Abstract:
A method for aligning an optical assembly, including the steps of emitting at least one beam from an emitter substantially along a first axis, disposing a cylindrical lens in said at least one beam to form at least one line image, wherein a longitudinal axis of said cylinder lens is substantially parallel to a second axis which is different from said first axis, displaying at least one vertical profile of said at least one line image, defocusing said at least one line image until a first peak and a second peak of said at least one profile are displayed and adjusting in a third axis which is different from said first axis and said second axis a position of said cylindrical lens relative to said emitter until said first peak and said second peak are symmetric.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to alignment of optical devices. More particularly, this invention relates to a method, and the apparatus used therefor, for the axial alignment of the end face of an optical fiber or an array of optical fibers with a cylindrical lens and for evaluating the quality of the light that is emitted by the fiber or the array. 
     2. Description of the Related Art 
     In the past, the assembly and manufacture of optical assemblies having a linear array of optical elements has been time consuming and prone to quality control problems. The latest developments in optical cross-connect assemblies have only magnified these problems. Precisely engineered optical receiver arrays are required in these assemblies. A general demand for more precisely constructed assemblies having greater reliability has translated into a demand for better manufacturing apparatus and processes 
     Optical devices of the type addressed by the present invention currently in use involve an array of optical fibers having light transmitted therethrough. In typical devices the light exiting the end faces of the fibers is scattered, and it is necessary to collect it using collimation lenses or focusing optics. The focusing optics may include a precisely aligned cylindrical lens. 
     In current devices, it is required to precisely position a light source, which can be an optical fiber, or an array of optical fibers with respect to a horizontally oriented cylindrical lens within tolerances of a few microns in the vertical axis. It would be desirable to evaluate the quality of light that is emitted by the source at the time the alignment is performed, since setup costs have already been incurred. This would avoid the cost of performing a separate quality control procedure. 
     SUMMARY OF THE INVENTION 
     It is therefore a primary object of some aspects of the present invention to provide an improved method for precisely aligning a cylindrical lens with a fiberoptic array. 
     It is another object of some aspects of the present invention to provide an improved method for the evaluation of a beam emitted by a light source in an optical assembly 
     These and other objects of the present invention are attained by an optical arrangement in which the vertical alignment of an optical assembly is evaluated and adjusted. The assembly includes an array of emitters, such as an array of optical fibers, and a cylindrical lens. An optical stage or a vacuum chuck is used to adjust the vertical position of either the emitter or the cylindrical lens. Evaluation of alignment and beam quality is achieved using a defocused diffraction pattern produced by the cylindrical lens that is imaged onto the detector plane of a camera, and is captured by the camera. The output of the camera is linked to a display monitor, enabling qualitative evaluation of the image. A computer having a display monitor is also linked to the camera, using a frame grabber, and produces a plot of a vertical profile of the camera image The relative vertical position of the emitter and the cylindrical lens is then adjusted until the diffraction peaks seen on the computer monitor are symmetric and have the same amplitude. Using qualitative evaluation the source of defects can be differentiated by translating the cylindrical lens along its longitudinal axis. 
     The invention provides a method for aligning an optical assembly, including the steps of emitting a beam from an emitter, and disposing a cylindrical lens in the beam to form a diffraction pattern which is imaged onto the detector plane of a camera, wherein the longitudinal axis of the cylindrical lens is horizontally oriented. The method includes displaying a vertical profile of the line image, defocusing the line image until a first peak and a second peak of the profile are displayed, and adjusting the vertical position of the cylindrical lens relative to the emitter until the first peak and the second peak are symmetric. 
     In an aspect of the method, adjusting the vertical position is performed until the amplitude of the first peak is identical to the amplitude of the second peak. 
     According to a further aspect of the method, the line image is captured on a camera, which may be an infra-red camera. 
     In yet another aspect of the method, the profile is displayed by connecting a computer to the camera. 
     According to still another aspect of the method, the emitter includes a fiberoptic array. 
     One aspect of the method includes detecting an irregularity in the line image, horizontally displacing the cylindrical lens in a direction of its longitudinal axis, and determining a positional change of the irregularity. 
