TWO-DIMENSIONAL, ANTI-SCATTER GRID AND COLLIMATOR DESIGNS, AND ITS MOTION, FABRICATION AND ASSEMBLY

Abstract: A grid (30), for use with electromagnetic energy emitting devices, includes at least metal layer, which is formed, for example, by electroplating. The metal layer includes top and bottom surfaces, and a plurality of solid integrated walls (32). Each of the solid integrated walls extends from the top to bottom surface and having a plurality of side surfaces. The side surfaces of the solid integrated walls (32), are arranged to define a plurality of openings extending entirely through the layer. At least some of the walls also can include projections extending into the respective openings formed by the walls. The projections can be of various shapes and sizes, and are arranged so that a total amount of wall material intersected by a line propagating in a direction along an edge of the grid is substantially the same as another total amount of wall material intersected by another line propagating in another direction substantially parallel to the edge of the grid at any distance from the edge.

Description: TWO-DIMENSIONAL, ANTI-SCATTER GRID AND COLLIMATOR DESIGNS, AND ITS MOTION, FABRICATION AND ASSEMBLY This is a continuation-in-part of U.S. Patent Application Serial No. 09/459.597. filed on December 13. 1999. the entire contents of which being expressly incorporated herein by reference. The invention was made with Government support under Grant Number 1 R43 CA76752-01 awarded by the National Institutes of Health, National Cancer Institute. The Government has certain riεhts in the invention. BACKGROUND OF THE INVENTION Field of the Invention: The present invention relates to a method and apparatus for making focused and unfocused grids and collimators which are movable to avoid grid shadows on an imager. and which are adaptable for use in a wide range of electromagnetic radiation applications, such as x-ray and gamma-ray imaging devices and the like. More particularly, the present invention relates to a method and apparatus for making focused and unfocused grids, such as air core grids, that can be constructed with a very high aspect ratio, which is defined as the ratio between the height of each absorbing grid wall and the thickness of the absorbing grid wall, and that are capable of permitting large primary radiation transmission therethrough. Description of the Related Art: Anti-scatter grids and collimators can be used to eliminate the scattering of radiation to unintended and undesirable directions. Radiation with wavelengths shorter than or equal to soft x-rays can penetrate materials. The radiation decay length in the material decreases as the atomic number of the grid material increases or as the wavelength of the radiation increases. These grid walls, also called the septa and lamellae, can be used to reduce scattered radiation in ultraviolet, x-ray and gamma ray stems, for example. The grids can also be used as collimators. x-ray masks, and so on. For scatter reduction applications, the grid walls preferably should be two- dimensional to eliminate scatter from all directions. For many applications, the x-ray source is a point source close to the imager. An anti-scatter grid preferably should also be focused. Methods for fabricating and assembling focused and unfocused two- dimensional grids are described in U.S. Patent Number 5.949.850. entitled "A Method and Apparatus for Making Large Area Two-dimensional Grids " , the entire content of which is incorporated herein by reference. When an anti-scatter grid is stationary during the acquisition of the image, the shadow of the anti-scatter grid will be cast on the imager. such as film or electronic digital detector, along with the image of the object. It is undesirable to have the grid shadow show artificial patterns. The typical solution to eliminating the non-uniform shadow of the grid is to move the grid during the exposure. The ideal anti-scatter grid with motion will produce uniform exposure on the imager in the absence of any objects being imaged. One-dimensional grids, also known as linear grids and composed of highly absorbing strips and highh transmitting interspaces which are parallel in their longitudinal direction, can be moved in a stead} manner in one direction or in an oscillator}- manner in the plane of the grid in the direction perpendicular to the parallel strips of highly absorbing lamellae. For two-dimensional grids, the motion can either be in one direction or oscillator} in the plane of the grid, but the grid shape needs to be chosen based on .specific criteria. The following discussion pertains to a two-dimensional grid with regular square patterns in the x-y plane, with the grid w alls lined up in the x-direction and y- direction. If the grid is moving at a uniform speed in the x-direction. the film will show unexposed stripes along the x-direction. which also repeat periodically in the y- direction. The width of the unexposed strips is the same or essentially the same as the thickness of the grid w alls. This grid pattern and the associated motion are unacceptable. If the grid is moving at a uniform speed in the plane of the grid, but at a 45 degree angle from the x-axis. the image on the film or imager is significantly improved. However, strips of slightly overexposed film parallel to the direction of the motion at the intersection of the grid w alls w ill sti ll be present. As the grid moves in the x-direction at a uniform speed, the grid w alls block the x-rays e\ erywhere. except at the wall intersection, for the fraction of the time 2d ' D . where ./ is the thickness of the grid walls and D \s the periodicity of the grid walls. At the wall intersection, the grid walls blocks the x-rays for the fraction of the time 2d l D ≤ t ≤ d l D . depending on the location. Thus, stripes of slightly ox erexposed x-ra_\ film are produced. Methods for attempting to eliminate the overexposed strips discussed above are disclosed in U.S. Patent Nos. 5.606.589. 5.729.585 and 5.814.235 to Pellegrino et al.. the entire contents of each patent being incorporated herein by reference. These methods attempt to eliminate the ox erexposed strips b} rotating the grid b} an angle A. w here . 1 = atan ( /? m ). and in and n are integers. Howe\ er. these methods are unacceptable or not ideal for man} applications. Accordingly, a need exists for a method and apparatus for eliminating the overexposed strips associated with two-dimensional focused or unfocused grid intersections. SUMMARY OF THE INVENTION An object of the present invention is to provide a grid where the walls focus to a point, a grid where the walls focus to a line or an unfocused grid with parallel walls that is configured to minimize grid shadow when the grid is moved during imaging. Another object of the present im ention. therefore, is to provide a method and apparatus for manufacturing a focused or unfocused grid which is configured to minimize overexposure at its wall intersections when the grid is moved during imaging. A further object of the present i ntion is to provide a method and apparatus for moving a focused or unfocused grid so that no perceptible areas of variable density are cast by the grid onto the film or other two-dimensional electronic detectors. These and other objects of the present im ention are substantiall achieved by providing a grid, adaptable for use ith electromagnetic energy emitting devices. The grid comprises at least one solid metal layer, formed by electroplating. The solid metal layer comprises top and bottom surfaces, and a plurality of solid integrated, intersecting walls, each of which extending from the top to bottom surface and having a plurality of side surfaces. The side surfaces of the walls are arranged to define a plurality of openings extending entirely through the layer, and at least some of the side surfaces have projections extending into respecth e ones of the openings. The projections can be of various shapes and sizes, and are arranged