
Publish with us For authors Submit manuscript. Search Search articles by subject, keyword or author. Wiley, New York , , Chap. Courjon , J. Bulabois , and W. Mendlovic , G. Shabtay , and A. Mertz and N. Habell , ed. Chapman and Hall, London p. Worthington Jr.
Carter and E. Acta 28 , — Rosen and A. A 13 , — A 4 , — Itoh and Y. Takeda , H. Ina , and S. Optica participates in Crossref's Cited-By Linking service. Citing articles from Optica Publishing Group journals and other participating publishers are listed here.
Alert me when this article is cited. Click here to see a list of articles that cite this paper. Learn more. Allow All Cookies. Optics Express Vol. Open Access. Express 13 , More Like This Real-time coherence holography. Vectorial coherence holography. The topics in this list come from the Optics and Photonics Topics applied to this article. Introduction 2. Principles 3. Experiments 4.
Conclusions References and links. The beam is incident on the holographic plate at the same angle as the reference beam that was used when the image was formed on the holographic plate. The term for the beam used to replay the holographic image is the playback beam. When a holographic plate that has had an image recorded onto it then has a playback beam directed through it, the light at each point on the holographic plate is diffracted by the holographic plate.
The diffracted light from different points on the holographic plate interferes. This is shown in the following figure. The interfering light waves from the holographic plate produce a virtual image of an object imaged on the holographic plate. The image produced represents the distances between the points on the object that was imaged and so appears three-dimensional to a viewer. A replayed holographic image has another interesting property, which is that if the playback beam is incident at some angle other than the angle at which the reference beam used to form the image on the holographic plate was incident, the resulting interference between the waves in the playback beam is changed.
The changed interference pattern produces a changed image. The change in a replayed image that results from a change in the angle of incidence of the playback beam is that the same object is imaged, but the angle from which the object is viewed is changed proportionally to the change in the playback beam angle.
The diagram shows a laser being used to record a holographic image of a cylindrical object and then to display the image recorded on the holographic plate. Which of the virtual images would be observed by a viewer at the position shown? The eye of the viewer is shown to be at a position that is not along the line of the playback beam used to replay the recorded holographic image. This position difference of the viewer and the line of the playback beam has an equivalent effect to the changing of the direction of the playback beam.
This means that the viewer would not see a virtual image that was identical to the recorded object. The viewer does not then see virtual image A. If virtual image A will not be seen alone, then it will not be seen simultaneously or alternatingly with another virtual image, so the options stating that both virtual images would be seen can be eliminated.
Light passing through the holographic plate can reach the eye of the viewer, so it is not correct to say that no virtual image is seen. The correct option is that virtual image B would be seen. Virtual image B is an image of the object that was recorded but viewed from a different position. An interesting property of holographic images results from the diffuse reflection of light from an imaged object. We recall that this results in light from points very close together on an object being incident at points more or less anywhere on a holographic plate.
This means that each point on a holographic plate can have received light from almost the entire object that was imaged. If a holographic plate is broken into fragments, each fragment will consist of many points that have each received light from almost the entire object that was imaged.
Let us now look at an example involving the replayed image produced by parts of a holographic plate. If a holographic plate was broken into pieces and a laser was used to view the image contained on one of the pieces, which of the following would the image show?
The question states that a laser is used to view the image on the pieces of the holographic plate, and so a virtual image of something would be seen rather than nothing or an interference pattern. These options can be eliminated. Any part of an object that was not scanned by the object beam when the image was recorded cannot be part of the holographic image recorded, so the option that an unscanned part of the object would be seen cannot be correct.
For a photographic image, the obviously correct option would be that a part of the imaged object would be seen. This is not correct for a holographic image, however, as each point on a holographic plate can have received light from almost the entire object that was imaged.
This means that any part of the holographic plate can reconstruct the image of the object that was imaged. A part of a holographic plate did not receive all the light from the object that was received by the whole of the holographic plate, however, so the image produced by a fragment of the plate would be an imperfect blurred version of the image that would be produced by the whole holographic plate.
The resolution of the replayed image would be lower.
0コメント