News Column

Patent Issued for Semiconductor Laser Assembly and Packaging System

September 3, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- SemiNex Corporation (Peabody, MA) has been issued patent number 8811439, according to news reporting originating out of Alexandria, Virginia, by VerticalNews editors.

The patent's inventors are Bean, David M. (Middleton, MA); Callahan, John J. (Wilmington, MA).

This patent was filed on November 23, 2009 and was published online on August 19, 2014.

From the background information supplied by the inventors, news correspondents obtained the following quote: "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 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."

Supplementing the background information on this patent, VerticalNews reporters also obtained the inventors' summary information for this patent: "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."

For the URL and additional information on this patent, see: Bean, David M.; Callahan, John J.. Semiconductor Laser Assembly and Packaging System. U.S. Patent Number 8811439, filed November 23, 2009, and published online on August 19, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8811439.PN.&OS=PN/8811439RS=PN/8811439

Keywords for this news article include: Electronics, Laser Diodes, Semiconductor, SemiNex Corporation.

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Source: Electronics Newsweekly


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