# US 2014/0152972 A1 · Orientation independent focus mechanisms for laser radar > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0152972 A1 - Document ID: US20140152972A1 - Status: Published application - Kind: A1 - Application number: 13/833,726 - Filed: 2013-03-15 - Published: 2014-06-05 - Earliest claimed: 2012-08-31 - Assignees: Nikon Corporation; Lorri L. Watson - Inventors: Alec Robertson; Douglas C. Watson; Alexander Cooper - Web page: https://patentgrep.com/patent/US20140152972A1 ## CPC - F16H 35/06: Gearings designed to allow relative movement between supports thereof without ill effects (special means compensating for misalignment of axes F16H1/26, F16H1/48) - G01S 7/4813: {Housing arrangements} - G01S 7/4818: {using optical fibres} - G01S 7/4972: {Alignment of sensor} - G02B 7/08: adapted to co-operate with a remote control mechanism - G02B 7/1805: {for prisms (G02B7/181 takes precedence)} - Y10T 29/49: Method of mechanical manufacture - Y10T 74/18888: Reciprocating to or from oscillating - F16H: GEARING - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract Focus arrangements for laser radar and other applications provide compensation of orientation-dependent gravitational forces. A linear stage can be preloaded and provided with balanced linear encoders so that gravitational force induced pitch, yaw, and roll can be reduced, detected, or compensated. Alternatively, movable focus elements can be secured to actuator driven spring assemblies that are controlled to compensate orientation-dependent gravitational forces. ## Claims ### Claim 1 A focus stage, comprising: a linear stage that includes a carriage and a guide; a motor configured to translate the carriage along an axis defined by the guide; and first and second linear encoders oppositely situated along the axis and configured to provide an indication of carriage position based on combination of encoder signals from the first and second linear encoders. ### Claim 2 (depends on 1) The focus stage of claim 1, wherein the motor is a piezoelectric motor. ### Claim 3 (depends on 1) The focus stage of claim 1, further comprising an optical element secured to the carriage. ### Claim 4 (depends on 3) The focus stage of claim 3, wherein the optical element is secured to the carriage so as to have a nodal point equidistant from the first and second linear encoders. ### Claim 5 (depends on 1) The focus stage of claim 1, wherein the optical element is a focus adjustment optical element for a laser radar. ### Claim 6 (depends on 5) The focus stage of claim 5, wherein the optical element is a corner cube. ### Claim 7 (depends on 1) The focus stage of claim 1, further comprising a retro-reflector secured to the carriage and having a nodal point equidistant from the first and second linear encoders. ### Claim 8 (depends on 4) The focus stage of claim 4, wherein the first and second encoders include respective read heads and linear scales situated in line with the nodal point. ### Claim 9 An actuator system, comprising: a first actuator configured to be secured to an optical system and scan the optical system along an axis from an initial position; a second actuator; and an elastic member coupled to the second actuator, wherein the second actuator is configured to apply a force with the elastic member to compensate an orientation-dependent gravitational force on the optical system. ### Claim 10 (depends on 9) The actuator system of claim 9, wherein the applied force is selected so as to return the optical system to the initial location. ### Claim 11 (depends on 9) The actuator system of claim 9, wherein the elastic member is a spring. ### Claim 12 (depends on 10) The actuator system of claim 10, wherein the initial location is associated with an optical system location without a displacement due to optical system weight. ### Claim 13 (depends on 9) The actuator system of claim 9, wherein the initial location is associated with an optical system location without a displacement due to optical system weight. ### Claim 14 (depends on 9) The actuator system of claim 9, further comprising a position sensor configured to determine a position of the optical system, wherein the second actuator is configured to apply a force based on the determined position. ### Claim 15 (depends on 9) The actuator system of claim 9, further comprising an inclinometer configured to establish a tilt of the scan axis with respect to a vertical axis, wherein the second actuator is configured to apply a force with the elastic member based on the determined tilt. ### Claim 16 An apparatus, comprising: an optical element secured to a first actuator; an elastic member secured to a second actuator, wherein at least one of the optical element and the first actuator are coupled to the elastic member, and at least one of the first actuator and the second actuator are configured so that a force on the optical element associated with the elastic member corresponds to an orientation-dependent gravitational force. ### Claim 17 (depends on 16) The apparatus of claim 16, wherein the second actuator is configured so that the force on the optical element associated with the elastic member corresponds to an orientation-dependent gravitational force on the optical element. ### Claim 18 A focus system, comprising: a linear stage that includes a carriage and a guide; a motor configured to translate the carriage along an axis defined by the guide; first and second linear encoders oppositely situated along the axis and configured to provide an indication of carriage position based on combination of encoder signals from the first and second linear encoders; a focus adjustment optical element; and an actuator and an elastic member coupled to the focus adjustment optical element so as to compensate orientation-dependent forces. ### Claim 19 (depends on 18) The focus system of claim 18, wherein the actuator is configured to apply a force to the focus adjustment optical element so as to compensate an orientation-dependent gravitational force. ### Claim 20 (depends on 18) The focus system of claim 18, wherein the actuator is coupled to apply a compensating force to the focus adjustment optical element based on a position of the focus adjustment optical element reported by the first and second linear encoders. ### Claim 21 (depends on 20) The focus system of claim 20, wherein the elastic member is a spring. ### Claim 22 (depends on 18) The focus system of claim 18, wherein the focus adjustment optical element is a corner cube or a roof prism. ### Claim 23 A measurement device, comprising a linear stage that includes a carriage and a guide; a motor configured to translate the carriage along an axis defined by the guide; first and second linear encoders oppositely situated along the axis and configured to provide an indication of carriage position based on a combination of encoder signals from the first and second linear encoders; a focus adjustment optical element configured to produce a measurement beam from a light source and to receive a return beam from a target; and a signal processor configured to provide an estimated target distance for at least one target location based on the return beam ### Claim 24 (depends on 23) A method for manufacturing a structure, comprising: producing the structure based on design information; obtaining shape information of the structure using the measurement device of claim 23; and comparing the obtained shape information with the design information.