     According to an additional aspect of the method, the irregularity is detected by visual inspection. 
     According to one aspect of the method, the irregularity is detected by automatic computer implemented pattern recognition. 
     According to another aspect of the method, the beam includes a first beam that is emitted from a first element of the emitter, and a second beam that is emitted from a second element of the emitter. The line image includes a first line image that is projected by the first beam, and a second line image that is projected by the second beam The profile includes a first profile of the first line image and a second profile of the second line image. The method includes performing a θZ movement of the emitter relative to the cylindrical lens until the first peak and the second peak of the first profile, and the first peak and the second peak of the second profile are simultaneously symmetric. 
     According to an additional aspect of the method, the beam includes a first beam that is emitted from a first element of the emitter and a second beam that is emitted from a second element of the emitter. The line image includes a first line image that is projected by the first beam, and a second line image that is projected by the second beam. The profile includes a first profile of the first line image and a second profile of the second line image. The method includes adjusting the first line image to produce a predetermined pattern, performing a θY movement of the emitter relative to the cylindrical lens until the first line image and the second line image simultaneously have the predetermined pattern. 
     According to another aspect of the method, the predetermined pattern is a unimodal peak on the first profile and the second profile. 
     According to a further aspect of the method, the predetermined pattern is a multimodal peak on the first profile and the second profile. 
     The invention provides a method for aligning an array of optical fibers with a lens, including the steps of horizontally orienting a longitudinal axis of a cylindrical lens emitting a first beam from a first optical fiber of an optical fiber array, disposing the cylindrical lens in the first beam to form a first line image, displaying a first vertical profile of the first line image, defocusing the first line image until a first peak and a second peak of the first vertical profile are displayed, and adjusting a vertical position of the cylindrical lens relative to the optical fiber array until the first peak and the second peak are symmetric. 
     According to an aspect of the method, adjusting the vertical position is performed until the amplitude of the first peak is identical to the amplitude of the second peak. 
     According to one aspect of the method, the first line image is captured on a camera, which may be an infra-red camera 
     According to a further aspect of the method, the first vertical profile is displayed by connecting a computer to the camera. 
     Yet another aspect of the method includes detecting an irregularity in the first line image, horizontally displacing the cylindrical lens in a direction of the longitudinal axis, and determining a positional change of the irregularity. 
     According to yet another aspect of the method, the irregularity is detected by visual inspection. 
     According to still another aspect of the method, the irregularity is detected by automatic computer implemented pattern recognition. 
     An additional aspect of the method includes emitting a second beam from a second optical fiber of the optical fiber array toward the cylindrical lens to form a second line image, and displaying a second vertical profile of the second line image. The method includes performing a θZ movement of the optical fiber array relative to the cylindrical lens until the cylindrical lens and the optical fiber array are rotationally aligned, such that the first peak and the second peak of the first vertical profile are symmetric, and the first peak and the second peak of the second vertical profile are symmetric. 
     According to another aspect of the method, the first optical fiber and the second optical fiber are alternately illuminated by a light source. 
     One aspect of the method includes adjusting the first line image to produce a predetermined pattern, emitting a second beam from a second optical fiber of the optical fiber array toward the cylindrical lens to form a second line image, displaying a second vertical profile of the second line image The method includes performing a θY movement of the optical fiber array relative to the cylindrical lens until the cylindrical lens and the optical fiber array are rotationally aligned, such that the first line image and the second line image have the predetermined pattern. 
     According to a further aspect of the method, the first optical fiber and the second optical fiber are alternately illuminated by a light source. 
     According to another aspect of the method, the predetermined pattern is a unimodal peak. 
