HK1169219A - Digital heat injection by way of surface emitting semi-conductor devices - Google Patents

Description

Digital heat injection by means of surface emitting semiconductor devices

Cross reference to related applications

The present application is based on and claims priority from the following applications: united states provisional application No. 61/224,765 filed on 7/10, 2009 and united states provisional application No. 61/157,799 filed on 3/5, 2009, both of which are incorporated herein by reference in their entirety.

Incorporated by reference:

united states patent number 7,425,296, united states patent number 11/448,630 filed on 7.2006, united states patent number 12/135,739 filed on 9.2008, and united states provisional patent application number 61/157,799 filed on 3.5.2009, are hereby incorporated by reference in their entirety.

Technical Field

The present invention relates generally to a novel method of digitally injecting heat into a wide range of products with a novel incorporation of a special class of semiconductor lasers (in one form, surface emitting devices). The present invention relates to a more specific and advantageous way of practicing the prior art of directly injecting narrow band radiant energy that desirably matches the absorption specification of a particular material at a given wavelength.

Background

The general techniques for practicing the prior art are fully described in U.S. patent No. 7,425,296 (identified above) and related patent families. The above patent families generally teach a technique known as narrow-band digital heat injection by absorption spectrum matching, or simply digital heat injection or DHI. An important DHI concept that must be fully understood is the concept of matching the wavelength of irradiation to the particular wavelength at which the target has the most desirable absorption coefficient for the desired application result. Since each type of material has its own unique absorption spectrum resulting from the atomic absorption properties of its molecules, it is necessary to know what the absorption spectrum profile looks like for any given target material to be treated with DHL. A locus of points representing a complete set of absorption coefficients for each wavelength of irradiation will constitute a complete absorption curve for the material. The complete spectral absorption curve is often referred to as the spectral curve or other abbreviation. As practitioners simplify DHI technology to actually practice for a given application, there is a wide range of things to consider, as described more fully in the above-mentioned family of' 296 patents.

Although the term narrowband is properly applied to all DHI applications, some applications are more critical than others. For example, in some applications, a bandwidth of two or three hundred nanometers may be narrow enough to match a particular region of the absorption curve of a given product. Although each different material or compound has its own characteristic absorption curve shape, it often changes shape slowly in one portion of the curve or changes shape sharply in other portions of the curve.

It is difficult to generalize since each different type of material has its own characteristic curved shape, but while some materials will have a gently changing absorption curve, the absorption curves of many other materials have regions with a rapidly or sharply changing shape somewhere between the UV and long infrared. These regions will be regions in the absorption curve with very steep slopes so that small changes in wavelength equate to very large changes in absorption coefficient. For example, pizza dough, water, sausage, and cheese all have active and rapidly changing curves in the 900 to 1500 nanometer range, where there is a point where a wavelength change of less than 50 nanometers will result in an absorption coefficient difference of 3 to 5X. There are other materials for blow molding beverage and food containers, such as polyethylene terephthalate (or PET) material, which have portions with very steep absorption curves. Targeting the exact point on this steep curve to take advantage of the exact absorption coefficient that is optimal for heating the material in the desired manner requires a laser device that can be economically manufactured at a very high level of wavelength precision that is highly repeatable. Similarly, wavelength accuracy is also required if one tries to hit a narrow peak or trough in the absorption curve (typically plotted using absorption on the y-axis and wavelength on the x-axis). The penalty of a wavelength change from the desired center wavelength in this case means that the irradiation will miss a peak and actually hit the target with energy that will be at a substantially different absorption than planned. The result will require a large change in the amount of energy required to achieve the desired heating or energy deposition.

Another concept of digital thermal injection involves selecting a wavelength for a desired result when multiple different material types are involved. For example, a material is selected that has at least one wavelength at which both materials have desirably different absorptions. When one material is highly transmissive at a wavelength at which the other material is highly absorptive, substantial absorption by the second material can be achieved with a minimum of the energy of the heating shot to break down the first transmissive material while with a desired level of heating. This concept can be extended for more than two materials, but the wavelength precision level can be raised even further. Additives may also be used which induce high absorption peaks to enhance the usability of this concept, but which may further require a high level of wavelength selection and precision to achieve the desired system results.

