Abstract:
Method and apparatus for providing a linearly or non-linearly tapered bore, with minor undulations within the bore wall, in vitreous tubing includes a laser and elements for focusing the laser onto the vitreous tubing. The vitreous tubing is rotated in the laser beam and is moved in the laser beam to provide a taper in the interior bore. The power of the laser beam is controlled and a lens, to provide a desired width of the beam at the vitreous tubing to produce the desired features, appropriately focuses the laser beam.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to vitreous unions that are used to couple glass and silica capillary elements together, their use and methods of their manufacture.  
         BACKGROUND OF THE INVENTION AND DESCRIPTION OF THE PRIOR ART  
         [0002]    U.S. Pat. No. 4,185,883 (Chown et al) discloses an optical fiber coupling element that includes a glass sleeve secured to a length of optical fiber. The optical fiber is placed in the glass sleeve, and the sleeve is heated so that it collapses around the fiber to hold the fiber in place.  
           [0003]    U.S. Pat. No. 4,869,745 (Flaming) discloses a micropipette puller that includes a mirror that is oscillated to move energy of a laser along a selected portion of glass tubing. The mirror varies the amount of heat transmitted to the glass tubing as the tubing is being pulled.  
           [0004]    U.S. Pat. No. 4,921,522 (Flaming) discloses a variation of the &#39;745 Patent. The &#39;522 Patent is a Continuation-in-Part of the &#39;745 Patent. A concave mirror is used in the &#39;522 Patent to direct the energy from a laser against glass tubing being pulled.  
           [0005]    It will be noted that none of the above-described patents refers to providing a non-linear taper in the glass or quartz tubing elements involved in the patents.  
           [0006]    U.S. Pat. No. 5,512,078 (Griffin) discloses a smooth surfaced linearly tapered bore, formed from glass tubing and using a controlled laser apparatus.  
           [0007]    It will be noted that the above-described patent describes unions for highly circular cross-section capillary elements.  
         SUMMARY OF THE INVENTION  
         [0008]    The invention claimed and described herein comprises a linear taper in vitreous tubing for connecting capillary circular and non-circular cross-section capillary elements, and the method and apparatus for making said linear connecting union.  
           [0009]    Energy from a laser is modulated by a chopper, which comprises rotating blades moved into and out of the laser beam. The modulated energy from the laser is directed against a rotating glass/quartz/silica tube through a focusing lens. The glass/quartz/silica tube is rotated and is moved, either in space or in time, in the laser beam. The more intense the beam, or the longer the beam impinges on a particular location of the glass tubing, the more the tubing bore collapses. Linear movement of the tubing in rotation and linear laser energy ramps result in linearly tapered interior bore of the quartz/glass/silica tubing. Application of energy of sufficient energy density and/or rapid, linear movement within the focal point of the laser forms a linear taper with slightly raised spiral ridges.  
           [0010]    Among the objects of the present invention are the following:  
           [0011]    To provide a new, non-linear taper in vitreous tubing;  
           [0012]    To provide a new and useful method for obtaining a non-linear taper in vitreous tubing;  
           [0013]    To provide a new and useful apparatus for non-linearly tapering the interior bore of vitreous tubing;  
           [0014]    To provide a new, linear taper in vitreous tubing;  
           [0015]    To provide a new and useful method for obtaining a linear taper in vitreous tubing;  
           [0016]    To provide a new and useful apparatus for linearly tapering the interior bore of vitreous tubing;  
           [0017]    To provide a new and useful apparatus for forming unions for joining capillary elements of similar and dissimilar diameters;  
           [0018]    To provide a new and useful apparatus for forming unions for joining capillary elements with non-circular shapes; and  
           [0019]    The novel features that are considered characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its structure and its operation together with the additional objects and advantages thereof will best be understood from the following description of the preferred embodiment of the present invention. Unless specifically noted, it is intended that the words and phrases in the specification and claims be given the ordinary and accustomed meaning to those of ordinary skill in the applicable art or arts. If any other meaning is intended, the specification will specifically state that a special meaning is being applied to a word or phrase. Likewise, the use of the words “function” or “means” in the Description of Preferred Embodiments of the invention is not intended to indicate a desire to invoke the special provision of 35 U.S.C. §112, paragraph 6 to define the invention. To the contrary, if the provisions of 35 U.S.C. §112, paragraph 6, are sought to be invoked to define the invention(s), the claims will specifically state the phrases “means for” or “step for” and a function, without also reciting in such phrases any structure, material, or act in support of the function. Even when the claims recite a “means for” or “step for” performing a function, if they also recite any structure, material or acts in support of that means of step, then the intention is not to invoke the provisions of 35 U.S.C. §112, paragraph 6. Moreover, even if the provisions of 35 U.S.C. §112, paragraph 6, are invoked to define the inventions, it is intended that the inventions not be limited only to the specific structure, material or acts that are described in the preferred embodiments, but in addition, include any and all structures, materials or acts that perform the claimed function, along with any and all known or later-developed equivalent structures, materials or acts for performing the claimed function. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0020]    [0020]FIG. 1 is a stomatic diagram of the apparatus for making the present invention.  