     According to a further aspect of the method, the predetermined pattern is a multimodal peak. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of these and other objects of the present invention, reference is made to the detailed description of the invention, by way of example, which is to be read in conjunction with the following drawings, wherein: 
     FIG. 1A schematically illustrates an optical arrangement for aligning optical devices constructed and operative in accordance with a preferred embodiment of the invention; 
     FIG. 1B is a simplified illustration of a rotation of the cylindrical lens of the optical arrangement of FIG. 1A about a Y-axis in accordance with a preferred embodiment of the invention; 
     FIG. 1C is a simplified illustration of a rotation of the cylindrical lens of the optical arrangement of FIG. 1A about a Z-axis in accordance with a preferred embodiment of the invention; 
     FIG.  2 A and FIG. 2B show screen displays that are generated for the objective lens, which is located in the focal plane of the cylindrical lens of the optical arrangement of FIG. 1A in accordance with a preferred embodiment of the invention; 
     FIG.  3 A and FIG. 3B show screen displays that are generated for the objective lens, which is located between the focal plane of the cylindrical lens and the objective lens of the optical arrangement of FIG. 1A in accordance with a preferred embodiment of the invention; 
     FIG.  4 A and FIG. 4B show screen displays that are generated for the objective lens, which is located farther from the focal plane of the cylindrical lens than for the objective lens location of FIG. 2, in accordance with a preferred embodiment of the invention, 
     FIG. 5 illustrates a screen display that is generated for the objective lens, which is shifted from the cylindrical lens and beyond its line of focus, in accordance with a preferred embodiment of the invention; 
     FIG. 6 is a flow chart of an alignment procedure that is operative in accordance with a preferred embodiment of the invention; 
     FIG. 7 shows a screen display that is generated by the arrangement shown in FIG. 1A in accordance with a preferred embodiment of the invention; 
     FIG. 8 is a flow chart illustrating the process of θZ adjustment of a fiberoptic array in accordance with a preferred embodiment of the invention; 
     FIG. 9 is a flow chart illustrating the process of θY adjustment of a fiberoptic array in accordance with a preferred embodiment of the invention; and 
     FIG. 10 is a flow chart of a procedure for detecting defects in components of the optical arrangement shown in FIG. 1A in accordance with a preferred embodiment of the invention; and 
     FIG. 11 shows a screen display that is generated by the arrangement shown in FIG. 1A, which is used to evaluate the quality of the components in the optical arrangement shown in FIG. 1A in accordance with a preferred embodiment of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent however, to one skilled in the art that the present invention may be practiced without these specific details. 
     In describing the embodiments herein, the following conventions are used. The Z-axis is nominally horizontal, and coincides with the optical axis of an optical element that is being manipulated. The X-axis refers to the horizontal axis that is orthogonal to the Z-axis The Y-axis is the vertical axis, and is orthogonal to both the X-axis and the Z-axis Rotation about the X-axis, Y-axis, and Z-axis is referred to as θX, θY and θZ motion or rotation respectively The terms θY and θZ adjustment refer to rotational movements of a first component relative to a second component about the Y-axis and Z-axis of the first component respectively. Of course, it is possible to use the method and apparatus disclosed herein in many positions and orientations, in which case the X-axis, Y-axis, and Z-axis are appropriately translated. 
     Optical Arrangement—General Description 
     Turning now to the drawings, reference is made to FIG. 1A, which schematically illustrates an optical arrangement  10  that is constructed and operative in accordance with a preferred embodiment of the invention. The optical arrangement  10  comprises a fiberoptic array  12  having a plurality of optical fibers  14 . Inlets of the optical fibers  14  are coupled to a radiation source, such as an infra-red laser (not shown) The optical fibers  14  output an infra-red beam  16  that is emitted through an exit plane  18 , at where are located the outlets of the optical fibers  14 . In a current application the cores of the optical fibers  14  each typically have a diameter of approximately 9 μm. The outputs of individual ones of the optical fibers  14  are referred herein to as sub-beams if they are combined into a single output beam. 
     In FIG. 1A, the beam  16  is typically emitted from the outlet of a marginal off-center optical fiber  20 . However in some aspects of the operation of the apparatus shown in FIG. 1A, the beam  16  may be emitted from the outlet of another optical fiber of the fiberoptic array  12 , such as a corresponding marginal off-center optical fiber  22 . The outlets of the individual optical fibers  14  are linearly arranged and substantially parallel to a line  24 , which is located in the exit plane  18  The beam  16  is directed toward a cylindrical lens  26 , the longitudinal axis of which is substantially parallel with the exit plane  18  The cylindrical lens  26  emits a focused beam  28  towards an objective lens  30  The objective lens  30  receives a line image from the cylindrical lens  26 , and focuses a beam  32  onto an infra-red camera  34 . Suitable cameras are commercially available from Electrophysics Corp, 373 Route 46 West Fairfield, N.J. 07004-2442 The output of the camera  34  is connected to a display monitor  36  and to a computer  38 , which can be a general purpose computer. The computer  38  is also provided with a display monitor  40  and executes frame grabber software. 
