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A Fast Multiobjective Optimization Strategy for Single-Axis Electromagnetic MOEMS Micromirrors
摘要： Micro-opto-electro-mechanical (MOEMS) micromirrors are an enabling technology for mobile image projectors (pico-projectors). Low size and low power are the crucial pico-projector constraints. In this work, we present a fast method for the optimization of a silicon single-axis electromagnetic torsional micromirror. In this device, external permanent magnets provide the required magnetic field, and the actuation torque is generated on a rectangular multi-loop coil microfabricated on the mirror plate. Multiple constraints link the required current through the coil, its area occupancy, the operating frequency, mirror suspension length, and magnets size. With only rather general assumptions about the magnetic field distribution and mechanical behavior, we show that a fully analytical description of the mirror electromagnetic and mechanical behavior is possible, so that the optimization targets (the assembly size, comprising the mirror and magnets, and the actuation current) can be expressed as closed functions of the design parameters. Standard multiobjective optimization algorithms can then be used for extremely fast evaluation of the trade-offs among the various optimization targets and exploration of the Pareto frontier. The error caused by model assumptions are estimated by Finite Element Method (FEM) simulations to be below a few percent points from the exact solution.
关键词： MOEMS,micromirrors,magnetic actuation,pico-projectors,Micro-electro-mechanical systems (MEMS),multiobjective optimization
更新于2025-09-23 15:21:01
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Laser speckle reduction utilized by lens vibration for laser projection applications
摘要： In this paper, a compact speckle reduction method utilizing vibrating lenses for laser beam scanning is proposed and demonstrated. The maximum speckle reduction ef?ciency was found to be 75.6% and 81.25% for a 532 nm diode-pumped solid-state (DPSS) laser and a 520 nm laser diode (LD), respectively. The minimum speckle contrast ratio observed using our method was 0.11 for the DPSS laser and 0.06 for the LD. The proposed method can provide speckle reduction with minimal power requirements, a low implementation cost, and no bending for the optical path of the laser beam. Additionally, this method is promising to withstand high-power lasers for use in high lumen laser projectors by optimizing the lens parameters. The demonstrated technique has a small form factor while simultaneously demonstrating a high degree of speckle reduction, which shows potential for speckle reduction in mini- and pico- laser projector applications.
关键词： pico-projectors,compact method,laser displays,vibrating lens,speckle reduction,mini-projectors,low cost
更新于2025-09-23 15:19:57
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Polychromatic speckle reduction in laser pico-projectors using stationary dual Hadamard diffusers
摘要： Speckle from coherent light sources continues to be a limiting factor in the design and manufacturing of laser projectors. Utilizing diffractive diffusers has been an effective method for reducing monochromatic speckle contrast. Color laser projection devices require the use of red, green, and blue laser sources therefore; using a monochromatic diffractive diffuser may not be optimal for color speckle contrast reduction. A new static dual-diffuser system utilizing Hadamard matrices has been designed to reduce full color speckle. This paper analyzes the effectiveness of the new Hadamard diffusers in reducing speckle using three separate RGB laser diodes. A simulation of the Hadamard diffusers is conducted to determine the optimum spacing between the two diffusers for polychromatic speckle reduction. Experimental measured results are presented using the optimal spacing of Hadamard diffusers for RGB color speckle reduction showing 60% reduction in contrast.
关键词： speckle contrast reduction,Hadamard matrix,diffractive diffusers,Polychromatic speckle,laser pico-projectors
更新于2025-09-16 10:30:52
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Speckle reduction by employing two green lasers and two-dimensional vibration of lenses
摘要： A method of speckle reduction suitable for use in a laser projector was proposed in the paper. Speckle contrast ratio (SCR) reduction was achieved by combining wavelength diversity and angular diversity methods. First, wavelength diversity was demonstrated by the use of two green laser sources (a 520 nm laser diode (LD) and a 532 nm diode-pumped solid-state (DPSS) laser) at a power ratio of 4:1. Second, angular diversity was achieved via the vibration of two lenses in two orthogonal directions placed directly after the laser source. The vibrating lenses are small and do not require changes to the beam path of the laser source, allowing for more compact projector designs. The frequency of vibration of these lenses was optimized to minimize the SCR in the output image. A SCR of less than 4% was achieved without the use of optical diffusers, which significantly reduces optical losses. Optical transmission could be further increased with the optimization of optical coatings on the lenses. This result shows great promise for applications such as laser pico-projectors within the realm of heads-up displays (HUDs) and mobile devices.
关键词： two-dimensional vibration of lenses,speckle reduction,mini-/pico-projectors
更新于2025-09-16 10:30:52