WO1995000865A1

WO1995000865A1 - Improved optical beam integration system

Info

Publication number: WO1995000865A1
Application number: PCT/US1993/008692
Authority: WO
Inventors: Michael A. Fortin; Theodore H. Dang
Original assignee: Xmr, Inc.
Priority date: 1993-06-17
Filing date: 1993-09-10
Publication date: 1995-01-05

Abstract

An optical beam homogenizer has been improved to emphasize a dual axis, high aspect ratio spot sizing capability. The optical system alters the aspect ratio of the beam by moving three of the four lenticular arrays (12, 14, 16, 18) within the homogenizer. The integrity of dimensional control is maintained by use of a microprocessor (97). The homogenizer can be readily adapted by the addition of a photodetector (95) and the use of the microprocessor to provide continuous beam monitoring for both beam uniformity and tip or tilt of the substrate or stage assembly. The system also has the capability of taking the input beam into the homogenizer, breaking up the beam and recombining it to eliminate most of the optical diffraction present in current homogenizer designs.

Description

IMPROVED OPTICAL BEAM INTEGRATION SYSTEM

Background

This invention relates to optical systems. More particularly, the invention is directed to radiant energy beam integration optics for improving beam intensity profile uniformity in the case of various lasers or other radiant energy sources having a nonuniform beam intensity profile characteristic.

For example, ultraviolet (UN) excimer lasers have recently been applied as semiconductor processing tools. Typical applications have included semiconductor annealing, microphotolithography, photodeposition, laser-induced chemical vapor deposition (CND), gas immersion laser doping (GILDing), micromachining, and several other processes. In nearly all of these applications, laser output beam intensity profile uniformity is of paramount importance. Hereafter the term "beam uniformity" will be employed to refer to beam intensity profile uniformity. Present discharge UN excimer laser technology does not produce laser output beams of adequate uniformity while maintaining required laser output energy.

Currently, most of the work invested toward improving UN excimer laser output beam uniformity has concerned the laser configuration itself. Optical resonator design, electrode profiling techniques, and improvement of discharge preionization uniformity have increased the laser output beam uniformity significantly. By using available technology, it is possible to construct excimer lasers with relatively uniform output beam profiles. However, typical laser output beam uniformity of even +5 percent or so may be only marginally suitable for some illumination applications in which the laser output beam must be reduced to typical semiconductor die sizes in the range of 0.5 to 2.0 cm². In addition, few if any commercial UN excimer lasers maintain this level of uniformity over enough area of their output beams to ensure sufficient energy density. Further complicating this problem is the presence of occasional and essentially unpredictable changes in laser output beam uniformity on a shot-to-shot basis. Also, as semiconductor structures and device tolerances become smaller, the requirements for laser output beam uniformity become more severe. Therefore, the future development of semiconductor processing techniques using UN excimer lasers will require increasingly uniform laser output beams.

In contrast to optimizing the configuration of the laser itself, the present invention relates to improving beam uniformity based on optical techniques which act on the laser output beam. Specifically, the invention is directed to improved optical beam integration techniques.

Optical integrators have been incorporated into various types of illumination systems for many years. In most of these optical integrators, the homogenization of the input beam occurs in one or two ways. Optical integration techniques typically involve either some kind of randomization of the laser output beam (in phase or amplitude) or optical integration performed by the overlapping of numerous beam segments or "beamlets". The input beam can either be "scrambled" by a diffuser; a set of lenses with partially overlapping outputs (Oriel Corporation, 15 Market Street, Stamford, CT 06902, product model 6567-1, for example); random phase shift masks (Y. Kato and K. Mima, Appl. Physics B29, 186 (1982)) or echelons (R.H. Lehmberg and S.P. Obenschain, Optics Comm. 46, 27 (1983)); or by multiple scatterings in a tube much like a kaleidoscope (R.E. Grojean, D. Feldman, and J.F. Roach, Rev. Sci. Inst. 51, 375 (1989)). Alternatively, the input beam can be broken apart into segments and these segments then imaged on top of one another to average out fluctuations in beam intensity. U.S. Patent No. 4,733,944 to Fahlen et al. ("Fahlen") provides an example of a conventional optical beam integration system for homogenizing an input beam having a nonuniform beam intensity profile characteristic. The homogenized beam produced by the optical beam integration system in accordance with Fahlen has a constant image or work plane. Preferably, the optical beam integration system in accordance with Fahlen is adjustable for selectively setting the spot size produced by the homogenized beam in the work plane.

The improvements and advantages achieved by the present invention over a conventional system for homogenizing an input beam can best be appreciated by a comparison with the U.S. Patent No. 4,733,944. Referring to Figure 1, a conventional system, as represented by Fahlen, discloses an optical beam integration system responsive to an input beam of radiant energy 2 having a nonuniform beam intensity profile characteristic, which is produced by a radiant energy source. The optical beam integration system comprises: a first crossed lenticular cylindrical lens means 4 having a first predetermined focal length and aligned in a plane substantially orthogonal to the input beam; a second crossed lenticular cylindrical lens means 6 having a second predetermined focal length and positioned at a distance D from the first crossed lenticular cylindrical lens means 4 and on an opposite side of the first crossed lenticular cylindrical lens means from the source. The second crossed lenticular cylindrical lens means 6 is aligned in a plane substantially orthogonal to the input beam 2 and in a plane parallel to the plane of the first crossed lenticular cylindrical leans means. A focusing lens 8 is interposed between the second crossed lenticular cylindrical lens means 6 and work plane 10 at a distance creating a separation from the work plane. The input beam refracts sequentially through the first and second crossed lenticular cylindrical lens means and the focusing lens onto the work plane.

In this way, the input beam is homogenized so as to produce an image in the work plane having a relatively uniform intensity profile characteristic. Preferably, the first predetermined focal length and the second predetermined focal length equal a given focal length f. Also, the distance D between the first crossed lenticular cylindrical lens means and the second crossed lenticular cylindrical lens means is preferably in the range of zero to two times the given focal point. Furthermore, at least one of the first crossed lenticular cylindrical lens means 4 and the second crossed lenticular cylindrical lens means 6 can be movably mounted so that the distance D between the first and second crossed lenticular cylindrical lens means is selectively settable. Means can be connected to the movable crossed lenticular cylindrical lens means for enabling the distance D between the first crossed lenticular cylindrical lens means and the second crossed lenticular cylindrical lens means to be adjusted, whereby the size of the image in the work plane is adjustable.