so that a total amount of wall material intersected by a line propagating in a direction, for example, along an edge of the grid, for each period along the grid is substantially the same and is also substantially the same as another total amount of wall material intersected by another line for each period propagating in another direction substantially parallel to the edge of the grid at any distance from the edge. These and other objects are further substantially achieved by providing a method for minimizing scattering of electromagnetic energy in an electromagnetic imaging device which is adapted to obtain an image of an object on an imager. The method includes placing a grid between an electromagnetic energy emitting source of the electromagnetic imaging device and the imager. The grid comprises at least one metal layer including top and bottom surfaces and a plurality of solid integrated, intersecting walls, each of which extending from the top to bottom surface and having a plurality of side surfaces, the side surfaces of the walls being arranged to define a plurality of openings extending entirely through the layer, and at least some of the side surface having projections extending into respecth e ones of the openings. The method further includes moving the grid in a grid moving pattern while the electromagnetic energy emitting source is emitting energy toward the imager. BRIEF DESCRIPTION OF THE DRAWINGS These and other features and advantages of the present invention will be more readily apprehended from the following detailed description when read in connection with the appended drawings, in which: Fig. 1 shows a section of a focused stationary grid according to an embodiment of the present invention, in which the grid openings are focused to a point x-ray source: Fig. 2a is a schematic of the grid shown in Fig. 1 rotated an angle of 45 degrees w ith respect to the x and y axes, and being positioned so that the central ray- emanates from point x-ray source onto the edge of the grid: Fig. 2b is a schematic of the grid shown in Fig. 1 rotated at an angle of 45 degrees w ith respect to the x and y axes, and being positioned so that the central ray- emanates from point x-ray source onto the center of the grid: Fig. 3 is an example of a top view of a grid layout as shown in Fig. 1, modified and positioned so that one set of grid walls are perpendicular to a direction of motion along the x-axis and the other set of grid walls is at an angle θ with respect to the direction of motion, thus forming a parallelogram grid pattern applicable for linear grid motion: Fig. 4 is an example of a top view of a grid layout as shown in Fig. 1. modified and positioned so that one set of grid walls is perpendicular to the direction of motion along the x-axis and the other set of grid walls makes an angle θ with respect to the direction of motion, thus forming another parallelogram grid pattern applicable for linear grid motion: Fig. 5 is an example of a top view of a grid layout as shown in Fig. 1. modified so that the angle of the grid walls are neither parallel nor perpendicular to the direction of grid motion along the x-axis. thus forming a further parallelogram grid pattern applicable for linear grid motion: Fig. 6 is a λ ariation of the grid pattern show n in Fig. 5. in which the grid openings are rectangular: Fig. 7 is a \ ariation of the grid pattern shown in Fig. 5 in which the grid openings are squares: Fig. 8 is a variation of the grid pattern shown in Fig. 5 having modified corners at the wall intersections according to an embodiment of the present invention for eliminating artificial images or shadows on the imager along the direction of linear motion of the grid: Fig. 9 is the top view of only the additional grid areas that w ere added to a square grid shown in F ig. 7 to form the grid pattern show n in Fig. 8: Fig. 10 is the top view of a grid w ith modified corners at the wall intersections according to another embodiment of the present invention for eliminating artificial images or shadows on the imager along the direction of linear motion of the grid; Fig. 1 1 is a top \ iew of only the additional grid areas that were added to a square grid shown in Fig. 7 to form the grid pattern shown in Fig. 10: Fig. 1 2 is a detailed \ iew of a w all intersection of the grid illustrating a general arrangement of an additional grid area that is added to the wall intersection of the grid: Fig. 1 3 is a detailed view of a w all intersection of the grid illustrating a general arrangement of an additional grid area that is added to the w all intersection of the grid; Fig. 14 is a detailed view of a wall intersection of another grid according to an embodiment of the present invention, illustrating a general arrangement of an additional grid area that is added proximate to the wall intersection and not connected to any of the grid walls; Fig. 15 is a detailed view of a wall intersection of another grid according to an embodiment of the present invention, illustrating a general arrangement of an additional grid area that is added to the w all intersection of the grid, such that two rectangular or substantially rectangular pieces are placed at opposing (non-adjacent) left and right corners of the w all intersection: Fig. 16 is a detailed \ iew of a wall intersection of another grid according to an embodiment of the present invention, ill ustrating a general arrangement of an additional grid area that is added to the wall intersection of the grid, such that two trapezoidal pieces are placed at opposing (non-adjacent) left and right corners of the wall intersection; Fig. 1 7 shows a top λ iew of a portion of a grid according to an embodiment of the present im ention. having more than one ty pe of modified corner as show n in Figs. 12- 16: Fig. 1 8 show s one layer of grid to be assembled from two sections and their joints, using the pattern as show n in Fig. 7: Fig. 1 show s the location o the imaginary central ray and reference lines for photoresists exposures using the grid shape of Fig. 4: Figs. 20a and 20b illustrate exemplary patterns of x-ray masks used to form the grid pattern shown in Fig. 19 according to an embodiment of the present invention: Figs. 21 a and 21b show an exposure method according to an embodiment of the present invention which uses sheet x-ray beams, such that Fig. 21 a shows the cross-section in the plane of the sheet x-ray beam and Fig. 21 b shows the cross- section perpendicular to the sheet x-ray beam, and the x-ray mask and the substrate are tilted with respect to the sheet x-ray beam to form the focusing effect of the grid; Fig. 21 c shows another exposure method according to an embodiment of the present invention which uses sheet x-ray beams to form the focusing effect of the grid: Fig. 22 shows an exposure method according to an embodiment of the present invention which is used in place of the method shown in Fig. 21b for exposing grids or portions of grids where the walls, joints or holes are not focused; Fig. 23 shows an example the top and bottom patterns of the exposed photoresists exposed according to the methods shown in Figs. 21 a and 21 b: Fig. 24 shows an example of the top and bottom patterns of an incorrectly exposed photoresists which was exposed using only two masks and a sheet x-ray beam: Figs. 25a and 25b show an example of x-ray masks used to expose the central portion of right-hand-side of a focused grid shown in Fig. 1 8 using a sheet x-ray beam according to an embodiment of the present invention: Fig. 25c shows an example of an x-ray mask used to expose the grid edge joints o the right-hand-side of a focused grid for a point source shown in Fig. 18 using a sheet x-ray beam according to an embodiment of the present invention: Fig. 26 shows a portion of the grid including the left joining edge and a wide border: Fig. 27 shows an example of an x-ray mask used to expose the grid edge joint and the border of Fig. 26. which is in addition to the masks already shown in FIGS. 25a and 25b. according to an embodiment of the present invention: Figs. 28a and 28b show an example of an x-ray masks used to expose the photoresist for the focused grids for a point source show n in f igs. 7. 