Abstract:
A beam reformatter to receive and split a beam into a plurality of beam portions, and further distribute and propagate two or more of the plurality of beam portions in substantially the same direction to create a reformatted composite beam, wherein the plurality of beam portions each contain the same spatial and spectral information as the received beam. An optical slicer to receive and configure a beam for generating an output spot from the configured beam, comprising: a beam reformatter to receive and split a beam into a plurality of beam portions, and further distribute and propagate two or more of the plurality of beam portions in substantially the same direction to create a reformatted composite beam; and at least one of a beam compressor and a beam expander wherein the plurality of beam portions each contain the same spatial and spectral information as the received beam; and the output spot has different dimensions relative to a spot produced in the same manner from the beam received by the optical slicer.

Description:
RELATED APPLICATIONS 
     This application is a continuation of application Ser. No. 12/896,604, filed Oct. 1, 2010, which claims priority from U.S. Provisional Application No. 61/247,762 filed Oct. 1, 2009 and U.S. Provisional Application No. 61/350,264 filed Jun. 1, 2010, and the contents of each foregoing application are herein incorporated by reference. 
    
    
     FIELD OF INVENTION 
     This invention relates to the field of spectroscopy and more specifically relates to improved apparatus and methods for improving spectral resolution. 
     BACKGROUND 
     A typical optical spectrograph includes a small input aperture, typically a slit, however, can alternatively be a circular pinhole or an optical fiber; however, for the sake of brevity, will hereinafter be referred to as a slit. A converging cone of light, is projected towards the slit and a portion of the light passes through the slit. In a typical optical spectrograph, this slit of light is projected onto a lens which collimates the slit of light to form a beam of parallel light rays. In a typical optical spectrograph, a dispersive element, such as, a prism, a transmission grating, or reflection grating, bends the collimated beams by differing amounts, depending on the wavelength of the light. Typically, a camera lens brings these bent collimated beams into focus onto an array detector, such as, a charged-coupled device (CCD) detector located at the final focal plane, and which may record the light intensities of the various wavelengths. 
     In a typical optical spectrograph, the collimating lens and the camera lens act as an image relay, to create images of the light passing through the slit on the detector, such as a CCD detector, which may be displaced laterally depending on the wavelength of the light. The resolution of an optical spectrograph, i.e., its ability to detect and measure narrow spectral features such as absorption or emission lines, can be dependent upon various characteristics. Such characteristics may include the dispersing element, such as, the prism, transmission grating, or reflection grating; the focal length of the camera lens; and the width of the slit. For a particular disperser and camera lens, the resolution of the spectrograph can be increased by narrowing the width of the input slit, which causes each image of the light passing through the slit (depending on the wavelength of the light) and onto a detector, subtending a smaller section of the detector, allowing adjacent spectral elements to be more easily distinguished from each other. 
     By narrowing the width of the input slit, less light passes therethrough, which can reduce the quality of any measurements due to a reduction in the signal-to-noise ratio. In some applications, such as astronomical spectroscopy, high-speed biomedical spectroscopy, high-resolution spectroscopy, or Raman spectroscopy, this loss of efficiency can be a limiting factor in the performance of the optical spectrograph. A device which increases the amount of light that can pass through the slit by horizontally compressing and vertically expanding a spot image of an input beam of light, producing a slit, while substantially maintaining light intensity or flux density, would be advantageous in the field of optical spectrography. 
     A person of skill will understand that the terms horizontal, vertical and other such terms used throughout this description, such as, above and below, are used for the sake of explaining various embodiments of the invention, and that such terms are not intended to be limiting of the present invention. 
     Optical slicers can be useful to receive an input beam and produce output beams for generating slits. The use of transparent prisms and plates to slice an input beam can produce a slit that is tilted along the optical axis, and additionally the slicing of an optical beam can occur along the hypotenuse of a 45° prism, which can result in focal point degradation due to different sections of the sliced image being located at different focal positions. The performance of such slicers can depend on the absorption coefficient and index of refraction of the prism used (both wavelength dependent). These deficiencies can limit the use of such slicers as broadband devices. 
     Other slicers, such as pupil slicers, possess drawbacks such as the inability to obtain high-resolution spectral information from different portions of an image. Additionally, such slicers can be large in size, and can result in reduced or inefficient implementation with a variety of systems. Current slicers that employ a glass-based design tend to use a Lagrange-constant transformer to bring light from a Raman optical source to an optical spectrometer. The transformer involves eight different cylindrical and spherical lenses, as well as two stacks of ten precisely positioned cylindrical lenses. The resulting device can have a length of more than 58 inches along the main optical axis, a size at which it tends to be both difficult to maintain alignment, and difficult to maneuver or employ in any setting outside of a tightly-controlled laboratory. 
     In some pupil slicers, two slit images can be generated on different portions of a CCD detector. This implementation can present the disadvantage that the slit images are spaced on the detector with gaps in between, which can add noise to the signal, decreasing the quality of the output data. Additionally, in such slicers, the gaps can waste valuable detector area, limiting the number of spectra (or spectral orders) that can be fit upon the detector. Further, when using such slicers, the detector readout may not be optimal due to the spectrum being spread over the detector area. 
     Slicers using optical fiber bundles to allow the extended (often round) image of an input source to be formed into a narrow slit can cause the degradation of the output ratio to be large and the total performance to be inefficient. Existing slicer devices uniformly suffer this decreased efficiency and output ratio, representing a clearly-defined objective of slicer design and implementation. 
     SUMMARY OF THE INVENTION 
     In an aspect of the present invention there is provided an optical slicer for generating an output spot comprising an image compressor which receives a substantially collimated input beam and compresses the beam, wherein the input beam, if passed through a focusing lens, produces an input spot; an image reformatter which receives the compressed beam to reformat the beam into a plurality of sliced portions of the compressed beam and vertically stacks the portions substantially parallel to each other; and an image expander which expands the reformatted beam to produce a collimated output beam which, if passed through the focusing lens, produces an output spot that is expanded in a first dimension, and compressed in a second dimension, relative to the input spot. 
     In some embodiments of the present invention, the compressed beam may be compressed vertically and be substantially similar horizontally relative to the input beam and the output beam may be expanded horizontally relative to the reformatted beam and may have substantially similar dimensions to the input beam. 