     In the presently preferred embodiment, the cylindrical lens  26  and the objective lens  30  and the other members of the optical arrangement shown in FIG. 1A are typically sensitive to radiation in the infra-red spectrum. However, it is appreciated that radiation in other spectral bands of the electromagnetic spectrum, such as the visible spectrum, may also be used. For such a case, the source of the radiation and the members of the optical arrangement of FIG. 1A, are sensitive to the particular radiation in use. 
     The display monitor  36  produces an analog representation of the image captured by the camera  34 . The display monitor  40  presents the output of the computer  38 , and it displays plots of the vertical profile of the image captured by the camera  34 . 
     The fiberoptic array  12  is preferably fixed in position and the cylindrical lens  26  is mounted on a conventional optical stage (not shown), such as a vacuum chuck stage, having freedom of movement along the X-, Y-, and Z-axes, and being capable of theta-Y and theta-Z motion. The movements of the cylindrical lens  26  are thus relative to the fiberoptic array  12 . It is also possible to manipulate the position of the fiberoptic array  12  relative to the cylindrical lens  26  by attaching the fiberoptic array  12  to a vacuum held chuck, and fixing the position of the cylindrical lens  26 . The beam  16  that is emitted from the core of each of the optical fibers  14  is a Gaussian beam. The beam  16  diverges as it exits from the exit plane  18 . The cylindrical lens  26  is placed at a distance from the exit plane  18 , such that its vertical dimension corresponds to the vertical spread of the beam  16 . The image profile in the vertical direction at the focus of the cylindrical lens  26  is a line image, the length of which is a function of the distance between the fiberoptic array  12  and the cylindrical lens  26 . 
     The optical arrangement  10  is useful in accomplishing two objectives: (1) the accurate positioning of the cylindrical lens  26  with respect to the line  24 ; and (2) the qualitative evaluation of the individual sub-beams emitted by the optical fibers  14 . In some embodiments, it is possible to qualitatively evaluate all the sub-beams collectively There are certain considerations in establishing the physical relationship between the outlets of the optical fibers  14  and the cylindrical lens  26 , which are disclosed hereinbelow. 
     In placing the longitudinal axis of the cylindrical lens  26  substantially perpendicular to the optical axis of the optical fibers  14 , the Z-axis, the optimum distance between the exit plane  18  and the cylindrical lens  26  depends both on the vertical dimension of the cylindrical lens  26  and the vertical spread of the beam  16 . This distance affects the location on the Z-axis of the focused line image that is projected by the beam  28   
     The location of the cylindrical lens  26  along the X-axis is not critical, as variation in the horizontal direction does not cause any change in the direction of the beam  28 . 
     The optical arrangement  10  is extremely sensitive to misalignment in the Y-axis between the cylindrical lens  26  and the exit plane  18 . It is necessary to accurately align the longitudinal axis of the cylindrical lens  26  relative to the optical axes of the optical fibers  14 , with a tolerance of only a few microns. This degree of accuracy is very difficult to achieve, mainly due to the fact that the distance between the cylindrical lens  26  and the exit plane  18  along the Z-axis is several orders of magnitude greater than the tolerance in the Y-axis. 
     A θY adjustment, which is a rotation about the Y-axis in the X-Z plane, is generally necessary in order to align the longitudinal axis of the cylindrical lens  26  substantially parallel to the exit plane  18  (FIG.  1 B). 