Figure 2 shows a side view, and Figure 3 shows a top view of a conventional optical beam integration systems represented by U.S. Patent No. 4,733,944. The first crossed lenticular cylindrical lens means preferably comprises at least a first cylindrical lens 12 having the given focal length and having a longitudinal axis aligned in a plane substantially orthogonal to the input beam 2 and a convex face oriented toward the source, and at least a second cylindrical lens 14 having the given focal length and positioned proximate to the first cylindrical lens and on an opposite side of the first cylindrical lens from the source. The second cylindrical lens 14 has a longitudinal axis aligned in a plane substantially orthogonal to the input beam 2 and has a convex face oriented toward the source. The longitudinal axis of the second cylindrical lens is oriented substantially perpendicular to the longitudinal axis of the first cylindrical lens. Furthermore, the second crossed lenticular cylindrical lens means preferably comprises at least a third cylindrical lens 16 having the given focal length and positioned at a first spacing dl from the first cylindrical lens and on the side of the second cylindrical lens opposite the source. The third cylindrical lens 16 has a longitudinal axis aligned in a plane substantially orthogonal to the input beam and has a convex face pointed away from the source, the longitudinal axis of the third cylindrical lens, being parallel to the longitudinal axis of the first cylindrical lens. At least a fourth cylindrical lens 18 has a given focal length and is positioned proximate to the third cylindrical lens 16 and on the side of the third cylindrical lens opposite from the source. The fourth cylindrical lens is positioned at a second spacing d2 from the second cylindrical lens 14. The fourth cylindrical lens has a longitudinal axis aligned in a plane substantially orthogonal to the input beam 2 and a convex face oriented away from the source. The longitudinal axis of the fourth cylindrical lens is also oriented substantially perpendicular to the longitudinal axis of the third cylindrical lens. The longitudinal axis of the fourth cylindrical lens is

» parallel to the longitudinal axis of the second cylindrical lens.

The input beam refracts sequentially through the first, second, third and fourth cylindrical lenses and the focusing lens onto the work plane. At least one of the first 12 and third 16 cylindrical lenses, as well as at least one of the second 14 and fourth 18 cylindrical lenses, are preferably movably mounted so that the first spacing dl, as well as the second spacing d2, are selectively settable, and means can be connected to each movable cylindrical lens for enabling the first spacing, as well as the second spacing, to be adjusted, whereby the aspect ratio of the image in the work plane is adjustable.

A conventional system such as U.S. Patent No. 4,733, 944 fails, however, to provide a means for independently adjusting the distances between all of the cylindrical lenses. This places constraints on the configuration of the output beam. Referring to Figures 1, 2 and 3, a conventional system is constrained by the housing for the lenses such that D, dl and d2 can be adjusted only to a limited degree. The first and second cylindrical lenses, 12 and 14, respectively, are mounted in lens brackets which in turn are secured to a movable platform. The third and fourth cylindrical lenses, 16 and 18, respectively, are mounted in lens brackets which are fixedly mounted to a housing. The movable platform may be moved along a ball bearing slide to adjust the distance D between the first crossed lenticular cylindrical lens means and the second crossed lenticular cylindrical lens means. This adjusts the size of the image in the work plane without changing the aspect ratio.

The lens brackets for the first and second cylindrical lenses, 12 and 14, are each attached to the movable platform via a ball bearing slide. Thus, within a certain limited range, the first and second lens brackets may be moved independently of one another and the platform along their respective ball bearing slide. The first lens 12 can be moved to adjust the distance dl between the first and third cylindrical lenses, 12 and 16, and the second lens 14 can be moved to adjust the distance d2 between the second and fourth cylindrical lenses, 12 and 18. Adjusting the distances, dl and d2, adjusts the aspect ratio of the image in the work plane. Adjustment of the first spacing dl determines the horizontal size of the image, and adjustment of the second spacing d2 determines the vertical size of the image.

The need for an aspect ratio to be independently adjustable in both the X and Y axes was not apparent in a conventional beam integration system such as that represented by U.S. Patent No. 4,733,944. There was no need for large aspect ratios in conventional beam integration systems because of the state of the art of process applications at that time.

It is desirable to create very high and very low aspect ratios. Long/narrow and short/wide beams are useful for ablation and annealing. It would be desirable, therefore, to produce a long, rectangular beam for semiconductor or VLSI process applications. A conventional system, as depicted in Figures 1 through 3, allows d2 to be reduced while dl stays large. This produces a wide beam. However, dl cannot be reduced while d2 stays large to produce a long beam, because the second cylindrical lens 14 blocks the path of the first cylindrical lens, 12. The first cylindrical lens 12 can only be moved significantly toward the third cylindrical lens 16 if the second cylindrical lens 14 is moved toward the fourth cylindrical lens 18.

A conventional beam integration system, as represented by U.S. Patent No. 4,733,944, suffers from a serious disadvantage in that it is limited with respect to how far the second cylindrical lens 14 can be moved forward. If the second cylindrical lens 14 is moved too far forward, this limits the spot size on the third lens 16. Accordingly, the focused energy of the beam can cause the third lens to burn and thus be unusable. It is difficult to design a housing that allows both dl and d2 to be adjusted independently across a wide range of distances. One possibility is to allow the third and fourth cylindrical lenses to be adjusted, but ball bearing slides or rails may not be placed in the same manner as they are for the first and second cylindrical lenses. The third and fourth cylindrical lenses cannot be attached to the movable platform. They must be fixed relative to the movable platform, so the distance D between the first crossed lenticular cylindrical lens means and the second crossed lenticular cylindrical lens means may be adjusted.

Another problem to be overcome in a conventional beam integration system is that allowing additional movable lenses increases tolerance build-up error. A difficulty with a conventional system, is that error may be introduced by each of the lenses, particularly the movable lenses which may not be adjusted perfectly. The mechanical errors accumulate as the beam passes through the lens. This may result in significant error or "tolerance build-up" in the beam when it emerges from the fourth cylindrical lens. It is difficult and unduly time consuming to determine where the error is introduced.

In conventional systems, tolerance errors must be corrected manually by trial and error which is difficult and time consuming. Having the third and fourth cylindrical lenses fixed reduces the number of places where error may be introduced and may make corrective adjustment slightly more manageable. However, as discussed above, this has the disadvantage of limiting the variability of the aspect ratio. This consequently constrains the size of the output beam and limits its usefulness.

A further difficulty with a conventional beam integration system relates to the multiple cylindrical lenses used to integrate the coherent light beam. The first and second cylindrical lenses break the beam up into beamlets which essentially scramble the beam. The third and fourth lenses reconstitute the beam in homogenized form. This is done to even out random unevenness in the beam intensity profile. However, dividing a coherent light source into adjacent beamlets and recombining them also causes interference patterns or fringing. The more beamlets into which the beam is divided, the more uniform the beam profile. However, this has the disadvantage of increasing the amount of fringing. Therefore, what is needed is a beam integration system which provides both a uniform beam profile and minimized or no fringing.