     In other embodiments, the optical slicer may have a slicing factor, n. The number of sliced portions of the compressed beam may be equal to n and the output beam may be expanded vertically by the factor n and compressed horizontally by the factor n, relative to the input spot. 
     In preferred embodiments n is a whole number from 2 to 64, more preferably from 2 to 32. Most preferably the value of n is 2, 4, 8, 16 or 32. 
     The compressor may have a convex lens and a concave lens, wherein the convex lens may receive the input beam and may produce a converging beam, and the compressed beam may be formed by the converging beam passing through the collimating lens. In alternative embodiments, the image compressor may have a concave reflective surface and a convex reflective surface and the concave reflective surface may receive the input beam and may produce a converging beam, and the compressed beam may be formed by the converging beam reflecting off the concave reflective surface. 
     The image reformatter may have at least two reflective surfaces, where one of the reflective surfaces may receive a portion of the compressed beam and may reflect the portion for at least one reflection back and forth between the at least two reflective surfaces, wherein each of the sliced portions may be formed by a second portion of compressed beam passing by the at least two reflective surfaces after each of the at least one reflection. 
     The image expander may comprise a concave lens and a convex lens, wherein the concave lens may receive the reformatted beam and may produce a diverging beam and the output beam may be produced by the diverging beam passing through the convex lens. In alternative embodiments, the image expander may comprise a convex reflective surface and a concave reflective surface, wherein the convex reflective surface may receive the reformatted beam and may produce a diverging beam and the output beam may be formed by the diverging beam reflecting off the concave reflective surface. 
     In some embodiments of the present invention, the output spot may have a light intensity value that is substantially the same as the light intensity of the input spot. 
     In another aspect of the present invention there is provided a method of generating an output spot comprising the steps of compressing a collimated input beam, wherein the input beam, if passed through a focusing lens, produces an input spot; reformatting the compressed beam into a plurality of sliced portions substantially vertically stacked and substantially parallel to each other; and expanding the reformatted beam to produce a collimated output beam which, when passed through a focusing lens, produces the output spot that is expanded in a first dimension, and compressed in a second dimension, relative to the input spot. 
     In some embodiments, the compressed beam may be compressed vertically and may be substantially similar horizontally relative to the input beam and the output beam may be expanded horizontally relative to the reformatted beam and may have substantially similar dimensions to the input beam. 
     In some embodiments, the number of sliced portions may be equal to a slicing factor, n, and the output spot may be expanded vertically by the factor n and compressed horizontally by the factor n, relative to the input spot. 
     In a further aspect of the present invention, an optical slicer having a slicing factor, n, is presented, the optical slicer comprising an image compressor which receives a substantially collimated input beam and compresses the beam, wherein the collimated beam, if passed through a focusing lens, produces an input spot; an image reformatter which receives the compressed beam to reformat the beam into n sliced portions of the compressed beam and vertically stacks the portions substantially parallel to each other; and an image expander which expands the reformatted beam to produce a collimated beam which, when passed through the focusing lens, produces an output spot compressed by the factor n in a first dimension relative to the input spot and expanded by the factor n in a second dimension relative to the input spot. 
     In another aspect of the present invention a multiplicative optical slicer comprising a first optical slicer having a first slicing factor, m, and a second optical slicer having a second slicing factor, n, the first and second optical slicers being placed in series, and the multiplicative optical slicer having a slicing factor of m×n. 
     In another aspect of the present invention, there is provided a beam reformatter comprising optical elements configured to receive a beam and to split the beam into a plurality of beam portions, the optical elements being further configured to distribute and propagate two or more of the plurality of beam portions in substantially the same direction to create a reformatted composite beam, wherein the plurality of beam portions each contain the same spatial and spectral information as the received beam. In some embodiments, the optical elements may comprise one or more pairs of reflective surfaces. In still further embodiments, the optical elements may be configured so that at least one of the plurality of beam portions pass by the one or more pairs of reflective surfaces without reflection. 
     In other aspects of the present invention, an optical slicer is disclosed that receives a beam and configures the beam for generating an output spot from the configured beam, comprising: a beam reformatter comprising optical elements to receive a beam and to split the beam into a plurality of beam portions, the optical elements further configured to distribute and propagate two or more of the plurality of beam portions in substantially the same direction to create a reformatted composite beam; and at least one of a beam compressor comprising optical elements configured to receive the beam and compress the beam, and a beam expander comprising optical elements configured to receive the beam and expand the beam, wherein the plurality of beam portions each contain the same spatial and spectral information as the received beam; and wherein the output spot has different dimensions relative to a spot produced in the same manner from the beam received by the optical slicer. 
     In some embodiments, the at least one of a beam compressor and a beam expander may comprise a beam expander, the beam expander receiving the reformatted beam from the beam reformatter and expanding the beam to produce the configured beam for producing the output spot with different dimensions relative to a spot produced in the same manner from the beam received by the optical slicer. In other embodiments, the at least one of a beam compressor and a beam expander can tend to comprise both a beam compressor and a beam expander, the beam compressor receiving the beam and compressing the beam and passing the compressed beam to the beam reformatter, and the beam expander receiving the reformatted beam from the beam reformatter and expanding the beam to produce the configured beam for producing the output spot that is expanded in a first dimension and compressed in a second dimension relative to a spot produced in the same manner from the beam received by the optical slicer. 
     In further embodiments, the optical elements of the beam reformatter may comprise at least one pair of reflective surfaces. In further embodiments, the optical elements may comprise at least one of a segmented mirror, a flat non-mirror surface coated with a reflective substance, a refractive element, a prism, a Fresnel lens, a toroidal mirror or lens, a cylindrical minor or lens, and a diffraction grating. 
     In some embodiments, the configured beam can tend to have substantially dissimilar dimensions relative to the beam received by the optical slicer, while in other embodiments the configured beam can tend to have substantially similar dimensions relative to the beam received by the optical slicer. In other embodiments, the configured beam is expanded in a first dimension and compressed in a second dimension relative to the beam received by the optical slicer. 
     In some embodiments, the beam compressor comprises a convex lens and a concave lens, wherein the convex lens receives the beam and produces a converging beam and the beam is compressed by the converging beam passing through the concave lens. In other embodiments, the beam compressor comprises a concave reflective surface and a convex reflective surface, wherein the concave reflective surface receives the beam and produces a converging beam and the beam is compressed by the converging beam reflecting off the convex reflective surface. 
