A third, much less common way of producing a retroreflector is to use the nonlinear optical phenomenon of phase conjugation. Mungan, spring 2001 the eye of a cat can be modeled as a lens with a mirror at the focal plane. The key point to appreciate is that a conjugate mirror yields reflected wavefronts that are identical to those of the incident ones. By measuring both the angle through which the output beam is steered and the angle through which the output coupler is tuned it is found that the direction of propagation of the laser output is parallel to the normal to the mirror irrespective of the angle with the retroreflector. Basic methods and algorithms the retroreflective property of a retroreflector results from three reflecting faces which are mutually perpendicular to each other. Phase conjugate mirrors require a comparatively expensive and complex apparatus, as well. Practical nonlinear phase conjugators, however, add a constant phase. Retroreflector definition of retroreflector by merriam. By using a hollow retroreflector, it is insensitive to the orientation of the four mirror retroreflector, i. We report what is to our knowledge the first demonstration of brillouinenhanced fourwave mixing over a long atmospheric path. One of the most popular types of unconventional mirror is the phase conjugation mirror pcm 1. Electromagnetic equivalent model for phase conjugate. The apparatus uses a shared aperture component to sample the outgoing laser beam and the incoming target beam, a retroreflector array to reverse the direction of the subaperture samples of the.
For the love of physics walter lewin may 16, 2011 duration. The added phase is the key difference between a retroreflector and a phase conjugator fig. Evaluation of the returned electromagnetic signal from retro. Unlike the picture of the aollo 11 array, this one has sunlight on its face, enabling a better view of the array of corner cubes. Pdf ray trace through a cornercube retroreflector with complex. The bandwidth of a batio 3 selfpumped phase conjugate mirror is measured in three different ways. He institute for lasers, photonics and biophotonics, state university of new york at buffalo. Evaluation of the returned electromagnetic signal from. In a twodimensional retroreflector figure 2, is con structed through the vertex parallel to the incident ray and the reflected ray s. Phaseconjugated directional diffraction from a retroreflector array hologram. A simple retroreflector can be made by placing three ordinary mirrors mutually perpendicular to one another a corner reflector. Lasers at observatories on earth are aimed at retroreflectors planted on the moon during the apollo program 11, 14, and 15, and the two lunokhod missions. Our mrr mems device has the characteristic that it can be made to act as a normal plane mirror, or it can be deformed. Papers phase conjugate optics and realtime holography core.
In addition to these three reflecting faces, there is a. Phase conjugated directional diffraction from a retroreflector array hologram. Phaseconjugate mirrors on the basis of photorefractive crystals offer interesting possibilities of application for optical measurement systems. This is expected with phase conjugate resonators 8. Broadband hollow retroreflectors newport corporation. Polarization change after propagation through a prism retroreflector output polarization of laser light measured after reflection from each sextant of a prism retroreflector. Retroreflector definition of retroreflector by the free.
Here, we present optical phase conjugationmirror with a one wave configuration for both input and phase conjugated beams fig. A phase conjugate mirror pcm has a remarkable property of cancellation the backscattering wave of the lossless scatterers. Retroreflectors are used in transportation systems as unlighted nighttime. Phaseconjugated directional diffraction from a retroreflector array. Two scattered beams are generated that are counterpropagating to the pumps and are their phase conjugate replicas. Electromagnetic equivalent model for phase conjugate mirror based on the utilization of lefthanded material guoan zheng1, lixin ran3, and changhuei yang1, 2 1department of electrical engineering, california institute of technology, pasadena, california 91125 2department of bioengineering, california institute of technology, pasadena, california 91125. The ongoing lunar laser ranging experiment or apollo landing mirror measures the distance between surfaces of earth and the moon using laser ranging. Amplitude noise reduction of ion lasers with optical feedback. The solution is based on a set of two coupled secondorder wave equations and does not assume the slowly varying envelope approximation. The angle of incidence at which the device or surface reflects light in this way is. Phaseconjugate mirrors are used to provide optical feedback, thresholding, and gain.
Both operate on similar principals, however with variations. Apr 28, 2014 phase conjugate mirrors on the basis of photorefractive crystals offer interesting possibilities of application for optical measurement systems. Despite atmospheric effects the phaseconjugate return energy measured. Phase conjugation is an interesting wave phenomenon in which both the direction of propagation and the overall phase factor for each arbitrary plane wave component are precisely reversed during reflection from a phase conjugate mirror pcm 1, 2.