A variety of techniques have been designed to reduce fringing. U.S. Patent No. 5,091,744 to Omata uses a plurality of mutually incoherent laser beams from separate laser sources to reduce the effects of fringing. However, this approach has a serious disadvantage in terms of increased complexity and expense of using multiple laser sources and combining their beams. U.S. Patent No. 5,153,773 to Muraki et al. uses a single laser source and divides it into two beams. This system forces the two beams to travel along optical paths of significantly different lengths, such that they are incoherent with each other at the time they reach the integrator. Each beam independently causes some fringing when integrated, but the beams are then superposed one upon the other to form a more uniform illuminance distribution. This system also suffers from the disadvantage of undue complexity. For example, the system includes multiple mirrors and lenses to create the different optical paths for the beams and also requires a rotating lens with a driving means. Another approach is partially disclosed in Masato Muraki, "Excimer

Laser Stepper", Technical Proceedings, Semicon/Japan, (Semiconductor Equip. & Materials Int'l Oct. 22-24, 1990). Referring to Figure 5, this approach involves dividing a laser beam into four separate beamlets. The beamlets are rotated and focused on an integrator at different angles. The beamlets are emitted from the beam splitter and are focused on the integrator by a prism unit. Nothing in the article suggests or indicates that the prism is anything other than a standard, fixed prism. While each beamlet produces fringes independently, the fringes are largely canceled by the other beamlets which enter the integrator at different angles and are superposed on one another.

For the foregoing reasons, there is a need for an improved optical beam integration system with the ability to vary independently the distance between multiple cylindrical lenses to provide long, narrow beams with uniformity.

It is also desirable to provide an improved optical integration system with the ability to produce beams having long narrow aspect ratios and having the ability to vary the aspect ratios along both the X and Y axes. There is also a need for an improved optical beam integration system with the ability to quickly compensate for tolerance build-up, without the need for time consuming realignment of all of the cylindrical lenses. Summary

In order to overcome the above discussed disadvantages of conventional optical beam integration systems, an aspect of the present invention provides an improved optical beam integration system which is capable of producing long, rectangular beams of uniform intensity which are useful for annealing, ablation, and other semiconductor process applications. While conventional beam integration systems such as U.S. Patent No. 4,733,944 discuss the employment of a cylindrical lens, it is understood by persons of ordinary skill in the art that each cylindrical lens comprises an array of cylinder lenses. Thus, it is to be understood that a so-called cylindrical lens itself comprises an array of cylinder lenses or "lenslets. " Thus, the term cylindrical lens as referred to herein, is understood by persons skilled in the art to comprise an array of cylinder lenses and therefore may be called a cylindrical lens array.

Another aspect of the invention enables the distances between the cylindrical lens arrays to be independently varied without damaging the cylindrical lenses by increasing the beam intensity on one or more of the cylindrical lens arrays.This aspect of the invention overcomes the inability of conventional optical integration systems to move the second cylindrical lens array forward without burning the third cylindrical lens array. In accordance with this aspect of the invention, a separate path is provided which enables relative movement of the third cylindrical lens with respect to the first and second cylindrical lenses. This advantageously enables the aspect ratio of the output beam to be varied along both the X and Y axes. Thus, long, narrow rectangular beams can be produced along both the X and Y axes with greater uniformity and control than was previously possible. This provides an advantage over conventional systems for use in annealing and ablation applications.

In another aspect of the invention, the focusing lens is mounted so as to be movable with three degrees of freedom to quickly compensate for mechanical error or so-called build-up of tolerance errors. This provides the advantage of ease of alignment of the output lens in order to compensate for all tolerance errors. Another aspect of the invention provides additional cylinder lens arrays that make up the cylindrical lens means. That is, a cylindrical lens means for breaking up the beam comprises one or more cylindrical lenses. Each cylindrical lens in turn comprises an array of cylinder lenses. This enables a greater portion of the beam to be broken up in comparison with conventional systems, thereby resulting in greater uniformity of the output beam. The effect of greater uniformity of the output beam is achieved by the beam splitting aspect of the present invention. The additional cylinder lenses allow the beam to be split up into multiple beam paths which project generally along a general beam path thereby increasing uniformity.

In another aspect of the invention, a mirror arrangement is provided for creating a higher angle of incidence and for creating different path lengths for each of the beamlets produced by a pyramidal mirror or other means in order to reduce fringing. Another aspect of the invention comprises a photodetector operatively linked with a microprocessor which in turn actuates a plurality of motors for continuous adjustment of the mirrors and output focusing lens in order to provide automatic focusing and compensation for tolerance build-up errors. Yet another aspect of the invention uses additional expanding and focusing optics at the output end of the beam path for enabling a beam to be produced which is a square in the neighborhood of 500 mm. Using the other aspects of the invention, the square beam of 500 mm can be varied to produce long narrow beams (500 mm x 1 mm) in both the X and Y directions for ablation and other process applications. Brief Description of the Drawings

FIG. 1 is a side view of a first embodiment of a conventional optical beam integration system;

FIG. 2 is a side view of a second embodiment of a conventional optical beam integration system;

FIG. 3 is a top view of a second embodiment of a conventional optical beam integration system;

FIG. 4 illustrates an example of a conventional method for reducing fringe effects in an optical beam integration system; FIG. 5 is a side view of a first embodiment of an improved housing for an optical beam integration system according to the present invention;

FIG. 6 is a perspective view of a first embodiment of an improved housing for an optical beam integration system according to the present invention; FIG. 7 is a side view of a second embodiment of an improved optical beam integration system according to the present invention;

FIG. 8 is a schematic view of an adjustable output focusing lens system according to the present invention.

FIG. 9 is a schematic view of the present invention combined with expanding and focusing optics to produce ultra long, narrow beams for process applications. Description of the Preferred Embodiments

This invention relates to improvements to a conventional optical beam integration system. One aspect of this invention relates to increasing the range of aspect ratios and sizes that can be obtained with a conventional optical beam integration system. Referring to Figures 2 and 3, this can be achieved by movably mounting at least one of the first cylindrical lenses 12 and fourth cylindrical lenses 18, as well as both of the second cylindrical lenses 14 and third cylindrical lenses 16, so that the first spacing dl, as well as the second spacing d2, are selectively settable. Means are connected to each movable cylindrical lens for enabling the first spacing dl, as well as the second spacing d2, to be adjusted. It will be appreciated that this also enables the aspect ratio of the image in the work plane to be adjustable.

Referring to Figure 5, one aspect of the present invention provides an improved housing which enables the second cylindrical lens 14 and third cylindrical lens 16 as well as at least one of the first cylindrical lenses 12 and fourth cylindrical lenses 18 to be movably adjusted. As used herein, a lens may comprise a grouping or array of lenses. The term lenticular, as defined herein, means a grouping or array of lenses. As shown in Figure 5, the fourth cylindrical lens 18 comprises one or more arrays of adjacent cylinder lenses. In a preferred embodiment, cylindrical lens 18 comprises nine arrays of adjacent cylinder lenses. Similarly, the third cylindrical lens 16 comprises a plurality of adjacent cylinder lenses, for example, nine.

As shown in Figures 5 and 6, one embodiment of the present invention provides a housing 20 with at least a first interior surface 22 and a second interior surface 24. A first guide path means for enabling the cylindrical lenses, 14 and 12, to be moveable back and forth along a predetermined path, such as a first rail 26, is mounted to the first interior surface 22. A second guide path means, such as a second rail 28, is mounted to the second interior surface 24. Other equivalent means for enabling the lenses to be slidably moveable with respect to one another along a beam path, may be employed. These include sliding means or rail means, such as a ball bearing slide and/or air bearings, and/or linear motors. One can appreciate that the guide path means, such as rail 26 in combination with rail 28, enable the cylindrical lenses 12, 14 and 16 to be independently moveable with respect to one another.