     In still further embodiments of the optical slicer, the optical elements are configured to alter the dimensions of the beam differently along a first dimension relative to a second dimension. In still further embodiments, the optical elements have different focal lengths along different axes of the same optical element. 
     In some embodiments, the beam expander comprises a concave lens and a convex lens, wherein the concave lens receives the beam and produces a diverging beam and the expanded beam is produced by the diverging beam passing through the convex lens. In other embodiments, the beam expander comprises a convex reflective surface and a concave reflective surface, wherein the convex reflective surface receives the beam and produces a diverging beam and the expanded beam is formed by the diverging beam reflecting off the concave reflective surface. 
     In some embodiments, the beam compressor and beam expander compresses or expands, respectively, the beam along only one axis of the beam. In additional embodiments, the configured beam has a light intensity substantially the same as the light intensity of the beam received by the optical slicer. 
     In some embodiments, the beam received by the optical slicer or the configured beam is at least one of a collimated, diverging or converging beam. 
     In some embodiments, the slicer is positioned upstream of the optical input slit of a spectrometer to direct the output spot therethrough. 
     In other aspects of the present invention there is provided a method of configuring a beam for generating an output spot from the configured beam, comprising: receiving a beam and splitting the beam into a plurality of beam portions; distributing and propagating two or more of the plurality of beam portions in substantially the same direction to create a reformatted composite beam; and at least one of compressing the beam and expanding the beam, wherein the plurality of beam portions each contain the same spatial and spectral information as the received beam, and the output spot produced from the configured beam has different dimensions relative to a spot produced in the same manner from the beam prior to configuration. 
     In some embodiments of the method, the configured beam has substantially dissimilar dimensions relative to the beam prior to configuration. 
     In another aspect of the present invention there is provided a method of reformatting a beam received at a beam reformatter, comprising splitting the beam into a plurality of beam portions, and distributing and propagating two or more of the plurality of beam portions in substantially the same direction to create a reformatted composite beam, wherein the plurality of beam portions each contain the same spatial and spectral information as the received beam. 
     In some embodiments of the method, optical elements are used to distribute and reposition the beam, and at least one of the plurality of beam portions passes by the optical elements. 
    
    
     
       BRIEF DESCRIPTION OF FIGURES 
       For a better understanding of embodiments of the system and methods described herein, and to show more clearly how they may be carried into effect, reference will be made by way of example, to the accompanying drawings in which: 
         FIG. 1A  shows a block diagram representation of an optical slicer having a slicing factor of two; 
         FIG. 1B  shows a block diagram representation of an optical slicer having a slicing factor of four; 
         FIG. 2  shows an isometric view of an embodiment of an optical slicer having a slicing factor of two; 
         FIG. 3  shows an isometric view of an alternative embodiment of an optical slicer having a slicing factor of two; 
         FIG. 4  shows an isometric view of an embodiment of an optical slicer having a slicing factor of four; 
         FIG. 5A  shows an isometric view of an alternative embodiment of an optical slicer having a slicing factor of four; 
         FIGS. 5B-5G  shows isometric and plan views of embodiments of optical elements of the optical slicer of  FIG. 5A ; 
         FIGS. 5H-5I  shows an isometric view of an embodiment of a housing cover for the optical slicer shown in  FIG. 5A ; 
         FIGS. 6A-6D  show representations of alternative embodiments of compressors for use in an embodiment of an optical slicer; and 
         FIGS. 7A-7C  show representations of alternative embodiments of reformatters having a slicing factor of four for use in an embodiment of an optical slicer. 
     
    
    
     DETAILED DESCRIPTION 
     It will be appreciated that for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements or steps. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the embodiments described herein. Furthermore, this description is not to be considered as limiting the scope of the embodiments described herein in any way, but rather as merely describing the implementation of the various embodiments described herein. 
     With reference to  FIG. 1A , a representation of optical slicer  100  is shown, optical slicer including image compressor  170 , image reformatter  172  and image expander  174 . Optical slicer  100  receives input beam  102 , as a collimated beam, which can be produced, for example by a collimating lens or a curved mirror. Input beam  102  also generates input spot  180  when focused by a focusing lens having substantially the same focal length as the collimating lens or curved minor used to produce input beam  102 . 
     Image compressor  170  of optical slicer  100  receives input beam  102  and outputs vertically compressed beam  114 , anamorphically compressed in the vertical dimension, and having a smaller vertical dimension than and a greater horizontal dimension than that of input beam  102 . Additionally, vertically compressed beam  114 , if passed through a focusing lens with the same focal length as the collimating lens or curved mirror used to produce input beam  102  produces compressor spot  182 , resulting in the focusing of compressed beam  114  to project an image that is substantially similar in the horizontal dimension as compared to input spot  180 , while being expanded in the vertical dimension. 
     In some embodiments, the image projected by vertically compressed beam  114  may have the same horizontal width as input beam  102 ; however, the vertical height of vertically compressed light  114  may be compressed by the slicing factor. The term “slicing factor” is used to describe the value of the horizontal compression and vertical expansion of the output spot generated by the output beam of an optical slicer as compared to the horizontal and vertical dimensions of the input spot generated by the input beam into the optical slicer, the output and input spots being generated when the output and input beams are each respectively focused by the same focusing lens. 
     For example, for an optical slicer with a slicing factor of two, such as the optical slicer represented in  FIG. 1A , the output slicer produces output beam  156 , which, if focused through a focusing lens having a focal length substantially equal to the focal length of the collimating lens or convex minor that generated input beam  102 , causes the generation of output spot  186 . Focusing input beam  102  through the same focusing lens will tend to generate input spot  180 . Output spot  186  having a vertical dimension that is twice that of input spot  180  and a horizontal dimension that is half that of input spot  180 . Thus, the slicing factor of the optical slicer produced by this configuration is two. 
