Patent Application
20070270258
The present embodiments will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that the accompanying drawings depict only typical embodiments and are therefore not to be considered to limit the scope of the disclosure, the embodiments will be described and explained with specificity and detail in reference to the accompanying drawings, herein described.
The embodiments of this disclosure will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. It will be readily understood that the components of the embodiments as generally described and illustrated in the Figures herein could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of various embodiments, as represented in the Figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of various embodiments. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated. In addition, the steps of a method do not necessarily need to be executed in any specific order or even sequentially, unless otherwise specified.
The phrases “connected to,” “coupled to,” and “in communication with” refer to any form of interaction between two or more entities, including mechanical, electrical, magnetic, electromagnetic, fluid, and thermal interaction. Two components may be coupled to each other even though they are not in direct contact with each other. The term “in electrical communication with” is not to be construed to require coupling or physical connection, but only electrical signal coordination or the ability to “talk” electrically between components through a circuit.
Any industry that uses robotics or automated processing may favorably employ a single-axis, two-dimensional specimen position shifter in ways known in the art. This may include shifting conveyor belts to different locations to drop manufactured items of different types into varying locations or to place a particular circuit component in the proper place on a printed circuit board to repair a circuit or chip in the electronics and semiconductor industries. The possible applications are thus almost limitless in today's world of automated manufacturing processes and research facilities. Thus, while use of a single-axis drive mechanism may be used for shifting optical elements in lasers, as herein discussed in detail, the scope of the disclosure easily extends beyond any single implementation or embodiment of such a device and associated methods.
As one skilled in the art will appreciate, certain embodiments may be capable of achieving certain advantages over the known prior art, including some or all of the following: (1) providing for a two-dimensional specimen position-shifting apparatus that may be driven by a single-axis motor or driver, together with a simple set of motion translation structures; (2) minimizing the control hardware and software, and thus the number of potential errors in tracking and feedback regarding the structure to be shifted; and (3) where that structure is an optical element, simultaneously lengthening the life of that element, such as a laser crystal, thus reducing replacement and down-time costs. These and other advantages of various embodiments will be apparent upon reading the following.
One application for spatially distributing laser beam spots over a crystal volume is described in U.S. Pat. No. 6,890,474 to Gruber et al. (“the '474 patent”). The '474 patent describes use of algorithms for enhancing the lifetime of critical components in a laser system, including components such as the crystal through which a laser beam passes. These algorithms use functional and physical limits of the crystal, spot lifetime measurements, and laser parameters such as power, energy, repetition rate, input and output wavelengths, pulse duration, and beam divergence over which the crystal is expected to maintain a specified performance. Based on the input of these data and these measurements and parameters, software algorithms calculate initial maximum dwell times on indexed macro-spots and enable monitoring for sudden power degradations to be incorporated in real-time. Incorporation of initial maximum dwell times with real-time updates may be translated into shorter dwell times, causing the crystal to be moved to subsequent macro-spots having longer dwell times, thus using more of the crystal before it needs to be replaced.
Although use of algorithms may be useful, their development is time-consuming and entails for each additional crystal, adjustment for factors such as linearity, size, and application, in addition to the input parameters already mentioned. Miscalculations or the input of erroneous initial information for a given crystal or application, not to mention software glitches and computer hardware problems, may all lead to compromise of the crystal or other optical components, to include damage to coatings and infrastructure of a crystal, as well as continued operation in a macro-spot undergoing power degradation. Therefore, the simpler and more automated in mechanical structures the process of shifting is, the fewer the opportunities will be that these problems will shorten the longevity of a position shifting apparatus or system.
While the systems and methods of the present disclosure may be used in conjunction with the algorithms and software-controlled microcontrollers taught in the '474 patent, it will be apparent to one skilled in the art that the use of the latter may be greatly reduced by employment of the former.