         [0021]    [0021]FIG. 2 is the view in partial section taken generally along line  2 - 2  of FIG. 1.  
         [0022]    [0022]FIG. 3 is a side view in partial section of vitreous tubing representative of the prior art.  
         [0023]    [0023]FIG. 4 is a side view in partial section of vitreous tubing made with the apparatus and by the method of the present invention.  
         [0024]    [0024]FIG. 5 is a block diagram illustrating the control systems of the present invention.  
         [0025]    [0025]FIG. 6 is a side view in partial section through a union of the present invention.  
         [0026]    [0026]FIG. 7 is a side view in partial section of a splitter precursor of the present invention.  
         [0027]    [0027]FIGS. 8A, 8B,  8 C,  8 D, and  8 E are sequential views in partial section illustrating the making of a splitter of the present invention.  
         [0028]    [0028]FIGS. 9,10, and  11  are side views in partial section illustrating the use of elements made by the present method and apparatus in their use environments. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0029]    A coupling element or union  160  of non-linear prior art is illustrated in FIG. 3. FIG. 3 comprises a view in partial section through the coupling portion of the quartz-tubing union  160 . A coupling element of union  180  of linear taper prior art is illustrated in FIG. 4, comprising a view in partial section through the coupling portion of the quartz tubing union.  
         [0030]    [0030]FIG. 7 is a side view in partial section of a union or coupling element  260  made by the apparatus of FIG. 1. The cross sectional configurations of the ferrule or coupling elements  160 ,  180  and  260  are clearly set forth.  
         [0031]    In FIG. 3, the coupling element  160  includes a bore  162  and a bore  166  spaced apart from each other and separated by a coupling bore  164 . The bores  162  and  166  have a relatively constant diameter, while the bore  164  has a varying diameter. When examined along the length of the bore, the diameter of the bore  164  is curved.  
         [0032]    For the coupling element or union  180  of FIG. 4, there are two linearly tapered bore portions  182  and  186  that taper inwardly towards a minimum diameter portion or throat  184 . The linear bores  182  and  186  may be similar or dissimilar in the shape of their taper, which taper is a uniform taper. Additionally, there is a groove or raised pattern  181  that is manufactured on at least the inner diameter of the union  180 , such as in bores  182  and  186 , respectively.  
         [0033]    For the coupling element or union  260  of FIG. 7, there are two linearly tapered bore portions  262  and  266  that taper inwardly towards a minimum diameter portion or throat  264 . The linear bores  262  and  266  may be similar or dissimilar in the shape of their taper, which taper is a uniform taper. Additionally, there is a groove or raised pattern  261  that is manufactured on at least the inner diameter of the union  260 , such as in bores  262  and  266 , respectively.  
         [0034]    The apparatus of FIG. 1 is used to make the patterns  261  and tapers  262  and  266  of the union  260 . The apparatus of FIG. 1 includes a carbon dioxide laser  12 , which provides an output light beam  14 . The power of the output light beam  14  is directed toward a beam splitter  16 . The beam splitter  16  reflects a portion  18  of the beam  14  to a power sensor  20 .  
         [0035]    The power sensor  20  senses the power output of the laser  12 . The laser power is modulated as appropriate through a pair of motors. The motors include a motor  24  that is coupled to a chopper  30 . The chopper  30  comprises a configured disk having a plurality of blades, and the blades rotate in the path of the beam  14 . The motor  24  rotates the chopper  30 .  
         [0036]    The motor  24  is mounted on a rack  50  that is coupled to a pinion gear  52 . The pinion gear  52  is in turn coupled to the output shaft of a reversible motor  54 . Rotation of the gear  52  by the motor  54  moves the chopper motor  24  towards and away from the beam  14 .  