8. 10 or 1 7 using a sheet x-ray beam according to an embodiment of the present invention: Fig. 28c shows an example of an x-ray mask required to expose the additional grid structure for linear motion according to an embodiment of the present invention; Fig. 29 is a side view of an example of a grid including a frame according to an embodiment of the present invention; > Fig. 30 illustrates a top view of the frame shown in Fig. 29. less the grid lay ers: and Fig. 31 illustrates pieces of a grid layer that can be assembled in the frame shown in Fius. 29 and 30. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a method and apparatus for making large area, two-dimensional, high aspect ratio, focused or unfocused x-ray anti-scatter grids, anti- scatter grid/scintillators. x-ray filters, and the like, as well as similar methods and apparatus for ultraviolet and gamma-ray applications. Referring now to the drawings. Fig. 1 shows a schematic of a section of a two-dimensional, focused anti- scatter grid 30 produced by a method of grid manufacture according to an embodiment of the present invention, as described in more detail in U.S. Patent No. 5.949.850 referenced e. The object to be imaged (not shown ) is positioned between the x-ray source and the x-ray grid 30. The grid openings 3 1 which are defined by walls 32 are square in this example. However, the grid openings can be any practical shape as would be appreciated bv one skilled in the methods of grid construction. The walls 32 are uniformly thick or substantially uniformly thick around each opening in this figure. but can vary in thickness as desired. The walls 32 are slanted at the same angle as the angle of the x-rays emanating from the point source, in order for the x-rays to propagate through the holes to the imager w ithout significant loss. This angle increases for grid walls further away from the x-ray point source. In other words, an imaginary line extending from each «ι d wall 32 along the x-axis 40 could intersect the x-ray point source. A similar scenario exists for the grid walls 32 along the y-axis 50. As shown, the x-ray propagates out of a point source 61 with a conical spread 60. The x-ray imager 62. w hich may be an electronic detector or x-ray film, for example, is placed adjacent and parallel or substantially parallel to the bottom surface of the x-ray grid 30 with the x-ray grid between the x-ray source 61 and the x-ray imager. Typically, the top surface of the x-ray grid 30 is perpendicular or substantially perpendicular to the line 63 that extends between the x-ray source and the x-ray grid 30. To facilitate the description below, a coordinate system in which the grid 30 is omitted w ill now be defined. The z-axis is line 63. which is perpendicular or substantially perpendicular to the anti-scatter grid, and intersects the point x-ray- source 61 . The r = 0 coordinate is defined as the top surface of the anti-scatter grid. As further show n, the central ray 63 propagates to the center of the grid 30. w hich is marked by a virtual "+ " sign 64. Figs. 2a and 2b show schematics of two air-core x-ray anti-scatter grids, such as grid 30 shown in Fig. 1 . w hich are stacked on top of each other in a manner described in more detail below to form a grid assembly . These lay ers of the grid walls can achieve high aspect ratio such that they are structurally rigid. The stacked grids 30 can be moved steadily along a straight line (e.g.. the x-axis 40) during imaging. As shown in these figures, the grids 30 have been oriented so that their w alls extend at an angle of 45° or about 45° w ith respect to the 50. The top surface of the top grid 30 is in the x-y plane. The central ray 63 from the x-ray source 61 is perpendicular or substantially perpendicular to the top surface of the top grid 30. For mammographic applications. the central ray 63 propagates to the top grid 30 next to the chest wall at the edge or close to the edge of the grid on the x-axis 40. which is marked as location 65 in Fig. 2a. For general radiology, the central ray 63 is usually at the center of the top grid 30. which is marked as location 64 in Fig. 2b. In this example, the line of motion 70 of the grid assembh is parallel or substantially paral lel to the x-axis 40. In the x-y plane. one set ofthe walls 32 u e the septa) is at 45° with lespect to the line of motion 70. and the shape ofthe grid openings 31 is nearly square The grid assembly can move m )ust one dnection oi it can move in both directions in the \-\ plane Duπng motion, the speed at which the giid moves should be constant oi substantially constant Two categories ot giid patterns can be used with hneai grid motion to eliminate non-uniform shadow of the grid The description below pertains to portions of the giid not at the edges of the giid so the border is not shown For illustiation purposes only, the dimensions ofthe drawings aie not to scale, nor have they been optimized foi specific applications I Gnd Design \ιt T pe 1 loi I meal Motion As discussed above the piesent invention pi ov ides a two-dimensional grid design and a method foi moving the grid so that the image taken will leave no substantial artificial images loi eithei focused oi unfocused gnds foi some applications In pailiculai as will now be descnbed the present invention piovides methods loi constiuctmg gnd designs that do not have squaie patterns The rules of construction foi these gnds aie discussed below Essentially. Type 1 methods for eliminating grid shadows produced by the mteisection of the gnd walls aie based on the assumptions that (1) there is image bluiimg dining the conveision ol x-iavs to visible photons oi to electncal chaige and oi (2) the lesolution ol the imaging device is low \ geneial method oi grid design provides a gnd pattern that is periodic in both paiallel and perpendicular (oi substantiallv paiallel and perpendiculai ) directions to the dnection ol motion The construction uiles foi the diffeient gnd vanutions aie discussed below Gnd Design \ aπation I 1 V Set of Parallel Gnd Walls Peipendiculai to the Line ol Motion I lg " shows a top v iew ol an exemplaiv gnd lav out that can be emploved in a gnd 30 as discussed abo The gnd lav out consists of a set of gnd walls 1 that aie perpendicular or substantially peφendicular to the direction of motion, and a set of grid walls. B. intersecting A . The thicknesses of grid walls A and B are a and b. respectively . The thicknesses a and b are equal in this figure, but they are not required to be equal. The angle θ is defined as the angle of the grid wall B with respect to the x-axis. The grid moves in the x-direction as indicated by 70. /\ and / > , are the periodicities o the intercepting grid w all pattern in the x- and y-directions. respectiveh . D κ and D represent the pitch of grid cells in the x- and y-directions. respectiv eh . The periodicity of the grid pattern in the x-direction is P λ = MD v . where M is a positiv e integer greater than 1 . The periodicity of the grid pattern in the y-direction is P, = M[D ' Λ j. where N is a positive integer greater than or equal to 1 . M ≠ N and P - |tan (#)| E 1 . For linear motion, the grid pattern can be generated given __ . ( θ or D ). ( M or /\ ) and ( Y or P ). The parameter range for the angle θ is 0° < θ < 90 " . The best alues for the angle θ are away from the two end limits. 0° and 90°. The grid intersections are spaced at intervals of P, ι M in the y -direction. If D . θ. Λ/ and .V are giv en, the parameters P . P • and D can be calculated Figure 3 is a plot of a section of the grid for the follow ing chosen parameters: θ = 45°. M = 3 and Λ ' = 1 . If the parameters ϋ . D . Λ/ and Λ are chosen, the angle θ. I and P, can be calculated: P = Λ/ , . P = \ D and tf = ± atan (y P ) . Figure 4 is a plot of a section of the grid for the parameters Λ = 2. M - 7 and 0 - - atan (2/ ) 7 If \ . Grid Design Variation 1.2: Grid Walls Not Perpendicular to the Line of Motion Figure 5 is the top view of a section of the grid lay out w here neither grid walls A nor B are perpendicular to the direction of linear motion. I he thicknesses of grid walls .