     In alternative embodiments, such as the representation of optical slicer  100  shown in  FIG. 1B , output spot  186  can similarly be generated by focusing output beam  156  through a focusing lens having a focal length substantially equal to the focal length of the collimating lens or convex minor that generated input beam  102 . Focusing input beam  102  through the same focusing lens generates input spot  180 . In this embodiment, output spot  186  has a vertical dimension that is four times that of input spot  180  and has a horizontal dimension that is ¼ that of input spot  180 , thus, the slicing factor of optical slicer  100  represented in  FIG. 1B  is four. 
     Other values of the slicing factor n are possible. The output spot generated by the output beam in a substantially similar manner as discussed above, may have a vertical dimension that is n times larger than the vertical dimension of the input spot generated by the input beam and may tend to have a horizontal dimension that is 1/n of the horizontal dimension of the input spot. 
     Referring back to  FIG. 1A , vertically compressed beam  114  is received by image reformatter  172  which outputs reformatted beams  136  and  138 ; such reformatted formatted beams  136  and  138  being substantially vertically stacked and substantially parallel. Reformatted beams  136  and  138  are sliced portions of vertically compressed beam  114 . In the embodiment shown, image reformatter  172  outputs two beam slices, which, in this embodiment, is equal to the slicing factor of optical slicer  100 ; however, in some embodiments, image reformatter  172  may produce a number of slices that is greater than or less than the slicing factor of optical slicer  100 . 
     Each of reformatted beams  136  and  138 , if passed through a focusing lens having the same focal length as the collimating lens or curved minor used to produce input beam  102 , produces reformatter spot  184 . Reformatter spot  184  is substantially the same dimension both horizontally and vertically, as compressor spot  182 . Since reformatted beams  136  and  138  are substantially vertically stacked and substantially parallel, the individual reformatter spots generated by each of reformatted beams  136  and  138 , combined to form reformatter spot  184 , are projected atop one another, so as to double the light intensity of reformatter spot  184  as compared to the individual reformatter spots generated from each of beams  136  and  138  individually. 
     While the light intensity of reformatter spot  184  in the embodiment shown in  FIG. 1A  is double, as compared to the light intensity of each individual reformatter spot generated by each reformatted beam, in other embodiments, the light intensity of reformatter spot  184 , as compared to the light intensity of each individual reformatter spot generated by each reformatted beam, corresponds to the number of sliced portions generated by image reformatter  174 . For example, with reference to  FIG. 1B , optical slicer  100  is shown having image reformatter  172  that produces reformatted beams  136 A,  136 B,  138 A and  138 B, each of the reformatted beams being substantially parallel and substantially vertically stacked. Reformatted beams  136 A,  136 B,  138 A and  138 B are sliced portions of vertically compressed beam  114 . Reformatter spot  184 , generated by reformatted beams  136 A,  136 B,  138 A and  138 B in a substantially similar manner as discussed above, has about four times the light intensity of each individual reformatter spot generated from each reformatted beam  136 A,  136 B,  138 A and  138 B. 
     With reference back to  FIG. 1A , reformatted beams  136  and  138  are received by image expander  174  which expands reformatted beams  136  and  138  by a factor of the slicing factor. In the embodiment shown, the reformatted beams  136  and  138  are expanded by a factor of two, in both the horizontal and vertical directions (non-anamorphically), to produce output beam  156 , output beam  156  which is made up of sliced beams  158  and  160 . Sliced beams  158  and  160  are expansions of reformatted beams  136  and  138 . Output beam  156  has substantially similar dimensions to that of input beam  102 . Projecting output beam  156  onto a lens, such lens having substantially the same focal length as the collimating lens or curved mirror used to produce input beam  102 , focuses output beam  156  to produce output spot  186 . Output spot  186  produces an image of input spot  180  that can be compressed in the horizontal direction by the slicing factor and stretched in the vertical direction by the slicing factor while maintaining a similar light intensity as input spot  180 . In embodiments, such as the embodiment represented in  FIG. 1A , output spot  186  can be two times larger in the vertical direction as input spot  180  and can be compressed by two times in the horizontal direction as input spot  180 . 
     In other embodiments, such as the embodiment shown in  FIG. 1B , reformatted beams  136 A,  136 B,  138 A and  138 B are received by image expander  174 , which may be an anamorphic horizontal beam expander, to produce output beam  156 , made up of output slices  158 A,  158 B,  160 A and  160 B, which are expansions of reformatted beams  136 A,  136 B,  138 A and  138 B, expanded in the horizontal direction. In some embodiments, output beam  156  has similar dimensions as input beam  102 . With respect to the embodiment represented by  FIG. 1B , representing an optical slicer having a slicing factor of four, when output beam  156  is projected onto a lens having substantially the same focal length as the collimating lens or curved minor used to produce input beam  102 , output beam  156  is focused to produce output spot  186 . Output spot  186  can be four times larger in the vertical direction as input spot  180  and can be compressed by four times in the horizontal direction as input spot  180 , while maintaining a similar light intensity as input spot  180 . 
     It will be understood by those skilled in the art that the resulting output beam  156  of optical slicer  100 , where optical slicer  100  has a slicing factor of n, when focused by a focusing lens having substantially the same focal length as the collimating lens or curved minor used to produce input beam  102 , produces an output spot that is n times larger in the vertical direction and compressed by n times in the horizontal direction, as compared to the input spot generated by input beam  102  passing through the same focusing lens, while maintaining a similar light intensity as the input spot. 
     With reference to  FIG. 2 , optical slicer  100  is shown, including image compressor  170 , image reformatter  172  and image expander  174 . In  FIG. 2 , optical slicer  100  has a slicing factor of two. Input beam  102  can be a substantially collimated beam, which can be produced by a collimating lens or a curved minor. Input beam  102  generating an input spot when focused by a focusing lens having the same focal length as the collimating lens or curved minor used to produce input beam  102 . 
     Input beam  102  is received by image compressor  170  which outputs vertically compressed beam  114 . Image compressor  170  has convex cylindrical lens  104  which receives input beam  102  and outputs vertically converging beam  108 . Vertically converging beam  108  is received by concave cylindrical lens  110  which collimates vertically converging beam  108  and outputs vertically compressed beam  114 . In other embodiments, a pairing of multiple convex lenses can output vertically compressed beam  114 . In such alternative embodiments lens  104  can be a convex lens and lens  108  can be a convex lens. 