It will be appreciated that the cylindrical lenses 12, 14 and 16 are fully adjustable with respect to one another and are adjustable with respect to the fixed output focusing lens 8 and output lens array 18. All of the foregoing lenses are coaxial along a beam path 9 which emanates from beam source 49.

The first cylindrical lens 12 is mounted in a first lens holder 30; the second cylindrical lens 14 is mounted in a second lens holder 32; the third cylindrical lens 16 is mounted in a third lens holder 34; and the fourth cylindrical lens 18 is mounted in a fourth lens holder 36. The cylindrical lens holders 30, 32, 34 and 36 comprise means for mounting the cylindrical lenses in a coaxial arrangement in a beam path. The first lens holder 30 is movably mounted to the first rail with a first mounting bracket 38, the second lens holder 32 is movably mounted to the first rail by a second mounting bracket 40, and the third lens holder 34 is movably mounted to the second rail by a third mounting bracket 42. Adjusting means are provided for drawing or for pushing the lens arrays back and forth along the beam path for adjusting the aspect ratios as will be explained. In a preferred embodiment, the adjusting means comprise lead screws 47 and 48 which are driven by corresponding motors 44 and 46, respectively. The lead screws provide a means for selectively moving the lens holders 30, 32, and 34 along a respective guide path means by a precise, predetermined amount. It is understood that a third motor and corresponding lead screw (not shown for simplicity) move lens holder 32. The first mounting bracket 38 extends from the first lens holder in a direction opposite a plane containing the second lens 14, and the second mounting bracket 40 extends from the second lens holder in a direction opposite a plane containing the first lens 12 such that the first and second lens holders may be moved toward each other without impedance from the first and second mounting brackets.

The third mounting bracket 42 extends from the third lens holder in a direction opposite a plane containing the fourth cylindrical lens 18 such that the third lens holder may be moved toward the fourth lens holder 36 without impedance from the third mounting bracket.

A first clearance distance cl is defined between the second lens holder 32 and the second interior surface, and a second clearance distance c2 is defined between the third lens holder 34 and the first interior surface 22. The third mounting bracket 42 and the second rail 28 have a combined height less than the first clearance distance cl, and the second mounting bracket 40 and the first rail 26 have a combined height less than • the second clearance distance c2, such that the second and third lens holders may be moved toward each other without impedance from the second and third mounting brackets.

Adjusting means such as lead screws 47, 48 are operatively connected to each movable cylindrical lens 12 and 16 through a corresponding mounting bracket or lens holder 32, 34 for enabling the first spacing dl, as well as the second spacing d2, to be independently variable. As set forth above, a third motor and corresponding lead screw (not shown for simplicity) are provided for moving cylindrical lens 14 through corresponding lens holder 32. The fixed fourth cylindrical lens array 18 is held by a fourth cylindrical array mount 36. This aspect of the invention enables the aspect ratio of the image in the work plane to be independently adjustable. Also, this advantageously provides a high aspect ratio and enables the aspect ratio to be varied along both the X and Y axes. In a preferred embodiment, conventional motors 44, 46 are provided for driving each respective lens holder, 30 and 34, through a corresponding lead screw 47, 48, respectively. Lens holder 32 is driven through a third lead screw (not shown) as described above.

This arrangement allows the first spacing dl to be adjusted to be significantly less than the second spacing d2. Moreover, the second spacing d2 is adapted to be adjusted to be significantly less than the first spacing dl. Even when dl is large and the second cylindrical lens 14 prevents the first cylindrical lens 12 from moving toward the third cylindrical lens 16, d2 may be reduced by moving the third cylindrical lens 16 toward the first cylindrical lens 12.

It will be appreciated that this aspect of the present invention enables the third cylindrical lens 16 to be moved independently of the first and second cylindrical lenses 12 and 14. This also overcomes the problem in the prior art wherein the intensity of the beam from cylindrical lens 14 was focused upon a fixed third cylindrical lens 16 and damaged the third cylindrical lens. Also, by making, as here, the third cylindrical lens 16 independently moveable with respect to the first cylindrical lens 12 and second cylindrical lens 14 advantageously creates large aspect ratios in both the X and Y axes. This aspect of the invention advantageously enables large aspect ratios to be created and to be varied along both the X and Y axes in order to provide greater flexibility and control over the output beam for annealing and ablation applications. This is a significant advantage over conventional optical integration systems wherein the third lens 16 was fixed and consequently the aspect ratio could not be varied along both the X and Y axes.

In the presently preferred embodiment, the first spacing dl is fully adjustable independently of the second spacing d2. The second spacing d2 is also fully adjustable independently of the first spacing dl. Thus, lens holder 30 and first cylindrical lens 12 can be moved in a range of approximately 3.7 inches down to a 1 mm air space between the first cylindrical lens 12 and the second cylindrical lens 14. Similarly, the second cylindrical lens 14 and its associated lens holder 32 can be moved in a range of approximately 3.7 inches down to a 1 mm air gap between the second cylindrical lens 14 and third cylindrical lens array 16. Similarly, the third cylindrical lens 16 can be moved to within a 1 mm air space from the fourth cylindrical lens 18. In conventional beam homogenizers, the third cylindrical lens 16 was not independently moveable. Thus, it was not possible to vary the aspect ratio of the output beam in both the X and Y axes. At the time, dual axis, high aspect ratios were not required for processing techniques. The present invention, for the first time, solves the problem of producing long, narrow beams with high aspect ratios which can be varied in both the X and Y directions for state of the art processing applications.

This aspect of the invention allows great flexibility in adjusting the aspect ratio of the image in the work plane. Long/narrow and short/wide beams may both be produced by simply adjusting the first, second and third cylindrical lenses. Thus, this aspect of the invention provides at least three cylindrical lenses 12, 14 and 16 which are independently moveable with respect to each other. This is capable of producing high aspect ratios of homogenized energy of a predetermined wavelength. The aspect ratios are also capable of being varied along both the X and Y axes. This is accomplished by providing a separate guide path means for moving the lens holder 34 of the third cylindrical lens 16 along a path of travel in the beam path.

The first and second cylindrical lenses are movably mounted to the first guide path means 26 for defining a path of travel. The third cylindrical lens is movably mounted to a second guide path means 28 for defining a path of travel such that the first, second and third cylindrical lenses are adapted for independent coaxial movement on the path of travel. It will be appreciated that the first, second and third cylindrical lenses all move independently and coaxially with respect to a beam path 9. One can also appreciate that the third cylindrical lens 16 moves along a different path of travel which is separate from and does not interfere with the movement of the first and second cylindrical lenses 12 and 14, respectively. This enables the beam size to be shaped from large to small. By moving the third cylindrical lens 16 forward, it is possible to produce a large beam. Moving the third cylindrical lens 16 in a rearward direction produces a small beam. Since the third cylindrical lens 16 is moveable along a separate guide path which does not interfere with the first and second cylindrical lenses, moving the third cylindrical lens 16 also enables one to change the aspect ratio in both the X and Y direction as described previously. It will be appreciated that this aspect of the invention enables an excimer laser to produce high energy beams with dual axis, high aspect ratios for annealing and processing techniques.

