Apparatus for microindentation hardness testing and surface imaging incorporating a multi-plate capacitor system
DCFirst Claim
1. In a scanned probe microscope apparatus having a probe and a scanning head arranged for operative engagement of a surface of a sample for measuring a surface topography thereof, the improvement comprising:
- a. said probe having a hardness greater than a sample to be tested;
b. a force sensor operatively located to measure the force between said sample and said probe, said force sensor having an output signal, wherein said force sensor includes,i. a pair of capacitive transducers, each transducer including a separate drive plate, the first of said drive plates having a hole centrally disposed therethrough, and a shared pick-up plate, said pick-up plate positioned between said separate drive plates and separated from each drive plate by an insulating spacer, said drive plates having spaced opposing conductive surfaces when said pick-up plate is mounted therebetween, said pick-up plate further including a conductive central plate suspended by spring means between said drive plates, wherein said central plate is capable of deflection between the conductive surfaces of each of said drive plates; and
ii. means for transmitting force from a point remote from said central plate to said central portion; and
c. means for measuring the output signal of said force sensor and utilizing said output signal to control a vertical movement of said scanning head to maintain a constant force on a sample as said surface topography is measured.
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Accused Products
Abstract
A force, weight or position sensor unit and sensor element in a first embodiment. In a second embodiment, the sensor element of the first embodiment is incorporated into an apparatus for microindentation hardness testing and surface imaging which allows immediate imaging of the surface subsequent to hardness testing. The sensor uses a multi-capacitor system having drive and pick-up plates mounted on an appropriate suspension system to provide the desired relative motion when a force is applied to the pick-up plate. The output signal is run through a buffer amplifier and synchronously demodulated to produce a signal proportional to force or displacement. The sensor element is mounted on a scanning tunneling microscope base and a sample mounted on the sensor. The force sensor is used for both measuring the applied force during microindentation or micro hardness testing and for imaging before and after the testing to achieve an atomic force microscope type image of the surface topography before and after indentation testing.
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Citations
40 Claims
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1. In a scanned probe microscope apparatus having a probe and a scanning head arranged for operative engagement of a surface of a sample for measuring a surface topography thereof, the improvement comprising:
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a. said probe having a hardness greater than a sample to be tested; b. a force sensor operatively located to measure the force between said sample and said probe, said force sensor having an output signal, wherein said force sensor includes, i. a pair of capacitive transducers, each transducer including a separate drive plate, the first of said drive plates having a hole centrally disposed therethrough, and a shared pick-up plate, said pick-up plate positioned between said separate drive plates and separated from each drive plate by an insulating spacer, said drive plates having spaced opposing conductive surfaces when said pick-up plate is mounted therebetween, said pick-up plate further including a conductive central plate suspended by spring means between said drive plates, wherein said central plate is capable of deflection between the conductive surfaces of each of said drive plates; and ii. means for transmitting force from a point remote from said central plate to said central portion; and c. means for measuring the output signal of said force sensor and utilizing said output signal to control a vertical movement of said scanning head to maintain a constant force on a sample as said surface topography is measured. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. In a scanned probe microscope apparatus having a probe and a scanning head arranged for operative engagement of a surface of a sample for measuring a surface topography thereof, the improvement comprising:
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a. said probe having a hardness greater than a sample to be tested; b. a force sensor operatively located to measure the force between said sample and said probe, said force sensor having an output signal, wherein said force sensor includes, i. a pair of capacitive transducers, each transducer including a separate drive plate, the first of said drive plates having a hole centrally disposed therethrough, and a shared pick-up plate, said pick-up plate positioned between said separate drive plates and separated from each drive plate by an insulating spacer, said drive plates having spaced opposing conductive surfaces when said pick-up plate is mounted therebetween, said pick-up plate further including a conductive central plate suspended by spring means between said drive plates, wherein said central plate is capable of deflection between the conductive surfaces of each of said drive plates; and ii. means for transmitting force from a point remote from said central plate to said central portion; c. means for measuring the output signal of said force sensor and utilizing said output signal to control a vertical movement of said scanning head to maintain a constant force on a sample as said surface topography is measured; and d. wherein said probe is mounted on said force sensor and said force sensor is further mounted on said scanning head for operatively engaging said sample on a fixed surface.