-] and B are α and h. respectiv ely . The thicknesses α and h are equal in this figure, but they are not required to be. The angles between the grid w alls Λ and B relativ e to the x-axis are φ and θ. respectively Choosing ϋ . ( .1/ or /\ ). (A ' or P t ). and angles (θ or , ) and φ. then P = |tan(^)_°, . N = P D and (M = P D ). The centers of grid intersections are separated by a distance E ( / in the y-direction. Fig. 5 shows an example where θ = - 1 5° . φ = -80° . Λ = 5 and .Y = 1 . Fig. 6 is the top view of a section of the grid lay out where neither grid walls A or B are perpendicular to the direction of motion, but grid wall A is perpendicular to grid wall B. thus a special case of Fig 5. where the grid openings are rectangular. The thicknesses of grid w alls A and B are a and b. respectively. The thicknesses are equal in this figure, but again, they are not required to be equal. The angles between the grid walls A and B relativ e to the x-axis are φ and θ. respectively. By choosing D . (M or Λ)- G or A ), ( θ or P ) and φ. then P = tan(ø)/ 5 P t = A ' , . and P, = MD . The centers of grid intersections are separated by a distance / > , I M in the y-direction. Fig. 6 show s an example where # = 10° . φ = -80° . Λ/ = 10 and N = 1 . Comments on the Grid Motion Associated with Grid Design I For all grid lay out methods, the range of parameters for the grid can vary depending on many factors, such as film versus digital detectors, the ty pe of phosphor used in film, the type of application, and whether there is direct x-ray conversion or indirect x-ray conversion, etc. The ultimate criteria are that the ov erexposed strip caused by grid intersections is close enough to each other so that they do not appear in the imaging sy stem. Some general conditions can be given for the range of parameters for Grid Design Type I and associated motion. It is better for grid openings to be greater than the grid wall thicknesses a and b. For film. P ' ../ should be smaller than the x-ray to optical radiation conv ersion blurring effect produced by the phosphor. l or digital imagers with direct x-ray conversion, it is preferable that pixel pitch in the y-direction is an integer multiple of the spacing. T 3 , I M . Otherwise, the grid shadows will be unevenly distributed on the pixels. The distance of hneai travel. L. of the grid duπng the exposure should be many times the distance Λ vvhere kP > L>(kP -δL) . D >OL>asm(φ). D >δl >b sin ( ( 9) δl P « 1 k»\ and k is an integer The latio of δLIL should be small to minimize the effect ot shadows caused by the start and stop The 5 distance L can be tiaveised in a steady motion m one direction if it is not too long to affect the transmission of primary ladiation Assuming that the x-ray beam is uniform ovei time, the speed the gnd tiaveises the distance / should be constant but the dnection can change In geneial the speed at which the gnd moves should be proportional to the powei of the x-ray source If the distance L to be traveled in any 0 one direction at the desned speed is too long, causing reduction of primary radiation, then it can be tiaveised bv steadv hneai motion that reverses direction II Gnd Design Tvpe II foi Lineai Motion The present invention provides other two-dimensional grid designs and 5 methods of moving the grid such that the x-iay image will have no oveiexposed strips at the intei section of the gnd walls \ and B The pπnciple is based on adding additional cross-sectional areas to the grid to adjust for the increase ofthe pπmary radiation caused by the overlapping of the gnd walls This gnd design and construction pi o\ ides unifoim \-rav exposure " Two lllustiations of the concept aie given below followed bv the geneiahzed constiuction iules 1 his gnd design is feasible foi the SL1G \ fabπcation method descπbed in L S Patent 5949850 lefeienced above because x-iav lithography is ace in ate to a fi action of a micion ev en foi a thick photoresist _ Gnd Design Vaπation II 1 Squaie Gnd Shape with an Additional Squaie Piece Fig 7 shows a section of a square patterned gnd with unifoim grid wall thickness a and h totated at a 45° angle with lespect to the dnection of motion When squaie pieces in the shape of the septa inteisection die added to the gnd next to the intei section with one per inteisection as shown in Fig 8 the gnd walls lea e no shadow for a grid moving with linear motion 70. In the Fig. 8. D =D = P x = P and θ = 45° . The additional grid area is shown alone in Fig. 9. Grid Design Variation II.2: Square Grid Shape w ith Two Additional Triangular Pieces Fig. 1 0 shows another grid pattern, w hich has the same or essentiallv the same effect as the grid pattern in Fig. 8. by placing two additional triangular pieces at opposite sides of intersecting grid walls. In this Fig. 10 example. D =D = P x = P and θ = 45° . The additional grid area is shown alone in Fig. 1 1 . With these modified corners added to the grid, there w ill not be am artificial patterns as the grid is moved in a straight line as indicated by 70 for a distance L. where kD > L ≥ (kD - ό L). D » δL > s . δL « L . k » \ and k is an integer. Along the x-axis. the grid wall thickness is v and the periodicity of the grid i / 3 = I ) I he distance of linear trav el L should be as large as it can be w hile keeping the maximum transmission of primary radiation. The condition for linear grid motion in just one direction is easier for grid Design Type II to achieve than grid Design Ty pe I or the designs in U.S. Patents by Pellegrino et al.. because P x > D x for grid Design Type 1. General Construction Methods for Quadrilateral Grid Design Ty pe II for Linear Motion The exact technique for eliminating the effect of slight ov ere.xposure caused by the intersection of the grid walls w ith linear motion is to add additional grid area at each corner. Two special examples are show n in Figs. 8 and 10 discussed above, and the general concept is described below and illustrated in Figs. 12- 16. The general rule is that the ov erlapping grid region C formed by grid walls A and B has to be "added back " to the grid intersecting region, so that the total amount of the w all material of the grid intersected by a line propagating along the x-direction remains constant at any point along the y axis. In other w ords, the total amount of wall material of the grid intersected by a line propagating in a direction parallel to the x-axis along the edge of a grid of the type shown, for example, in Figs. 8 or 10. is identical to the amount of wall material of the grid intersected by a line propagating in a direction parallel to the x-axis through any position, for example, the center of the grid. This concept can be applied to any grid layout that is constructed with intersecting grid walls A and B. The w idths of the intersecting grid walls do not have to be the same and the intersections do not have to be at 90°. but grid lines cannot be parallel to the x-axis. The width of the parallel walls B do not have to be identical to each other, nor do they need to be equidistant from one another, but they do have to be periodic along the x-axis with period P . The widths of the parallel lines A do not have to be identical to each other, nor do they need to be equidistant from one another, but they do have to be periodic along the y-a.xis with period P . The generalized construction rules are described using a single intersecting corner of walls A and B for illustration as shown in Figs. 12- 16. The top and bottom corners of parallelogram C are both designated as y and the right and left corners of the parallelogram C as β l and β2. respectively. Dashed lines, f. parallel to the x-axis. the direction of motion, are placed through