The above exemplary embodiment is offered primarily for illustration. Other equivalent arrangements may be used to allow at least one of the first and fourth, as well as both the second and third, cylindrical lenses to be movably adjusted, thereby adjusting the first and second spacing.

For instance, when the guide path means for moving the separate lenses comprises a rail, the third and fourth cylindrical lenses may be movably attached to a first rail while the second cylindrical lens may be movably attached to a second rail. Alternatively, all four cylindrical lenses could be movably attached to rails. In the exemplary embodiment, the fourth cylindrical lens could be movably mounted on the second rail. In addition, the first rail could be replaced with two separate rails, one for the first lens holder and one for the second lens holder. The present invention is intended to encompass all such embodiments.

Another aspect of the present invention relates to a method for enhancing uniformity and for reducing fringe effects in an optical beam integration system with movable lenses. Referring to Figure 7, an input beam 2 is directed toward a first mirror 46. Mirror 46 is a conventional mirror used for directing the input beam 2 to a beam expander means 47 for expanding the diameter of input beam 2. The expanded input beam 2 is then directed to a means for collimating 48 which collimates the input beam 2 and directs it toward a beam splitter means 50. In this case, the beam splitter means 50 comprises a four sided pyramidal mirror. Other equivalent conventional beam splitting devices may be substituted for the four sided pyramidal mirror 50. A plurality of pivotable mirrors 52 are pivotally mounted and dispersed about the beam splitter means 50. For simplicity, only two pivotable mirrors 52a, 52b are shown. The beam splitter means 50 divides the input beam 2 into a plurality of beamlets 54a, 54b, 54c, 54d. Each beamlet emerges from the beam splitter means 50 and travels to a corresponding pivotal mirror 52a, 52b, etc. It is understood by persons skilled in the art that beamlets 54c and 54d, denoted by dotted lines in Figure 7, are actually orthogonal to the plane of the drawing. If the device shown in Figure 7 were rotated 90 degrees about an axis of rotation defined by the beam path for output beam 90, beamlets 54c and 54d would be essentially in the same position as beamlets 54a and 54b as shown in Figure 7. For the sake of simplicity, beamlets 54c, 54d are shown as dotted lines culminating in arrows. It is to be understood that corresponding pivotable mirror means 52 are provided for reflecting each associated beamlet 54c and 54d.

Each beamlet 54a, 54b, 54c, 54d, is reflected from its corresponding pivotable mirror 52a, 52b to a first crossed lenticular cylindrical lens means 4 at an angle of incidence of sufficient size to reduce interference between the beamlets. It is to be understood by persons skilled in the art that the drawing is not to scale. In accordance with an aspect of the invention, the pivotable mirrors 52 are disposed such that each corresponding beam path for each beamlet 54a, 54b, 54c, 54d, has a different path length with respect to the other beam paths. Each beam path for the beamlets 54a, 54b, 54c, 54d has a different path length, in order that the beamlets 54 do not recombine in terms of their phase. This achieves the advantage of reducing fringing.

It will be appreciated that first and second cylindrical lenses 70 and 72 comprise the first crossed lenticular cylindrical lens means 4. Similarly, third and fourth cylindrical lenses 74 and 76 comprise the second crossed lenticular cylindrical lens means 6. Each of the lenses 70, 72, 74 and 76 is held by a corresponding lens holder means 60, 62, 64 and 66. Each lens holder means 60, 62, 64 is movably mounted along a guide path for movement in a forward or rearward direction. Lens holders 60, 62 are movably mounted on a first guide path means 80 for allowing relative, independent movement between each of the lens holders. Similarly, lens holder 64 is movably mounted on a second guide path means 82. The guide path means 82 advantageously enables the third cylindrical lens 74 to be moved independently relative to the other three lenses.

As shown in Figure 7, lens holder 60' is lens holder 60 disposed in a forward position. It is understood that, when in this position, lens holders 64 and 62, respectively, are disposed between lens holder 66 and 60'. This view is provided to show the tilted beam paths of beams 54a and 54b. As lens holder 60 assumes the position of 60' then beam paths 54a and 54b assume the position of 54a' and 54b'.

The beam splitting means divides the input beam 2 into a plurality of beamlets 54, there being one pivotable mirror 52 corresponding to each beamlet. Each beamlet emerges from the beam splitting means and travels to the corresponding pivotable mirror. Each beamlet 54 is reflected from the corresponding pivotable mirror 52 to the first crossed lenticular cylindrical lens means 4 at an angle of incidence of sufficient size to reduce interference between the coherent beamlets. The beamlets 54a-, 54b, 54c, 54d, refract sequentially through the first crossed lenticular lens means 4 and second crossed lenticular lens means 6 and the focusing lens 8 onto the work plane 10.

The input beam 2 is homogenized so as to produce an image in the work plane having a relatively uniform intensity profile characteristic. This aspect of the present invention enables additional cylindrical lenses to be used in the crossed lenticular lens means than is possible in conventional beam integration systems, since uniformity is enhanced and beam size is increased.

The first and second crossed lenticular cylindrical lens means 4 and 6, respectively, and the corresponding cylindrical lenses 70, 72 and 74 are adapted to be movably mounted in the guide paths 80, 82 such that movement of one cylindrical lens does not interfere with the movement of an adjacent cylindrical lens. As any of the lenses are moved, the pivotable mirrors 52 adjust in order to keep the beamlets aimed at the lenses, and to control the incidence angle. Well known systems of optical feedback control, which can be readily implemented by those skilled in the art without undue experimentation, are connected to the pivotable mirrors for pivoting the mirrors such that the mirrors continue to reflect the beamlets through the first and second crossed lenticular cylindrical lens means despite any adjustment of the distance between the first and second crossed lenticular cylindrical lens means, or any of the cylindrical lenses making up the cylindrical lens means.

A separate conventional motor (not shown for simplicity) is provided for independently moving pivotable mirrors 52a, 52b and so on, which it is understood are provided for reflecting beamlets 52a, 52b, and so on.

Referring again to Figure 7, the input beam 2 is expanded by the two adjacent lenses 47 and 48 prior to being directed toward pyramidal mirror 50. The two lenses 47 and 48 have a magnification ratio preferably on the order of 1.8:1. The purpose of the magnification is to evenly illuminate the first crossed lenticular lens means 4.

In accordance with another aspect of the invention, a focusing output lens 8 is adapted to be moved in response to the angle of the output beam 90 in relation to the work plane 10. A feedback control system is provided for optimizing the angle of incidence between the output beam 90 and work plane 10. As shown in Figure 8, output beam 90 is concentrated by the second crossed lenticular lens means 6 comprising cylindrical lenses 76 and 74, respectively. The arrows indicate the incoming beam which is concentrated about the central axis of the beam path of output beam 90. The output beam 90 then is applied through the output focusing lens 8 to a work plane 10. A photodetector system and/or interferometric system is provided for detecting back-scattered light from the output beam 90 as it strikes the surface of work plane 10. The photodetector system includes a CCD 92 or other convenient photodetector means having an active scanning region for detecting back scattered light from the work plane 10. The photodetector means 92 in accordance with techniques which are well known, produces output signals on lead 94 to a photodetector signal processor and amplifier 95. This amplifies the relatively weak signals from the photodetector means 92 and filters out noise. The amplified signals are then applied over lead 96 to a microprocessor 97. The amount of back- scattered light detected by the photodetector means 92 is a function of the angle of incidence of output beam 90 in relation to the surface of work plane 10.