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13. In a scanned probe microscope apparatus having a probe and a scanning head arranged for operative engagement of a surface of a sample for measuring a surface topography thereof, the improvement comprising:
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a. said probe having a hardness greater than a sample to be tested; b. a force sensor operatively located to measure the force between said sample and said probe, said force sensor having an output signal, wherein said force sensor includes, i. a first substrate layer having a metalized inner and a metalized outer surface, said metalized outer surface defining a first exterior surface of said force sensor and said metalized inner surface including a first plate of a first variable capacitor, said first plate further having a hole centrally disposed therethrough; ii. a second substrate layer including an insulating layer, said second substrate layer having an open central portion, said second substrate layer further having a first and second surface, said first surface mounted in planar contact with said inner surface of said first substrate layer; iii. a third substrate layer having a first and second surface, said first surface mounted in planar contact with said second surface of said second substrate layer, said third substrate layer made from a conducting material and having a central plate which is suspended by spring means; iv. a fourth substrate layer including an insulating layer, said fourth substrate having an open central portion, said fourth substrate layer further having a first and second surface, said first surface mounted in planar contact with said second surface of said third substrate layer; v. a fifth substrate layer having a metalized inner and a metalized outer surface, said metalized outer surface defining a second exterior surface of said force sensor and said metalized inner surface forming a first plate of a second variable capacitor, said inner surface of said fifth substrate mounted in planar contact with said second surface of said fourth substrate; and vi. means for transmitting force from a point remote from said central plate to said central plate; and c. means for measuring the output signal of said force sensor and utilizing said output signal to control a vertical movement of said scanning head to maintain a constant force on a sample as said surface topography is measured. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. In a scanning tunneling microscope apparatus having a base for mounting a sample thereon and a piezo actuated head having a probe mounted thereon for operative engagement of a sample mounted on said base for measuring a surface topography, the improvement comprising:
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a. a probe having a hardness greater than a sample to be tested mounted on said piezo actuated head; b. a force sensor mounted on said base for mounting a sample, said force sensor having an output signal, wherein said force sensor includes, i. a pair of capacitive transducers, each transducer including a separate drive plate, the first of said drive plates having a hole centrally disposed therethrough, and a shared pick-up plate, said pick-up plate positioned between said separate drive plates and separated from each drive plate by an insulating spacer, said drive plates having spaced opposing conductive surfaces when said pick-up plate is mounted therebetween, said pick-up plate further including a conductive central plate suspended by spring means between said drive plates, wherein said central plate is capable of deflection between the conductive surfaces of each of said drive plates; and ii. means for transmitting force from a point remote from said central plate to said central plate; and c. means for measuring the output signal of said force sensor and utilizing said output signal to control a vertical movement of said piezo actuated head to maintain a constant force on a sample as said surface topography is measured. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32)
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33. In a scanning tunneling microscope apparatus having a base for mounting a sample thereon and a piezo actuated head having a probe mounted thereon for operative engagement of a sample mounted on said base for measuring a surface topography, the improvement comprising:
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a. a probe having a hardness greater than a sample to be tested mounted on said piezo actuated head; b. a force sensor mounted on said base for mounting a sample, said force sensor having an output signal, wherein said force sensor includes, i. a first substrate layer having a metalized inner and a metalized outer surface, said metalized outer surface defining a first exterior surface of said force sensor and said metalized inner surface including a first plate of a first variable capacitor, said first plate further having a hole centrally disposed therethrough; ii. a second substrate layer including an insulating layer, said second substrate layer having an open central portion, said second substrate layer further having a first and second surface, said first surface mounted in planar contact with said inner surface of said first substrate layer; iii. a third substrate layer having a first and second surface, said first surface mounted in planar contact with said second surface of said second substrate layer, said third substrate layer made from a conducting material and having a central plate which is suspended by spring means; iv. a fourth substrate layer including an insulating layer, said fourth substrate having an open central portion, said fourth substrate layer further having a first and second surface, said first surface mounted in planar contact with said second surface of said third substrate layer; v. a fifth substrate layer having a metalized inner and a metalized outer surface, said metalized outer surface defining a second exterior surface of said force sensor and said metalized inner surface forming a first plate of a second variable capacitor, said inner surface of said fifth substrate mounted in planar contact with said second surface of said fourth substrate; and vi. means for transmitting force from a point remote from said central plate to said central plate; and c. means for measuring the output signal of said force sensor and utilizing said output signal to control a vertical movement of said piezo actuated head to maintain a constant force on a sample as said surface topography is measured. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40)
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Specification