Abstract:
An apparatus and method for protecting at least one component of a light source are provided. The apparatus includes a shield for the component, with this shield having a plurality of locations that are substantially transparent to an emission wave length of the light source. The shield is positioned such that during use of the light source, one of the substantially transparent locations of the shield is disposed between the at least one component of the light source and an object that is to be irradiated. The apparatus also includes a mechanism for advancing the shield upon activation of the light source or an element thereof in order to be able to dispose a different one of the substantially transparent locations of the shield between the at least one component of the light source and an object that is to be irradiated.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an apparatus and method for protecting at least one component, especially an optical component, of a light source. 
     Sources of light beams, and in particular laser systems, are used for ablating biological and non-biological substrates and for cutting various materials. In such applications, energy, especially laser energy, is applied to heat the substrate or material, or some component thereof, causing controlled vaporization. In the case of lasers, the systems thereof generally include a light source for generating laser light, and optical components for directing the laser beam to a target. The laser source may produce continuous or pulsed laser energy output. The delivery of laser energy to a target specimen and subsequent vaporization of a portion of the specimen often produces byproducts, such as smoke, carbonized particles and/or splattered particles from the specimen. These byproducts pose a threat to the consistent operation of the laser system in that they may be deposited upon the objective optics of the system, thus damaging or altering the optical components, reducing output power, distorting the pattern of energy distribution within the light or laser beam, or otherwise contributing to the degradation of the system. 
     One particular application of such laser systems includes laser finger perforators that are used to sample capillary blood for analysis of glucose and other blood chemistry measurement. The laser penetrates the finger by vaporizing and ablating tissue to create a small hole in the skin down to and including intersecting some of the capillaries. The vapor and additional small particles that are ablated when creating the hole in the finger can adhere to the surface of the laser lens. As described above, such adhered material will change the characteristics of the lens, such as its focus and light transmission parameters. These resultant changes can cause pain to the patient and/or make it more difficult to draw blood. 
     In view of the foregoing, it can be seen that there is a great need for providing means to protect the components of a light source, and in particular the optics thereof. This has been addressed by the prior art in several ways. One such way is to position the optics at a distance from a specimen that is great enough that vaporized or ablated material from the target area cannot reach the optics. Such a passive approach makes for a rather large device and is not a satisfactory solution. U.S. Pat. No. 5,148,446, Radich, discloses the protection of the objective lens of a laser system by directing a flowing fluid, such as air, over and away from the surface of the lens, thus directing ejected particulates away from such lens. This system is complicated and expensive, generally requires external power supply and pumps, and is not amenable to miniaturization. Also known are disposable protective devices that are manually inserted between the objective optics of laser system and the source of possible ablated material. Such protective devices are single-use components that must be discarded and replaced for each procedure (see PCT publications WO 98/04201 and WO 98/47435). 
     It is therefore an object of the present invention to provide an improved means for protecting components of a light source, and in particular an apparatus and method that can be used for extended procedures and/or for multiple procedures, thereby reducing the amount of waste generated, the number of disposable components that need to be provided, the danger of forgetting to replace a used protective device, and possibly also reducing the cost of operation of such a system. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     This object, and other objects and advantages of the present invention, will appear more clearly from the following specification in conjunction with the accompanying schematic drawings, in which: 
     FIG. 1 illustrates a laser finger perforator employing the novel protection apparatus of the present invention; 
     FIG. 2 a  illustrates one exemplary embodiment of the inventive protection apparatus; 
     FIGS. 2 b  and  2   c  show exemplary advancement means for the protection apparatus of FIG. 2 a;    
     FIGS. 3 a - 3   c  show further exemplary embodiments of the inventive protection apparatus in the form of disks; and 
     FIG. 4 shows another exemplary embodiment of an inventive protection apparatus. 
    
    
     SUMMARY OF THE INVENTION 
     The inventive apparatus and method for protecting at least one component of a light source are characterized primarily by means for shielding the component, and by means for advancing the shielding means. The means for shielding is held by the light source, and especially by a housing thereof, and is provided with a plurality of locations that are substantially transparent to an emission wave length of the light source, with such means for shielding being positioned such that during use of the light source, one of the substantially transparent locations is disposed between the component of the light source and an object that is to be irradiated. The means for advancing the shielding means operates upon activation of the light source or an element thereof, such as a control lever, lens cover, etc., in order to be able to dispose a different one of the substantially transparent locations of the shielding means between the component of the light source and the object that is to be irradiated. 
     The present invention thus discloses a device for use with light sources, and especially laser systems, with such device being replaceable or disposable after multiple use thereof. The inventive device or apparatus includes a substantially transparent location, such as a thin strip or sheet of film, glass or crystalline material, that is disposed between an object, such as the surface of skin, and an optical element of the light source. The area of the substantially transparent material either has a cross-sectional area that is many times that of the light beam that is emitted by the light source, or has several such sections. Thus, the area of the lens shielding means through which the light beam passes can be renewed, i.e., a fresh section can be provided, by moving a new section of material to the area through which the beam of light passes. 