An important and often very basic concept behind DHI technology involves choosing the right wavelength to have exactly the desired amount of absorption in the target. As taught in the family of the' 296 patent indicated above, practitioners of digital heat injection will typically desire to select two, three, or more wavelengths, as each of them has a desirable absorption coefficient at their respective wavelength. By irradiating with the selected dosing, this allows the skilled practitioner to specify the exact combination of penetration and absorption that may be ideal for a given application. While DHI technology can work with reduced wavelength accuracy, it has been found that substantial improvements can be made in the practice of the technology by incorporating much higher levels of wavelength accuracy. It has also been found that certain specialized types of semiconductor hardware may be necessary to further optimize the implementation and hit exactly the desired wavelength with very narrow band energy and to economically implement the implementation. Since lasers and other narrow band irradiation sources used for many DHI applications must be of a type and design that they are economically manufactured and implemented for wide commercialization, it is important to carefully select such lasers, LEDs or other narrow band emitting devices, and the manufacturing process.

While digital thermal injection techniques can be practiced using almost any type of laser or narrow band irradiator where they are fabricated at the correct output wavelength of the application, there are certain practical situations that determine the preference for certain types of irradiators for the desired application. In general, semiconductor lasers, also known as diode lasers, tend to be more practical because they facilitate high-production manufacturing at lower cost. The semiconductor laser also provides the ability to fabricate it with a much wider specific wavelength range, greater compactness, durability, electrical efficiency, ruggedness, and other advantages.

However, typical diode or semiconductor lasers also have certain limitations and manufacturing challenges. One troublesome problem is the normal process variations that occur during manufacturing, which can cause the final laser device to have a wider output wavelength range than desired. Thousands of devices are fabricated on a single fabrication 'wafer' or substrate disk. It is not unusual for the wavelengths of devices from the same wafer to vary randomly +/-10 nanometers or more even for well-controlled processes. The device may be spread around the component in a normal statistical spread, or it may be heavily skewed in either direction from the target/desired center wavelength. If it is desirable to hit a particular center wavelength (e.g., +/-1 or 2 nanometers) very precisely, then only the option is to sort the devices individually and only pick devices that are in the desired range of the target. This may mean that perhaps 80% or more than 80% of the production lot would need to be discarded. Of course, it can sometimes be used for another application that requires a nearby wavelength, but for most cases this is not a reliable business plan. This sorting procedure can easily result in production yields below 20% when all other production drop causes are included. This is a major problem for high production and high power use of such devices. For best economics and for robust commercialization of various products where DHI technology can be expected, it is necessary to produce a large number of devices at a given wavelength.

The design of conventional diode lasers necessitates several manufacturing steps that make integration into applications expensive and automation expensive and complex. The first aspect is that most diode lasers are chemically fabricated in a layer-by-layer approach in MOC-VD wafer fabrication machines. The final lasing direction of each device is generally parallel to the plane of the wafer. Thousands of devices are produced from a single wafer by sawing or scribing and cleaving to cut them into individual devices. Sometimes, instead of cutting them into individual devices, they are kept physically connected as a row of devices, which is then called a laser bar. The bar may contain N lasers but typically may be 20 or more than 20 different laser devices, each of which functions individually. The laser is still mechanically joined to its neighbor because it is never separated from the neighbor. Whether it be in a 'stripe' configuration or whether it be an individual laser diode device for a conventional 'edge-emitting' laser, it is necessary to perform polishing and other processes on the edge or end of each device, one of which will become the emitting facet. The vast majority of all diode lasers are fabricated as these 'edge emitting' devices. In an improved design, all such additional processing and attention to the edges would be beneficially eliminated from the manufacturing process in order to eliminate several production steps and costs.