points y. The points where the dashed lines f intersect the edges of the grid lines are designated as αl . α2. α.3 and α4. Fig. 12 shows the addition to the grid in the form of a parallelogram F formed by three predefined points: α l . α2. β l . and δ. where δ is the fourth corner. This is the construction method used for the grid pattern shown in Fig. 8. Fig. 13 shows the addition of the grid area in the shape of two triangles. E l and E2. formed by connecting the points α l . α.2. β l and α.3. α4. β2. respectively. This is the construction method used to make the grid pattern shown in Fig. 10. There are an unlimited variety of shapes that would produce uniform exposure for linear motion. Samples of three other alternatives are shown in Figs. 14-16. They produce uniform exposure because they satisfy the criteria that the lengths through the grid in the x-direction for any value y are identical. There is no or essentially no difference in performance of the grids if motion is implemented correctly. Additional grid areas of different designs can be mixed on any one grid without visible effect w hen steadv hneai motion is implemented Fig 1 7 for example, illustrates and arrangement where different combinations of grid corners are implemented in one grid However, the choice of grid corners depends on the ease of implementation and practicality Also, since it is desirable for the transmission of pπmaiy ladiation to be as laige as possible, the gnd walls occupv onh a small percentage of the cross- sectional area General Constiuction Methods for Grid Design Ty pe II foi Lineal Grid Motion It should be fu st noted that this concept does not limit grid openings to quadnlaterals Rathei . the gnd opening shapes could be a w ide lange of shapes, as long as they are periodic in both x and y directions The grid wall intercepts do not have to be defined by four straight line segments Artificial non-uniform shadow will not be intioduced as long as the length of the lines thiough the gnd in the x-direction ai e identical thiough anv v cooi dinate In addition to adding the cornei pieces the width of some sections of the grid walls would hav e to be adiusted foi generalized grid openings Howev ei not ev en gnd shape that is combined w ith steady linear motion pi oduces unif oi m exposui e w ithout artificial images The desirable grid patterns that produce unifoim exposuie hav e to satisfy at a minimum the follow ing u iteπa • The grid pattern has to be periodic in the dnection of motion with periodicity P • No segment of the gnd w ll is pπmaπlv along the direction of the grid motion • The grid w alls block the x-ray ev erv whete fot the same fi action of the time per spatial peπod P at any position perpendicular to the direction of motion • The gi id w alls do not hav e to ha\ e the same thickness • The grid patterns ai e not limited to quadπlateials • These grid patterns have to be coupled with a steady linear motion such that the distance of the grid motion. L. satisfies the condition described in Sections Grid Design Type I and Type II for Linear Motion. • If the walls are not continuous at the intersection or not identical in thickness through the intersection, the construction rule that must be maintained is that the length of the line through the grid in the x-direction is identical through any y-coordinate. Hexagons with modified corners are examples in this category. Implementation of the Grid Design Ty pe II for Linear Grid Motion The additional grid area at the grid wall intersections can be implemented in a number of ways for focused or unfocused grids to obtain uniform exposure. The discussion will use Figs. 8 and 10 as examples. 1. The grid patterns with the additional grid area, such as Figs. 8. 10, 17. and so on. may have approximately the same cross-sectional pattern along the z-axis. 2. Since the additional pieces of the grid are for the adjustment of the primary radiation, these additional grid areas in Figs. 8. 10. 17. and so on. only have to be high enough to block the primary radiation. This allows new alternatives in implementation. • A portion of the grid layer need to have the additional grid area, while the rest of the grid layer do not. For example, a layer of the grid is made with pattern shown in Fig. 8. while the other layers can have the pattern shown in Fig. 7. • The portion of the grid w ith the shapes shown in Figs. 8. 10. 17. and so on. can be released from the substrate for assembly or attached to a low atomic weight substrate. • The portion of the grid w ith the pattern shown in Figs. 8. 10. 1 7. and so on. can be made from materials different from the rest of the grid. For U example, these layers can be made of higher atomic weight materials, while the rest of the grid can be made from fast electroplating material such as nickel . The high atomic weight material allows these parts to be thinner than if nickel were used. For gold, the height of the grid can be 20 to 50 μm for mammographic applications. The height of the additional grid areas depends on the x-ray energy, the grid material, the application and the tolerances for the transmission of primary radiation. • The photoresist can be left in the grid openings to provide structure support, with little adverse impact on the transmission of primary radiation. 3. The additional grid areas shown in Figs. 9. 1 1 . and so on. can be fabricated separately from the rest of the grid. • These areas can be fabricated on a low atomic w eight substrate and remain attached to the substrate. • These areas can be fabricated along with the assembly posts, which are exemplified in Figs. 16a and 16b of U.S. Patent Number 5.949.850. referenced abov e. • Patterns shown in Figs. 9, 1 1. and so on. can be made of a material different from the rest of the grid. For example, these layers can be made from materials w ith higher atomic weight, while the rest of the grid can be made of nickel. The high atomic weight material allows these parts to be thinner than if nickel were used. For gold, the height of the grid can be 20 to 1 00 μm for mammographic applications. The height of the additional grid areas depends on the x-ray energy , the grid material, the appl ication and the tolerances for the transmission of primary radiation. • The photoresist can be left on for low atomic weight substrate to provide structure support with little adverse impact on the transmission of primary radiation. Grid Parameters and Design Examples of the parameter range for mammography application and definitions are given below. Grid Pitch is P . Aspect Ratio is the ratio between the height of the absorbing grid wall and the thickness of the absorbing grid wall. Grid Ratio is the ratio between the height of the absorbing wall including all layers and the distance between the absorbing walls. Howev er, it should be noted that different parameter ranges arc used for different applications, and for different radiation w avelengths. III. Grid Joint Design Designs of grid joints w ere described in U.S. Patent Number 5.949.850. referenced. Fig. 1 8 show s a grid to be assembled from two sections, using the pattern of Fig. 7 as an example. The curved corner interlocks in the shape of 1 10 and 1 1 1 shown in FIG. 1 8 are found to be more desirable structurally than other grid joints. The details o the corner can v ary depending on the implementation of the additional grid structure w ith motion. Straight line boundaries are also acceptable as long as thev retain their relative alignments. I A ' . Grid Fabrication Unfocused grids of any design can be easily fabricated with one mask and a sheet x-rav beam. When grid size is too large to be made in one piece, sections oi grid parts can be made and assembled from a collection of grid pieces Grids with high grid ratios can be obtained by stacking if thev cannot be made the desned thickness in one layer Focused grids of any pattern can be fabπcated by the method described in U.S Patent Number 5.949.850. referenced above For focused grids for point