New multiple aperture arrangements for speckle photography

Tebaldi, Myrian; Toro, Luciano Angel; Trivi, Marcelo; Bolognini, Néstor

doi:10.1016/s0030-4018(00)00813-0

Cited by 14 publications

(4 citation statements)

References 11 publications

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“…In particular, the speckle formation using diffusers modulated by different single (linear, circular, conical, quadratic, elliptical, modulated graded index and truncated apertures) and multiple apertures is analyzed [12][13][14][15][16][17][18][19]. Although an optical system with a single-aperture pupil is usually employed, some advantage is achieved by use of a double [20] or in general a multiple-aperture pupil [21,22].…”

Section: Introductionmentioning

confidence: 99%

Analysis of tilt by modulated speckles generated with a double aperture pupil mask

Prado

Bolognini

Tebaldi

2015

Optics Communications

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Section: Introductionmentioning

confidence: 99%

Analysis of tilt by modulated speckles generated with a double aperture pupil mask

Prado

Bolognini

Tebaldi

2015

Optics Communications

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“…In this way, the signal spectrum can occupy an adequate dimension that allows processing it more easily. The introduction of a spatial frequency carrier through the modulation technique has been applied to optical information processing and metrology [17][18][19][20]. Our proposal consists in modulating each encrypted data with a different grating.…”

Section: Introductionmentioning

confidence: 99%

Multi-user multiplexed scheme for decoding modulated-encoded sequential information

et al. 2011

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Encrypting procedures with multiplexed operations exhibit an inherent noise. We presented options to avoid background noise arising from the non-decoded images. We have a coding mask corresponding to each single input object, thus resulting in a static decrypting mechanism. Besides, if we manage the spatial destination of each decoded output, then we avoid the noise superposition. In those schemes, the displaying output order was irrelevant. However, when we face a sequence of events including multi-users, we need to develop another strategy. We present a multi-user encrypting scheme with a single encoding mask that removes the background noise, also showing the decrypted data in a prescribed sequence. The multiplexing scheme is based on the 4f double random phase encryption architecture and a theta modulation method, which consists in superposing each encrypted information with a determined sinusoidal grating. Afterwards we proceed to the completely encoded data multiplexing. In a multi-user scheme, we employ different encrypting masks in the 4f optical setup for each user, and the same mask is employed for the user sequence. We store the encrypted data in the single medium. After a Fourier transform operation and an appropriate filtering procedure, we reach the sequence of isolated encrypted spots corresponding to the right user. With the aid of the pertaining decoding mask, the user can decrypt the sequence. We avoid the noise by the appropriate choice of the modulating gratings pitch as to elude the overlapping of spots at the Fourier plane, which is the cause of information degradation.

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“…Also, this behavior still maintains the information about displacements on an interferometric scale if required. To a certain extent, metrological speckle techniques have been implemented on the basis of the speckle internal modulation which can be achieved by attaching a pupil mask with several apertures behind the imaging lens [3][4][5]. The mentioned speckle modulation not only exhibits more complexity but it offers larger capabilities in terms of potential applications [6][7][8].…”

Section: Introductionmentioning

confidence: 99%