     Additionally, vertically compressed beam  114 , if passed through a focusing lens with the same focal length as the collimating lens or curved mirror used to product input beam  102  produces a compressor spot having a substantially similar dimension in the horizontal direction and expanded in the vertical direction by a factor of the slicing factor as compared to the input spot generated by passing input beam  102  through the same focusing lens. In the embodiment shown, the slicing factor is two, when compared to the input spot generated by input beam  102  using the same focusing lens. 
     With reference to  FIGS. 6A-6D , alternative embodiments of image compressor  170  are shown. Referring to  FIG. 6A , image compressor  170  has cylindrical lens  602  which receives compressor input beam  600  and focuses compressor input beam  600  for subsequent projection onto collimating cylindrical lens  604  to produce an output beam that is compressed relative to compressor input beam  600 . In the embodiment shown in  FIG. 6A , collimating cylindrical lens  604  is positioned beyond the focal point of cylindrical lens  602 , collimating cylindrical lens  604  outputting an inverted image of compressor input beam  600  that is compressed vertically. 
     With reference to  FIG. 6B , image compressor  170  has an optical element  612  having first surface  614  which focuses compressor input beam  600  in the vertical direction and second surface  616  which substantially collimates the focused beam produced by first surface  614 . The beam output from optical element  612  produces an output beam compressed vertically when compared with compressor input  600 . 
     With reference to  FIG. 6C , image compressor  170  has anamorphic prisms  622  and  624 , oriented such that compressor input beam  600  is refracted at the output face of each of anamorphic prisms  622  and  624 . The resulting output beam of image compressor  170  in this embodiment produces an output beam compressed vertically when compared with compressor input beam  600 . 
     With reference to  FIG. 6D , image compressor  170  has mirrors  632  and  634 , compressor input beam  600  reflecting off concave surface of mirror  634  and projecting onto convex surface of minor  632 , to produce an output beam compressed vertically when compared with compressor input beam  600 . 
     Skilled persons will understand that obvious variants of the compressors described herein, and obvious orientations of such compressors elements may be implemented to produce a beam that is compressed vertically as compared to compressor input beam  600 . 
     With reference back to  FIG. 2 , vertically compressed beam  114  is received by image reformatter  172  which outputs reformatted beams  136  and  138 , such reformatted beams  136  and  138  being substantially parallel and substantially vertically stacked. Image reformatter  172  includes side-by-side flat mirrors  116  and  118  and vertically stacked flat mirrors  128  and  130 . 
     Side-by-side flat minors  116  and  118  can receive vertically compressed beam  114 , a portion of vertically compressed beam  114  being received by side-by-side flat mirror  116  and another portion of vertically compressed beam  114  being received by side-by-side flat mirror  118 , which slices vertically compressed beam  114  producing sliced beams  124  and  126 . Sliced beams  124  and  126  are reflected from side-by-side flat minors  116  and  118  onto vertically stacked minors  128  and  130 , sliced beam  124  being reflected onto vertically stacked mirror  128  and sliced beam  126  being reflected onto vertically stacked mirror  130 . 
     Sliced beams  124  and  126  are reflected off vertically stacked mirrors  128  and  130  to produce reformatted beams  136  and  138 . Reformatted beams  136  and  138  are similar to sliced beams  124  and  126  but are substantially vertically stacked and substantially parallel. In some embodiments, vertically stacked minors  128  and  130  are D-shaped minors and can be optically flat and fully aluminized, or mirrorized, to within 50 μm of their adjacent edges; however, a skilled person will understand that other reflective properties may achieve substantially similar results. 
     If reformatted beams  136  and  138  are passed through a focusing lens with the same focal length as the collimating lens or curved minor used to produce input beam  102 , a reformatter spot is produced. In the embodiment shown, this reformatter spot has the same horizontal dimension and a vertical dimension which is four times that of the input spot formed by passing input beam  102  through the same focusing lens, while maintaining a similar light intensity as the input spot. 
     With reference to  FIGS. 7A-7C , alternative embodiments of image reformatter  172  are shown. Referring to  FIG. 7A , image reformatter  172  has multiple pairs of mirrors each to receive a portion of reformatter input beam  700  and each positioned to produce a portion of reformatted beam  720 , reformatted beam  720  being made up of beam portions  720 A,  720 B,  720 C and  720 D, each beam portion being substantially parallel and substantially vertically stacked and being a sliced portion in reformatter input beam  700 . Minor pairs  702  and  712  can receive a first portion of reformatter input beam  700 , the first portion reflecting off minor  702  and received by mirror  712 , mirror  712  being aligned to produce beam portion  720 D. Mirror pairs  704  and  714  receive a second portion of reformatter input beam  700 , the second portion reflecting off mirror  704  and received by minor  714 , minor  714  being aligned to produce beam portion  720 C. Mirror pairs  706  and  716  receive a third portion of reformatter input beam  700 , the third portion reflecting off minor  706  and received by mirror  716 , minor  716  being aligned to produce beam portion  720 B. Minor pairs  708  and  718  receive a fourth portion of reformatter input beam  700 , the fourth portion reflecting off mirror  708  and received by mirror  718 , minor  718  being aligned to produce beam portion  720 A. A skilled person will appreciate that the addition of additional minor pairs can increase the number of beam portions of reformatted beam  720 . 
     Referring to  FIG. 7B , image reformatter  172  includes reflective surfaces  730  and  732 . When in use, reformatter input  700  is received by reflective surface  730  and can be reflected back and forth between reflective surface  732 , a portion of the reflected beam being reflected off reflective surface  732  and passing by reflective surface  730  to produce a beam portion of output beam  720  until each of beam portions  720 A,  720 B,  720 C and  720 D are generated, each beam portion being substantially parallel and substantially vertically stacked relative to one another and each being a sliced portion of reformatter input  700 . A skilled person will appreciate that additional beam portions may be generated by adjusting the position of reflective surfaces  730  and  732  to produce additional reflections back and forth between reflective surfaces  730  and  732 , each of the reflections continuing to provide for a portion of the reflected beam to pass by reflective surface  730  to form a beam portion of output beam  730 . 