source, methods for exposing the photoresist using a sheet of parallel x-ray beams are described below Grid Design Type I Foi Lineai Motion and Single Piece If the pattern of the gnd in the x-y plane can be made in one piece (not including the bordei and other assembly parts) the easiest method is to expose the photoiesist tw ice w ith two masks The pattern of I lg 4 is used as an example to assist in the explanation below This method can be applied to any gnd patterns with quadrilateral shapes formed by two intersecting sets of parallel lines 1 Foi exemplaiv pm poses the case wheie the cential lav is located at the center of the grid, as shown in Fig 19 which is maiked by a v irtual '-•- " sign 100. will be considered Two imaginary reference lines 101 are drawn running through the "- " sign, parallel to grid walls A and B 2 T he gnd pattern is to be pioduced bv two sepaiate masks The desired patterns for the two masks aie shown in I lg 20a and 20b 3 T he photoiesist exposuie pioceduie bv the sheet x-iav beam is show n Figs 21 a and 21 b For the first exposuie. an x-ray mask 730 with pattern shown in Fig 20a oi 20b. is placed on top of the photoresist 710 and pioperly aligned. as follows In Fig 21 a. the sheet x-iay beam 700 is oriented in the same plane as the paper, and the ieference lines 101 in Figs 20a or 20b of the x-iay masks 730 are parallel to the sheet x-ray beam 700 In Fig 21 b. the sheet x-ray beam 700 is oπented peipendiculai to the plane of the papei as aie the lelerence lines of x-iay mask 7 " U) T he x-i av mask 730 photoiesist 710 and substiate 720 foim an assembly 750 The assembly 750 is positioned in such a w ay that the line 740 that connects the v irtual ' + " sign 100 with the v irtual point x-ray source 62 is peipendiculai to the photoresist 710 The angle α is 0° when the reference line 101 is in the plane of the x-ray source 700 To obtain the focusmg effect in the photoresist 710 by the sheet x-iay beam 700, the 5 assembly 750 rotates around the virtual point x-iay source 62 in a circular arc 760 T his method w ill pioduce focused grids with opening that are focused to a virtual point above the substrate There are situations that one would like to pioduce a layer of the grid with that are focused to a virtual pomt below the substrate as shown in Fig 10 21 c In Fig 21 c. the sheet x-ray beam 700 is oπented peipendicular to the plane of the papei. as are the reference lines of x-ray mask 730 The assembly 750 is positioned in such a way that the lme 740 that connects the virtual ''+" sign 100 with the v irtual point x-iay source 62 is peipendiculai to the photoiesist 710 The angle α is 0° w hen the lclerence line 101 is in the plane ι 5 of the x-iay souice 700 1 o obtain the focusmg effect in the photoiesist 710 by the sheet x-ray beam 700. the assembly 750 rotates around the virtual point x- ray source 62 in a circular arc 770 4 For the second exposure, the second x-ray mask is properly aligned with the photoiesist 710 and the substiate 720 The exposure method is the same as in 5 To facilitate assembly , a bordei is desirable The border can be part of Figs 20a oi 20b. oi it can use a thud mask The grid border mask should be aligned w ith the photoiesist 71 and its exposuie consists of moving the assembly 750 such that the sheet x-ray beam 700 always lemains 5 perpendicular to the photoresist 710. as shown in Fig 22 The assembly 750 mo\ es along a direction 780 6 The lest of the fabncation steps aie the same as in described U S Patent No 5.949 850, referenced abov e Grid Design Type I For Linear Motion and Multiple Pieces Joint Together per Layer If two or more pieces of the grid are required to make a large grid, the grid exposure becomes more complicated. In that case, at least three masks will be required to obtain precise alignment of grid pieces. The desired exposure of the photoresist is shown in Fig. 23. using pattern 1 1 5 show ; n on the right-hand-side of Fig. 1 8 as an example. The effect of the exposure on the photoresist outside the dashed lines 202 is not shown. The desirable exposure patterns are the black lines 1 20 for one surface of the photoresist, and are the dotted lines 130 for the other surface. The location of the central x-ray is marked by the virtual " + " sign at 200. The shape of the left border is preserved and all locations of the grid wall are exposed. Although the procedures discussed above with regard to Figs. 21 a and 21 b are generally sufficient to obtain the correct exposure near the grid joint using two masks. one for wall A and one for wall B. incorrect exposure may occur from time to time. This problem is illustrated in Fig. 24. The masks are made so as to obtain correct photoresist exposure at the surface of the photoresist next to the mask. The dotted lines 130 denote the pattern of the exposure on the other surface of the photoresist. Some portions of the photoresist will not be exposed 140. but other portions that are exposed 141 should not be. The effect of the exposure on the photoresist outside the dashed lines 202 is not shown. At least three x-ray masks are required to allev iate this problem and obtain the correct exposure. Each edge joint boundary needs a mask of its own. These are shown in Figs. 25a-25c. Fig. 25a shows a portion of the grid lines B as lines 150. w hich do not extend all the way to the grid joint boundary on the left. Fig. 25b shows a portion of the grid lines A as items 160. w hich do not extend all the w ay to the grid joint boundary on the left. Fig. 25c shows the mask for the grid joint boundary on the left. The virtual "- " 200 shows the location of the central ray 63 in Figs. 25a-25c. The distances from the joint border to be covered by each mask depend on the grid dimensions, the intended grid height, and the angle. The exposures of the photoresist 710 by all three masks shown in FIGS. 25a- 25c follow the method described above with regard to Figs. 21a and 21 b or Figs. 21a and 21c. The three masks have to be exposed sequentially after aligning each mask with the photoresist. If this pattern is next to the border of the grid as shown in Fig. 26. then the grid boundary 180 can be part of the mask of the grid joint boundary on the left, as shown in Fig. 27. At a minimum, the grid border 180 consists of a wide grid border for structural support, may also include patterned outside edge for packaging, interlocks and peg holes for assembly and stacking. The procedure would be to expose the photoresist 710 by masks shown in Figs. 25a and 25b following the method described in Figs. 21 a and 21 b or Figs. 21a and 21 c. The exposure of the joint boundary section 170 in Fig. 27 follows the method described in Figs. 21 a and 21 b or Figs. 21 a and 21 c while the exposure of the grid border section 180 in Fig. 27 follows the method described in Fig. 22. Grid Design Type II For Linear Motion The exposure of the photoresist for a "tall " type II grid pattern design for linear grid motion, such as those grid patterns illustrated in Figs. 8. 10. 17. and so on. can be implemented based on the methods described in U. S. Patent Number 5.949.850, referenced abov e. The grid is considered " tall " when where // is the height of a single layer of the grid. Φ m x is the maximum angle for a grid as shown in Figs. 2 and 3. and s is related to the thickness of the grid wall as shown in Figs. 7. 8. 10 and 1 7. "High " grids are not easy to expose using long sheet x-ray beams when the same grid pattern is implement from top to bottom on the grid. As described in an earlier section, the grid shape shown in Figs. 8. 10. 