Referring to fig. 5, a typical edge-emitting device 10 is shown in the form of a strip 12 disposed on substrates 14 and 16. The substrate 14 (and/or 16, in some applications) may be a cooling substrate or system. Also, line D shows the general direction of the beam as it is generated in the wafer (ultimately output at facet 20). The emitting facet 20 (three examples of which are shown) is the surface that ultimately is the site of the most common cause of failure in a laser diode. The emitting facet 20 is fragile and critical to the lifetime of the laser diode. Any nicks, scratches, defects, contamination, and some other problems on the surface can result in additional localized or extensive heating, which in turn can lead to failure. This is commonly referred to as a 'catastrophic facet failure' and is the most common failure mode in semiconductor lasers. Moreover, the facets are generally rectangular in shape, and thus can present control and output uniformity issues with respect to the fast and slow axes of laser output.

Referring to fig. 6(a) and 6(b), another problem encountered during the manufacturing and installation of the conventional edge-emitting laser apparatus 10 is as follows. In order to maximize the lifetime and output of the diode laser, it is necessary to cool it sufficiently and uniformly. The laser emitting any substantial amount of power should be properly mounted to some kind of heat dissipating substrate, such as substrate 14, on at least one side of the laser diode. For optimal cooling and maximum device lifetime, the surfaces of the facets 20 must be absolutely flush and parallel with the edges of the heat sink cooled substrate 14 (as shown by the device 10-2 of fig. 6 (b)). If the laser diode is at any off-angle or not nearly perfectly flush with respect to the edge of the substrate (fig. 6(a)), then something that goes bad is left from the cooling standpoint that leads to early failure. If any portion of substrate 14 protrudes beyond the facet surface by a distance N, for example, it forms a location where contaminants can reside, as shown by device 10-3 of fig. 6(b), and the protruding substrate becomes a reflector/absorber of stray rays from the emitting facet. Both conditions can result in substantial additional heating of the facet material closest to the substrate. Also, if the facet 20 protrudes beyond the plane of the cooled substrate 14 (by a distance M) as shown in the device 10-1 of fig. 6(b), it prevents the substrate from dissipating heat out of the laser device, which can also lead to uneven heating and overheating of critical facet areas of the laser diode. Similarly, any interface media or coating that has been laminated between the cooling substrate or cooling circuit board and the laser diode may not extend all the way to level or may be exposed and cause an overhang material condition. This can also lead to or cause catastrophic facet failure, as well as other conditions. To eliminate these problems, it would be highly desirable to incorporate a laser diode that can be quickly installed and cost effective without having to worry about the problems just described.

Since many DHI applications utilize more than one laser diode for sufficient irradiation energy to a target, the installation complexity and number of diodes required can substantially increase the cost of manufacturing the DHI system. Thus, another limitation of current technology is the limited power that can be generated from a single laser diode. If the laser diode is driven harder or designed into a larger package in order to achieve a larger power output, it boosts the power density that must pass through the output facet. As the power density increases, the inevitable heat must be dissipated more carefully. The trade-off that is usually made is to slow down the device to keep efficiency and longevity reasonable.

Careful control of the temperature of the laser device or laser array is critical not only to the lifetime of the device, but it is also critical in other respects. As the temperature of the laser diode increases, the radiation output decreases. Furthermore, as the temperature changes, the wavelength of the radiation output of the laser diode device also changes. For most conventional semiconductor lasers, the junction temperature change per degree celsius of output varies by 3 nanometers. This is problematic because in a DHI system, it is more expensive and more energy can be used to precisely control the temperature of the device.

The substantial problem list as detailed above is a challenge that practitioners of digital thermal injection technology will encounter when trying to commercialize systems that are economically built fundamentally around conventional edge-emitting laser diodes and some other narrow-band devices that add the novel ideas represented by the present invention.