In accordance with techniques which are well known to those skilled in the art, the signals representative of the back-scattered light which are sent to the microprocessor 97 are correlated to determine the angle of incidence of output beam 90 on work plane 10 with extreme precision. The microprocessor 97 in accordance with techniques which are well known, calculates the angle of incidence of output beam 90 and is adapted to produce corrective feedback signals to first motor 98 and second motor 99 over leads 100 and 102, respectively. The signals produced by the microprocessor 97 cause the motors 98 and 99 to move the output lens 8 so as to always maintain the proper angle of the output beam 90 on the surface of work plane 10. In accordance with an aspect of the invention, the motors 98 and 99 are adapted for moving the focusing lens 8 with three degrees of freedom. This enables the angle of the output beam 90 to be maintained in a constant relation to the surface of working plane 10 with greater accuracy than was previously possible using conventional optical integration systems. In accordance with this aspect of the invention, each motor 98, 99 is adapted for the movement of focusing lens 8 in the X, Y or XY directions in response to control signals from the microprocessor 97. The XY direction is understood by those skilled in the art to be a tilt axis. In addition, each motor 98, 99 is operatively connected with an opposite end of output lens holder 37.

Referring to Figures 7 and 8, it will be appreciated that output lens holder 37 supports the output lens 8 and is adapted to be moved with three degrees of freedom by first and second motors 98 and 99, respectively. For example, output lens holder 37 is adapted to move in a left or right direction transversely to the beam path of output beam 90. Output lens holder 37 is also adapted to be tilted up or down, or titled transversely to a tilt axis or tilted to the right or left in response to the adjusting motors 98 and 99. The amount of left or right motion and up or down tilting of the output lens holder 37 is determined by the size of the actuating space 105. In a preferred embodiment, the motors 98 and 99 are adapted for turning a series of lead screws which are disposed at diametrically opposed points for varying the orientation of the output lens 8 so as to maintain a constant or predetermined angle of incidence between output beam 90 and work plane 10. It will be appreciated that any equivalent actuation means responsive to electric signals for applying an actuating force to control the movement of the output lens holder 37 with three degrees of freedom may be employed to achieve this aspect of the invention. For example, hydraulic or other actuating means could also be used to exert pressure on oppositely disposed ends of the lens holder 37 to tilt the output lens in the X, Y or XY directions, or with three degrees of freedom with respect to the output beam path 90. It is understood by those skilled in the art that one could use the above described details of the invention to easily implement an interferometry based system for providing active feedback control of the output lens. Therefore it is understood that this aspect of the invention intended to encompass an interferometry feedback system and all equivalent arrangements for active feedback control. It will be appreciated that any convenient means for adjustably moving the output lens holder 37 may be employed to achieve this aspect of the invention.

This aspect of the present invention enables the output lens to compensate automatically for errors in tolerance build-up or to automatically compensate for inaccuracies due to thermal expansion and contraction. It will be appreciated that this enables the incident angle of the output beam 90 with respect to a work plane 10 to be controlled with an extreme degree of precision which was not previously possible in conventional beam integration systems. This provides the advantage of enabling the output beam 90 to be precisely tracked to any predetermined point on the surface of work plane 10 with greater precision than was previously possible. The foregoing capability for moving focusing lens 8 with three degrees of freedom coupled with the ability to maintain a constant angle of incidence between output beam 90 and surface of work plane 10 provides the additional advantage of enabling an optical beam integration system in accordance with this aspect of the present invention to compensate for and to automatically overcome errors in tolerance or so-called "tolerance build-up." That is, the numerous beam paths which are produced by the beam splitters, expanders and lens arrays are subject to minor variation due to temperature, vibration and other common factors which may lead to minor misalignments. The minor misalignments of beam paths and lens arrays are cumulative and result in tolerance build-up. The foregoing aspect of the present invention enables tolerance build-up to be compensated for and substantially eliminated by a corrective feedback control which provides continual adjustment of the focusing lens 8. This was not previously possible using conventional optical integration devices. The present invention also dispenses with the need for deactivating the homogenizer in order to make manual adjustments to compensate for tolerance build-up error. Thus, the present invention greatly enhances throughput in a processing application. The foregoing features of the present invention enable an output beam to be produced which is characterized by an ultra long aspect ratio. Also, for the first time the foregoing features of the invention enable the aspect ratio to be varied in both the X and Y axes. With the addition of expanding and focusing optics which are well known, it is now possible to employ the present invention for producing ultra long narrow beams, variable in both the X and Y axes, for process applications. The expanding and/or focusing optics would have to be rotated about the axis of beam path 90 either electrically or mechanically. Using the present invention, one skilled in the art now can produce a beam of laser energy in the neighborhood of 500mm square working spot size.

By changing the aspect ratio in both the X and Y directions, in accordance with an aspect of the invention, for example, a 500mm spot size can be varied to produce a beam of 500mm x 1mm by employing the features of the present invention as described above. It is also possible to produce other ranges of beam dimensions which are variable. Thus, the present invention in combination with expanding and focusing optics enables one to advantageously produce long, narrow beams or beams with ultra long aspect ratios. Such beams are particularly advantageous for applications in which it is necessary to scan a long, narrow beam of energy across a surface, such as for annealing or other process applications.

Conventional expanding and focusing optics could be employed for producing ultra high aspect ratio beams. However, such beams would be fixed and incapable of being varied for a specific application.

With the addition of the foregoing details of the invention it is now possible to produce ultra long aspect ratio beams which are variable.

Figure 9 is a schematic view of the present invention combined with expanding and focusing optics to produce an ultra long, narrow beam for process applications.

Referring to Figure 9, with the addition of expanding and focusing optics which are well known, it is possible to employ the present invention for producing ultra high aspect ratio beams, variable in both the X and Y directions, variable in both length and width, for process applications. Output beam 90 from the homogenizer 117 of the present invention is applied through the output lens 8. The output beam 90 is then directed through an expansion lens 120, reflected off cylindrical mirror 121, reflected off cylindrical mirrors 122a and 122b and focused onto the work plane 10. This configuration demonstrates a cylindrical analog of the Schwarschild Objective (Kingslake, Optical Design, p. 258). It will be appreciated to those skilled in the art of optical design that this or several other equivalent configurations may be employable to produce the results discussed herein. It will also be appreciated that as beam 90 exits homogenizer 117, that as configured in Figure 9, the beam has a high aspect ratio and is being expanded by lens 120, which in accordance with the present invention is variable in both length and width. By changing the axis of rotation of cylindrical mirrors 121, 122 and adjusting the aspect ratio rotation axis of the present invention, ultra high aspect ratio beams are achievable.