1 7. and so on. need only be just high enough to block the primary radiation without causing undesirable exposure. Using the grid pattern show n in Fig. 10 as an example, three x- ray masks. Figs. 28a. 28b and 28c can be used for the exposure. Additional x-ray masks might be required for edge joints and borders. The exposure of the photoresist for the joints and borders would be the same as for that describing Fig. 27. The virtual "- " 210 shows the location of the central ray 63 in Figs. 28a. 28b and 28c. The dashed lines 21 1 denote the reference line used in the exposure of the photoresist by sheet x-ray beam as described in Figs. 21 a and 21b or Figs. 21a and 21 c. The three masks have to be exposed sequentially after aligning each mask with the photoresist. A ; . Packaging The grids have to be assembled, and sealed for protection and made rigid for sturdiness. as will now be described. 1 . Assembly: A layer o the grid can be made in one piece or assembled together using a number of pieces and stacking the layers using pegs, as described in U.S. Patent Number 5.949.850. referenced above. 2. Sturdiness: The grid can be made rigid when two or more layers become physically attached after stacking to make a higher grid. A few of these methods are described below . • The grid and pegs can be soldered together along the outer border. • A layer of the grid, made of lead/tin. can be placed next to a layer of the grid made of a different material such as nickel. When heated, these two layers will be attached. This process can be repeated until the desired height is reached for the grid. • A layer of the grid does not hav e to be electroplated using just one type of material. For example, either the top or bottom surface, or both surfaces. of a predominantly nickel grid layer can be electroplated with lead/tin next to the nickel before it is polished to the desirable height. When layers of grids made by this approach are stacked together and heated, the various layers become phy sically connected. This method does not coat the whole grid with solder. • Many parts of an assembled and stacked nickel grid will be fused together w hen the grid is brought up near the annealing temperature. 3. Framed Construction: Instead of using pegs and fixed posts, a thick and wide frame can be sued for assembly and packaging. Fig. 29 is a side v iew of the grid showing frame 400. The bottom layer 401 of the grid has extra material at corners of the intersections of its walls as shown, for example, in Figs. 8, 10 and 1 7. to provide uniform exposure during grid motion, and the other grid lay ers 402 do not have extra material at the corners of their wall intersections. The frame 400 can be made by the SLIGA process as known in the art. Fig. 30 illustrates a top view of an exemplary frame 400. The shape of the frame wall can be any design appropriate for interlocking, and the material of w hich the frame is made can be any suitable material, as long as it is not excessiv ely soft. Also, the frame 400 can be made by joining two or more pieces together. The grid is assembled by fitting grid layers 401 and 402 into the frame. If grid layer 401 is attached to the substrate but the photoresist is removed, the frame 400 can be fitted over grid lay er 401. and the grid layers 402 can then be fit into the frame. Since the frame 400 provides structural support and alignment of the openings in the grid layers 400 and 401. the joints of the grid pieces as shown in Fig. 3 1 can be relaxed to straight borders 1 10 and 1 1 1. and do not need to be rounded as sho n in Fig. 1 8. for example. 4. Sealing: To protect the assembled grid, the grid has to be cov ered and sealed using low atomic number materials. There are a wide variety of commercially- av ai lable choices for sealing material. Although only a few exemplary embodiments of this invention have been described in detail above, those skilled in the art w ill readily appreciate that many modifications are possible in the exemplary embodiments w ithout materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims.

Claims: What is claimed is: 1. A grid, adaptable for use with an electromagnetic energy emitting device, comprising: at least one metal layer comprising: top and bottom surfaces: and a plurality of integrated, intersecting walls, each of which extending from said top to bottom surface and having a plurality of side surfaces, said side surfaces of said walls being arranged to define a plurality of openings extending entirely through said layer, at least one of said openings including at least one projection extending therein. 2. A grid as claimed in claim 1. wherein: said intersecting walls form said openings in a periodic pattern in a first direction along said top surface and in a direction perpendicular to said first direction. 3. A grid as claimed in claim 2. wherein: said projections are arranged such that a total amount of material of said walls intersected by a line propagating in a first direction for the length of one period along the grid is substantially the same for any period along the first direction. 4. A grid as claimed in claim 2. wherein: said projections are arranged such that a total amount of material of said walls intersected by a line propagating in a first direction for a first distance including at least one period along the grid is substantially the same as another total amount of material of said walls intersected by another line propagating in a second direction substantially parallel to said first direction for a second distance substantially equal to said first distance. 5. A grid as claimed in claim 1. wherein: said projections extend from intersecting locations at w hich certain of said walls intersect. 6. A grid as claimed in claim 5. wherein: at certain of said intersecting locations, two of said projections extend in opposite directions into different ones of said openings. 7. A grid as claimed in claim 6. wherein: said two projections have substantially the same area. 8. A grid as claimed in claim 6. wherein: said two projections have different areas. 9. A grid as claimed in claim 1 . wherein: at least one of said projections has two sides, each extending from a different one of said walls. 10. A grid as claimed in claim 9. w herein: said two sides extend substantially peφendicular to each other. 1 1 . A grid as claimed in claim 9. w herein: said two sides extend at an angle other than 90° w ith respect to each other. 12. A grid as claimed in claim 1. wherein: at least one of said projections has a side extending in a substantially straight direction between two of said w alls. 13. A grid as claimed in claim 1. wherein: at least one of said openings has a material disposed therein which is adapted to permit said electromagnetic energy to pass therethrough, an a second material suspended in said material which is adapted to substantially prohibit said electromagnetic energy from passing therethrough 14 \ grid as claimed in claim 1 wheiein at least one of said walls has a thickness different from at least one other of said walls 15 A grid as claimed in claim 1 wherein at least some of said walls intersect at an angle othei than 90° with lespect to each other 16 A gnd as claimed in claim 1 tuithei comprising a plurality ol said layers which aie stacked on top of each othei such that w alls of the lay ers aie substantially aligned so that the openings m the layers aie substantially aligned to foim openings which pass entuely thiough the gnd 1 7 A grid as claimed in 1 wherein each said projection is connected to at least one of said walls 18 A grid as claimed in claim 1 wheiein at least one said pi ojeclion is sepaiated h orn all ot said walls 19 A grid as claimed in 1 turthei compnsing at least one second metal lavei compnsing second top and bottom sui faces and a plurality of tegiated inteisecting second walls each ot which extending from said second top to bottom surface and hav ing a plurality of second side surfaces said second side sui faces of said second w alls being arranged to define a plui alitv ot second openings extending entnelv thiough said second lav er and said first and second layers are stacked on top of each other such that said first and second walls of said first and second layers are substantially aligned so that said first and second openings in said first and second layers are substantially aligned to form openings which pass entirely through the grid. 20. A grid as claimed in claim 1 . wherein: said first layer includes a material different from a material included in said second layer. 