     A θZ adjustment, which is a rotation about the Z-axis in the X-Y plane, is generally necessary in order to align the longitudinal axis of the cylindrical lens  26  substantially parallel with the line  24  in the exit plane  18  (FIG. 1C) 
     Reference is now made to FIGS. 2A and 2B, which illustrate screen presentations of the display monitor  36  and the display monitor  40 , respectively. The description of FIGS. 2A and 2B is to be read in conjunction with FIG.  1 A. The following discussion illustrates the role of the display monitor  36  and the display monitor  40  during alignment of the optical arrangement  10 . When the objective lens  30  is optimally positioned at the focus of the cylindrical lens  26 , the result is a line image which is seen on a screen display  42  of the display monitor  36  as a distribution of image lines  44  (FIG. 2A) The typical width of an optimally focused line image is only a few microns, depending on the quality of the cylindrical lens  26 . A screen display  46  of the display monitor  40  displays the line image as an intensity distribution  48 , having a single peak  50  (FIG.  2 B). 
     Reference is now made to FIGS. 3A and 3B, which illustrate screen presentations of the display monitor  36  and the display monitor  40 , respectively. The description of FIGS. 3A and 3B is to be read in conjunction with FIG.  1 A. As shown in a screen display  52 , which appears on the display monitor  36 , shifting the objective lens  30  slightly toward the cylindrical lens  26  results in loss of focus, and the occurrence of a diffraction pattern produced by the cylindrical lens  26  that is imaged onto the detector plane of the camera  34 . The screen display  52  (FIG. 3A) shows the splitting of the line image into two lines  54 ,  56 . A corresponding screen display  58  (FIG.  3 B), which appears on the display monitor  40 , shows an intensity distribution  60 , having two peaks  62 ,  64 . 
     Reference is now made to FIGS. 4A and 4B, which illustrate screen presentations of the display monitor  36  and the display monitor  40 , respectively The description of FIGS. 4A and 4B is to be read in conjunction with FIG.  1 A. FIGS. 4A and 4B show the effect of shifting the objective lens  30  toward the cylindrical lens  26 , so that the line image produced by the cylindrical lens  26  is further defocused than for the case shown in FIGS. 3A and 3B As shown on a screen display  66  (FIG.  4 A), which appears on the display monitor  36 , there are now three lines  68 ,  70 ,  72 . It is seen that the intermediate line  70  is less prominent than the lines  68 ,  72 . On a screen display  74  (FIG.  4 B), which appears on the display monitor  40 , an intensity distribution  76  features three peaks  78 ,  80 ,  82 , of which the middle peak  80  is smaller than the peaks  78 ,  82 . In some cases, depending on the geometry of the various components in the optical arrangement  10 , the three peaks  78 ,  80 ,  82  may be nearly equal in amplitude. 
     If the objective lens  30  is shifted even closer to the cylindrical lens  26 , then four, five, or even a larger number of lines appear on the display monitor  36  and a corresponding number of peaks can be resolved on the display monitor  40 . 
     Reference is now made to FIG. 5, which illustrates a screen presentation of the display monitor  40 . The description of FIG. 5 should be read in conjunction with FIG.  1 A and FIGS. 2A and 2B. The objective lens  30  is now shifted in a direction away from the cylindrical lens  26 , beyond its line of focus. This results in spreading of the displayed peak On a screen display  84 , which appears on the display monitor  40 , an intensity distribution  86  features a single peak  88 , which is relatively broad, when compared with the appearance of the peak  50  on the screen display  46  (FIG.  2 B). 
     Thus it is possible to determine the position of the objective lens  30  relative to the line of focus of the cylindrical lens  26  by inspection of the display monitor  40   
     Vertical Alignment 
     Reference is now made to FIG. 6, which is a flow chart for performing a vertical alignment of the fiberoptic array  12 , using the optical arrangement  10 , which is operative in accordance with a preferred embodiment of the invention. The description of FIG. 6 is to be read in conjunction with FIG.  1 A. The optical arrangement  10  is initially configured at initial step  90 , during which the cylindrical lens  26  is placed in an approximate location in front of the exit plane  18 . At least one of the optical fibers  14 , for example the optical fiber  20 , as shown in FIG. 1A, is connected to the laser source or another similar suitable radiation source (not shown). The positions of the objective lens  30  and the camera  34  are adjusted, so that the image at the focus of the cylindrical lens  26  is visible on the display monitor  36 , and a plot appears on the display monitor  40   
     Next, at step  92 , the position of the objective lens  30  is adjusted in the Z-axis relative to the cylindrical lens  26  to produce a diffraction pattern that is imaged onto the detector plane of the camera  34 , and displayed on the display monitor  40  similar to the screen display  58  (FIG.  3 B). The peaks of the screen display  58  are symmetrical only if there is no misalignment in the Y-axis between the longitudinal axis of the cylindrical lens  26  and the optical axis of the optical fiber  20 . 
