MEMS Based Speckle Reduction Obtain by Angle Diversity for Fast Imaging

Peled, Itay; Zenou, Michael; Greenberg, B.; Kotler, Zvi

doi:10.1364/cleo.2009.jtud44

Cited by 9 publications

(4 citation statements)

References 2 publications

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“…Angular diversity for speckle reduction can be achieved with MEMS scanning devices working at 2-10 kHz that generate different illumination angles. Each angle of illumination provides a particular speckle image, and the contrast can be reduced to half of its initial value by averaging different speckle images within the exposure time of the sensor (e.g., within 1=60 s for the human eye) [73].…”

Section: A Techniques For Speckle Reductionmentioning

confidence: 99%

Laser-based displays: a review

2010

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After the invention of lasers, in the past 50 years progress made in laser-based display technology has been very promising, with commercial products awaiting release to the mass market. Compact laser systems, such as edge-emitting diodes, vertical-cavity surface-emitting lasers, and optically pumped semiconductor lasers, are suitable candidates for laser-based displays. Laser speckle is an important concern, as it degrades image quality. Typically, one or multiple speckle reduction techniques are employed in laser displays to reduce speckle contrast. Likewise, laser safety issues need to be carefully evaluated in designing laser displays under different usage scenarios. Laser beam shaping using refractive and diffractive components is an integral part of laser displays, and the requirements depend on the source specifications, modulation technique, and the scanning method being employed in the display. A variety of laser-based displays have been reported, and many products such as pico projectors and laser televisions are commercially available already.

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Section: A Techniques For Speckle Reductionmentioning

confidence: 99%

Laser-based displays: a review

2010

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“…20 Using a moving diffuser plate to achieve the spatial-temporal averaging; 21,22 By passing the laser light through a time-varying refractive index gating generated by ultrasonic wave; 23,24 Using a silicon-based mechanically scanning micro-electro-mechanical system device. 25,26 By splitting the laser into two paths with sufficient path length difference and different polarization. 27,28 However, all the methods discussed so far reduce the C at the expense of the brightness and require complicated optical setups.…”

Section: Introductionmentioning

confidence: 99%

“…For example, using a broadband source or array of sources with different wavelengths to reduce the temporal coherence of laser beam 20 . Using a moving diffuser plate to achieve the spatial‐temporal averaging; 21,22 By passing the laser light through a time‐varying refractive index gating generated by ultrasonic wave; 23,24 Using a silicon‐based mechanically scanning micro‐electro‐mechanical system device 25,26 . By splitting the laser into two paths with sufficient path length difference and different polarization 27,28 .…”

Section: Introductionmentioning

confidence: 99%

Laser speckle reduction via TiO₂‐sapphire composite rotating wheel in laser projection

Shi

Guo

et al. 2022

J Am Ceram Soc.

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Laser sources have been considered to be better light sources compared to traditional lamps or light‐emitting diodes used in projectors, which enables the projector to create images with higher color saturation, brightness, and energy efficiency. However, the speckle noise caused by the coherent nature of the laser is a major technology obstacle for laser projection, which severely affects the image quality. To suppress laser speckle, a TiO2‐sapphire composite (TSC) with rough and high reflectivity surface and high thermal conductivity substrate is designed, which reduces the laser speckle by creating spatial diversity. Moreover, combined with a micro motor, the design and fabrication of the TSC rotating wheel are realized, which further reduces the laser speckle by creating time diversity. The experimental results show that the laser speckle contrast can be reduced from 9.0% to 2.2% when placing the TSC rotating wheel in the light path, which is below the speckle perception limit of the human eye (<4%). This new type of laser speckle suppression device is simple to use, low in cost, high in energy utilization, high in thermal conductivity, easy to mass production, and has great application potential in high‐power laser projection.

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“…Considerable efforts have been made to minimize the speckle noise in projection displays with the laser light source. Different methods have been developed, such as by using moving random diffuser plate placed at the image plane 2 , by rotating a diffractive optical element in the path of the laser beam 3 , by modulating a laser beam with traveling ultrasonic waves in a liquid cell 4 , by using several lasers with different wavelength and incident angles for illumination 5 , by using a rotating micro-lens array in the laser illumination path 6 , by using a stationary phase plate based on the Barker or Barker-like binary phase code at the intermediate image plane [7][8][9] , by using partially coherent beams 10 , by using changing Hadamard phase patterns inside each detector resolution pixel at the intermediate image plane 11,12 and by using an oscillating micro-mirror to introduce angular diversity 13 . When a mechanically vibrating or rotating element is used such as those in 2, 3, 6, 11, 12 , a bulky component (motor) is needed to provide the vibration or rotation at high speed which can be inconvenient and unreliable.…”

Section: Introductionmentioning

confidence: 99%

Speckle suppression in projection displays by using a motionless changing diffuser

Карташов¹,

Akram²

2010

SPIE Proceedings

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Speckle suppression in projection displays with the laser light source can be achieved by imaging a changing diffuser with random phase cells onto the screen. Theoretical expressions for the speckle contrast in this method have been earlier obtained in the case when different realizations of the phase diffuser produce statistically independent patterns of the light field on the screen [J. W. Goodman]. In the present paper, these expressions are generalized in the case when different realizations of the phase diffuser produce partly correlated speckle patterns. Both cases when the diffuser just fills or overfills the projection optics are considered. Possible structure of a motionless changing diffuser is presented. It includes the dynamic diffractive optical element (DDOE) and a light homogenizer. The DDOE can be based on the electrically controlled spatial light modulator with a deformable polymer layer (SLMDPL). The SLMDPL can handle high light power and therefore, can be used in projection displays with powerful laser beams.

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MEMS Based Speckle Reduction Obtain by Angle Diversity for Fast Imaging

Cited by 9 publications

References 2 publications

Laser-based displays: a review

Laser-based displays: a review

Laser speckle reduction via TiO₂‐sapphire composite rotating wheel in laser projection

Speckle suppression in projection displays by using a motionless changing diffuser

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MEMS Based Speckle Reduction Obtain by Angle Diversity for Fast Imaging

Cited by 9 publications

References 2 publications

Laser-based displays: a review

Laser-based displays: a review

Laser speckle reduction via TiO2‐sapphire composite rotating wheel in laser projection

Speckle suppression in projection displays by using a motionless changing diffuser

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Product

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Laser speckle reduction via TiO₂‐sapphire composite rotating wheel in laser projection