     The inventive apparatus can be disposed of and replaced after the multiple substantially transparent locations of the shielding means thereof have been all used. Alternatively, the shielding means of the inventive apparatus can be in the form of an endless or reversible strip or disk, which can then be continuously or periodically cleaned to remove material that has adhered thereto, thus affording the inventive apparatus a very long useful life. 
     Further specific features of the present invention will be described in detail subsequently. 
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now to the drawings in detail, although the present invention will be described primarily in conjunction with a laser device for perforating the skin of a living being, it is to be understood that any other device that uses a light source and involves potential splattering of a lens or other critical components of the device with debris, for example with blood, body fluid or non-living matter, and therefore requires protection of such component, is contemplated by the present invention. 
     FIG. 1 schematically illustrates a laser perforator that is provided with the novel protection apparatus of this invention, which is generally indicated by the reference numeral  20 . The laser perforator includes a housing  10  in which is disposed a light source  11 , which in the illustrated embodiment is a laser source. The laser perforator also includes a lens or other optical component  12  through which the laser source  11  emits a light beam  13 , here a laser beam, which is then focused by the lens  12 . The focused laser beam  13  exits the housing  10  via the aperture  14 , whereupon the beam  13  perforates the skin surface  15 . Hingedly connected to the housing  10  is an optional lens cover  16 . The protection apparatus or lens shield  20  is disposed between the lens or optical component  12  and the aperture  14  in the housing  10 . Although the lens shield  20  is shown as extending over the entire width of the housing  10 , it need not do so. 
     One preferred specific embodiment of the inventive lens shield  20  is illustrated in FIGS. 2 a  and  2   b . In particular, in this embodiment the lens shield  20  is in the form of a reel-to-reel or spool-to-reel cartridge or cassette  21 . This cartridge has a housing  22  in which is disposed a thin strip of film  23  that is initially wound on a first spool  24  (or similar film storage means) and extends to a second spool or reel  25  that is adapted to receive the film  23  from the first spool. The film  23  is substantially transparent to an emission wavelength of the light source  11 , in other words, is substantially transparent to the laser beam  13 . Since the strip of film  23  has a given length, it has a plurality of substantially transparent locations for the laser beam  13 , with such plurality of locations being provided by advancement of the film  23  in a manner to be described in detail subsequently. To allow the laser beam  13  to pass through the lens shield  20 , one side  27  of the housing  22  of the cartridge  21  is provided with a window  28  in front of which the strip of film  23  passes. A window  29  is aligned with the window  28  on an opposite side  30  of the housing  22 . Alternatively, the side  30  of the housing  22  could be essentially open. The cartridge  21  can be removably supported in the housing  10  of the laser perforator, for example in brackets provided on the housing. 
     The inventive protection apparatus or lens shield  20  is also provided with means  32  for advancement of the shield means, in other words, the strip of film  23 . FIG. 2 b  shows one exemplary embodiment of such advancement means, which in this case is an automatic advancement means. In the illustrated embodiment, a rod  33  is pivotably mounted to the lens cover  16  of the laser perforator. The rod  33  is a rack that is provided with teeth  34  that mesh with a tined wheel  35  that is mounted on the winding spool  25 . Thus, when the lens cover  16  is opened in order to be able to use the laser perforator, the rod  33  will be pulled in the direction of the arrow through a slot in the end wall of the housing  10  and will rotate the wheel  35  as a result of engagement of one of the teeth  34  with one of the tines  36 , thereby rotating the spool  25  and hence automatically winding the strip of film  23  further onto the spool  25  and thereby advancing a clean location of the film  23  in front of the window  28  of the cartridge  21 . When the film is completely used, the cartridge can be removed and disposed of; a new cartridge  21  is then inserted into the housing  10 . 
     It is to be understood that other means for activating the advancement means  32  could also be provided. For example, as shown in FIG. 2 c , a rod  37  could be connected to a control lever  38  or wheel on the housing  22 . One end of the rotatably mounted rod  37  is provided with teeth  34 ′ that are adapted to mesh with the teeth of a wheel  35 ′, which is mounted on the spool  25  and can be a toothed gear or a tined wheel similar to the wheel  35  of the advancement means  32  illustrated in FIG. 2 b . When the lever  38  is pulled, the rod  37  rotates in the direction of the arrow, thereby rotating the wheel  35 ′ and hence the spool  25 , thereby again advancing the film or strip  23 . The teeth  34 ′ of the rod  37  could also mesh with internal teeth provided in the spool  25  or an extension thereof. In addition, the rod  33  or  37  could be connected to a separate motor that could be activated by an on/off switch or that can be electronically controlled in response to operating parameters of the laser perforator. Such a motor could also be directly connected to the winding spool  25 . Thus, the means for advancing the film or other shield means could be automatically or manually activated means, such as mechanical linkage means or electronic means. 
     The laser perforator, or similar light-emitting device, can be provided with an interlock or disabling means so that the device cannot be operated unless a shield means is present at all and/or the advancement means has operated to dispose a clean or renewed section of the strip of film or shield means in the path of the light beam  13  that is to be emitted. The light-emitting device can also be provided with a sensor or other means to detect and indicate whether or not a cartridge  21  or other type of lens shield has been inserted into the device. 
     In the embodiment illustrated in FIGS. 2 a - 2   c  the strip of film  23  is provided in the cartridge  21 . However, it is to be understood that a strip of film similar to the film  23  could be wound directly onto spools that are preferably both rotatably mounted on the housing  10 . In such a case, rather than replacing the cartridge  21 , the strip of film  23  itself would have to be replaced. 
     FIG. 3 a  shows a further exemplary embodiment of the inventive protection apparatus or lens shield, which in this case is indicated generally by the reference numeral  20 A. In this embodiment, the lens shield is in the form of a disk  39  that is provided with a plurality of windows  40 . A sheet  41  of film, glass or crystalline material, which as in the case of the strip or film  23  is substantially transparent to an emission wavelength of the light source, is disposed behind the windows  40 . Rather than utilizing the sheet  41 , it would also be possible to provide discrete pieces of film, glass or crystalline material behind each individual window  40 . As was the case with the lens shield  20 , the lens shield  20 A is disposed between the optical component  12  and the aperture  14 . The disk  39  is again advanced by advancement means, similar to the means  32  of the previously described embodiments, in order to advance the windows  40  in front of the aperture  14  of the housing  10 . This can be accomplished, for example, by providing the rod  37  with teeth that can engage internal teeth provided in the central portion  42  of the disk  39 , or by having the teeth  34  of the rack  33  engage teeth provided on the periphery of the disk  39 . 
     In the embodiment illustrated in FIG. 3 b , rather than having discrete windows  40 , the disk  39  is provided with a continuous window  43 , thus exposing a ring of the sheet  41  of film, glass or crystalline material. 
     The lens shield  20 C of the FIG. 3 c  is a disk  39  formed entirely of, for example, glass or crystalline material  44 . 
     A further exemplary lens shield  20 D is illustrated in FIG.  4 . In this embodiment, a thin sheet of film, glass or crystalline material  45  is disposed in a frame  46 , which can be made of any suitable material, including plastic, cardboard or metal, as is also the case with the embodiments of FIG. 3 a  and  3   b . The lens shield  20 D could also be provided with discrete windows as in the previously described embodiment. To advance the lens shield  20 D through the housing  10 , the means  32  for advancement can, via an appropriate gear wheel or the like, engage the sprocket means  47  provided on one side of the frame  46 . 
     It is to be understood that in all of the illustrated embodiments, the plane of the film, glass or crystalline material  23 ,  41 ,  44  or  45 , when the same is aligned with the aperture  14  of the housing  10 , is generally perpendicular to the axis of the light or laser beam  13 . 
     It should be noted that the strip of film could also be an endless strip or a reversible strip. In such a case, a cleaning means is provided for cleaning the film. Such a cleaning means could also be provided for the disks of FIGS. 3 a - 3   c , or the sheet of FIG.  4 . 
     Instead of the housing  10  being provided with an end wall that is then provided with the aperture  14  for the light beam  13 , the inventive protection apparatus or lens shield  20 - 20 D could itself form the end of the housing  10 . 
     It should also be noted that where the objective lens of the light source or laser device is required to be a focusing lens for certain applications in order to generate relatively high laser energy at a target surface, it is preferable in such instances to locate the inventive lens shield at a distance from the area of highest intensity in order to avoid thermal damage to the lens shield material, especially the strip or sheet of film, glass, or crystalline material. 
     As indicated previously, the rate of advance of the various lens shields of the present invention could be controlled as a function of various parameters of the light source device. For example, when used with a continuous wave type laser device, the lens shield could be advanced continuously at a rate dependent upon the output power of the laser device, moving slowly when a low power is used and more quickly when high power is being used, and stopping altogether when no laser light is being emitted. Similarly, when used with a pulsed laser device the lens shield could be advanced after each pulse, or after a given number of pulses. Furthermore, as indicated previously, the lens shield could be automatically advanced each time that the light or laser device is activated. 
     The glass, film or crystalline material of the inventive lens shields has a thickness preferably ranging from 20 μm to 2 mm. As indicated, the thin sheet or strip can be made of glass, polymeric material, such as polyester or polypropylene, or crystalline material, such as sapphire, CaCl, garnets, including yttrium aluminum garnet (YAG), and other suitable materials. The selection of material depends upon the requirements and properties of the laser system. The lens shield could be provided to produce simultaneous controlled alteration of the laser beam, for example, polarization, spatial filtering or spectral filtering of the beam as it passes through the strip or sheet of material. The glass, film or crystalline material could also be provided with a pattern such that the transparent areas differ in degree of transparency, diffractivity, or refractivity. Holographic filters could also be provided. 
     In view of the foregoing, it can be seen that this invention not only provides a new protection apparatus or lens shield for light-emitting sources, but also this invention provides a new method for protecting components of a light source. 
     The present invention is, of course, in no way restricted to the specific disclosure of the specification and drawings, but also encompasses any modifications within the scope of the appended claims.