Optical: systems and elements – Optical modulator – Light wave temporal modulation
Reexamination Certificate
1999-11-30
2001-05-01
Mai, Huy (Department: 2873)
Optical: systems and elements
Optical modulator
Light wave temporal modulation
C359S283000, C359S291000, C359S324000
Reexamination Certificate
active
06226116
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to light spatial modulators, and more specifically to magnetic micro-shutters used to modulate light.
BACKGROUND OF THE INVENTION
Micro-shutters have been used within the prior art as spatial light modulators. One of the more notable of these is U.S. Pat. No. 5,784,189 issued to Bozler et al. and assigned to Massachusetts Institute of Technology (MIT), hereinafter referred to as the Bozler '189 patent. This prior art disclosure taught making spatial light modulators using micro-shutters that were lithographically generated and electrostatically controlled. The individual micro-shutters employed aluminum and require electrostatic control. While useful as teaching a method towards fabricating light modulation devices with small apertures, the Bozler '189 fails to teach micro-shutter fabrication techniques that are useful under magnetic control.
Electrostatically controlled micro-shutters require additional processing steps to ensure that the moving micro-shutter element and its complementary electrode remain insulated from one another. Also, electronics of some sophistication is needed to address and actuate individual micro-shutter elements.
Magnetically controlled micro-shutters have the ability to respond to magnetic fields and as such do not require control electronics. Also, magnetic micro-shutters do not need to be insulated from a complementary electrode because no electrodes are required.
As shown in U.S. Pat. No. 4,012,828, a Digital Frame Counter is described where the exposures used for a camera are displayed in a digital format. Such a digital frame counter could be a Liquid Crystal Display (LCD). The advantages of this type of display are that individual numbers can be larger than the above discussed rotating wheel, (no discussion has been made) and each frame number can be displayed without resorting to the use of dots as intermediate frame numbers. The disadvantages of this type of display are that LCD's are relatively expensive, require support electronics and can appear dark in low light situations due to their dependence on polarizing filters for them to function.
As seen by the foregoing discussion, it should be readily apparent that there remains a need within the art for a magnetically controlled micro-shutter that is inexpensive to fabricate.
SUMMARY OF THE INVENTION
The present invention provides a method and apparatus for a spatial light modulation device that is formed by placing a nickel layer upon a substrate and a magnet below the device. The nickel layer is forced to roll and unroll in response to a magnetic field created by the magnet. The magnetic field draws the nickel layer towards the magnet below the device.
This present invention provides a spatial light modulation device comprising a substrate material of one of the following: (glass, quartz, single crystal silicon, ceramic, or a metal), a plurality of photoresist layers with the corrugations being formed in the top photoresist layer away from the substrate wherein the photoresist layer forms a release layer on the substrate that can peel away from the substrate, a pair of nickel layers with a first nickel layer having a compressive stress and a second nickel layer having a tensile stress formed on the release layer. The pair of nickel layers having a thickness of about 500 Angstroms. The method for creating the apparatus envisions providing the nickel layer upon a photoresist layer, the photoresist layer being patterned to create the fixedly attached end of the segment with the remaining portion of the segment being removably attached.
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Dowe David R.
Reznik Svetlana
Eastman Kodak Company
Mai Huy
Watkins Peyton C.
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