         [0037]    [0037]FIG. 2 comprises a front or plan view of the chopper  30 . FIG. 2 is taken generally along line  2 -- 2  of FIG. 1.  
         [0038]    The chopper  30 , as indicated above, comprises a disk having a plurality of blades. The chopper  30  is illustrated as having four blades, including blades  32 ,  34 ,  36 , and  38 . The configuration of the blades  32 ,  34 ,  36 , and  38  provides a varying amount of surface area that reflects energy from the light beam  14  to a beam dump (not shown). The tips of the blades are the thinnest portions, and the thickness of the blades increases as the blades  32  . . .  38  go inwardly towards the shaft to which they are secured.  
         [0039]    Stated in the opposite manner, the thickness of the blades  32  . . .  38  tapers outwardly from a maximum to a minimum at the outer distal point or tips of the blades. The geometry or blade configuration may vary, as desired. The geometry of the blades varies the amount of energy from the beam  14  that is used, ultimately, in the manufacture of elements, such as the union  180  of FIG. 6, as the chopper  30  is moved into and out of the beam  14 .  
         [0040]    It will accordingly be understood that the closer to the beam  14  that the chopper center is, the greater the amount of that energy will be reflected by the chopper and the lesser the amount of energy that will be directed to the splitter  16  and onward from there, as will be discussed below.  
         [0041]    For maximum energy transmitted onward, the chopper  30  will be moved away from the beam  14  and will thus have a minimum surface area directed into the beam  14 , or no surface within the beam at all.  
         [0042]    By varying the location of the chopper  30  relative to the output beam  14  of the laser  2 , the output of the beam  14  may be modulated or controlled as desired.  
         [0043]    While a small portion  18  of the beam  14  is directed by the splitter  16  towards the power sensor  20 , the remaining portion of the beam, indicated by reference number  58 , is directed through the splitter  16  and through a shutter  60  to a lens  70 . The shutter  60  includes a housing  62  through which extends an aperture  64 . The aperture  64  is controlled by a shutter element  66 . The shutter element  66  is moved by a motor  68  or a solenoid to either allow the passage of the light beam  58  through the shutter  60  or block the aperture  64  and thus prevent the transmission of the light beam  58  to the lens  70 .  
         [0044]    The lens  70  is a focusing lens that may be moved to adjust the width of the beam  58  relative to a length of vitreous tubing  110 . The lens  70  is secured to a rack  72  that is moved through a pinion gear connected to a motor  74 . The rotation of the shaft of the motor  74  moves the lens  70  towards or away from the tubing  110  to focus the beam  58  on the tubing  110 , as desired.  
         [0045]    As illustrated in FIG. 1, the beam  58  is focused at a point on the tubing  110  to provide maximum intensity of the beam  58  at the location of the focus point on the tubing  110 .  
         [0046]    Movement of the lens  70  changes the focus of the beam  58 , and accordingly changes the concentration of the power of the beam relative to the tubing  110 .  
         [0047]    A motor  120 , to which the tubing  110  is appropriately secured through a chuck or collet, in a spindle, rotates the tubing  110 . The tubing  110  is also moved vertically relative to the beam  58  by means of a motor  130 . The motor  130  drives a screw  132  to which a nut  122  is secured. The nut  122  is in turn secured to the motor  120  so that rotation of the screw  130  moves the nut  122 , the motor  120 , and the tubing  110  vertically relative to the beam  58 .  
         [0048]    The tubing  110  is, of course, preferably a vitreous form of silica, but may be other vitreous or crystalline materials and still fall within the scope of the present invention, and the heating thereof produces vapor and dust. The vapor and dust are removed from the tubing  110  by means of a vacuum head  140  that is connected to a vacuum conduit  142 . A vacuum pump motor  144 , illustrated in FIG. 5, in turn produces the vacuum necessary for the removal of the dust or particulates to an appropriate trap through the conduit  142 .  
         [0049]    Control of the apparatus is illustrated in FIG. 5, which comprises a block diagram of the various control elements involved. There are two control systems involved, a computer control system  200  and a manual control system  220 . The manual control system  220  comprises override controls, which move the various elements to the starting positions as desired.  