     Referring to  FIG. 7C , image reformatter  172  may be comprised of two stages, a first stage being comprised of reflective surfaces  740  and  742  and a second stage being comprised of reflective surfaces  744  and  746 . A portion of reformatter input  700  passing by reflective surface  740 , producing beam portion  750 B of first output beam  750 , and a second portion of input beam may be reflected off reflective surface  740  onto reflective surface  742  to form beam portion  750 A of first output beam  750  which tends to pass by reflective surface  740 . Each of beam portions  750 A and  750 B being substantially parallel and substantially vertically stacked. Beam  750  may then partially be received by reflective surface  744 , a portion of beam  750  passing by reflective surface  744  to produce output beams  720 C and  720 D, the remaining portion of beam  750  being reflected off reflective surface  744  onto reflective surface  746 . The reflection of the beam portion off reflective surface  746  producing output beam portions  720 A and  720 B of output beam  720 , which can pass by reflective surface  744 . Beam portions  720 A,  720 B,  720 C and  720 D being substantially vertically stacked and substantially parallel and being sliced portions of reformatter input  700 . A skilled person will appreciate that by adding additional stages, output beam can be made up of additional beam portions. For example, adding an additional stage may produce eight beam portions, and a further stage producing sixteen beam portions. 
     Referring back to  FIG. 2 , reformatted beams  136  and  138  are received by image expander  174  producing output beam  156 , output beam  156  being made up of sliced beams  158  and  160 . Image expander  174  has concave lens  142  which can receive reformatted beams  136  and  138 , and can uniformly expand reformatted beams  136  and  138  producing expanding beam  146 . Image expander  174  can additionally have collimating lens  148  which receives expanding beam  146  and substantially collimates expanding beam  146 , producing output beam  156 . In some embodiments, concave lens  142  and collimating lens  148  may be cylindrical lenses which can expand reformatted beams  136  and  138  horizontally, while maintaining their vertical dimension. 
     Passing output beam  156  through a focusing lens having substantially the same focal length as the collimating lens or curved mirror used to produce input beam  102 , focuses output beam  156  to produce an output spot. This output spot can project an image of the input spot generated by passing input beam  102  through the same focusing lens, the output spot being compressed in the horizontal direction by the slicing factor and expanded in the vertical direction by the slicing factor, while maintaining a light intensity that is similar to the light intensity of the input spot generated by input beam  102  passing through the same focusing lens. In the embodiment of optical slicer  100  shown in  FIG. 2 , the output spot generated by output beam  156  is two times larger in the vertical direction and compressed by two times in the horizontal direction, compared to the input spot generated by passing input beam  102  through the same focusing lens. 
     With reference to  FIGS. 6A-6D , a skilled person would appreciate that the various alternative embodiments of the compressor shown in  FIGS. 6A-6D  can be used as expanders as well, if such embodiments are implemented with the light beams being projected in the opposite direction as the light beams shown in  FIGS. 6A-6D . Additionally, skilled persons will appreciate that other apparatus comprising of optical elements can be implemented and positioned appropriately to produce expanded beam  156 . 
     With reference to  FIG. 3 , an embodiment of optical slicer  100  is shown. Optical slicer  100  having image compressor  170 , image reformatter  172  and image expander  174 . In the embodiment shown in  FIG. 3 , optical slicer has a slicing factor of two. Image compressor  170 , having converging lens  302 , reflective surfaces  304  and  306  and collimating lens  310 , receives an input beam at converging lens  302 , producing a converging beam, being received and reflected by reflective surface  304  to reflective surface  306 . The converging beam reflecting off reflective surface  306  where it passes through collimating lens  310 , substantially collimating the beam, and directing the collimated beam to image reformatter  172   
     Image reformatter has reflective surfaces  312  and  316 , each of reflective surfaces  312  and  316  being connected to mounting brackets  314  and  318  respectively, for securement to housing  320  of optical slicer  100 . Reflective surfaces  312  and  316  can be D-shaped minors and reflective surface  312  can be oriented vertically, with the flat edge being the closest edge to the reformatted beam output by reformatter and reflective surface  316  oriented with the curved edge facing downwards. 
     The compressed beam output from compressor  170  passes by reflective surface  312  and a portion of the compressed beam passes by reflective surface  316 , the remaining portion of the compressed beam reflecting off reflective surface  312  back towards reflective surface  316 . This first beam portion of the compressed beam passing by both reflective surfaces forming a first portion of the reformatted beam output by image reformatter  172 . The remaining portion of the compressed beam reflecting back towards reflective surface  316 , and reflecting back and forth between reflective surfaces  316  and  312  each time a portion of the reflected compressed beam passing by reflective surface  312  forming a subsequent beam portion of reformatted beam. The portions of reformatted beam being substantially vertically stacked and substantially parallel, and each representing a sliced portion of the compressed beam. 
     Image reformatter  172  in the embodiment shown in  FIG. 3  forming a reformatted beam made up of two beam portions, the two portions substantially parallel and substantially vertically stacked and each representing a portion of the compressed beam output from image compressor  170 . A first portion of the compressed beam reflecting off reflective surface  312  and back towards reflective surface  316 , this portion subsequently being reflected off reflective surface  316  and passing by reflective surface  316 , resulting in the reformatted beam having two portions. Skilled persons will understand that an increase in the number of back and forth reflections between reflective surfaces  316  and  312  can increased the number of portions of the reformatted beam. 
     Image expander  174 , in the embodiment shown in  FIG. 3 , receives the reformatted beam from image reformatter  172  and produces an expanded collimated output beam, the expanded collimated output beam being of similar dimensions as the input beam directed into optical slicer  100 . Image expander  174 , in the embodiment shown in  FIG. 3 , can be comprised of appropriate lenses and/or mirrors, to expand and collimate reformatted beam appropriately. 
     The resulting output beam, when passed through a focusing lens having substantially the same focal length as the collimating lens or curved minor that generated the collimated input beam, focuses the output beam to produce an output spot. This output spot producing an image of the input spot that would be generated if the input beam were passed through the same focusing lens being compressed in the horizontal direction by the slicing factor of optical slicer  100  and expanded in the vertical direction by the slicing factor of optical slicer  100 , while maintaining a similar light intensity as the input spot generated by the input beam when passed through the same focusing lens. The output spot generated by the output beam of optical slicer  100  shown in  FIG. 3  being two times compressed in the horizontal direction and expanded by two times in the vertical direction, optical slicer  100  shown in  FIG. 3  being an optical slicer having a slicing factor of two. 