21 . A grid as claimed in claim 1. comprising: a plurality of said layers, at least one of said layers including a material different from a material included in any other of said layers. 22. A grid as claimed in claim 1. wherein: at least one said layer is attached to a substrate. 23. A grid as claimed in 1 . wherein: said walls extend between said top and bottom surfaces at respective angles to focus at a point which is at a distance from said top surface of said grid. 24. A grid as claimed in 1 . wherein: said walls extend between said top and bottom surfaces substantially parallel to each other. 25. A grid is claimed in 1. wherein: a first group of said walls extending along said grid in a first direction parallel to said top and bottom surfaces are substantially parallel to each other: and a second group of said w alls extending along said grid in a second direction parallel to said top and bottom surfaces each extend between said top and bottom surfaces at a respective angle with respect to said top and bottom surfaces to focus at a line extending in a direction substantially parallel to said top surface at a distance from said top surface. 26. A grid as claimed in 1. wherein: at least one said layer includes a plurality of sections, adapted to couple together to form said at least one said layer. 27. A method for minimizing scattering of electromagnetic energy in an electromagnetic imaging device that is adapted to obtain an image of an object on an imager. comprising: placing a grid between an electromagnetic energy emitting source of the electromagnetic imaging device and said imager. said grid comprising at least one metal layer including top and bottom surfaces and a plurality of solid integrated. intersecting walls, each of w hich extending from said top to bottom surface and having a plurality of side surfaces, said side surfaces of the walls being arranged to define a plurality of openings extending entirely through said layer, at least one of said openings including at least one projection extending therein: and moving said grid in a grid moving pattern while said electromagnetic energy emitting source is emitting energy toward said imager. 28. A method as claimed in claim 27. wherein: at least one of said openings has a non-square shape at said top surface, and said walls form said openings in a periodic pattern extending along said top surface of said grid in a first direction and a second direction substantially perpendicular to said first direction; and said moving step moves said grid in a direction of movement which is substantially parallel to said first direction, substantially perpendicular to said second direction, and transverse to respectiv e directions in w hich said walls extend along said grid. 29 A method as claimed in claim 27 wherein said mov ing includes mov ing said gnd along a substantially straight line at a substantially uniform speed 30 A method as claimed in claim 27 wherein said mov ing includes movmg said gnd in a forward and reverse oscillatory motion along a substantially straight lme at a substantiall y unifoim speed 31 A method foi minimizing scatteπng of electromagnetic energy in an electromagnetic imaging dev ice that is adapted to obtain an image of an object on an imagei. comprising placing a gnd betw een an electi omagnetic enei gv emitting source ot the electi omagnetic imaging dev ice and said imagei said gnd compnsing at least one metal lavei including top and bottom surfaces and a pluiahty of solid integrated. intersecting walls, each of which extending from said top to bottom suiface and having a pluiahtv of side sui laces said side surfaces of the walls being airanged to define a plui ahty ot openings extending entu elv thi ough said lav ei at least one of said openings hav ing a non-square shape at said top surface, and mov ing said grid in a gnd mov ing pattern while said electromagnetic energy emitting soui ce is emitting enei gv tow ai d said imagei 32 \ method as claimed in claim A w heiein said w alls forms said openings in a peπodic pattern extending along said top surface of said grid in a fust dnection and a second dnection substantially pei pendicular to said iii st dnection 33 A method as claimed in claim 32 wheiein said moving step mov es said gnd in a dnection oi mov ement w hich is substantially paiallel to said fu st dn ection substantially pei pendiculai to said second direction, and transverse to respective diiections in which said walls extend along said 34 A method as claimed in claim 31. w herein at least one of said openings including at least one projection extending therein 35 \ method as claimed in claim 31 wherein said moving includes movmg said gnd along a substantially stiaight line at a substantially uniform speed 36 \ method as claimed m claim 31 wheiein said moving includes moving said gnd in a foi aid and leveise oscillatory motion along a substantially stiaight line, at a substantially unifoim speed " >7 \ method foi making a gnd compnsing at least one layer having a pluiahty of mieisectmg walls defining openings therein, and being adaptable foi use with electromagnetic energy emitting devices, the method comprising apply ing a resist coating onto a substrate stiucture, covering at least a portion of the lesist with a first mask having a plurality of apei tines theiein niadiatmg lays of eneigy onto the fust mask such that some of the lays of energy enter at least some ofthe apertuies in the mask. iemovmg the portions of the lesist altei all lequired exposuies that weie irradiated by the lavs ol eneigv to cieutc openings in a lemaining portion oi the icsist and intioducing matenal into the openings in the lemaining portion of the lesist such that the matenal forms the inteisecting walls of the at least one layer of the gnd with at least one piojection extending mto at least one of said openings in the grid 38 A method as claimed in claim 37 tuithei compnsing after performing said covering and irradiating steps and prior to performing said removing step, performing the following: covering another portion of the resist with a second mask having a plurality of apertures therein: and irradiating rays of energy onto the second mask, such that some of the rays of energy enter at least some of the apertures in second mask. 39. A method as claimed in claim 37. wherein the rays of energy include X-rays, and the resist includes an X-ray resist. 40. A method as claimed in claim 37. wherein the rays of energy include UV rays, and the resist includes a UV resist. 41 . A method as claimed in claim 37. wherein said introducing step comprises electroplating the material into the openings in the resist. 42. A method as claimed in claim 37. further comprising: remov ing the remaining portion of the resist. 43. A grid, adaptable for use vv ith an electromagnetic energy emitting device, comprising: at least one metal layer comprising: top and bottom surfaces: and a plurality of periodic, solid integrated, intersecting walls, each of which extending from said top to bottom surface and having a plurality of side surfaces, said side surfaces of the walls being arranged to define a plurality of openings extending entirely through the lay er, al least one of said openings being non- square shaped, and said intersecting w alls forming said openings in a periodic pattern in a first direction along said top surface and in a direction perpendicular to said first direction. 44. A grid as claimed in claim 43, wherein: said layer includes a plurality of sections, adapted to couple together to form said layer. 45. A grid as claimed in claim 43, wherein: said layer includes at least one projection extending into at least one of said openings.

Inventors: TANG CHA-MEI, TANG, CHA-MEI
Applicants: CREATV MICROTECH INC, TANG CHA MEI, CREATV MICROTECH, INC., TANG, CHA-MEI
Application year: 2000
Main classification: G21K1
IPC codes: G21K1