Disclosure of Invention

In one aspect of the presently described embodiments, a system includes: means operative to position a target in an irradiation zone that facilitates application of radiant heating into the target; at least one semiconductor-based narrowband radiation emitting device element, the at least one narrowband radiation emitting device operative to emit radiation at a radiant heat output narrow wavelength band that matches a desired absorption characteristic of the target, the at least one narrowband radiation emitting device being a mounted surface emitting laser diode device, the at least one narrowband radiation emitting device being mounted to a mounting entity comprising at least one of a circuit board and a cooling substrate so as to direct a central axis of an irradiance pattern from the at least one narrowband radiation emitting device substantially orthogonally relative to a maximum plane of the mounting entity; a mounting arrangement configured to position the at least one narrow band radiation emitting diode device so as to direct irradiation from the at least one narrow band radiation emitting diode device to a target in the irradiation zone; and means operative to supply current to the at least one narrowband radiation emitting device.

In another aspect of the presently described embodiments, the at least one semiconductor-based narrowband radiation emitting device element forms an array of more than one surface emitting laser diode device.

In another aspect of the presently described embodiments, the array comprises an X by Y matrix of surface emitting laser diode devices, wherein both X and Y are greater than one (1).

In another aspect of the presently described embodiments, the array is in the form of an engineered array of more than one surface emitting laser diode devices, such that relative geometric positions have been determined to provide better irradiation of a given target to be irradiated, taking into account the combined irradiation output pattern of the laser diode devices.

In another aspect of the presently described embodiments, one of a lens treatment arrangement or a reflector arrangement is superimposed between the array and the target for the purpose of improving the irradiance pattern at the point where the irradiance reaches the intended target.

In another aspect of the presently described embodiments, devices of at least two different device types are included in the array, the device types defined by at least one of: different wavelengths are generated, manufactured from different wafer substrate chemistries, have different physical sizes, different power outputs, and have different device output types.

In another aspect of the presently described embodiments, the array of at least two different device types is characterized by three or more different device types.

In another aspect of the presently described embodiments, the different device types included in the array can produce at least two different wavelengths, the wavelengths being centered within 100nm of each other.

In another aspect of the presently described embodiments, the different device types included in the array can produce at least two different wavelengths that are centered over 150nm from each other.

In another aspect of the presently described embodiments, the means operative to supply current to the at least one narrowband radiation emitting device consists of a system selectively supplyable with current by means of: at least one current controlled power supply controllable by an intelligent controller, the intelligent controller controlling the power supply consisting of at least one of: programmable logic controller, control panel based on microprocessor, computer control system and embedded logic controller.

In another aspect of the presently described embodiments, the intelligent controller has the ability to selectively control irradiation from the at least two different device types.

In another aspect of the presently described embodiments, the intelligent controller operates to digitally control radiation from the at least one narrowband radiation emitting device, where the device is configured to irradiate more than one irradiation zone on the target.

In another aspect of the presently described embodiments, the intelligent controller operates to digitally control radiation from the at least one narrow band radiation emitting device, wherein the device is configured to irradiate at varying wavelengths corresponding to different absorption characteristics of the target.

In another aspect of the presently described embodiments, the geometric arrangement of the surface emitting laser diode devices is arranged such that the irradiance output pattern does not require any refractive, diffractive or reflective devices to be superimposed between the laser diode devices and the irradiation target.

In another aspect of the presently described embodiments, more than eight surface emitting devices are mounted on at least one of the circuit board and the cooling substrate.

In another aspect of the presently described embodiments, the at least one narrowband radiation emitting device consists of an array of integrated circuit chips of more than one surface emitting device fabricated as a unit on a wafer level.

In another aspect of the presently described embodiments, the laser emission inside each laser diode device occurs in a direction parallel to a mounting plane of the device, while the central axis of the output irradiance pattern is generally orthogonal to the mounting plane.

In another aspect of the presently described embodiments, the output irradiance pattern of at least some of the devices is collimated photon energy along at least one of two substantially 90 ° relative axes thereof.

In another aspect of the presently described embodiments, no component of the external irradiance pattern of each device is parallel to the largest plane of the laser diode device itself.

In another aspect of the presently described embodiments, the component of the external irradiance pattern of each device is parallel to the largest plane of the mounting substrate.