This is the main this is the main conceptbehindtherealtimeholography,betterknownasdegeneratefourwave. A preliminary study of a retroreflective mirror resonator. The apollo 14 retroreflector array is very much like the apollo 11 array in design. The most economic choice is a solid glass retroreflector, where the input and return beams travel through glass such as nbk7, but its applications are more limited.
The earth is a nonlinear medium, and provides a very good phase conjugate mirror in the range of 0. The nonlinearity is typically observed only at very high light intensities values of atomic electric fields, typically 10 8 vm such as those provided by lasers. The resulting amplified output returns to the retroreflector owing to its phaseconjugate nature. The retroreflector is used as a stable mirror in one arm. A retroreflector sometimes called a retroflector or cataphote is a device or surface that reflects light back to its source with a minimum of scattering. Overview our broadband hollow retroreflectors are constructed of three frontsurface mirrors assembled into a cornercube. Retroreflector definition is a device that reflects radiation such as light so that the paths of the reflected rays are parallel to those of the incident rays. Osa phase conjugation through brillouinenhanced four. Multidirectional retroreflector assembly with a common. The vertex of a retroreflector is balh7ay between the lines defined by the incident and the reflecte rays. A process and apparatus are disclosed for aligning a laser beam from a laser transmitter with an incoming laser beam, and driving any sensed tilt differences on an aperture and subaperture basis to zero. In the plane of the aperture stop there is an amplitudephase.
How retroreflectors measure the moon as a piece of common safety equipment, retroreflectors have saved countless lives. Phase conjugate mirrors are used to provide optical feedback, thresholding, and gain. The pcm conjugates the phase on the mirror surface, and causes the reflected light to rewind through the path that input light have travelled. Method for autoalignment of digital optical phase conjugation. Megahertzrate shockwave distortion cancellation via. Pdf phaseconjugated directional diffraction from a.
An ideal phase conjugate mirror pcm reflects a light wave in which the wave vector and amplitude are reversed and are complex conjugated to the incident wave to create pcw 6,7. An optical adaptive resonance neural network utilizing phase conjugation. The solution to the boundaryvalue problem for a simple model of the phase conjugate mirror is presented. The double phase conjugate mirror dpcm is a selfpumped fourwave mixing geometry in which two mutually incoherent noncollinear pump beams intersect in a photorefractive nonlinear medium fig. Electromagnetic equivalent model for phase conjugate mirror based on the utilization of lefthanded material guoan zheng1, lixin ran3, and changhuei yang1, 2 1department of electrical engineering, california institute of technology, pasadena, california 91125. By using a hollow retroreflector, it is insensitive to the orientation of the fourmirror retroreflector, i. The patented fabrication technique enables as fine as 1 arc second return beam parallelism with 3 wavefront distortion at an affordable price. Weak laser light reflected from a remote retroreflector was input to a highgain conjugate mirror.
Soviet journal of quantum electronics nonlinear optical. Pdf an optical adaptive resonance neural network utilizing. A surface can be made partially retroreflective by depositing a layer of tiny refractive spheres on it or by creating small pyramid like structures. Aberration correction in doublepass amplifiers through the.
Unlike an ordinary mirror, a retroreflector bounces an oncoming beam of light straight back to its source, no matter the angle. We propose and experimentally demonstrate naturally occurring phase conjugation by actively coupling arbitrary light fields into a singlemode. Mzthod of caicuiating retroreflectorarray trahisfer functions david a. This page was last edited on 10 january 2019, at 00. The resulting amplified output returns to the retroreflector owing to its phase conjugate nature. Onewave optical phase conjugation mirror by actively. Multidirectional retroreflector assembly a common virtual. The physics of phase conjugate mirrors 5 basov et al. The mirror causes incident light to be backreflected through the eye, thereby doubling its intensity inside the active layer and improving the cats night vision. Optical measurements with phaseconjugate mirrors springerlink. That is, the highly pressurized internal portions of the earth are already trembling, electro magnetically at those frequencies, but in scalar em resonance due to combined em waves and their phase conjugate replicas. Aberration correction in doublepass amplifiers through. Optical devices such as retroreflectors scotchlite for example.
The physics of phase conjugate mirrors sciencedirect. A retroreflecting mirror was positioned one cavity length 170 cm from the output coupler of a largeframe cw arion laser that was operated in a single line 514 nm multilongitudinalmode configuration, i. The bandwidth of a batio3 selfpumped phase conjugate mirror is measured in three different ways. Typically they are constructed in one of two different forms, 90deg corner cubes or high indexofrefraction transparent spheres with a reflective backing.