         [0050]    There are stepper motor drivers  202  that are connected to the motors  54  and  130 . The motors  54  and  130  are stepper motors that move incrementally, as desired. The motor  54  moves the chopper  30  and its motor  24  towards and away from the beam  14 . It will be noted that the chopper  30  is disposed at about a 45-degree angle to the light beam  14 .  
         [0051]    The motor  130  is a stepper motor, which moves the tubing  110  and its rotational motor  120  vertically relative to the beam  58 .  
         [0052]    To begin the operations, the shutter  66  must be withdrawn from the aperture  64 . A shutter controller  204  controls the movement of the shutter  66 .  
         [0053]    A spindle rotation controller  206  controls the control of the spindle rotation motor  120 , which rotates the tubing  110 .  
         [0054]    Finally, there is a lens position motor controller  208  that controls the motor  74  to move the lens  70  relative to the light beam  58  and to the tubing  110 .  
         [0055]    Each of the controllers may be manually adjusted by the plurality of manual controls  220 . This allows the various controllers to be moved to the starting positions, as required. There is also a manual control for actuating the vacuum pump motor  144 .  
         [0056]    [0056]FIG. 6 is a view in partial section through union  260 . The union  260  is shown in partial section, with its three bore portions  262 ,  264  and  266 . It will be understood that during manufacture the beam remains fixed in place, and that the union  260  itself moves. For purposes of illustration however, the union  260  is shown in cross section.  
         [0057]    Initially the focus of the carbon dioxide laser  12  is displaced outward from the union  260 . Power is held steady at low power and the union  260  is moved through the laser  12  focal region under relatively rapid rotation and relatively rapid translation. The rotational speed and translational speed are adjusted to provide an outer groove or pattern  261 , which is an undulation spacing, as desired on the outer diameter of the union  260 . This outer pattern  263  on the outer diameter is translated, via melting, to an inner groove or pattern  261 on the inner diameter, such as bores  262  and  266 , but to a lesser (or greater) extent. More closely spaced patterning is accomplished using a tighter laser focus and slower translation. In an alternate embodiment, the undulating spacing pattern may be desired to have two different directions. In this embodiment, the union  260  may be “screwed on” to two capillaries at the same time, from opposing directions, as in a threaded cable tensioner. This pattern is accomplished by closing the shutter at mid-point and reopening it for the untreated half on the reverse rotational direction. It is recognized that a wide variety of different patterns, such as helical, evenly spaced grooves, non-evenly spaced grooves, a series of dimples, and the like may be produced and therefore also fall within the scope of the present invention.  
         [0058]    Once the desired groove pattern is produced, a cone shape in the inner diameter of the union  260  is formed. The wide end of the bore  182  starts with low power to the laser, and as the power increases, the diameter of the bore decreases. Thus, the bore  182  tapers from a maximum diameter to the center portion  184 , which is minimum diameter. The center portion  184  comprises a maximum power output of the carbon dioxide laser  12  focused on the union  260 . The modulation of the power of the laser  12  is accomplished by movement of the chopper  30  into and out of the output beam  14  of the laser  12 , as discussed above.  
         [0059]    Alternatively, one might elect to split the carbon dioxide laser output to into tightly focused and less focused portions, imparting the glass tube simultaneously forming both the general conical and undulating thread pattern in a single pass through the beam. In some dimensional embodiments, it may be preferable to form the general conical tapers prior to the undulating thread pattern as well.  
         [0060]    [0060]FIG. 7 is a view in partial section through a splitter precursor  260 . The splitter precursor  260  is shown in partial section. The splitter precursor  260  includes at least an inner pattern  261  and three bore portions, a tapered bore portion  262 , a curved central bore portion  264 , and a second tapered bore portion  266 . The bore portions  262  and  266  are mirror images of each other, while the bore portion  264 , between the bores  262  and  266 , comprises a generally oval shaped bore portion in which the diameter increases from a minimum to a maximum and then decreases from the maximum to the minimum. The bore portion  264  is a curved bore, as opposed to the linear taper of the bores  262  and  266 . The central bore  264 , rather than having a uniform cross section, as does the bore portion  264  of the coupler  240 , has a curved configuration, as indicated above. The oval curvature of the bore  264  is accomplished by increased translational speed of the element  260  in the beam  58 .  
