Dual sensor assemblies for positional output feedback

• US 7,280,935 B2
• Filed: 09/02/2004
• Issued: 10/09/2007
• Est. Priority Date: 09/02/2004
• Status: Expired due to Fees

• Current Assignee: Imation Corporation (Glassbridge Enterprises, Inc.)
• Original Assignee: Imation Corporation (Glassbridge Enterprises, Inc.)
• Inventors: Edwards, Jathan D.
• Primary Examiner(s): Barlow; John
• Assistant Examiner(s): KUNDU, SUJOY K
• Application Number:
  US10/933,992
• Publication Number:
  US 20060047470A1
• Time in Patent Office: 1,132 Days
• Field of Search: 702/150, 360/73.03
• US Class Current: 702/150
• CPC Class Codes: G01D 5/2417 by varying separation

Abstract

A system for precisely determining a position with resolution on the order of nanometers or sub-nanometers is described. In particular, a system is described that utilizes a first and a second sensor assembly to determine a position of a movable element over a distance many times the capable range of operation of either of the individual sensor assemblies. The two sensor assemblies leap-frog one another in an incremental fashion to ensure that at least one of the sensor assemblies is always within it operational range. Positional signals generated by one of the sensor assemblies can be used to calibrate the other sensor assembly, following an adjustment of the other sensor assembly. The described invention may be implemented in an optical storage disk mastering system to determine the position of mastering optics as the mastering optics translate over the surface of a storage master disk.

Claims

1. A system comprising:

a first sensor assembly including a first sensor element attached to a first sensor arm, a second sensor element attached to a movable element, and a first actuator that adjusts the first sensor arm, wherein the first sensor assembly generates first positional signals indicative of a first distance between the first and second sensor elements;

a second sensor assembly including a third sensor element attached to a second sensor arm, a fourth sensor element attached to the movable element, and a second actuator that adjusts the second sensor arm, wherein the second sensor assembly generates second positional signals indicative of a second distance between the third and fourth sensor elements; and

a sensor assembly controller coupled to the first and second sensor assemblies that receives the first and second positional signals and identifies a position of the movable element based on at least one of the first and second positional signals,

wherein the sensor assembly controller causes the first and second sensor arms to adjust in a leapfrogging fashion to ensure that at least one of the first and second sensor assemblies is always within its respective operational range as the movable element moves,

wherein the sensor assembly controller causes the first actuator to adjust the first sensor arm when the first positional signals indicate that the first sensor assembly is out of range, and re-calibrates the first sensor assembly following adjustment of the first sensor arm based on the position of the movable element as determined by the second positional signals, and

wherein the sensor assembly controller associates the first distance following adjustment of the first sensor arm with the position of the movable element as determined by the second distance to re-calibrate the first sensor assembly.

3. The system of claim 1, wherein the sensor assembly controller causes the second actuator to adjust the second sensor arm when the second positional signals indicate that the second sensor assembly is out of range and re-calibrates the second sensor assembly following adjustment of the second sensor arm based on the position of the movable element as determined by the first positional signals.

4. The system of claim 3, wherein sensor assembly controller re-calibrates the second sensor assembly by associating the second distance following adjustment of the second sensor arm with the position of the movable element as determined by the first distance.

5. The system of claim 1, wherein the sensor assembly controller stores information indicative of the position of the movable element based on the first and second positional signals.

6. The system of claim 1, wherein the system comprises an optical mastering system and the movable element comprises mastering optics that provides light to expose a master, the optical mastering system further comprising:

an optics controller that controls positioning of the mastering optics and controls on-off switching of light provided by the mastering optics;

a spindle that spins the master;

a spindle controller that controls a rate at which the spindle spins; and

a system control that controls the optics controller and the spindle controller in response to user input and positioning feedback received from the sensor assembly controller.

7. The system of claim 6, wherein the sensor assembly controller determines the position of the mastering optics relative to the master based on the first and second positional signals.

2. A system comprising:

a first sensor assembly including a first sensor element attached to a first sensor arm, a second sensor element attached to a movable element, and a first actuator that adjusts the first sensor arm, wherein the first sensor assembly generates first positional signals indicative of a first distance between the first and second sensor elements;

a second sensor assembly including a third sensor element attached to a second sensor arm, a fourth sensor element attached to the movable element, and a second actuator that adjusts the second sensor arm, wherein the second sensor assembly generates second positional signals indicative of a second distance between the third and fourth sensor elements; and

a sensor assembly controller coupled to the first and second sensor assemblies that receives the first and second positional signals and identifies a position of the movable element based on at least one of the first and second positional signals,

wherein the first, the second, the third, and the fourth sensor elements comprise capacitive sensor elements, and wherein the first actuator and the second actuator comprise stepper motors.

8. A system comprising:

a first senor assembly including a first sensor element attached to a first sensor arm, a second sensor element attached to a movable element, and a first actuator that adjusts the first sensor arm, wherein the first sensor assembly generates first positional signals indicative of a first distance between the first and second sensor elements;

a second sensor assembly including a third sensor element attached to a second sensor arm, a fourth sensor element attached to the movable element, and a second actuator that adjusts the second sensor arm, wherein the second sensor assembly generates second positional signals indicative of a second distance between the third and fourth sensor elements; and

a sensor assembly controller coupled to the first and second sensor assemblies that receives the first and second positional signals and identifies a position of the movable element based on at least one of the first and second positional signals,

wherein the system comprises a lithography system and the movable element comprises a wafer stage.

9. A system comprising:

a master disk;

mastering optics that provides light to expose the master disk;

an optics controller that controls positioning of the mastering optics and controls on-off switching of light provided by the mastering optics;

a spindle that spins the master disk;

a spindle controller that controls the rate at which the spindle spins;

a first capacitive sensor assembly including a first capacitive sensor element attached to a first sensor arm, a second capacitive sensor element attached to the mastering optics, and a first actuator that adjusts the first sensor arm, wherein the first capacitive sensor assembly generates first positional signals indicative of a first distance between the first and second capacitive sensor elements of the first capacitive sensor assembly;

a second capacitive sensor assembly including a third capacitive sensor element attached to a second sensor arm, a fourth capacitive sensor element attached to the mastering optics, and a second actuator that adjusts the second sensor arm, wherein the second capacitive sensor assembly generates second positional signals indicative of a second distance between the third and fourth capacitive sensor elements of the second capacitive sensor assembly;

a sensor assembly controller coupled to the first and second capacitive sensor assemblies that receives the first and second positional signals and identifies a position of the mastering optics with respect to the master based on the first and second positional signals.

10. The system of claim 9, wherein the sensor assembly controller causes the first actuator to adjust the first sensor arm when the first positional signals indicate that the first sensor assembly is out of range, and re-calibrates the first sensor assembly based on the second positional signals following adjustment of the first sensor arm.

11. The system of claim 10, wherein the sensor assembly controller re-calibrates the first sensor assembly by associating the first distance following adjustment of the first sensor arm with the position of the mastering optics relative to the master disk as determined by the second distance.

12. The system of claim 9, wherein the sensor assembly controller stores information indicative of position of the mastering optics relative to the master disk based on the first and second positional signals.