     With reference to  FIG. 4 , optical slicer  100  is shown having image compressor  170 , image reformatter  172  and image expander  174 . In the embodiment shown in  FIG. 4 , optical slicer  100  has a slicing factor of four. Input beam  102  can be substantially collimated, which can be produced by a collimating lens or a curved mirror. 
     Input beam  102  is received by image compressor  170  can output compressed beam  452 . Image compressor  170  having cylindrical concave mirror  402  which reflects input beam  102  to generate vertically converging beam  450 . 
     With additional reference to  FIGS. 5A and 5B , cylindrical concave minor  402  can be mounted to mounting bracket  502  for securement to base plate  480  of optical slicer  100 . In some embodiments, cylindrical concave minor  402  may have a focal length of 103.360 mm and can be positioned at a 7.3 degree tilt horizontally and a 0.0 degree tilt vertically relative to the path of the incoming beam; however skilled persons will understand that other focal lengths and positioning can be used to produce vertically converging beam  450 . 
     Vertically converging beam  450  may be received by cylindrical convex mirror  404  which collimates vertically converging beam  450  outputting compressed beam  452 . With additional reference to  FIGS. 5A and 5C , cylindrical convex mirror  404  can be mounted to mounting bracket  504  for securement to base plate  480  of optical slicer  100 . In some embodiments, cylindrical convex mirror  404  can have a focal length of −25.84 mm and may be positioned at a 7.3 degree tilt horizontally and a 0.0 degree tilt vertically relative to the path of the incoming beam; however, skilled persons will understand that other focal lengths and positioning can be used to produce compressed beam  452 . 
     In some embodiments, compressed beam  452 , if passed through a focusing lens with the same focal length as the collimating lens or curved mirror used to produce input beam  102 , produces a compressor spot that is expanded in the vertical direction by the slicing factor and having a similar horizontal dimension when compared to the input spot generated by passing input source  102  through the same focusing lens. 
     With reference back to  FIG. 4 , compressed beam  452  is received by image reformatter  172  which outputs reformatted beam  456 , reformatted beam  456  being made up of portions  456 A,  456 B,  456 C and  456 D each being substantially parallel and substantially vertically stacked, and each being a sliced portion of compressed beam  452 . 
     With additional reference to  FIGS. 5A ,  5 D and  5 E, image reformatter  172  can have D-shaped minors  406  and  410 . D-shaped mirror  406  can be mounted to mounting bracket  408 , and can be secured to bracket  420 , bracket  420  secured to base plate  480  of optical slicer  100 . D-shaped mirror  406  can be vertically oriented with the flat edge being located closest to reformatted beam  456  when in use. D-shaped minor  406  can be positioned at a 2.5 degree tilt horizontally and a 2.7 degree tilt vertically downwards relative to the incoming path of compressed beam  452 , when compressed beam  452  first approaches D-shaped mirror  406 . 
     D-shaped mirror  410  can be mounted to mounting bracket  412 , which can be secured to bracket  422 , bracket  422  being secured to base plate  480  of optical slicer  100 . D-shaped minor  410  can be oriented horizontally with the flat edge being located closest to reformatted beam  456  when in use. D-shaped minor  410  can be positioned at a 2.5 degree tilt horizontally and a 2.7 degree tilt vertically upwards relative to the incoming path of compressed beam  452 , when compressed beam  452  first approaches D-shaped mirror  406 . In some embodiments, D-shaped mirrors  406  and  410  may be Thorlabs™ #BBD1-E02 mirrors. Skilled persons will understand that differently shaped mirrors or other reflective surfaces, including convex or concave shaped surfaces can be used to produce reformatted beam  456 , and additionally, alternative positioning of minors or other reflective surfaces may be implements to achieve substantially similar results. 
     When in use, compressed beam  452  can pass over D-shaped mirror  410  and can reach the position of D-shaped mirror  406 . In some embodiments, portion  456 A of compressed beam  452  passes by D-shaped mirror  406 , while the remaining portion of compressed beam  452  is reflected back and forth between D-shaped mirror  406  and D-shaped mirror  410  until reformatted beam  456 , made up of portions  456 A,  456 B,  456 C and  456 D is generated. With each reflection back and forth a portion of the reflected beam passes by D-shaped mirror  406  to produce a corresponding portion of reformatted beam  456 . For example, after portion  456 A has passed by D-shaped minor  406 , the remaining portion of compressed beam  452  is reflected off D-shaped mirror  406 , generating a first reflected beam directed toward at D-shaped minor  410 . 
     D-shaped mirror  410  reflects the first reflected beam back towards D-shaped minor  406 , a portion of this reflection passing by D-shaped mirror  406 , generating portion  456 B, the remaining portion of this reflection be directed back at D-shaped minor  410 . Portion  456 B being positioned below portion  456 A, and being substantially parallel to portion  456 A and substantially vertically stacked. 
     The remaining portion of the reflection directed at D-shaped minor  406 , generating a subsequent reflected portion, directed back to D-shaped minor  410 . This subsequent reflected portion contacting D-shaped minor  410  at a position below the contact position of the first reflected portion. This subsequent reflected portion reflecting off D-shaped minor  410  back towards D-shaped minor  406 , a portion passing by D-shaped mirror  406 , generating portion  456 C, the remaining portion of the reflected beam contacting D-shaped minor  406 . Portion  456 C being positioned below portion  456 B, each of portions  456 A,  456 B and  456 C being substantially parallel and substantially vertically stacked. 
     Again, the remaining portion of the reflection is directed at D-shaped minor  406 , generating a further reflected portion, directed back to D-shaped minor  410 . This further reflected portion contacts D-shaped minor  410  at a position below the contact position of the previous reflected portion. This further reflected portion reflects off D-shaped minor  410  and passes by D-shaped mirror  406 , generating portion  456 D. Portion  456 D is positioned below portion  456 C, each of portions  456 A,  456 B,  456 C and  456 D being substantially parallel and substantially vertically stacked and each being a sliced portion of compressed beam  452 . 
     While the embodiment shown in  FIG. 4  is an optical slicer that generates four beam portions, a person of skill will understand that an increase in the number of back and forth reflections between D-shaped mirrors  406  and  410  can increased the number of portions of reformatted beam  456 . Skilled persons will appreciate that the focal lengths and sizes of minors  402 ,  404 ,  414  and  416  may be adjusted appropriately to accommodate such modifications. 