In another aspect of the presently described embodiments, the control includes the ability to control how much of the accumulated energy is irradiated to a particular region of the target.

In another aspect of the presently described embodiments, the laser diode device operating temperature range of the device's center output wavelength per degree celsius is affected by less than 0.1 nanometers.

In another aspect of the presently described embodiments, a system includes: at least one semiconductor-based narrowband radiation emitting device element, the at least one narrowband radiation emitting device operative to emit radiation at a radiant heat output narrow wavelength band that matches a desired absorption characteristic of a target, the at least one narrowband radiation emitting device being a mounted surface emitting laser diode device, the at least one narrowband radiation emitting device being mounted to a mounting entity comprising at least one of a circuit board and a cooling substrate so as to direct a central axis of an irradiance pattern from the at least one narrowband radiation emitting device substantially orthogonally relative to a maximum plane of the mounting entity; a mounting arrangement configured to position the at least one narrow band radiation emitting diode device so as to direct irradiation from the at least one narrow band radiation emitting diode device to a target in the irradiation zone; and means operative to supply current to the at least one narrowband radiation emitting device.

In another aspect of the presently described embodiments, the at least one semiconductor-based narrowband radiation emitting device element forms an array of more than one surface emitting laser diode device.

In another aspect of the presently described embodiments, the array comprises an X by Y matrix of surface emitting laser diode devices, wherein both X and Y are greater than one (1).

In another aspect of the presently described embodiments, an irradiation array for generating radiant energy associated with an object comprises: a semiconductor irradiation array, wherein devices are not mounted flush with any edge of a board on which the array is mounted, wherein the mounting board is configured as a highly thermally conductive substrate having at least one layer to conduct heat and one layer to conduct supply current, wherein the array is comprised of surface emitting semiconductor laser devices, wherein an axis of optical photon output of the array of devices is substantially perpendicular to a major plane of the mounting substrate, and wherein the mounting board is configured to be thermally coupled to at least one of: a water jacket cooling system, a thermal radiation fin arrangement, a state change cooler, a compressed media cooler, and a thermoelectric cooler.

In another aspect of the presently described embodiments, the array is an X by Y array of surface emitting devices, whereby both X and Y are greater than one.

In another aspect of the presently described embodiments, the array is an arrangement of surface emitting devices whereby some of the devices are rotated relative to their neighbors.

In another aspect of the presently described embodiments, a method includes: introducing a target item into the irradiation zone; emitting radiation at a radiant heat output narrow wavelength band that matches desired absorption characteristics of the target item using a mounted surface emitting laser diode device, wherein the mounted surface emitting laser diode device is mounted to a mounting entity comprising at least one of a circuit board and a cooling substrate so as to direct a central axis of an irradiation pattern from the device substantially orthogonally with respect to a maximum plane of the mounting entity; and irradiating the target item based on the irradiation device.

In another aspect of the presently described embodiments, the target item is a food item.

In another aspect of the presently described embodiments, the target item is a preformed plastic bottle.

Drawings

FIGS. 1(a) to 1(d) are representations of surface emitting devices;

FIGS. 2(a) to 2(b) are representations of another surface emitting device;

FIGS. 3(a) through 3(d) are systems according to the presently described embodiments;

FIG. 4 is another system in accordance with the presently described embodiments;

FIG. 5 is a prior art configuration; and is

Fig. 6(a) to 6(b) are prior art configurations.

Detailed Description

The present invention describes a novel use of proven, but not well known, laser diode technology. This is a new class of devices that has just emerged from several advanced manufacturers as experimental devices and as a class called surface emitting diode lasers. The device has unique properties for practicing digital thermal injection techniques, and it does not have any of the limitations indicated above. While the device may not represent a substantial improvement over many conventional uses of laser diodes, it represents a substantially novel improvement over both the economics and practicality of practicing digital thermal injection techniques.

