Speckle reduction in laser picoprojector by combining optical phase matrix with twin green lasers and oscillating MEMS mirror for coherence suppression

Lee, Jae Yong; Kim, Tae Ha; Yim, Boobin; Bu, Jong Uk; Kim, Young Joo

doi:10.7567/jjap.55.08rf03

Cited by 9 publications

(3 citation statements)

References 29 publications

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“…In the application to laser projectors, the speckle phenomenon emerges by reflecting highly coherent laser beams with single wavelengths on random rough surfaces, resulting in a random spatial intensity distribution [ 18 ]. One of the criterion to describe speckle is speckle contrast ratio, which is defined as [ 19 ]:

where

and

represent the square mean value and the mean light intensity,

denotes the standard deviation.…”

Section: Application To Speckle Reductionmentioning

confidence: 99%

A Large-Size MEMS Scanning Mirror for Speckle Reduction Application

Zhou

Wang

et al. 2017

Micromachines

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Based on microelectronic mechanical system (MEMS) processing, a large-size 2-D scanning mirror (6.5 mm in diameter) driven by electromagnetic force was designed and implemented in this paper. We fabricated the micromirror with a silicon wafer and selectively electroplated Ni film on the back of the mirror. The nickel film was magnetized in the magnetic field produced by external current coils, and created the force to drive the mirror’s angular deflection. This electromagnetically actuated micromirror effectively eliminates the ohmic heat and power loss on the mirror plate, which always occurs in the other types of electromagnetic micromirrors with the coil on the mirror plate. The resonant frequency for the scanning mirror is 674 Hz along the slow axis, and 1870 Hz along the fast axis. Furthermore, the scanning angles could achieve ±4.5° for the slow axis with 13.2 mW power consumption, and ±7.6° for the fast axis with 43.3 mW power consumption. The application of the MEMS mirror to a laser display system effectively reduces the laser speckle. With 2-D scanning of the MEMS mirror, the speckle contrast can be reduced from 18.19% to 4.58%. We demonstrated that the image quality of a laser display system could be greatly improved by the MEMS mirror.

show abstract

where

and

represent the square mean value and the mean light intensity,

denotes the standard deviation.…”

Section: Application To Speckle Reductionmentioning

confidence: 99%

A Large-Size MEMS Scanning Mirror for Speckle Reduction Application

Zhou

Wang

et al. 2017

Micromachines

View full text Add to dashboard Cite

show abstract

“…In the application to laser projectors, the speckle phenomenon emerges by reflecting highly coherent laser beams with single wavelengths on random rough surfaces, resulting in a random spatial intensity distribution [18]. One of the criterion to describe speckle is speckle contrast ratio, which is defined as [19]:…”

Section: Application To Speckle Reductionmentioning

confidence: 99%

A large size MEMS scanning mirror for speckle reduction application

Shen

et al. 2017

2017 IEEE 12th International Conference on Nano/Micro Engineered and Molecular Systems (NEMS)

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Based on microelectronic mechanical system (MEMS) processing, a large-size 2-D scanning mirror (6.5 mm in diameter) driven by electromagnetic force was designed and implemented in this paper. We fabricated the micromirror with a silicon wafer and selectively electroplated Ni film on the back of the mirror. The nickel film was magnetized in the magnetic field produced by external current coils, and created the force to drive the mirror's angular deflection. This electromagnetically actuated micromirror effectively eliminates the ohmic heat and power loss on the mirror plate, which always occurs in the other types of electromagnetic micromirrors with the coil on the mirror plate. The resonant frequency for the scanning mirror is 674 Hz along the slow axis, and 1870 Hz along the fast axis. Furthermore, the scanning angles could achieve ±4.5 • for the slow axis with 13.2 mW power consumption, and ±7.6 • for the fast axis with 43.3 mW power consumption. The application of the MEMS mirror to a laser display system effectively reduces the laser speckle. With 2-D scanning of the MEMS mirror, the speckle contrast can be reduced from 18.19% to 4.58%. We demonstrated that the image quality of a laser display system could be greatly improved by the MEMS mirror.

show abstract

“…Micro-electronical mechanical system scanning mirror (MEMS-SM) has gained vastly in interest over the last decades, and is, by now, deployed in various fields. Its application ranges from laser pico-projectors [1,2], laser tracking on UAV (unmanned aerial vehicle) [3], dynamic solid state lighting [4], to MEMS imaging LiDAR (light detection and ranging) [5,6]. The application on MEMS imaging LiDAR grows especially fast in the last 5 years, with the rise of autopilot technology.…”

Section: Introductionmentioning

confidence: 99%

UKF-based MEMS micromirror angle estimation for LiDAR

Wang

Zhang

You

2019

J. Micromech. Microeng.

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Azimuth and distance measurement are two key technologies of MEMS LIDAR. In order to improve the accuracy of (micro-electronical mechanical system scanning mirror) MEMS-SM angle measurement, this paper proposes an angle estimation algorithm based on unscented Kalman filter (UKF), which can reduce the sensor noise by using the motion model of MEMS-SM. First, the angle measurement is given by the built-in angle sensor or transfer function model of MEMS-SM. Secondly, the dynamic model is established according to the Lissajous scanning mode of MEMS-SM. Then the UKF algorithm can be presented, including the measurement equation and the state equation, where the nonlinear equation is the inverse trigonometric function. Finally, Laser Doppler Velocimeter was adopted as a standard instrument to verify the accuracy of the proposed algorithm. The results showed that the UKF angle estimation algorithm based on MEMS-SM dynamic model improved the accuracy of the built-in sensor’s angle measurement by 5–10 times. And this method is suitable for LIDAR of different scanners’ types and different scanning modes, which can meet the demand of imaging MEMS LIDAR for the accuracy and stability of angle measurement.

show abstract

Speckle reduction in laser picoprojector by combining optical phase matrix with twin green lasers and oscillating MEMS mirror for coherence suppression

Cited by 9 publications

References 29 publications

A Large-Size MEMS Scanning Mirror for Speckle Reduction Application

A Large-Size MEMS Scanning Mirror for Speckle Reduction Application

A large size MEMS scanning mirror for speckle reduction application

UKF-based MEMS micromirror angle estimation for LiDAR

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