     Referring back to  FIG. 4 , if reformatted beam  456  is passed through a focusing lens with the same focal length as the collimating lens or curved mirror used to produce input beam  102 , a reformatter spot is produced. The produced reformatter spot producing an image of input beam  102 , that is expanded in the vertical dimension by the slicing factor and has a similar horizontal dimension as compared to the input spot generated by passing input beam  102  through the same focusing lens, while maintaining a similar light intensity as the input spot. 
     Reformatting beam  456  may be received by image expander  174 , producing output beam  156 . Image expander  174  having cylindrical convex minor  414  and cylindrical concave minor  416 . Cylindrical convex mirror  414  receiving and reflecting reformatted beam  456 , producing horizontally diverging reformatted beam  458  directed at cylindrical concave minor  416 . Cylindrical concave minor  416  receiving horizontally diverging reformatted beam  458  and substantially collimating horizontally diverging reformatted beam  458 , producing output beam  156 . With additional reference to  FIG. 5A , output beam  156  passes through output aperture  520 , which can be located below cylindrical convex minor  414  and through mounting bracket  514 . 
     The resulting output beam  156 , if passed through a focusing lens having substantially the same focal length as the collimating lens or curved mirror that generated the input beam  102 , focuses output beam  156  to produce an output spot. This output spot producing an image of the input spot that would be generated if input beam  102  is passed through the same focusing lens but being compressed in the horizontal direction by the slicing factor of optical slicer  100  and expanded in the vertical direction by the slicing factor of optical slicer  100 , while maintaining a similar light intensity as the input spot. 
     With additional reference to  FIGS. 5A and 5F , cylindrical convex mirror  414  can be secured to mounting bracket  514  for securement to base plate  480  of optical slicer  100 . In some embodiments, mounting bracket  514  can have output aperture  520  located therethrough, where in some embodiments output aperture  520  can be located below the position of cylindrical convex minor  414  when secured to mounting bracket  514 . In some embodiments, cylindrical convex minor  414  may have a focal length of −25.84 mm and may be positioned at a 0.0 degree tilt horizontally and a 6.3 degree tilt vertically downwards relative to the path of the incoming beam; however, skilled persons will understand that other focal lengths and positioning can be used to produce horizontally diverging reformatted beam  458 . 
     With additional reference to  FIGS. 5A and 5G , cylindrical concave minor  416  can be mounted to mounting bracket  516  for securement to base plate  480  of optical slicer  100 . In some embodiments, base plate  480  having an indent therein which can receive a portion of mounting bracket  516  to provide that a portion of concave mirror  416  can rest below a top surface of base plate  480 . In some embodiments, cylindrical concave minor  416  can have a focal length of 103.360 mm and can be positioned at a 0.0 degree tilt horizontally and a 6.3 degree tilt vertically upwards relative to the path of the incoming beam; however, skilled persons will understand that other focal lengths and positioning can be used to produce output beam  156 . 
     With reference to  FIG. 5H , optical slicer  100  can be covered by housing cover  486  secured to base plate  480  to protect the interior elements of optical slicer  100 , for example from dust and other particulates. Housing cover  486  can have input aperture  482  for receiving the input beam and can additionally have output aperture  484  for outputting the output beam from optical slicer  100 . 
     In some embodiments of the optical slicer described herein, a second optical slicer may be placed in series wherein output beam  156  from a first optical slicer may be input beam  102  into a second optical slicer. In such embodiments it has been found that the slicing factor may be multiplicative; for example, combining two slicers having a slicing factor of four in series may tend to result in an overall slicing factor of sixteen. 
     While the present invention can be used with any device that tends to use light as an input, one example of the use of the optical slicer described herein may be in the field of spectroscopy. A general spectrometer is a device that disperses light such that the intensity value of light as a function of wavelength can be recorded on a detector. For readings that require a higher spectral resolution, a narrower slit is needed in a direct relationship to spectral resolution and typically, a narrow slit will provide a reduction in the light intensity received by the general spectrometer device. Positioning an optical slicer in front of the input of a general spectrometer device can tend to produce an input into the general spectrometer device slit having an increased light intensity value as compared to a slit without an optical slicer, by the factor of the slicing factor, over the area of the slit, tending to provide increased spectral resolution without sacrificing light signal intensity. 
     A subset of spectroscopy is interferometric spectroscopy; the defining feature of interferometric spectrometers is that the dispersing element used is not a grating or a prism. Rather, the dispersion is achieved another way, such as by taking the Fourier transform of the pattern generated by two interfering beams. The slicer not only increases brightness of the output, but also allows large improvements in the contrast of the interference fringes, as well as signal-to-noise ratio. 
     An optical slicer can be used in a subset of OCT called Fourier domain OCT (FD-OCT), and more specifically in a specific implementation FD-OCT called Spectral Domain OCT (SD-OCT). An SD-OCT instrument is an interferometric spectrometer with a dispersive spectrometer to record the signal. An optical slicer can be included at the input to the dispersive spectrometer right before the dispersive beam element in a collimated beam path. 
     A further subset of interferometric spectrometry as pertains to medical imaging is Optical Coherence Tomography (OCT), a technique that uses an interferometric spectrometer to make an image. A slicer will improve the throughput, as well as the fringe contrast, of the OCT device; the result is that the slicer can improve the depth penetration possible with OCT systems, speeding imaging time and increasing the value of the captured image. An optical slicer can be included at the input to the OCT device. 
     A further application of the slicer is in the field of miniature spectroscopy, particularly as it pertains to Raman spectroscopy. Current Raman spectrometers have been implemented that are miniaturized to handheld scale. As the slicer can be used to increase throughput in any system wherein light is used as the input source, a miniaturized embodiment of the slicer can be used in conjunction with miniaturized spectrometers, like the Raman, to increase spectral resolution, increase output signal strength, and decrease scan time. An optical slicer can be included at the input to the Raman spectroscopy device. 
     The present invention has been described with regard to specific embodiments. However, it will be obvious to persons skilled in the art that a number of variants and modifications can be made without departing from the scope of the invention as described herein.