News Column

Researchers Submit Patent Application, "Orientation Independent Focus Mechanisms for Laser Radar", for Approval

June 26, 2014



By a News Reporter-Staff News Editor at Politics & Government Week -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors Robertson, Alec (Palo Alto, CA); Watson, Douglas C. (Campbell, CA); Cooper, Alexander (Belmont, CA), filed on March 15, 2013, was made available online on June 12, 2014.

The patent's assignee is Nikon Corporation.

News editors obtained the following quote from the background information supplied by the inventors: "Laser radar systems require precise focus mechanisms in order to provide the measurement accuracy demanded in many manufacturing applications. In one laser radar system, a probe laser beam is focused on a target by translation of a corner cube. While a corner cube tends to reduce errors associated with various tips and tilts, conventional translation mechanisms often lack the desired accuracy and stability because the focus stage is large and is situated a significant distance from beam-forming optical components such as focusing lenses. Linear guides can be used, but alignment is difficult and stability over a wide temperature range can be problematic."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "Focus stages comprise a linear stage that includes a carriage and a guide. A motor is configured to translate the carriage along an axis defined by the guide. First and second linear encoders are oppositely situated along the axis and provide an indication of carriage position based on a combination of encoder signals from the first and second linear encoders. In some examples, the motor is a piezoelectric motor and a focus adjustment optical element is secured to the carriage. According to some examples, the focus adjustment optical element is secured to the carriage so as to have a nodal point equidistant from the first and second linear encoders. In a specific embodiment, the focus adjustment optical element is configured to adjust a focus of a beam on a target in a laser radar and is a corner cube or roof prism. In other examples, a retro-reflector is secured to the carriage so that a nodal point is equidistant from the first and second linear encoders. In other examples, the first and second linear encoders include respective read heads and linear scales situated in line with the nodal point.

"Methods comprise supporting a movable element such that a force associated with translating the movable element is substantially independent of movable element orientation with respect to gravity. In some examples, the force associated with translating the movable element is based on an actuator-spring combination configured to compensate an orientation-dependent gravitational force.

"Apparatus comprise an optical element secured to a first actuator, and an elastic member secured to a second actuator. 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 is equal and opposite to an orientation-dependent gravitational force on the optical element.

"Actuator systems comprise a first actuator configured to be secured to an optical system and scan the optical system along an axis from an initial position. An elastic member is coupled to a 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. In typical examples, the applied force is selected so as to return the optical system to the initial location, and the elastic member is a spring. In other examples, the initial location is associated with an optical system location without a displacement due to optical system weight. In some examples, a position sensor is configured to determine a position of the optical system, wherein the second actuator is configured to apply a force based on the determined position. According to some examples, the position sensor includes one or more linear encoders. In further examples, an inclinometer is configured to establish a tilt of the scan axis with respect to a vertical axis, and the second actuator is configured to apply a force with the elastic member based on the determined tilt.

"Focus systems comprise a linear stage that includes a carriage and a guide, and a motor configured to translate the carriage along an axis defined by the guide. First and second linear encoders are oppositely situated along the axis and configured to provide an indication of carriage position. An actuator and an elastic member are coupled to a focus adjustment optical element so as to compensate orientation-dependent forces. In some examples, the actuator is configured to apply a force to the focus adjustment optical element so as to compensate an orientation-dependent gravitational force. In other examples, 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 one of the first or second linear encoders. According to some examples, the elastic member is a spring and the focus adjustment optical element is a corner cube or a roof prism.

"The foregoing and other objects, features, and advantages of the disclosed technology will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

"FIGS. 1A-1D illustrate a representative focus mechanism that includes a linear guide with oppositely situated encoders.

"FIGS. 2A-2C illustrate a focus system that includes an optic actuator configured to adjust a focus element and a spring actuator configured to establish orientation-independent forces for adjustment of the focus element.

"FIGS. 3A-3C illustrate operation of an uncompensated focus system.

"FIG. 4 is a block diagram of a focus system that includes an inclination sensor.

"FIG. 5 is a block diagram of a focus system that includes a force sensor.

"FIG. 6 is a block diagram of a representative method of compensating gravitational forces in moving an optical system.

"FIG. 7 is a block diagram of a laser radar system that includes a compensated focus adjustment mechanism for moving a corner cube.

"FIG. 8 is a block diagram of a representative manufacturing system that includes a laser radar or other profile measurement system to manufacture components, and assess whether manufactured parts are defective or acceptable.

"FIG. 9 is a block diagram illustrating a representative manufacturing method that includes profile measurement to determine whether manufactured structures or components are acceptable, and if one or more such manufactured structures can be repaired."

For additional information on this patent application, see: Robertson, Alec; Watson, Douglas C.; Cooper, Alexander. Orientation Independent Focus Mechanisms for Laser Radar. Filed March 15, 2013 and posted June 12, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=4500&p=90&f=G&l=50&d=PG01&S1=20140605.PD.&OS=PD/20140605&RS=PD/20140605

Keywords for this news article include: Physics, Nikon Corporation, Gravitational Forces.

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Source: Politics & Government Week


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