We have developed a high-throughput laser marking system using a programmable multi-spot modulated line beam capable of >13x throughput enhancement over a single-spot system. While commercially available lasers have been rapidly growing in output energy and power, single-spot marking systems cannot take full advantage of higher laser outputs without causing damage to the material. This system provides high throughput, high resolution marking on a variety of surfaces including stainless steel and polymer. This high productivity system is enabled by a high-power MEMS spatial light modulator called the Planar Light Valve (PLVTM). The PLV is a 1088-pixel device in a linear configuration supporting up to 200 kHz modulation. The PLV supports pulse energies of 920 μJ with pulse widths down to 200 femtoseconds and CW power of 1 kW at wavelengths of 355-1070 nm. In this system the PLV is imaged onto the work surface to create roughly 100 segments which are individually addressed to select the laser fluence in each spot with grayscale control. The linear array is scanned across the media using precision X-Y stages. The resulting feature size is 20 μm yielding high resolution 1270 dpi images. Each spot on the work surface is made up of several PLV pixels, which allows precise edge placements. In this demonstration a 100 W laser is used for a 13x throughput enhancement over a single-spot system with 4x better resolution. This optical system can be adapted for many laser processing applications such as additive manufacturing, lithography, and micromachining.
The “MEMS-in-the-lens” active lens for a laser scanning microscope comprises a high numerical aperture front element, a 3D+ MOEMS beam scanner and a collimating back lens. The scanner utilizes a silicon gimbal with SU-8 polymer flexures and deformable membrane mirror. The mirror aperture is 4 mm in diameter, and is capable of 9 μm deflection for focus control, with four annular electrodes to allow tuning of primary and secondary spherical aberration. The gimbal supports tip/tilt actuation up to ±3° for lateral beam scanning. We show confocal imaging using a benchtop mockup of the active lens, illustrating the potential for this approach to support 3D microscopy for optical biopsy applications.
This paper describes the incorporation of nanotextured black silicon as an optical absorbing material into silicon-based micro-optoelectromechanical systems devices to reduce stray light and increase optical contrast during imaging. Black silicon is created through a maskless dry etch process and characterized for two different etch conditions, a cold etch performed at 0°C and a cryogenic etch performed at −110°C. We measure specular reflection at visible wavelengths to be <0.001% at near-normal incidence for both processes, whereas the total diffuse scatter is <3% and 1% for the cold and cryogenic processes, respectively. These surfaces exhibit less reflectivity and lower scatter than black velvet paint used to coat optical baffles and compare favorably with other methods to produce black surfaces from nanotextured silicon or using carbon nanotubes. We illustrate the use of this material by integrating a black silicon aperture around the perimeter of a deformable focus-control mirror. Imaging results show a significant improvement in contrast and image fidelity due to the effective reduction in stray light achieved with the self-aligned black aperture.
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