Direct acting vertical thermal actuator with controlled bending

Abstract

A micrometer sized, single-stage, vertical thermal actuator with controlled bending capable of repeatable and rapid movement of a micrometer-sized optical device off the surface of a substrate. The vertical thermal actuator is constructed on a surface of a substrate. At least one hot arm has a first end anchored to the surface and a free end located above the surface. A cold arm has a first end anchored to the surface and a free end. The cold arm is located above the hot arm relative to the surface. The cold arm is adapted to provide controlled bending near the first end thereof. A member mechanically and electrically couples the free ends of the hot and cold arms such that the actuator bends generally at the flexure so that the member moves away from the substrate when current is applied to at least the hot arm.

What is claimed is:  
     
         1 . A vertical thermal actuator constructed on a surface of a substrate comprising: 
 at least one hot arm having a first end anchored to the surface and a free end located above the surface;    a cold arm having a first end anchored to the surface and a free end, the cold arm being located above the hot arm relative to the surface;    a flexure formed in the cold arm near the first end thereof adapted to provide controlled bending; and    a member mechanically and electrically coupling the free ends of the hot and cold arms such that the actuator bends generally at the flexure so that the member moves away from the substrate when current is applied to at least the hot arm.    
     
     
         2 . The apparatus of  claim 1  wherein the flexure comprises at least one of a recess, depression, cut-out, hole, location of narrowed, thinned or weakened material, alternate material or other structural features or material change that decreases resistance to bending in that location.  
     
     
         3 . A vertical thermal actuator constructed on a surface of a substrate comprising: 
 at least one hot arm having a first end anchored to the surface and a free end located above the surface;    a cold arm having a first end anchored to the surface and a free end, the cold arm being located above the hot arm relative to the surface;    a reinforcing member formed along a first portion of the cold arm, a second portion of the cold arm without the reinforcing member adapted to provide controlled bending; and    a member mechanically and electrically coupling the free ends of the hot and cold arms such that the member moves away from the substrate when current is applied to the hot arm.    
     
     
         4 . The apparatus of  claim 1  comprising a flexure formed in the second portion of the cold beam without the reinforcing member.  
     
     
         5 . A vertical thermal actuator constructed on a surface of a substrate comprising: 
 a first beam having a first end anchored to the surface and a free end located above the surface;    a second beam having a first end anchored to the surface and a free end located above the surface;    a member electrically and mechanically coupling the free end of the first beam to the free end of the second beam;    a third beam having a first end anchored to the surface and a free end mechanically coupled to the member, the third beam being located above the first and second beams relative to the surface;    a flexure formed in the third beam near the first end thereof adapted to provide controlled bending; and    first and second electrical contacts electrically coupled to the first ends of the first and second beams, respectively, such that current supplied to the first and second contacts causes the first and second beams to thermally expand and the member to move in an arc away from the substrate.    
     
     
         6 . A vertical thermal actuator constructed on a surface of a substrate comprising: 
 a first beam having a first end anchored to the surface and a free end located above the surface;    a second beam having a first end anchored to the surface and a free end located above the surface;    a member electrically and mechanically coupling the free end of the first beam to the free end of the second beam;    a third beam having a first end anchored to the surface and a free end mechanically coupled to the member, the third beam being located above the first and second beams relative to the surface;    a reinforcing member formed in a first portion of the third beam, a second portion of the third beam without the reinforcing member adapted to provide the vertical thermal actuator with controlled bending; and    first and second electrical contacts electrically coupled to the first ends of the first and second beams, respectively, such that current supplied to the first and second contacts causes the first and second beams to thermally expand and the member to move in an arc away from the substrate.