     Reference is now made to FIG. 7, which illustrates a screen display of the display monitor  40 . The description of FIG. 7 is to be read in conjunction with FIG. 1A, FIGS. 4A and 4B and FIG. 6. A screen display  94  features an intensity distribution  96 , having two resolved peaks  98 ,  100 . The amplitude of the peak  98  is greater than that of the peak  100 . The presence of two peaks indicates that the projected image is defocused, as explained above. The difference in the amplitudes of the peak  98  and the peak  100  indicates that the cylindrical lens  26  is not properly aligned in the Y-axis with respect to the exit plane  18   
     Referring again to FIGS. 3A and 3B, FIG. 6, and FIG. 7, at decision step  102  an evaluation of the screen display on the display monitor  40  is made to determine if the peaks have the same amplitude. If the peaks  98 ,  100  are different in amplitude, then at step  104 , a vertical adjustment of the objective lens  30  relative to the cylindrical lens  26  is performed. Control then returns to decision step  102 . If the vertical adjustment is performed in the wrong direction, then the difference in amplitude of the peaks increases in the next iteration, and appropriate correction in subsequent iterations must be made Generally, as the vertical adjustment approaches an optimum, the symmetry of the peaks also improves, so that they appear as shown in FIG.  3 B. 
     If the peaks displayed on the display monitor  40  are determined to have the same amplitude at decision step  102 , then it may be concluded that the cylindrical lens  26  and the objective lens  30  are in proper alignment in the Y-axis and the procedure terminates at final step  106 . 
     θZ Adjustment 
     Reference is now made to FIG. 8, which is a flow chart illustrating the process of θZ adjustment of the fiberoptic array  12  in accordance with a preferred embodiment of the invention The description of FIG. 8 should be read in conjunction with FIG. 1A, FIG. 6, and FIG.  7 . θZ adjustment is accomplished using an iterative cycle, in which the procedure shown in FIG. 8, is performed using the off-center element  20  of the optical fibers  14 . A similar screen display is also produced for the corresponding off-center element  22 . Following each iteration, a θZ adjustment is made by executing a θZ motion of the cylindrical lens  26  relative to the fiberoptic array  12 , and the results compared with the previous cycle. As the θZ alignment approaches an optimum, the peaks  98 ,  100  (FIG. 7) on the display monitor  40  (FIG. 1A) produced by the optical fiber  20  during a first measurement, and the peaks  98 ,  100  on the display monitor  40  produced by the optical fiber  22  during a second measurement in the same iteration all become symmetrical. In the event that the θZ motion was performed in the wrong direction, appropriate feedback is obtained at the conclusion of the following iteration, and the direction can then be reversed. 
     At initial step  108  the configuration of the apparatus, which was previously accomplished in initial step  90  (FIG.  6 ), is confirmed and adjusted if necessary, connecting the optical fiber  20  to the light source (not shown). At step  110 , a vertical alignment is performed as detailed in FIG.  8 . The appearance of the peaks  98 ,  100  (FIG. 7) on the display monitor  40  (FIG. 1A) during a first measurement is recorded in step  112  At step  114 , the optical fiber  20  is disconnected from the light source (not shown) and the optical fiber  22  connected to the light source. Alternatively, the optical fibers  20 ,  22  may each be connected to different light sources, which are enabled and disabled individually In step  116  the appearance of the peaks  98 ,  100  (FIG. 7) on the display monitor  40  during a second measurement is recorded. At decision step  118 , the records made in step  112  and step  116  are compared. The appearance of the peaks  98 ,  100  obtained in step  112 , should be symmetric as a result of the Y-axis alignment of step  110 , as is explained with reference to the detailed description of FIG.  6 . The record prepared in step  112  is also kept for documentation and quality control. In practice, it is sufficient in decision step  118  to assume that the peaks  98 ,  100  obtained in step  112  are symmetric, and to evaluate only the measurement that was obtained in step  116   
     If, at decision step  118 , the peaks  98 ,  100  that were recorded in step  116  are determined not to be symmetric, then a θZ adjustment of the cylindrical lens  26  relative to the fiberoptic array  12  is made at step  120 . Then, at step  122  the optical fiber  22  is disconnected from the light source (not shown), and the optical fiber  20  is reconnected to the light source. Control then returns to step  110 . Otherwise, θZ alignment is considered to be satisfactory, and the procedure terminates at final step  124 . 
     θY Adjustment. 
     The optimum location of the cylindrical lens  26  in the Z-axis relative to the fiberoptic array  12  depends on the position of the focus of the cylindrical lens  26 . The θY adjustment is not critical, and therefore can be accomplished manually, using the optical fiber  20  and the optical fiber  22  as alternate emitters. The general approach is as follows. The cylindrical lens  26  is rotated until a position is found at which a unimodal peak is seen on the display monitor  40  (FIG.  1 A), when the optical fiber  20  and the optical fiber  22  are alternately connected to the light source. The location of the cylindrical lens  26  in the Z-axis is adjusted by the operator as necessary, taking care to hold the Y-location of the cylindrical lens  26  in its position of alignment as previously determined 
     Reference is now made to FIG. 9, which illustrates a manual method of θY correction in accordance with a preferred embodiment of the invention. At initial step  126  the configuration of the apparatus, which was previously accomplished in initial step  90  (FIG.  6 ), is confirmed and adjusted if necessary. At step  128 , the optical fiber  20  is enabled by connecting it to the light source (not shown). At decision step  130  the display monitor  40  is inspected to determine if a bimodal or a unimodal peak is present If the determination at decision step  130  indicates a unimodal peak then control proceeds to step  132 . 
     If the determination at decision step  130  indicates that a bimodal peak is present then control proceeds to step  134 . The operator manually performs a θY movement of the cylindrical lens  26  by an amount, which he estimates will correct half of the erroneous pattern. This adjustment is empirical, as well as application specific. Then, at step  132 , the operator disables the optical fiber  20  by disconnecting it from the light source (not shown), and enables the optical fiber  22  using the same or a different light source (not shown) Enabling and disabling the optical fibers  20 ,  22  can be accomplished mechanically or electrically by conventional means. 
     At decision step  136 , the display monitor  40  is again inspected and a determination is again made whether a bimodal or a unimodal peak is present. If the adjustment in step  134  was properly made, particularly in the first iteration, there will generally still be a bimodal peak on the display monitor  40 . If the determination at decision step  136  indicates a bimodal peak exists, then control proceeds to step  138 . 
     However, in the event that the determination at decision step  136  indicates that a unimodal peak exists, the θY alignment may be considered to be within acceptable tolerance Control proceeds to final step  140  and the procedure terminates. 
     At step  138  the operator adjusts the position of the cylindrical lens  26  in the Z-axis until a unimodal peak appears on the display monitor  40 . Generally, some degree of θY misalignment will remain following completion of step  138 , particularly on the first iteration of the method. At step  142  the optical fiber  22  is disconnected from the light source (not shown), and control returns to step  128 . 