By using the details of the present invention it is possible to vary, for example, a 500mm square beam to produce a 500mm x 1mm beam in either the X or Y axis. While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements. For example, multiple cylinder lenses or "lenslets" may be incorporated in each cylindrical lens. However, it is not essential that each cylindrical lens comprise an array of cylinder lenses. Also, more or fewer than four cylindrical lenses may be employed. However, in such a structure the two separate guide path means still enable the multiple cylindrical lenses to be moved independently of one another, yet coaxially with respect to the beam path. Therefore, persons of ordinary skill in this field are to understand that all such equivalent arrangements are to be included within the spirit and scope of the appended claims.

Claims

What is claimed is:

1. An optical beam integration system responsive to an input beam of radiant energy from a radiant energy source, the input beam having a nonuniform beam intensity profile characteristic, comprising: at least a first cylindrical lens having a given focal length and having a longitudinal axis aligned in a plane substantially orthogonal to the input beam and a convex face oriented toward the source; and at least a second cylindrical lens having the given focal length and positioned proximate to the first cylindrical lens and on an opposite side of the first cylindrical lens from the source, the second cylindrical lens having a longitudinal axis aligned in a plane substantially orthogonal to the input beam and a convex face oriented toward the source, the longitudinal axis of the second cylindrical lens being oriented substantially perpendicular to the longitudinal axis of the first cylindrical lens; and at least a third cylindrical lens having the given focal length and positioned at a first spacing from the first cylindrical lens and on an opposite side of the second cylindrical lens from the source, the third cylindrical lens having a longitudinal axis aligned in a plane substantially orthogonal to the input beam and a convex face oriented away from the source, the longitudinal axis of the third cylindrical lens being parallel to the longitudinal axis of the first cylindrical lens; and at least a fourth cylindrical lens having the given focal length and positioned proximate to the third cylindrical lens and on an opposite side of the third cylindrical lens from the source, the fourth cylindrical lens being positioned at a second spacing from the second cylindrical lens, the fourth cylindrical lens having a longitudinal axis aligned in a plane substantially orthogonal to the input beam and a convex face oriented away the source, the longitudinal axis of the fourth cylindrical lens being oriented substantially perpendicular to the longitudinal axis of the third cylindrical lens, the longitudinal axis of the fourth cylindrical lens being parallel to the longitudinal axis of the second cylindrical lens; and the input beam refracting sequentially through the first, second, third, and fourth cylindrical lenses and a focusing lens onto a work plane; at least one of the first and fourth cylindrical lenses, as well as both of the second and third cylindrical lenses, are movably mounted so that the first spacing, as well as the second spacing, are selectively settable; and means connected to each movable cylindrical lens for enabling the first spacing, as well as the second spacing, to be adjusted, whereby the aspect ratio of the image in the work plane is also adjustable.

2. The optical beam integration system of claim 1 wherein the first spacing is adjustable in the range of two times the focal length of the first cylindrical lens independently of the second spacing, and the second spacing is adjustable in the range of two times the focal length of the first cylindrical lens independently of the first spacing.

3. The optical beam integration system of claim 1 wherein: the first and second cylindrical lenses are movably mounted to a first guide path means for defining a path of travel and the third cylindrical lens is movably mounted to a second guide path means for defining a path of travel such that said first, second and third cylindrical lenses are adapted for independent coaxial movement on said path of travel.

4. The optical beam integration system of claim 1 wherein the focusing lens is adapted to be moved with three degrees of freedom to compensate for tolerance build-up error.

5. An optical beam integration system comprising: a housing with at least a first interior surface and a second interior surface; a first guide path means for defining a path of travel mounted to the first interior surface and said second guide path means for defining a parallel path of travel mounted to the second interior surface; a first cylindrical lens defining a beam path and have a given focal length mounted in a first lens holder; and a second cylindrical lens disposed in said beam path and mounted in a second lens holder; and a third cylindrical lens disposed in said beam path and mounted in a third lens holder; and a fourth cylindrical lens disposed in said beam path and mounted in a fourth lens holder; and said first and second lens holders are movably mounted to said first guide path means, the third lens holder is movably mounted to said second guide path means, and the fourth lens holder is mounted to the housing such that a first spacing between said first and third cylindrical lenses is adapted to be adjusted to be significantly less than a second spacing between said second and fourth cylindrical lenses and the second spacing is adapted to be adjusted to be significantly less than the first spacing.

6. The optical beam integration system of claim 5 wherein: the first lens holder is movably mounted to the first rail with a first mounting bracket, the second lens holder is movably mounted to the first rail by a second mounting bracket, and the third lens holder is movably mounted to the second rail by a third mounting bracket; the first mounting bracket extending from the first lens holder in a direction opposite a plane containing the second lens, and the second mounting bracket extending from the second lens holder in a direction opposite a plane containing the first lens such that the first and second lens holders may be moved toward each other without impedance from the first and second mounting brackets; the third mounting bracket extending from the third lens holder in a direction opposite a plane containing the fourth cylindrical lens such that the third lens holder may be moved toward the fourth lens holder without impedance from the third mounting bracket; a first clearance distance being defined between the second lens holder and the second interior surface, and a second clearance distance being defined between the third lens holder and the first interior surface; the third mounting bracket and the second rail having a combined height less than the first clearance distance, and the second mounting bracket and the first rail having a combined height less than the second clearance distance, such that the second and third lens holders may be moved toward each other without impedance from the second and third mounting brackets.

7. The optical beam integration system of claim 6 wherein the first spacing is adjustable in the range of two times the focal length of the first cylindrical lens independently of the second spacing, and the second spacing is adjustable in the range of two times the focal length of the first cylindrical lens independently of the first spacing.

8. An optical beam integration system responsive to an input beam of radiant energy from a radiant energy source, the input beam having a nonuniform beam intensity profile characteristic, comprising: a beam splitting means; a plurality of pivotable mirrors pivotally mounted and dispersed about the beam splitting means; a first crossed lenticular cylindrical lens means having a first predetermined focal length and aligned in a plane; a second crossed lenticular cylindrical lens means having a second predetermined focal length and positioned at a distance from the first crossed lenticular cylindrical lens means and on an opposite side of the first crossed lenticular cylindrical lens means from the beam splitting means, the second crossed lenticular cylindrical lens means being aligned in a plane substantially parallel to the plane of the first crossed lenticular cylindrical lens means; and a focusing lens having a preselected focal length and interposed between the second crossed lenticular cylindrical lens means and a work plane at a separation from the work plane.

9. An optical integration system for reducing fringing comprising: beam splitting means dividing the input beam into a plurality of beamlets; a plurality of pivotable mirror means, one pivotable mirror means for reflecting each corresponding beamlet emerging from said beam splitting means to a first crossed cylindrical lens means at a different path length to reduce interference between the beamlets; and the beamlets refracting sequentially through said first crossed cylindrical lens means through a second crossed cylindrical lens means, and a focusing lens onto the work plane; whereby the input beam is homogenized so as to produce an image in the work plane having a relatively uniform intensity profile characteristic with reduced fringing.