The design and manufacture of DHI applications typically involves a large number of laser diode devices for each system-as such devices are often involved when irradiating relatively large surface areas with substantial amounts of energy and heating target items. Many conventional applications of power laser diodes use a small number of laser diodes and a more expensive non-automated mounting method may be considered reasonable. In contrast, for many DHI applications to be practical, it is necessary to use highly automated manufacturing methods and drive cost reductions through the best practices of high volume manufacturing. Device and manufacturing costs are so important for DHI applications that the number of applications that a consumer can consider reasonable is inversely proportional to the manufacturing costs, driven primarily by the cost of the mounted device. It is for this reason that the inventors of the present invention have sought novel ways of implementing laser diodes as a key step in making the technology commercially viable.

The implementation of this type of surface emitting device has the following advantages: precise alignment with respect to the edge of the cooling circuit board or substrate is not required at all. This is made possible by the device emitting energy normal to the plane of the production wafer from which it originates. The actual laser emission takes place parallel to the surface, but the energy is emitted from the laser diode device perpendicular to the direction of the laser emission. Since it is not a normal edge-emitting device, it eliminates concerns about tiny fragile facets and all problems associated with those facets.

The device has the further advantage of having the emitting facet in the plane of its largest or mounting surface, which is many times the size of the facet of the edge emitting device. This significantly reduces the energy density through the facet and thus substantially increases reliability. In some designs, the energy density has been shown to be as much as three orders of magnitude less with surface emitting arrangements compared to edge emitting devices. This should generally result in substantially longer life and improved more economical and efficient cooling configurations. One reason cooling is simplified is that the output direction can be perpendicular to the mounting plate — thus cooling can be achieved for many devices in the same plane.

The invention has the following advantages: having an aperture that increases proportionally with the geometric scale of the device makes possible a very high power output device with low energy density across the emitting facet.

The present invention has the further advantage of emitting radiant energy that has been collimated in at least one form along one axis and has only a modest divergence angle along the other axis. This allows for very easy handling of the radiant energy output and thus allows for the use of simpler and less expensive lenses or optical devices (e.g., cylindrical lens strips made of relatively inexpensive materials). In fact, this feature eliminates the need for any lens processing in many DHI applications. This is another cost reduction for fully configured systems. This also allows better zone control of the output of the device array, for example, designated for different target zones.

The invention has the following advantages: with very tight control of the irradiation wavelength. Typical production variations across the wafer are only +/-1 or 2 nanometers, which is sufficiently stringent for even the most critical DHI applications to eliminate the need for sorting into specific wavelengths. Where production classification is unnecessary for having very high yields, there is another substantial cost reduction benefit for typical high volume DHI applications. Thus, digital heat injection systems using these devices have a large surface area that achieves high reliability but emits at naturally precise wavelengths.

It is a further advantage of the present invention that changes in temperature have at least an order of magnitude less effect on the wavelength output of the device. The output variation is typically a change of about.03 nanometers per degree celsius junction temperature change. This is a significant advantage because it makes cooling less critical and makes simpler, less expensive cooling techniques practical for many DHI applications. For example, a complex chiller may not be needed, but rather air cooling with heat fins may be sufficient for many applications. Furthermore, the heat sink substrate may generally have a less complex design, which is a cost saving reality that cannot be achieved.

Another advantage is that the intended surface emitting device can be mounted on a mounting entity with more conventional, less precise pick and place type equipment in a manner more similar to how other non-optical circuit board components can be mounted.

Also, since the output of the device is perpendicular to the mounting plate, electrical connection can be made easier. Yet another advantage of the present invention is that the irradiation photons reflected back to the laser device are suppressed so that stray light is highly unlikely to cause damage to the junction regions inside the laser device.

And yet another advantage is that the form factor of the surface emitting device facilitates manufacturing of the device in a single device version at very high power. For example, a single diode laser may be fabricated that would exceed 75 watts.

Yet another advantage of surface emitting devices is that they can be fabricated on both gallium arsenide and indium phosphide substrates to facilitate use in a wide range of DHI applications.

Referring now to fig. 1(a) to 1(c), a surface emitting distributed feedback semiconductor laser diode device 100 is illustrated. Such a device can be manufactured in many different ways as described in various publications, but in one form can be manufactured according to, for example, the following documents: 5,345,466, 5,867,521, 6,195,381, and 2005/0238079. All of these documents are incorporated herein by reference in their entirety.

Briefly, in one exemplary form and without limitation, device 100 will generally include a laser diode portion 110 including an emitting surface 120. Notably, the fabrication of the diode also includes the provision of a cooling substrate 130.

In addition, the emission surface 120 comprises an emission region 140 to advantageously emit radiation 150 in a predetermined direction. Notably, the device 100 is capable of such performance and functionality due in part to an underlying grating surface (not shown). In this regard, the grating may be curved in nature.

Referring now to fig. 1(d), the devices 100, or variations thereof, are shown dispersed in an exemplary array 200. The device 100 is shown spread out in such a way that no radiation gaps of the array are provided. In some forms, the configuration of the array and the number of arrays used will allow advantageous control over regions of the array so that such regions can be controlled in an appropriate manner. Also, it may be advantageous to provide several arrays or groups of arrays electrically connected in series to achieve a desired drive voltage. This is substantially advantageous when practicing digital heat injection, so that the wire size can be kept to a reasonable gauge. Driving high wattage at low voltage will require large diameter wires due to high current requirements. Large diameter wires are expensive and it is substantially difficult to utilize and connect large diameter wires. In contrast, all laser diodes in a laser diode bar will be electrically parallel to each other due to the physical constraints of their packaging. Given the way the laser diodes must therefore be cooled and mounted, the convenience of achieving a series of electrical connections for an array of DHI configurations is challenging.

As mentioned above, surface-emitting distributed feedback semiconductor laser diodes (such as device 100) have significant advantages over more conventional laser-type devices. As can be seen, the alignment of the laser diode portion 110 on the cooling substrate 130 is no longer difficult. Which does not require precise edge alignment. Also, as shown in fig. 1(b) and 1(c), the radiation emitted from the emission surface 120 is collimated in one dimension (fig. 1(b) -side view) and is gently angled divergence in the other dimension (fig. 1(c) -end view). This is different from most laser diodes having divergent fast and slow axes. This has clear advantages in the contemplated DHI applications: the lens processing of the radiation, if necessary, becomes simplified in one dimension, thus facilitating a simpler form of lens processing and/or improved control over several regions in many applications. Moreover, the tolerances for these devices are on the order of + or-1 nanometer per wafer — this is in contrast to the much larger tolerances of conventional laser devices. Thus, a significant advantage of the device 100 is that a narrowed operating range will allow energy to be applied in the absorption range of the target over a very "steep" portion of its absorption curve.

FIGS. 1(a) -1 (d) show one exemplary embodiment of a device that may be implemented to achieve the purpose of the presently described embodiments. However, the surface emitting device according to the presently described embodiments may take a variety of forms. For example, these forms of devices will typically have an emission area greater than 35% (or so) including an emission surface perpendicular to the output direction (which may be a surface on the device having the target dimension).

Another example of a surface emitting device that may be advantageously implemented within the presently described embodiments is shown in fig. 2(a) and 2 (b). Such devices are disclosed in U.S. application nos. 2004/0066817 and 2005/0180482-both of which are incorporated herein by reference in their entirety.

As shown, the surface emitting device 10 includes a semiconductive die or substrate 12 that includes laser stripes 14 and reflective elements 16. Laser beams 18 are generated in laser stripes 14 and reflected off of elements 16 such that laser beams 18 are emitted from device 10 and in a direction generally perpendicular to surface 22 of substrate 12. In one form, as shown, the laser beam 18 travels in a direction toward the edge 20 of the device. Referring to fig. 2(b), the devices as shown in fig. 2(a) are arranged in an array. The one or more arrays may be configured in a variety of ways to achieve the objectives of the presently described embodiments. However, in at least one form, several devices 10 are arranged adjacent to one another to form a column or row and multiple columns or rows are provided on a particular substrate. Also, as can be seen, the plurality of devices forming the array emit radiation generally in a direction perpendicular to the surface 22 of the substrate 12 to provide a region 70 of the radiation beam.

