Speckle suppression in scanning laser display

Yurlov, Victor; Lapchuk, Anatoliy; Yun, Sangwoon; Song, Jay Hyok; Yang, Hilda

doi:10.1364/ao.47.000179

Cited by 78 publications

(50 citation statements)

References 5 publications

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“…The smallest ρ obtained was −0.431, and the corresponding C f was 0.535. In Equation (9), when the factor C 1 C 2 /C 2 avg < 1 for C 1 = C 2 , the sum pattern has a larger C f than the C f at C 1 = C 2 . This means that the lowest suppression result for a certain ρ occurs when the speckle contrasts of the two elementary patterns are equal.…”

Section: Suppression Factor Of the Sum Of Two Fully-developed Specklementioning

confidence: 99%

“…Using DOEs in laser scanning displays, the scanning spot was split into several randomly-spread small spots [6], or modulated with phase arrays [7][8][9][10]. In systems projecting full-frame images, the DOE functioned as a changing diffuser to generate partially coherent illumination [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

“…In holographic projection displays, a phase-only DOE encoding a target image was displayed in an LCoS spatial light modulator (SLM), and the Fourier transform of the DOE, showing the target image, was projected onto the screen [15][16][17][18]. Although static DOEs, such as in [7] and [9], require spatial motion or rotation to reduce speckle noise, most DOEs can be implemented using an SLM and take advantage of the rapid display of a sequence of phase arrays of DOEs to suppress speckles. The phase content of the DOE can be carefully calculated and accurately realized by an SLM to provide effective de-correlation of the light, resulting in low speckle noise.…”

Section: Introductionmentioning

confidence: 99%

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Speckle Suppression by Integrated Sum of Fully Developed Negatively Correlated Patterns in Coherent Imaging

Hsu¹,

Chu²

2011

PIER B

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Abstract-A coherent imaging system images a frame or an object onto a changing diffuser and projects the resulting pattern which generally contains speckles. Using a spatial light modulator (SLM) as the changing diffuser, the speckles in the pattern are suppressed without the need for any other mechanisms. With M random phasor arrays being displayed in the SLM during the integration time of a detector, a suppression factor (C f ) of speckles, 1/ √ M , is achievable in the projected pattern, which is the sum of the intensity of M uncorrelated patterns. This paper shows both theoretically and in simulations that the C f of the sum pattern was considerably reduced when two elementary patterns with fully developed speckles were negatively correlated. With the correlation coefficients of the elementary patterns found at [−0.3, −0.25], the C f of the sum of 10 negatively-correlated speckle patterns was 48% lower than the C f of the sum of 10 uncorrelated speckle patterns. The negatively correlated patterns can be implemented using spatial light modulators or diffractive optical elements, and are used to suppress speckle noise in digital holography, laser projection display, and holographic display projections with relatively high efficiency.

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Section: Suppression Factor Of the Sum Of Two Fully-developed Specklementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Speckle Suppression by Integrated Sum of Fully Developed Negatively Correlated Patterns in Coherent Imaging

Hsu¹,

Chu²

2011

PIER B

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“…In articles, 7,8 it was shown that a static phase code with delta-like auto-correlation function can be effective in reducing laser speckle in line-scan laser projectors. A Barker binary phase code was chosen to demonstrate the method and a maximum speckle reduction with speckle contrast factor of 13% theoretical and 17% experimental value was achieved.…”

Section: Introductionmentioning

confidence: 99%

Speckle reduction in line-scan laser projectors using binary phase codes: theory and experiments

et al. 2010

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Barker binary phase code of maximum length 13 has previously been used for speckle reduction in line-scan laser projectors, and a speckle contrast factor decreased down to 13% has been achieved. In this article, Barker-like binary phase codes of length longer than 13 are used at an intermediate image plane. It is shown by theoretical calculation that much better speckle reduction with speckle contrast factor up to 6% can be achieved by using longer binary phase codes other than the Barker code. Preliminary experimental results are also presented indictaing good speckle reduction.

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“…Small size and large optical efficiency are the main challenges in technology development of portable projection displays. Recently, the SOM device, the one-dimensional micro-actuation light modulator, is successfully developed by Samsung Electro-Mechanics for an accessory or embedded projection module [1][2][3][4][5][6][7][8][9][10]. But the previously developed SOM device, integrated in an optical module, has a volume bigger than 15 cc and entire module is considered to be too big in volume for being embedded in the mobile device.…”

Section: Introductionmentioning

confidence: 99%

Fine-pitch high-efficiency spatial optical modulator for mobile display applications

et al. 2009

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Diffractive spatial optical modulators (SOM) with fine pitch pixel array were introduced for the mobile applications of laser projection display which requires the small volume, low power consumption and high optical efficiency. Micromechanical designs of piezoelectric (PZT) actuator and mirror ribbon structure were optimized for small volume, but keeping the same level of the other performance. Even though the same design rule and fabrication equipment were used for 10 um pitch SOM and 16 um pitch SOM, the optical efficiency of the fine pitch SOM was 78 % for the 0 th order diffraction and is better than that of 16 um pitch SOM (73%). The full on/off contrast ratio has no difference between 10 um pitch and 16 um pitch SOM. All the optical characteristics coincide well with the theoretical estimations. High displacement of 500nm, which is enough to modulate the three Red, Green and Blue colors were achieved by the control of the thicknesses and stresses of constituent structural layers. It was found that the stress of Pt/PZT/Pt actuating layer was the main parameter affecting the initial gap height of the ribbon and also its displacement. For improving the optical properties of the SOM devices, the required ribbon-flatness could be achieved by applying a stress gradient on the SiN layer to compensate for the stress unbalance between Al mirror and SiN supprting layer. The temperature sensitive characteristics of the SOM device, which degrades the image quality, could be minimized by a mechanical compensation method using a thermal expansion effect of Si substrates. This concept could be applied in most of the bridge type MEMS structure. The most critical parameter which limit the SOM device lifetime was found to be the ribbon displacement degradation. By using a temperature accelerating lifetime measurement method based on the displacement degradation the estimated lifetime was more than 4,000 hrs and is of acceptable level in the mobile application. In short, the developed fine pitch SOM device, for making small volume of optical module, has sufficient response time and ribbon displacement for modulating the red, blue and green colors with one SOM chip and is suitable for high quality embedded laser projection displays. Optical module with VGA is successfully demonstrated for its potential applications in mobile laser projection display such as a embed projection cellular phone.

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Speckle suppression in scanning laser display

Cited by 78 publications

References 5 publications

Speckle Suppression by Integrated Sum of Fully Developed Negatively Correlated Patterns in Coherent Imaging

Speckle Suppression by Integrated Sum of Fully Developed Negatively Correlated Patterns in Coherent Imaging

Speckle reduction in line-scan laser projectors using binary phase codes: theory and experiments

Fine-pitch high-efficiency spatial optical modulator for mobile display applications

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