Double substrate reflective spatial light modulator with self-limiting micro-mechanical elements
First Claim
Patent Images
1. A spatial light modulator comprising:
- an optically transmissive substrate having an upper surface and a lower surface;
a deflectable element attached to the lower surface of the optically transmissive substrate, the deflectable element comprising a main portion and a motion stop such that during a deflection of the deflectable element, the motion stop moves towards the lower surface as the main portion moves away from the lower surface, and the deflection is limited by contact between the motion stop and the lower surface; and
a circuit substrate positioned below and spaced apart from the lower surface of the optically transmissive substrate.
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Abstract
A spatial light modulator includes an upper optically transmissive substrate held above a lower substrate containing addressing circuitry. One or more electrostatically deflectable elements are suspended by hinges from the upper substrate. In operation, individual mirrors are selectively deflected and serve to spatially modulate light that is incident to, and then reflected back through, the upper substrate. Motion stops may be attached to the reflective deflectable elements so that the mirror does not snap to the bottom substrate. Instead, the motion stop rests against the upper substrate thus limiting the deflection angle of the reflective deflectable elements.
576 Citations
62 Claims
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1. A spatial light modulator comprising:
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an optically transmissive substrate having an upper surface and a lower surface; a deflectable element attached to the lower surface of the optically transmissive substrate, the deflectable element comprising a main portion and a motion stop such that during a deflection of the deflectable element, the motion stop moves towards the lower surface as the main portion moves away from the lower surface, and the deflection is limited by contact between the motion stop and the lower surface; and a circuit substrate positioned below and spaced apart from the lower surface of the optically transmissive substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46)
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47. A process for the fabrication of a spatial light modulator, the process comprising:
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depositing a sacrificial layer over an optically transmissive substrate; etching a hole through the sacrificial layer; depositing a reflective layer over the sacrificial layer; patterning the reflective layer to define a reflective deflectable element, the deflectable element having a main portion and a motion stop such that during a deflection of the deflectable element, the motion stop moves toward the optically transmissive substrate as the main portion moves away from the optically transmissive substrate, and the deflection is limited by contact between the motion stop and the optically transmissive substrate; connecting the deflectable element to the optically transmissive substrate through the hole; removing the sacrificial layer so that the deflectable element is free to deflect; forming addressing circuitry and an electrode on a circuit substrate; and aligning and joining the optically transmissive substrate and the circuit substrate such that the deflectable element can be selectively activated by the addressing circuitry and the electrode. - View Dependent Claims (49, 50, 51, 52)
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48. The process for the fabrication of a spatial light modulator of claim further comprising:
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depositing an aperture layer on the optically transmissive substrate before depositing the sacrificial layer; and patterning the aperture layer to allow light to pass only through a portion of the optically transmissive substrate.
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53. A process for directing light comprising:
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providing a modulator comprising an optically transmissive substrate having a surface, and a substantially rigid deflectable element connected to the surface, the deflectable element having a reflective portion and a motion stop, wherein the deflectable element is configured to be positioned in an undeflected state and in a deflected state, and the motion stop moves towards, and can eventually contact, the surface as the reflective portion moves away from the surface; positioning the deflectable element in the undeflected state; shining a light beam from a light source through the substrate onto the reflective portion so that the light beam is reflected through the substrate in a first direction when the deflectable element is in the undeflected state; and positioning the deflectable element in the deflected state so that the light beam is reflected through the substrate in a second direction when the deflectable element is in the deflected state. - View Dependent Claims (54, 55, 56)
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57. A spatial light modulator fabrication process comprising:
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forming a sacrificial layer over an optically transmissive substrate; forming a hole through said sacrificial layer; forming and patterning a support layer over said sacrificial layer to define a deflectable element, said deflectable element having a main portion and a motion stop such that during a deflection of said deflectable element, said motion stop moves toward said substrate as said main portion moves away from said substrate, and said deflection is limited by contact between said motion stop and said substrate; forming and patterning a hinge layer over a portion of said deflectable element to define a hinge such that a portion of said hinge extends through said hole and attaches said deflectable element to said substrate; and removing said sacrificial layer so that said deflectable element may deflect. - View Dependent Claims (58, 59, 60)
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61. A spatial light modulator fabrication process comprising:
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forming a first sacrificial layer over an optically transmissive substrate; forming a first hole through said first sacrificial layer; forming and patterning a motion stop layer over said first sacrificial layer to define a motion stop; forming and patterning a hinge layer to define a hinge over a portion of said motion stop such that a portion of said hinge layer extends through said first hole and is coupled to said optically transmissive substrate; forming a second sacrificial layer over said hinge layer; forming a second hole through said second sacrificial layer to expose a portion of said hinge; forming and patterning a support layer over said second sacrificial layer to define a deflectable element such that a portion of said support layer extends through said second hole and is coupled to said hinge; and removing said first sacrificial layer and said second sacrificial layer.
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62. A spatial light modulator fabrication process comprising:
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forming a first sacrificial layer over an optically transmissive substrate; forming and patterning a support layer over said first sacrificial layer to define a deflectable element having a main portion and a motion stop such that a portion of said first sacrificial layer is exposed, and such that during a deflection of said deflectable element, said motion stop moves toward said substrate as said main portion moves away from said substrate, and said deflection is limited by contact between said motion stop and said substrate; forming a second sacrificial layer over the exposed portion of said first sacrificial layer and over said deflectable element; forming a first hole through said second sacrificial layer and positioned over said deflectable element, and a second hole through both said first sacrificial layer and said second sacrificial layer and positioned away from said deflectable element; forming and patterning a hinge layer to define a hinge such that a first portion of said hinge extends through said first hole and is coupled with said deflectable element, and such that a second portion of said hinge extends through said second hole and is coupled with said substrate so as to attach said deflectable element to said substrate; and removing said first sacrificial layer and said second sacrificial layer.
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Specification