Unlike an ordinary mirror, a retroreflector bounces an oncoming beam. To create the phase conjugate beam, the imaging beam with amplitude a 3 is first directed into a phase conjugate mirror fluid 55 cell. Introduction the work described in this report was begun as part of the lageos study program formerly called cannonball supported by grant ngr 09015164 from the national aeronautics and space administration nasa. Lasers at observatories on earth are aimed at retroreflectors planted on the moon during the apollo program 11.
The principle of operation of this relatively straightforward boresight control system is extended to a higher order control phase conjugate system by using a retroreflector array, and a matching deformable mirror and wavefront sensor as shown in fig. Geri abstract conjugateoptical retroreflector cor display systems have the potential for providing inexpensive h ighresolution imagery aheadmounted display hmd conf uration. While input beams normal to the base strike each face of the retroreflector at a roughly 55 angle of incidence 1, the s and p polarization components experience different phase delays and are split differently, depending on the order of surfaces they reflect from. Using this system, laser trackers are used to probe locations inaccessible to the more conventional srms. Oct 07, 20 theyre everywhere in car taillights, traffic signs, and reflective tape on clothing. Comparison of a phase conjugate mirror with a conventional mirror. As in time reversal, the wave reemitted by a phase conjugation mirror will autocompensate the phase distortion and autofocus itself on its initial source, which can be a moving object. Both techniques allow an amplification of the conjugate wave compared to the incident wave.
These results suggest that a retroreflector is similar to an optical phase conjugate mirror, but with important differences. Response of a batio 3 phase conjugate mirror to broadband and. Our retroreflectors use the corner cube method to reflect a parallel return beam back from its source. We show different schemes for realizing pcms and discuss characteristics such as reflectivity, fidelity, and time behavior. Phaseconjugate mirrors require a comparatively expensive and complex apparatus, as well. In this paper we report on the application of phase conjugate mirrors pcms for optical measurement techniques. In this paper we report on the application of phaseconjugate mirrors pcms for optical measurement techniques. The image produced is the inverse of one produced by a single mirror.
Files are available under licenses specified on their description page. Response of a batio 3 phase conjugate mirror to broadband. This technique is used in advanced optical systems such as highpower lasers and optical transmission lines. Electromagnetic equivalent model for phase conjugate mirror. In a retroreflector an electromagnetic wavefront is reflected back along a vector that is parallel to but opposite in direction from the waves source. In the language of nonlinear optics, the interacting beams result in a nonlinear polarization within the material, which coherently radiates to form the phase conjugate wave. There are a number of different studies of retroreflector arrays currently being done to assist in the design of future retroreflector arrays and obtain a better understanding of the properties of current retroreflector arrays. All structured data from the file and property namespaces is available under the creative commons cc0 license. Theyre everywhere in car taillights, traffic signs, and reflective tape on clothing. A phaseconjugatemirror inspired approach for building. Polarization change after propagation through a prism. Retroreflectors are used in various optical setups to return the incoming light parallel to the incoming beam, but with a lateral displacement. Dopc system, a retroreflector rf was temporarily inserted into the. Jackel, inon moshe, and raphael lavi aberration correction in doublepass amplifiers through the use of phaseconjugate mirrors andor adaptive optics.
Directional properties of the ccr are due to the total internal reflection tir from its three orthogonally placed mirror surfaces, and have found. In addition to corner reflectors, there are also cats eye reflectors and phase conjugate mirrors. Either a phase conjugate mirror pcm or conventional mirror cm can be used to accomplish the. Despite atmospheric effects the phase conjugate return energy measured. The solution to the boundaryvalue problem for a simple model of the phaseconjugate mirror is presented. The similarity of a phase conjugate mirror to the interface of a matched rhm righthanded material and a lhm lefthanded material prompts us to explore the potentials of using the rhmlhm structure to achieve the antiscattering property of the pcm. Osa phase conjugation through brillouinenhanced fourwave. Nonlinear optics nlo is the branch of optics that describes the behaviour of light in nonlinear media, that is, media in which the polarization density p responds nonlinearly to the electric field e of the light. The pump 1 beam amplitude a 1 is also delayed and directed. Retroreflectors reflect incident light back toward the direction of the light source, operating over a wide range of angles of incidence.
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