Optical encoder based on the Lau effect

Crespo, Daniel; Alonso, José María Rabal; Morlanes, T.; Bernabéu, Eusebio

doi:10.1117/1.602432

Cited by 41 publications

(15 citation statements)

References 10 publications

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“…There are a number of phenomena in which this general property is revealed: self-imaging or Talbot effect, joint Talbot effect, Lau effect, incoherent grating-lens imaging, misfocused diffraction convolution and generalized Lau effect or pseudo-imaging [1][2][3][4][5][6][7][8][9]. Many applications are based on these effects: e.g., moiré deflectometry and metrology, Talbot interferometry and a number of spectroscopic techniques based on Talbot and Lau effects are known and widely used [10][11][12][13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Grating pseudo-imaging with polychromatic and finite extension sources

García-Rodríguez¹,

Alonso²,

Bernabéu³

2004

Opt. Express

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Abstract:The pseudo-imaging process in a system consisting of two periodic gratings and illuminated by an incoherent polychromatic and finite extension source placed at a finite distance from the gratings is studied. An analytical expression of the irradiance distribution on a plane, also located at a finite distance from the gratings, has been obtained from previous results on monochromatic illumination. In the analysis presented, different imaging regimes are found and related to the parameters which characterize the double grating system. The pseudo-imaging phenomenon strongly depends on both the spatial and temporal coherence of the incident illuminating field. Certain pseudo-images are observed with polychromatic and incoherent incident light under some restrictions. On the other hand, pseudo-image process analogous to Talbot effect appears only by monochromatic and plane illuminating wavefront.

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Section: Introductionmentioning

confidence: 99%

Grating pseudo-imaging with polychromatic and finite extension sources

García-Rodríguez¹,

Alonso²,

Bernabéu³

2004

Opt. Express

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“…For such a configuration it is possible to obtain the maximum modulation of the fringes for a separation between gratings different from 0, which is not the case in the Talbot 10 or the Lau effect. 11 This could be used to improve the mechanical tolerances in some applications that make use of a double diffraction system.…”

Section: Introductionmentioning

confidence: 99%

Experimental measurements of generalized grating images

Crespo¹,

Alonso²,

Bernabéu³

2002

Appl. Opt.

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The term generalized grating imaging is used to describe the process of image formation of a grating using only another grating as imaging system. The moiré and the Lau effects could be regarded as particular cases of such a process. Here we deal with the less-studied case of images formed at finite distances from the gratings, using an extended monochromatic light source. Some experimental results are shown for the images obtained in this last case, and they are compared with theoretical predictions.

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“…Double grating systems are used in many applications such as, for example, in displacement measurement systems, interferometers, and spectrometers [1][2][3][4]. From the first studies based on diffraction theory [5], a model for pseudoimage formation based on Fresnel propagation of light has been progressively improved [6,7], introducing total incoherence [8], partially coherent light [9][10][11][12][13] and finite spectral width [14].…”

Section: Introductionmentioning

confidence: 99%

Invariant grating pseudoimaging using polychromatic light and a finite extension source

et al. 2008

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The Talbot effect is a well studied phenomenon by which grating pseudoimages appear at certain periodic distances when monochromatic light is used. Recently, numerical simulations have shown a new phenomenon; when a polychromatic light beam is used in a double grating system, the intensity of the pseudoimages presents a transverse-profile that remains unaffected over a wide range of propagation distances. This effect can be used to increase the tolerances of gratings based optical devices, such as displacement measurement systems, interferometers, and spectrometers. The pseudoimages formation with a polychromatic and finite extension light source is analytically and experimentally demonstrated. Relatively simple analytical expressions for the intensity and the contrast allow us to predict when pseudoimages present a constant contrast and when they disappear. Furthermore, we experimentally obtain the pseudoimages using the proposed configuration, corroborating the theoretical predictions.

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Optical encoder based on the Lau effect

Cited by 41 publications

References 10 publications

Grating pseudo-imaging with polychromatic and finite extension sources

Grating pseudo-imaging with polychromatic and finite extension sources

Experimental measurements of generalized grating images

Invariant grating pseudoimaging using polychromatic light and a finite extension source

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