10. The optical beam integration system of claim 9 wherein at least one of the first crossed cylindrical lens means and the second crossed cylindrical lens means is movably mounted so that the distance between the first and second crossed cylindrical lens means is selectively settable, and further comprising means connected to the movable crossed cylindrical lens means for enabling the distance between the first crossed cylindrical lens means and the second crossed cylindrical lens means to be adjusted.

11. The optical beam integration system of claim 10 further comprising: means connected to the pivotable mirrors for pivoting the mirrors such that the mirrors continue to reflect the beamlets through the first and second crossed cylindrical lens means despite any adjustment of the position of the first and second crossed cylindrical lens means.

12. The optical beam integration system of claim 9 wherein the beam splitting means is a pyramidal mirror.

13. The optical beam integration system of claim 9 wherein the focusing lens is adapted to be moved with three degrees of freedom to compensate for tolerance build-up error.

14. An apparatus for precisely maintaining an output beam of energy from a laser, or the like in a desired angle of incidence with a work surface comprising: an output focusing lens adapted to be moveable with three degrees of freedom for controllably directing said beam of energy to the work surface; sensor means having an active scanning region for detecting back scattered energy representative of the angle of incidence of said energy beam impinging on said work surface and for producing output signals representative of said sensed back scattered energy; microprocessor means responsive to said output signals for correlating said output signals with reference values representative of the desired angle of incidence of said beam with respect to said work surface and for producing corrective feedback signals representative of a desired angle of incidence for said beam of energy; motor means responsive to said corrective feedback signals and operatively connected with said output focusing lens for moving said output focusing lens with three degrees of freedom such that said beam is maintained in a desired angle of incidence with respect to said work surface.

15. An apparatus according to claim 14 wherein said motor means further comprises means operatively connected with a lens holder for holding said output focusing lens, said lens holder adapted for tilting said output focusing lens in an X, Y or XY direction in response to an actuation force applied by said motor means.

16. An apparatus according to claim 15 wherein said motor means further comprises actuation means operatively connected with opposed portions of said lens holder for applying an activation force to move said lens holder in three degrees of freedom in response to corrective feedback signals from said microprocessor means.

17. An apparatus according to claim 15 wherein said sensor means comprises an interferometric based system.

18. A method for maintaining a path of a beam of energy in a desired angle of incidence with respect to a work surface comprising the steps of: controllably directing an output focusing lens, moveable with three degrees of freedom, to direct the beam of energy at a predetermined angle of incidence with said work surface; detecting back scattered energy from said beam impinging upon said work surface; producing electrical signals representative of the angle of incidence of said back scattered energy in relation to said work surface; correlating said electrical signals with values representative of said desired angle of incidence of said beam path with respect to said work surface; producing corrective feedback signals from said correlated values; 5 applying said corrective feedback signals to an actuation means for moving the focusing lens to maintain the beam path in a desired angle of incidence with said work surface.

19. An optical beam integration system for producing ultra long aspect ratio beams variable in both the X and Y directions comprising: 10 a source of a homogenized beam of optical energy defining a beam path;

a housing with at least a first interior surface and a second interior surface; a first guide path means for defining a path of travel parallel to said 15 beam path mounted to the first interior surface and a second guide path means for defining a parallel path of travel with respect to said beam path . mounted to the second interior surface; a first cylindrical lens disposed in said beam path for receiving said homogenized beam and having a given focal length mounted in a first lens 20 holder; and a second cylindrical lens disposed in said beam path and mounted in a second lens holder; and a third cylindrical lens disposed in said beam path and mounted in a third lens holder; and 25 a fourth cylindrical lens disposed in said beam path and mounted in a fourth lens holder; and wherein said first and second lens holders are movably mounted to said first guide path means, the third lens holder is movably mounted to said second guide path means, and the fourth lens holder is mounted to the housing such that a first spacing between said first and third cylindrical lenses is adapted to be adjusted to be significantly less than a second spacing between said second and fourth cylindrical lenses and the second spacing is adapted to be adjusted to be significantly less than the first spacing; an output lens for focusing said beam of said optical energy an expanding lens means for receiving said beam of optical energy from said output lens and for expanding said beam of optical energy; first cylindrical mirror means for reflecting said expanded beam; one or more concave cylindrical mirror means disposed for receiving said reflected expanded beam from said first cylindrical mirror means and for reflecting one or more convergent beams of said optical energy to a focal point on a work plane to produce an ultra long aspect ratio and wherein said ultra long aspect ratio beam is variable in both length and width by reason of said adjustable spacings between said first and third and said second and fourth cylindrical lenses; and said ultra long aspect ratio beam is adjustable in both the X and Y axes by rotating said first cylindrical mirror means and said concave cylindrical mirror means.

20. The optical beam integration system of claim 19 wherein: the first lens holder is movably mounted to the first guide path means with a first mounting bracket, the second lens holder is movably mounted to the first guide path means by a second mounting bracket, and the third lens holder is movably mounted to the second rail by a third mounting bracket; the first mounting bracket extending from the first lens holder in a direction opposite a plane containing the second lens, and the second mounting bracket extending from the second lens holder in a direction opposite a plane containing the first lens such that the first and second lens holders are adapted to be moved toward each other without impedance from the first and second mounting brackets; the third mounting bracket extending from the third lens holder in a direction opposite a plane containing the fourth cylindrical lens such that the third lens holder may be moved toward the fourth lens holder without impedance from the third mounting bracket; a first clearance distance being defined between the second lens holder and the second interior surface, and a second clearance distance being defined between the third lens holder and the first interior surface; the third mounting bracket and the second rail having a combined height less than the first clearance distance, and the second mounting bracket and the first rail having a combined height less than the second clearance distance, such that the second and third lens holders may be moved toward each other without impedance from the second and third mounting brackets.

21. A method for producing ultra along, narrow beams of optical energy, variable in width and in length in both the X and Y directions comprising the steps of: guiding a source of homogenized optical energy on a beam path through a first cylindrical lens array having a predetermined focal length and moveable on a first guide path with respect to said beam path; directing said beam of optical energy through a second cylindrical lens array moveable along said first guide path; directing the beam of optical energy through a third cylindrical lens moveable along a second guide path spaced apart from the first guide path such that the third cylindrical lens array moves coaxially in said beam path with respect to first and second cylindrical lens arrays but does not impede the movement of the first and second cylindrical lens arrays; adjusting the distance between the first and third and between the second and fourth cylindrical lens arrays to vary the aspect ratio in two dimensions; directing the beam from the third lens array to an output focusing lens; focusing said beam of optical energy on a first cylindrical mirror means for expanding said beam of optical energy; reflecting said expanded beam of optical energy with one or more concave mirror means such that one or more beams are directed to converge on a work plane to produce a long, narrow aspect ratio beam which is variable as to length and width; rotating said first mirror means and said one or more concave mirrors means such that said long, narrow beam is adapted to have its major axis aligned in a X or Y direction on said work plane for process applications.