         [0061]    The translational speed of the element  260  is held constant while the power is increased to form the bore portion  262 . When the minimum diameter of the bore portion  262  has been received, the power is held steady for a period of time. The translational speed of the element  260  is held steady during the formation of the bore  262 . At a point in time corresponding to the beginning of the bore portion  264 , when the power is held steady at maximum power the translation speed is increased to a maximum. The translation speed is then held steady.  
         [0062]    At the end of the bore portion  264 , the translational speed is decreased suddenly and reversed twice before returning to the speed employed to produce  262  for producing  266 . The double reversal of translation serves to reheat the quartz before proceeding to formation of bore  266  providing similar conditions as were present when forming bore  262 .  
         [0063]    The fabrication of a splitter is illustrated in FIGS. 8A, 8B,  8 C, and  8 D.  
         [0064]    In FIG. 8A, the splitter precursor  260  is shown in cross section. In FIG. 8B, the precursor element  260  is shown with a hole  268  that extends radially through the precursor at the curved bore  264 . In FIG. 8C, the precursor element  260  is shown bent to receive a precursor half. The precursor half comprises the third leg of a complete splitter.  
         [0065]    [0065]FIG. 8D comprises a view in partial section of a half precursor  270 . The half precursor or precursor half  270  includes a half of a center curved bore  274  and a tapered bore  276 . The bore  274  comprises essentially half of the bore  264 , and the bore  276  corresponds to the bore  266 . The half element  270  is one half of a precursor element  260 . Accordingly, three precursor elements are used to make two splitter elements.  
         [0066]    A splitter  300  is shown in FIG. 8E in partial section. The splitter  300  comprises the splitter  260  of FIG. 8B bent to form an inverted “V”, as shown in FIG. 8C, with the splitter half  270  appropriately secured to the hole or aperture  268 , as widened by the bending of the splitter  260 . The splitter half  270  is then appropriately fused to the bent precursor splitter  260  to form the splitter  300 .  
         [0067]    [0067]FIG. 9 is a view in partial section of a union  260  used as a coupling element, coupling together two capillary elements of similar diameters. The capillary elements include a capillary element  310  and a capillary element  312 . The capillary element  310  is disposed in the bore  262 , and the capillary element  312  is disposed in the bore  266 . It will be noted that the ends of the capillary elements  310  and  312  are spaced apart an equal distance from the center  264  due to the symmetrical nature of the two bores  262  and  266  relative to the center bore portion  264 . The inner pattern  261  contacts and securely holds the capillary elements  310  and  312  even if they have non-uniform cross-section and slightly dissimilar diameters, through differential compression of the polymer buffer coatings.  
         [0068]    [0068]FIG. 10 is a view in partial section through the union  260  illustrating the coupling of capillary elements of dissimilar diameters. A capillary element  316  is shown disposed in the bore  262 , and a capillary element  318  is shown disposed in the bore  266 . The inner pattern  261 , in this embodiment, contacts and securely holds the capillary elements  316  and  318  even if they have non-uniform cross-section and widely dissimilar diameters.  
         [0069]    The diameter of the capillary element  316  is substantially larger than the diameter of the capillary element  318 . Accordingly, there is a substantial difference in the distance between the center portion  264 , which is the minimum diameter bore portion, and the inner end of the capillary element  316  relative to the inner end of the capillary element  318 . The inner end of the capillary element  318  is much closer to the center bore portion  264  than is the inner end of the larger diameter capillary element  316 .  
         [0070]    Since the bore portions  262  and  266  have substantially identical tapers, there is a common centerline or longitudinal axis of the two bores. Accordingly, the capillary elements  316  and  318  are aligned coaxially with respect to each other as well as with respect to the bores  262  and  266 . Similarly, the capillary elements  310  and  312  are coaxially aligned with each other since the bores  262  and  286  have substantially identical tapers.  
         [0071]    The preferred embodiment of the invention is described above in the Description of Preferred Embodiments. While these descriptions directly describe the above embodiments, it is understood that those skilled in the art may conceive modifications and/or variations to the specific embodiments shown and described herein. Any such modifications or variations that fall within the purview of this description are intended to be included therein as well. Unless specifically noted, it is the intention of the inventors that the words and phrases in the specification and claims be given the ordinary and accustomed meanings to those of ordinary skill in the applicable art(s). The foregoing description of a preferred embodiment and best mode of the invention known to the applicant at the time of filing the application has been presented and is intended for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and many modifications and variations are possible in the light of the above teachings. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application and to enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated.