Abstract:
A system for self-aligning assembly and packaging of semiconductor lasers allows reduction of time, cost and testing expenses for high power density systems. A laser package mounting system, such as a modified TO-can (transistor outline can), has modifications that increase heat transfer from the active laser to a heat exchanger or other heat sink. A prefabricated heat exchanger assembly mounts both a laser package and one or more lenses. Direct mounting of a fan assembly to the package further minimizes assembly steps. Components may be physically and optically aligned during assembly by clocking and other indexing means, so that the entire system is self-aligned and focused by the assembly process without requiring post-assembly adjustment. This system can lower costs and thereby enable the use of high powered semiconductor lasers in low cost, high volume production, such as consumer items.

Description:
RELATED APPLICATIONS 
     This application is a Divisional of U.S. application Ser. No. 12/623,886, filed on Nov. 23, 2009, now U.S. Patent Publication No. US 2011/0122905 A1, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Lasers have a wide variety of uses, and the number of uses expands as the benefits of lasers are tested in new markets. Such expanded uses often require significant innovation to meet the demands of new uses. Availability of new types of lasers is important in this process. Presently, many new wavelengths of inexpensive laser diodes are now available, and their properties have potential for broadening the use of lasers in industry, medicine and home uses, by opening up applications that require higher power lasers for high volume low cost applications. 
     To make such projects practical, it is necessary to solve key problems. In particular, higher power requires improvements in numerous areas, including heat dissipation, size, cost, and safety. It is especially important to be careful to minimize costs for laser systems intended for home use and other consumer or non-traditional laser markets. In such markets, there is a need for efficient manufacturing, to obtain costs suitable for mass marketing. 
     Cost minimization requires not only large volume production of components, but minimization of complexity and associated assembly labor. In particular, rework or manual adjustment of alignment should be avoided. Such problems have been solved for low power semiconductor optical devices, such as LEDs (light emitting diodes) used in reading optical discs and the like. In these systems the semiconductor LEDs need to have certain power levels, but precise optical alignment and focus are not required, because emission is close to the disc, and detection of signal does not require precise focusing. The absence of a requirement for focusing or re-focusing is typical of current large-volume laser chip applications. 
     However, emerging uses for low cost high power lasers, for example as described in our co-pending application PCT/US2009/001350, published as WO 2009/111010 A1, require precise optical alignment of a laser with an instrument, and in some cases a sharp focus. Yet in consumer uses, the cost of the laser components of a system must be minimized. The production cost of such systems comprises the production of the laser semiconductor chips; the mounting of the chips in a device; and the alignment and testing of the device. 
     SUMMARY OF THE INVENTION 
     Testing and alignment still require human participation for each device. Removal or minimization of human labor is a critical component for allowing the use of high power lasers in mass-market or other high volume devices, which can include portable medical equipment and other applications requiring high laser power, especially in those uses also requiring focus and/or alignment of the laser beam. 
     A potentially inexpensive laser system is described in which potentially multi-Watt laser capabilities are provided in a package suitable for mass production and consumer use. A wide variety of wavelengths can be provided by the system, including in particular wavelengths of 500-2000 nanometers (nm). For consumer use, eye-safe wavelengths emitted in regions of high water absorption are preferred. 
     Aspects of the present invention concern a laser system that is capable of making high powered laser techniques available for high volume market uses, for example in medical clinics, field medical applications, forensics/law enforcement, and/or consumer use. A key innovation is the combination of a variety of techniques to produce a laser system that can be assembled from simple parts in a few motions or manufacturing steps, and which can emerge from assembly in a state of optical alignment and “plug and play” operation, whether powered from a wall socket or a battery pack. 
     The system is characterized in being largely self assembling from suitably configured parts. In a first aspect, the system is made self-assembling by the provision of parts that can be assembled simply by physical contact of the parts. For example, a chip carrier and a heat sink are configured so that the carrier, with the chip bonded to it, can be inserted into the heat sink and held in place by closeness of fit, optionally augmented by adhesive or solder. In a second aspect, the system is self-clocking rotationally. In a third aspect, the components are self-aligned at least in part by their radial centering within a cavity in at least one component. 
     In other aspects, the system further comprises at least one optical element. The optical element is preferably mounted via the cavity in the system. A fan may be included in the system to improve heat removal. Each component which is not functionally rotationally symmetric is preferably clocked during the assembly process so as to be joined in a predetermined rotational position with respect to the rest of the system. 
     In general, according to one aspect, the invention features a laser system, comprising: a heat exchanger having a bore extending through the heat exchanger; a carrier on which a semiconductor gain chip is mounted, at least part of the carrier being mounted in the bore; and lens mounted on the heat exchange and over the bore. 
     In embodiment, a fan for flowing air over the heat exchanger is provided. In another example, the fan flows air on or about the area that the laser light is project onto. 
     In general, according to another aspect, the invention features a method for assembling high powered semiconductor laser systems to provide lasers which are passively or self-aligned and have predefined focal points or imaging planes without post-fabrication adjustment, wherein the method comprises: affixing a semiconductor laser chip to a carrier, said carrier having power connections and heat spreading means; placing said carrier into a heat-exchanging relationship with a heat exchanger, whereby said heat exchanger and said carrier are passively or self aligning into an efficient heat exchanging contact; and affixing an optical element to one or both of said heat exchanger for said diode laser, and said carrier; wherein laser systems produced by said method each have at least one output laser beam from each semiconductor laser chip, each beam having a predefined direction of propagation without post-fabrication adjustment. 
     In embodiments, the chip is connected to the carrier via a heat-spreading mount attached to a body of said carrier, mount has a body which sets the depth of engagement with the heat exchanger. The heat exchanger has a central bore, and the outer surface of the bore-entering portion of said mount and the inner surface of said bore are constructed to create close proximity between their surfaces, upon assembly, to allow efficient heat transfer between said laser diode and said heat exchanger. Preferably, the components are mutually self-aligned at least in part by their radial centering within a cavity in at least one component. In some cases each component which is not functionally rotationally symmetric is self-aligning during the assembly process so as to be joined in a predetermined rotational position with respect to the rest of the system. 
     For assembly, a basis for clocking is providing at least one of said fins to be distinguishable from other fins in shape or location. The laser facet is centered in the system when the assembly is completed by affixing said laser to a location on said carrier in a location that will be centered after the mutual alignment of said carrier and said heat exchanger. 
     In general according to another aspect, a method for assembling semiconductor laser systems to provide lasers which are self-aligned and have predefined focal distances or imaging planes, without post-fabrication adjustment, wherein the method comprises: affixing a semiconductor laser chip to a carrier; and placing said carrier into a heat-exchanging relationship with a heat exchanger, wherein said heat exchanger and said carrier are self aligning into a heat exchanging contact. 
     In general according to another aspect, a method for assembling optical systems which are self-aligned and have predefined focal distances or imaging planes, without post-fabrication adjustment, wherein the method comprises affixing an optical element to a heat exchanger for a diode laser; and placing said optical element into a heat-exchanging relationship with a heat exchanger, wherein said heat exchanger and said optical element are self aligning into a heat exchanging contact. 
     In general according to another aspect, the invention features a laser diode mounting system, the system comprising: a semiconductor laser; at least one heat spreading member; a heat exchanger; and at least one optical component, said optical component affixed to one or more of said carrier and said heat exchanger; wherein the lasers produced by said method each have an output laser beam from said semiconductor laser chip, each beam having a predefined direction of propagation without adjustment. 
     In general according to another aspect, the invention features a housing system, which acts as an enclosure for a laser system, with at least one contact located at the interface where the light is emitted, which when enabled, permits operation of the laser assembly. 
     In examples, a contact of is enabled by a rolling motion a pressure sensor. In some examples, the optical emission is proportionally controlled by feedback from the contact. 
     The above and other features of the invention including various novel details of construction and combinations of parts, and other advantages, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular method and device embodying the invention are shown by way of illustration and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the accompanying drawings, reference characters refer to the same or similar parts throughout the different views. The drawings are to scale. Of the drawings: 
         FIG. 1  is a partially-exploded perspective view of a laser system that embodies aspects of the invention. 
         FIG. 2  is a cross section of the laser system of  FIG. 1 . 
         FIG. 3  is a perspective view of the laser chip and its mounting. 
         FIG. 4  is a face-on front view of the mounted laser chip. 
         FIG. 5 a    is perspective view of a lens suitable for the laser system. 
         FIG. 5 b    is face-on view of a lens in the “x” direction suitable for the laser system. 
         FIG. 5 c    is face-on view of a lens in the “y” direction suitable for the laser system. 
         FIG. 6  is a face-on view of the lens mounted to the laser system of  FIG. 1 . 
         FIGS. 7 and 8  show a device that embodies aspects of the invention with an alternative lens mounting system. 
         FIGS. 9 and 10  show a device that embodies aspects of the invention having a simple mounting system when a finned or other high-area heat exchanger is not required. 
         FIG. 11  shows the instrument of  FIG. 1 or 7  with an attachable cooling fan. 
         FIGS. 12 and 13  show an example of methods that passively align the embodiments of a laser engine 
         FIG. 14  shows a method of a self-aligning laser engine. 
         FIG. 15  shows a perspective view of a housing system for enclosing an assembled laser engine with an embedded a sensor system. 
         FIG. 16  shows a perspective view of an alternate housing system from  FIG. 15  for enclosing an assembled laser engine with an embedded a sensor system. 
         FIG. 17  shows a block diagram of a housing system for enclosing an assembled laser engine with an embedded a sensor system. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Terms used herein generally have their conventional meanings. “Optical element” is used as a term known in the art, comprising components such as a lens, a prism, a mirror, a light pipe, a diffuser, or a similar element which changes the light pattern or acts on the optical profile of the laser output. “Clocking” or “clocked” denotes the provision or creation of proper rotational alignment between given members of an assembly. A laser power supply may be any power source, including a battery or a plug-in electrical supply of energy. “Passively-aligned” or “self-aligned” denotes the alignment of parts in an assembly in which the elements are aligned by mechanical or optical alignment elements, so that the laser diode does not necessarily need to be powered on to see where the light is focused or transmitted. A “heat spreader” is a form of heat sink comprising any device or portion thereof suitable for lowering the temperature of a locus in a device by conducting heat from a first region into a second region of greater area than the first. 
     In its basic structure, the improved packaging system for self-aligning assembly and packaging of semiconductor lasers, or more generally semiconductor gain chips, comprises at least a semiconductor gain chip (such as a laser chip), bonded to a suitable carrier and connected to a power supply, and a heat exchanger in contact with the carrier. Preferably, the components of the system are mutually self aligning upon assembly, or are readily aligned, by machine or manually, by the use of clocking and other orientation mechanisms. In particular, both a self-aligning laser system and a method of making it are provided. 
       FIG. 1  is a partially exploded overall view of a first embodiment of an assembled laser system. In  FIG. 1 , the system  100  has an application focusing lens  101 ; a heat dissipating device  103 , called a heat exchanger or a radiator herein, having a front face  102 ; a TO-can-type laser carrier  104  having refinements, described below; and one or more (typically two or three) power leads  105 ,  106 , for the laser and optionally for other sub-systems. In a finished device of this embodiment, air or other fluid is circulated past the fins of the heat exchanger  103 . A central bore  108  in the heat exchanger  103  provides a mounting place for other parts of the system, and contributes to their orientation. The lower edge  160  of the lens  101  is preferably used for rotational clocking during assembly. 
       FIG. 2  shows a cross-section of the system  100  of  FIG. 1 . The lens  101  is optionally held and mounted to the heat exchanger  103  with epoxy or solder that is applied to proximal face  102  of the heat exchanger  103  and/or within heat exchanger bore  108 , thereby aligning the lens  101  with the central bore  108  of the heat exchanger  103 . The semiconductor gain chip, such as a laser chip,  107  is mounted on the TO can assembly  104 , as shown in detail below, and is connected to power leads  105 ,  106 . The distance between the laser  107  and the focusing lens  101  is controlled by two detents  140 ,  142  in the central channel  108  of the heat exchanger  103 . In this embodiment, the corner of the channel at the front face  102  serves as a detent. A cross section of the trajectory of the light emitted from laser chip  107  is shown as  110  within the central channel  108  of the heat exchanger. 
     The space between the lens  101  and the TO can  104  is laterally delimited by the walls of the bore  108  is typically filled with air. In certain applications, the space is filled with a majority of an inert gas such as Nitrogen, Argon or mixture of gases. In other examples, the space is evacuated creating a vacuum. In instances where the space is filled with a controlled atmosphere such as a majority of an inert gas or contains a vacuum, a hermetic seal is created at the interface between lens  101  and the heat exchanger  103  and between the TO can assembly  104  and the heat exchanger  103 . 
     The TO can,  104 , is secured to the heat exchanger using an affixing medium such as epoxy or solder. The extent of the area to which the medium affixes the TO-can vary from enveloping the entire surface of the TO-can to only one point on the TO-can surface. 
       FIG. 3  shows the laser carrier  104  in more detail. The TO-style carrier  104  includes a cylindrical base  104 - 1  and a heat exchanger and mounting assembly (“mount”)  120  that projects from face  104 - 6  on the base  104 - 1 . The mount  120  has extensions  121 , a pedestal area  124  and an optional submount  126 , which may be of non-electrically conducting material or electrically-conducting material. The laser  107 , with a front facet  128  for light emission, is bonded to the submount  126 , for example by solder, and is electrically connected by wire bonds  130 ,  132  to leads  104 - 2  and  104 - 3 . The leads  104 - 2  and  104 - 3  extend through the base  104 - 1  which contains an electrically insulating material, (such as glass)  104 - 4  and  104 - 5  and are connected to the power electrodes or wires  105 ,  106  that extend through the base  104 - 1  of the carrier. The wires  105 ,  106  terminate on wire bonds  130 ,  132 . The anode wire bonds  130  are typically connected via a lead  134  which may be either circular, oval or flat in cross-sectional shape, and the cathode wire bonds  132  are typically connected directly to the mount  120 . The wire bonding may be reversed as an engineering choice to give one power lead the anode connection and the other the cathode. 
     The laser  107  is a semiconductor laser diode (or “chip”). Such lasers are described in the art, for example in our co-pending applications US 2007/0002915 A1 and PCT/US2009/001350, published as WO 2009/111010 A1, (which are incorporated herein in their entireties by reference wherever such incorporation is permitted.) However, other types of laser chips may be used, including gallium arsenide laser chips. Laser chips at any available wavelength and material system may also be used in this assembly. In the laser shown in  FIG. 3 , wires from each of the wire bonds  130 ,  132  apply a current across a semiconductor laser chip  107  (from top to bottom as shown in  FIGS. 2 and 3 ), and light is emitted perpendicular to the direction of current differential through the laser facet  128 . (The other surfaces will normally be coated so as to reflect the wavelengths being generated.) As can be seen schematically in the cross-section of  FIG. 2 , the emitting facet  128  is preferably centered on the lens  101 . 
       FIG. 4  shows the assembly of  FIG. 3  in face view, so that the relationships among the laser  107 , its optional support  126  and the wire bonds  130 ,  132  are clear. Also shown is the mechanical alignment interface that rotationally self aligns the carrier  104  with the heat exchanger  103 . In more detail, a notch  138  in the carrier  104  is shown. The mechanical notch  138  is used to rotationally orient carrier  104  with the heat exchanger by mating with a mechanical spline on the heat exchanger. In other examples, intermediate tooling (not illustrated) is used to fix the rotational orientation of the carrier  104  with respect to the heat exchanger  103  when the carrier  104  is inserted into the central bore  108  of the heat exchanger. The optional mechanical notch  138  or an optical fiducial may be useful to align the parts in mechanical fixturing during assembly, so that the parts are clocked, i.e. oriented correctly, while epoxy or solder bonds the parts together permanently. 
     The mount  120  of the carrier  104  of  FIG. 4  has features for facilitating heat transfer from the laser chip  107  to the heat exchanger  103 . First, the mount  120  has peripheral extensions  121 , with the outer surface of the extensions shaped, like the rest of the mount  120 , to provide increased surface contact and thus heat conductive contact with the bore of a heat exchanger, such as heat exchanger  103  of previous figures. The total circumferential coverage of the mount  120  plus the extensions  121  is preferably at least 200 degrees of circumference, or more, such as 240 degrees or more. Thermal contact is further improved by heat-conducting adhesives or solders if required. 
     Second, the mount  120  has a central extension or pedestal  124  in the middle of the mount, to position the laser  107 , for example at the center of rotation of the device, and also to act as a heat spreader to improve heat extraction from the laser  107  or the optional submount  126  into the mount  120 . The curved sides of the pedestal  124  are designed to improve such heat transfer. While not physically pictured, in other embodiments, a lens or other optical element, such as a volumetric Bragg grating or diffractive optic is affixed to the peripheral extensions or mount. 
       FIG. 5 a , 5 b , 5 c    shows a more detailed view of the lens  101 . The lens in such systems will typically be aspheric, and in particular differing in profile in the “x” vs. “y” directions, because the light emitted from the laser facet  128  (front face) has differing dispersion in the direction across its width (“y” in this figure), vs. its height (“x” in this figure). The lens is designed to create either a collimated beam or a focused spot. The lens radius of curvature is different in the x and y dimensions of the lens. This is done, in the present embodiment, by providing a volume of material of a suitable refractive index and casting the material to have a complex surface profile, as illustrated in  FIG. 5 a , 5 b , 5 c   . The curved surface  151  of the lens may have a different radius of curvature across the x-axis face as compared to the y-axis face, so that a locus of constant curvature  152  is not a circle, unlike a circularly symmetric lens. The lens  101  will typically comprise a pedestal  153 , transmissive to the light emitted, and also preferably a transmissive plate  154  for use in binding the complete lens  101  to the heat exchanger face  102  (see in  FIG. 1 ) or other location. The bulk materials for portions of the lens  151 ,  153  and  154  may be the same or different. Casting the entire lens assembly in a single operation from a single material is preferred for efficiency. An edge face  160  of the plate  154 , optionally rectangular, is preferably used for alignment of the lens  101  with respect to the face  102  of the heat exchanger  103 , as illustrated in  FIG. 1 , and thence with the laser facet  128 . There is preferably an anti-reflective material coating on the optical surfaces of the lens (not labeled). Coatings for other purposes, including scratch prevention, are also possible. 
       FIG. 6  shows the lens  101  with a selected edge  160  aligned with the heat exchanger  103 . In this embodiment, the radially extending fins of the heat exchanger  103  have exterior ends that are alternately straight ends  170  and T-shaped ends  171 , to maximize heat exchanging area. However, fin  172 , as shown here, would have a T-shaped end by this system, but in this embodiment does not. Using this anomaly as a reference then allows a reliable orientation of the heat exchanger  103  with respect to other components, including the carrier  104 , the laser  107  and the lens edge  160 , and provides routes so that this is achieved automatically during assembly. 
       FIG. 7  shows an alternative mounting arrangement in perspective view, and  FIG. 8  shows a cross section through the center of the same embodiment. A TO-can type assembly  204 , similar to carrier  104  of  FIG. 3 , is mounted in a cavity  208  in a heat exchanger  203 . The heat exchanger serves as a heat sink, and carries, in addition to the assembly  204 , an aspheric lens  264 , which is similar to the lens  101  in  FIG. 4 , in one implementation. As best seen in  FIG. 8 , the lens  264  is cut so as to be insertable into the cavity  208 . The lens is made in various ways to enable reliable orientation, including for example a flat edge  265  and/or an orientation dot  266 . Each of these components is held in place by epoxy or solder and aligned by mechanical flats or detents or by optical or mechanical alignment of fiducials, as in  FIG. 1 . 
       FIGS. 9 and 10  show a different style of assembly, especially suitable when removal of heat by flowing air is not required, so that the assembly need not be designed with internal air or other fluid cooling or conductive cooling.  FIG. 9  is a perspective view, and  FIG. 10  is a cross-sectional view. A laser package assembly  304  is similar to assemblies  104 ,  204  in the previous embodiments. The assembly  304  is held in a box-like heat exchanger enclosure  310  having a central bore  308 . The enclosure  310  also includes a pair of bolts  375  with hex screw tops  376 , which are shown as placed in the box in  FIG. 9 , and as bolted into a heat sink (not shown) in  FIG. 10  (cross-section), which may also serve to carry heat away from the block enclosure  310 . The heat exchanger enclosure  310  is designed to have two lenses,  381  and  382 , rather than a single lens as in previous embodiments, but can have only one lens. The central bore  308  has three indents  361 ,  362 , and  363  (see  FIG. 10 ) for providing reliable stops for the lenses and the assembly  304 . The assembly will typically be provided with a mechanical notch and spline, as in  FIG. 4  (not shown). The rectangular profile of the heat exchanger enclosure  310  combined with the oriented screws  375  will provide orientation for the assembly as a whole. 
     Two lenses,  381  and  382  are shown in  FIGS. 9 and 10 . The division of the optical functions into two lenses may simplify the construction and increase the reliability of the lens orientation, in this or other embodiments. In particular, the outer lens  381  may serve to focus the laser output on a target. Fiducial mechanisms for orienting the lenses may be provided. The slightly differing lens diameters in these figures provide a means for insuring proper lens installation sequence. 
     The designs shown here use conductive cooling or convective cooling. Other cooling methods may be used.  FIG. 11  shows the addition of a cooling fan to the system. To a device of  FIG. 1 , having a lens  101 , a heat exchanger  103  and a TO-can style laser/electronics carrier  104 , an adapter  190  is be added in some implementations. The adapter  190  has a first, proximal end  192  sized to fit into or onto the distal end of the heat exchanger  103 , and has a slot  195  or other provision for connection to power leads  196 . The adapter  190  has a second, distal end  194 , adapted to fit into or onto a prepackaged fan  198 . Thus, an accessory, such as a fan and/or another add-on, can readily be added in assembly of a final product, as well as having the option, as shown here, to be supplied as a post-fabrication accessory for the laser. 
       FIGS. 12 and 13  are cross sectional views that show two potential methods for passively aligning the embodiments of a laser engine. In  FIG. 12  the laser package assembly  104  fits onto a pedestal  401  that contains a thru hole  402  and a top face  403 . A key feature  404  aligns with the notch  138 . Face  104 - 6  of laser package assembly  104  sits flushly on top face  403 . Edge face  405  is used to align edge face  160  of lens  101 . 
     In  FIG. 13  the laser package assembly  104  fits onto a pedestal  501  that contains a thru hole  502  and a top face  503 . The face  104 - 6  of laser package assembly  104  sits flushly on top face  503 . A key feature  504  fits into the central channel  108  of the heat exchanger  103 . Edge face  506  of the key feature  504  aligns with edge face  405 . Face  505  is used to align the laser package assembly  104  by fitting closely to extensions  121 . Once the laser package assembly  104  is aligned to heat exchanger  103 , key feature  504  is removed from the central channel  108 . Edge face  405  is used to align edge face  160  of lens  101 , similar to what is shown in  FIG. 12   
       FIG. 14  shows a cross sectional view of a method for self aligning the embodiments of a laser engine. Heat sink  601  is similar to  103  except that central channel  602  extends towards the extensions  121  by a distance which limits the range of movement of unit  104  and allows laser package assembly  104  to fit in one direction. This allows  104  to self align to  601 . Face  603  is used to align the laser package assembly  104  by fitting closely to extensions  121 . Pedestal  153  of lens  101  fits into the lens channel  604  of the heat exchanger  601 . Edge face  160  is used to align the lens  101  with respect to heat exchanger  601  and laser package assembly  104 . 
       FIG. 15  and  FIG. 16  show prospective views of housing system for a laser engine. In  FIG. 15  the housing  701  is designed to fit a fully assembled laser system  100 . The housing  701  has an exit window  703  to allow the laser light to pass through, a series of vents  704  to allow for the passage of air, and a sensor system including one or more contacts, illustrated in this case by two contact wheels  702 . The sensor system is configured with the laser system  100  to act as a safety mechanism. The purpose of the sensor system is to detect pressure and motion in order to prevent the end user from unnecessary exposure to the laser light. In this case the contact wheels  702  or the spherical contact  712  from  FIG. 16  first act as a pressure sensor to confirm that the device is in contact with a treatment zone, such as the patient&#39;s skin, and second to act as a motion sensor to confirm that the device has been moved from the initial treatment zone by a certain distance to prevent damage from over exposure of the laser light. The contacts are preferably also used to control the emission from the laser assembly. An electrical signal is generated which is proportional to the amount of pressure and/or rotation from the contacts. The electrical signal is then be processed and used as a means for controlling the emission from the laser assembly. 
     Emission from the laser assembly  100  is controlled through the use of a control system which takes electrical input from the sensors  702  and generates an electrical signal which is applied to the laser assembly  100 .  FIG. 17  shows a block diagram of the housing and controls illustrated in  FIGS. 15 and 16 . Housing  701  contains the laser engine  100 , control system  721 , sensor system  702  and power supply  722 . The sensor system  702  is connected to the control system  721  by wiring. The control system  721  is connected to the laser assembly via a separate set of wiring. 
     In one implementation, when the sensor system  702  is activated either by pressure or by movement, an electrical signal is passed to the control system which then creates a different electrical signal which energizes the laser assembly and permits emission. The resultant emission from the laser assembly is usually either continuous or pulsed or a combination of both. The control board in  FIG. 17  is designed such that electrical feedback from the sensor system  702  is used to create an electrical signal which when applied to the laser assembly an emission pattern is created which is a function of the feedback. In one embodiment,  702  creates an electrical signal which is proportional to rate at which the housing  701  is moved. The electrical signal is transmitted to and processed by the control board  721 . The control board then outputs a continuous electrical signal to the laser engine which emits during the time motion is sensed. 
     The control board is also be used to supply a signal to the laser assembly  100  which is proportional to the signal received from the sensor system  702  which is created when the housing  701  is in contact with an object and is moved. When the sensor system  702  is placed in contact with an object and the housing  701  is moved, the sensor systems detects the rate of or change in motion and creates an electrical signal which is proportional to the rate or change in motion. The signal is passed to the control board  721 . For certain applications, the control board  721  outputs a pulsed electrical signal to the laser assembly  100  whose time on and or repetition rate is adjusted in proportion to the rate of movement during the time which motion is sensed. In other applications, the control board  721  outputs a constant electrical signal to the laser assembly  100  only when motion is sensed. 
     A system as shown in  FIGS. 15 and 16  has application in using a laser against the skin for treating wrinkles, acne, warts, skin cancer and/or other skin diseases. In one embodiment the fan blows air to cool the laser diode heat sink and the same fan air also cools the skin near and/or on the spot of tissue being treated with laser light. The lens in all embodiments is ideally designed to provide relatively uniform light on the surface of the target tissue such that there are no hot spots that will burn the tissue. Another embodiment incorporates a detractive lens to split the light into many discrete elements (or “dots” of light) to treat the tissue in some areas while leaving adjacent areas without significant treatment thereby allowing for faster healing of the tissue and limited burning. The rolling elements of  FIGS. 15 and 16  is used to trigger the laser to fire such that the skin is treated uniformly with a controlled amount of overlap of light pulse areas. This rolling element approach benefits the user because a large area of skin may be treated quickly as the laser fires automatically as new skin is presented to the laser tip. This allows the user to simply roll the device around the contours of their skin and treat areas with multiple smooth passes. In one embodiment, the rotating wheel is designed to only rotate in one direction, which prevents the laser from rolling back on skin that has recently been treated with the laser. This prevents a double treatment of given tissue which is typically undesirable because it can lead to pain and redness of the tissue. In another embodiment, the lenses are designed to create a sharp point of light of 500 um or less in diameter to create a concentrated light source that cuts tissue and coagulates the edges of the cut at the same time. In another embodiment, the laser lens is designed to achieve a spot that does not cut tissue, but coagulates a relatively large area of tissue such as a diameter of 5 to 10 mm. 
     Other Embodiments and Features 
     Many options and variants are available. In one embodiment, as shown, a fan is provided to blow air across the heat exchanger associated with a laser package, for example the fins of the device of  FIG. 1 . The fan is fixed to the apparatus by a clip, or a set screw, or a press fit. In the embodiment of  FIG. 11 , a fan is affixed “behind” the laser chip, with respect to the downstream optics, and blows or pulls air across the chip or its carrier. Such an arrangement makes minimal change to the device profile. 
     The lasers themselves and many of the components of the system are described above, or are known, and a variety of standard materials and components are used to make the inventive devices. 
     Solders for mounting the chip are preferably gold-tin or indium. Other materials include gold-germanium, tin-silver, tin-silver-copper, bismuth-tin, or binary or tertiary alloys of these materials. 
     A submount, if used, is usually made of aluminum nitride (preferred) or pure copper or copper/tungsten or beryllium oxide or aluminum oxide. Ideally, no submount at all is used, and the laser chip is mounted directly onto the heat sink, preferably using a soft solder such as indium to allow for thermal mismatch. 
     The TO-style carrier ( 104 , etc) is preferably copper, but other materials can be used, including aluminum, cold-rolled steel and nickel-cobalt ferrous alloy such a Kovar brand alloy. 
     Wire bonds: If an electrically insulative submount is used, such as aluminum nitride, then wire bonds  132  are required from the submount base (e.g.,  126  in  FIG. 4 ) to the copper lead to post  106 . If the chip is mounted directly onto pedestal  124 , then only one set of wire bonds, e.g.  130  in  FIG. 4 , are needed from the top surface of the chip to a lead pin. Wire bonds are made of conventional materials, such as copper, aluminum or gold. 
     Heat sink: The heat sink is preferably made of aluminum for good thermal dissipation, and optionally is black anodized to further maximize heat radiation dissipation. Copper may also be used, as well as other conventional heat sink materials. 
     Size of assembly: The laser system is preferably less than 2 inches in diameter and less than 6 inches long so it is portable and lightweight. 
     Leads material: cobalt-iron alloy material is preferred for devices which will carry a current of 4 Amps or more in many applications. In contrast, a standard industry type pin lead of 0.45 millimeters (mm) diameter made of conventional materials such as copper or Kovar alloy is likely to have thermal, mechanical and/or electrical breakdown at 4 Amps or more of current. 
     The particular style of the carrier, shown as a TO-can style herein, is not critical, and various proportions and shapes of the body, and different arrangements of the body and of other parts having similar functions are contemplated. Other TO-can embodiments include a square or rectangular mount which omit the extensions  121  and may have a curved shape opposite the surface to which the laser is mounted. Other embodiments may include more or fewer leads which pass through the base. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of skill in the art to which the disclosed invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods, devices, and materials are as described. Publications cited herein and the material for which they are cited are specifically incorporated by reference, where such incorporation is permitted. Nothing herein is to be construed as an admission that the invention is not entitled to antedate such disclosure by virtue of prior invention, where relevant. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.