A cam 42 includes cam shaft 38, which has a threaded distal end 46 to which a fork nut 48 extender is threadedly engaged for unrestricted rotation about longitudinal axis 40. Fork nut 48 has at its free end 50 two spaced-apart members 52 that define a generally U-shaped, open-ended slot 54. Cam 42 is supported on outer surface 36 of cam shaft 38 at a position between fork nut 48 and worm gear 28. Cam 42 includes a bearing and seal casing 56, which houses a bearing assembly (not shown) that facilitates the rotational movement of cam shaft 38. Cam 42 includes a throw 58 that is axially offset from longitudinal axis 40 and has an outer bearing surface 60 of changing radial distance from longitudinal axis 40 along an X-axis (
A U-shaped stages bracket 80 having a base portion 82 and spaced-apart, generally parallel side members 84 and 86 is slidably secured to support structure 11 (
In operation, motor 12 turns worm 20 about its longitudinal axis 16 and thereby causes worm 20 to turn worm gear 28 and perforce cam shaft 38 about its longitudinal axis 40. Turning cam shaft 38 rotates cam 42 and its throw 58 such that outer bearing surface 60 applies to contact point 92 of follower 90 a radially directed force that imparts to stages bracket 80 lateral displacement along the X-axis. The lateral displacement is of an amount and in a direction corresponding to the amount and direction of radial displacement of cam throw 58 relative to longitudinal axis 40. The placement of pin 88 between members 84 and 86 of stages bracket 80 allows pin 88 to slide along slot 54 of fork nut 48 as stages bracket 80 undergoes lateral displacement. The lateral displacement of stages bracket 80 takes place along the X-axis, which is transverse to longitudinal axis 40, and in a horizontal direction, as shown in
Turning cam shaft 38 also causes it to operate as a lead screw for fork nut 48, which is prevented by pin 88 from rotation in concert with the rotation of cam shaft 38. Fork nut 48 responds to rotation of cam shaft 38 by moving along its length either closer to or farther from cam 42, depending on the direction of rotation of worm gear 28. Pin 88 follows the linear movement of fork nut 48 and thereby causes longitudinal displacement of stages bracket 80. The longitudinal displacement of stages bracket 80 takes place along a Y-axis defined by longitudinal axis 40 and in a vertical direction, as shown in
Therefore, the number of turns of cam shaft 38 corresponds to the X-Y position of stages bracket 80, to which a target device is operatively attached (
Referring to
Stages bracket 80 is mounted to support surface 100 by a multi-stage bracket support assembly 118 that accommodates the X-Y displacement imparted to stages bracket 80 by rotation of cam shaft 38. Bracket support assembly 118 includes a Y-axis module 119 that is slidingly coupled to an X-axis module 120. X-axis module 120 is slidingly coupled to stages bracket 80; and Y-axis module 119 is rigidly coupled by fasteners 121 to a support structure (or surface) mounting bracket 122, which is mounted to support surface 100 of system support structure 11. Y-axis module 119 and X-axis module 120 are substantially identical with, oriented orthogonal to, and coupled to allow relative movement to each other.
Specifically, Y-axis module 119 has a surface 124 within which a spring-biased slidable rail 126 extends in a direction along the Y-axis. Y-axis module 119 has apertures 128 that extend through surface 124 and slidable rail 126. X-axis module 120 has a surface 130 within which a spring-biased slidable rail 132 extends in a direction along the X-axis. X-axis module 120 has apertures 134 that extend through surface 130 and slidable rail 132. Spring biased slidable rails 126 and 132 allow X-Y movement as well as naturally rest at a starting location representing reference coordinates (X, Y)=(0, 0), relative to the longitudinal axes 16 and 40, before any motor 12 action.
Stages bracket 80 is mounted to X-axis module 120 with threaded fasteners (not shown) or other means secured through stages bracket 80 and into apertures 134 of slidable rail 132. X-axis module 120 is mounted to Y-axis module 119 with threaded fasteners (not shown) secured through apertures 134 of X-axis module 120 and into apertures 128 of slidable rail 126. These interconnections of the components of multi-stage bracket support assembly 118 operatively secure to system support structure 11 the components connected to the distal end of cam shaft 38. One skilled in the art will appreciate other means by which multi-stage bracket support assembly 118 may be interconnected for mutual orthogonal movement of X-axis module 120 and Y-axis module 119 and secure mounting to surface 100.
Imparting two-dimensional specimen position shifting through a single longitudinal drive axis 40 makes for smooth shifting of crystal 160 without the vibration or noise normally associated with shifting imparted through dual-axis drives. Such vibration or noise may result not only in additional wear and tear of moving structures, but also in fluctuation of laser beam power levels associated with moving across the surface of a nonlinear crystal. Two-dimensional, position-shifting apparatus 10 dramatically reduces any such vibrations, especially for situations in which power required for shifting may be magnified through a worm 20 and worm gear 28 assembly. However, other means of power amplification known in the art, may of course be employed to drive cam shaft 38.
For instance,
Referring again to
Minimizing the use of software algorithms to track and control the laser beam location 162 on crystal 160 allows for simplicity of design and may lessen the chance of a software-related glitch that affects optimal power in the laser beam. Also, allowing motor 12 and associated rotary drive elements to essentially go to sleep during normal, non-shifting operation will conserve energy and extend the longevity of moving parts. Skilled persons will appreciate that worm gear 28 is self locking and, as a consequence, prevents external forces applied to cam 42 from changing its position set by operation of motor 12. The tightly fitted interconnection of the structures comprising the single longitudinal drive axis 40 allows such structures to start and stop motion abruptly, without slippage, thus providing accurate rotational position to transducer 112 at all times. This rotational position is used to also track the X-Y location 162 of the laser beam on crystal 160, as previously mentioned, so that the entire crystal 160 surface is used over its lifetime.
Those skilled in the art of robotics applications in a wide range of industries will appreciate that the need to shift optical elements in lasers likewise applies to robotics parts, to include optical elements and other micro-elements exposed to intense thermo, optical, or electrical power. Some applications may also apply to macro elements in robotics, in manufacturing, and in processing assemblies.
The terms and descriptions used herein are set forth by way of illustration only and are not meant as limitations. Those skilled in the art will recognize that many variations can be made to the details of the above-described embodiments without departing from the underlying principles of the invention. The scope of the invention should therefore be determined only by the following claims (and their equivalents) in which all terms are to be understood in their broadest reasonable sense unless otherwise indicated.