     While a unimodal peak is the preferred indicator on the display monitor  40  in the performance of the θY adjustment, it is possible to defocus the line image and use another well-defined pattern, such as a bimodal peak, so long as the appearance is identical when the optical fiber  20  and the optical fiber  22  are used as the alternate emitters 
     Qualitative Evaluation of Optical Fibers and Cylindrical Lens 
     Reference is now made to FIG. 10, which illustrates a method for qualitative evaluation of one or more optical fibers of the fiberoptic array  12  and the cylindrical lens  26 . The description of FIG. 10 should be read in conjunction with FIG.  1 A and FIGS. 3A and 3B. Preferably, the optics are carefully cleaned, as dirt on the cylindrical lens  26  may result in an unsatisfactory evaluation of the optical arrangement  10 . The method may be conveniently performed during the alignment process, as the equipment is appropriately configured at that time. The optical arrangement  10  is initially configured at initial step  144 , during which the cylindrical lens  26  is placed in a location in front of the exit plane  18 , as described hereinabove. At least one of the optical fibers  14  of the fiberoptic array  12  is connected to the laser light source or similar suitable radiation source (not shown) The objective lens  30  and the camera  34  are adjusted, so that the image at the focus of the cylindrical lens  26  is visible on the display monitor  36 , and a plot appears on the display monitor  40  (FIG.  1 A). 
     Next, at step  146 , the position of the objective lens  30  is adjusted relative to the cylindrical lens  26  to produce a diffraction pattern that is imaged onto the detector plane of the camera  34 , and displayed on the display monitor  36  similar to the screen display  52  (FIG.  3 A). It is now possible to analyze the quality and uniformity of the light that is emitted from the fiberoptic array  12 . If the optical fibers  14  being evaluated are also undistorted and the cylindrical lens  26  has no defects, the lines  54 ,  56  (FIG. 3A) are uniform, and free of distortion throughout their length, as evaluated qualitatively by the operator. 
     Reference is now made to FIG. 11, which illustrates a screen display of the display monitor  36  The description of FIG. 11 is to be read in conjunction with FIG. 1A, FIGS. 3A and 3B, and FIG. 10. A screen display  148  displays two lines  150 ,  152 , which are similar to the lines  54 ,  56  (FIG.  3 A). However, rather than being smooth and regular, the lines  150 ,  152  display irregular areas  154 ,  156 . 
     Referring again to FIG. 10, at decision step  158   a  qualitative evaluation of the lines displayed on the display monitor  36  is made. In the currently preferred embodiment of the invention, this evaluation is made by a human operator. It is also possible, using automatic computer implemented pattern recognition methods known to the art, to automate the evaluation of decision step  158  using a suitable program in the computer  38 . 
     If at decision step  158 , the display monitor  36  displays that the lines  150 ,  152  are regular and qualitatively smooth, substantially as shown in FIG. 3A, then at step  160  it is concluded that the quality of the optical arrangement  10  is satisfactory. The procedure terminates at step  162 . 
     However, if at decision step  158 , the display monitor  36  displays that the lines  150  and  152  show irregularities, such as the areas  154 ,  156  of the lines  150 ,  152  (FIG.  11 ), respectively, it may be concluded that a defect exists in at least one component of the optical arrangement  10 . Control then proceeds to step  164  and the cylindrical lens  26  is displaced along the X-axis. As explained above, the optical arrangement  10  is insensitive to misalignment of the cylindrical lens  26  and the optical fibers  14  in the X-axis. However, if the cylindrical lens  26  itself is dirty, or has another optical defect, displacement of the cylindrical lens  26  on the X-axis results in a corresponding horizontal translation of the irregular areas on the display monitor  36 . 
     At decision step  166 , a determination is made whether the irregularities noted at decision step  158  have changed in position. If so, then at step  168  it is concluded that the cylindrical lens  26  is defective and procedure proceeds to final step  162 . 
     However, if at decision step  166 , it is determined that the irregularities noted at decision step  158  have not changed in position, then at step  170  it is concluded that the beam  16  emitted from the fiber is distorted and that at least one of the optical fibers  14  is distorted or otherwise defective The procedure terminates at step  162 . 
     Additionally or alternatively, computer implemented pattern recognition methods known to the art may be applied in step  146  to evaluate the image presented on the display monitor  36  to produce quantitative data. In this case, the decision step  158  is performed utilizing the quantitative measurements obtained in step  146 . 
     It will be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove. Rather the scope of the present invention includes both combinations and subcombinations of the features described hereinabove as well as modifications and variations thereof which would occur to a person of skill in the art upon reading the foregoing description and which are not in the prior art.