The devices illustrated in fig. 2(a) and 2(b) have many of the same advantages as the devices illustrated in fig. 1(a) through 1 (d). One difference with the embodiments of the devices of fig. 2(a) and 2(b), however, is that the light emitted from device 10 is not necessarily collimated in one direction as with the devices of fig. 1(a) through 1 (d). Nor does the device 10 maintain an orifice as large as the device designed in fig. 1(a) to 1 (d). However, as with the devices of fig. 1(a) to 1(d), the devices of fig. 2(a) to 2(b) do contain a large surface area that emits at a precise wavelength. Furthermore, the emission direction is orthogonal to the large axis or plane of the device. This means that in many DHI applications the plane of the mounting circuit board may be orthogonal to the direction of irradiation. In this orientation, the radiation emission from the laser device may be directed toward the target. Thus, the lens processing arrangement of this system, whether it be one-dimensional or two-dimensional, is greatly simplified relative to other types of laser diode implementations. Importantly, both configurations of the surfaces in the emitting devices from both fig. 1(a) -1 (d) and from fig. 2(a) -2 (b) maintain the ease of the installation considerations described above. This will be described in more detail in connection with fig. 3(a) to 3(d) and fig. 4.

Furthermore, it should be appreciated that in at least one form, the surface emitting devices implemented in connection with the presently described embodiments are configured wherein the lasing inside each laser diode device occurs in a direction parallel to the maximum (or mounting) plane of the device, while the central axis of the output irradiation pattern is generally orthogonal to the maximum (or mounting) plane of the device. In at least one form, the output irradiance pattern of at least some of the devices is collimated photon energy along at least one of two substantially 90 ° relative axes thereof. In at least one form, the component of the external irradiance pattern of each device is not parallel to the largest (or mounting) plane of the laser diode device itself. Further, in at least one form, changes in the operating temperature of the laser diode device per degree celsius of the central output wavelength of the device are affected by less than 0.1 nanometers.

Referring now to FIG. 3(a), a system is shown into which the presently described embodiments are incorporated. The system 500 includes a control module 510 and an array 520 and lens arrangement 525 (if necessary). The array 520 may take any of the forms contemplated herein and irradiates the gantry region 530 to form an irradiation or target zone 540.

It should be appreciated that the control module 510 may take a variety of forms, including the form of an intelligent controller to control a current control power supply that controls the current to the surface emitting devices. It should be understood that the control module may include or control a means or mechanism or system to supply current to a surface emitting device. The intelligent controller may be a programmable logic controller, a microprocessor-based control panel, a computer control system, or an embedded logic controller. The intelligent controller has the ability to selectively control irradiation from at least two different device types. The intelligent controller has the ability to individually control radiation from at least one narrow band radiation emitting device, where the device is configured to irradiate into more than one irradiation zone on a target. Thus, in many forms, the control module 510 has the ability to control how much of the accumulated energy is irradiated to a particular region of the target.

The array 520 may take a variety of forms. However, in at least one form, the array includes at least one semiconductor-based narrowband radiation emitting device element, where the at least one narrowband radiation emitting device is operative to emit radiation at a radiant heat output narrow wavelength band that matches a desired absorption characteristic of a target and is a mounted surface emitting laser diode device. In at least one form, the device is configured to irradiate at varying wavelengths corresponding to different absorption characteristics of one or more targets. The at least one narrowband radiation emitting device may be mounted to a mounting entity, such as a circuit board and/or a cooling substrate, so as to direct a central axis of an irradiance pattern from the at least one narrowband radiation emitting device generally orthogonally with respect to a maximum plane of the mounting entity. The mounting arrangement may be configured to position the at least one narrow band radiation emitting diode device so as to direct irradiation from the at least one narrow band radiation emitting diode device to a target in an irradiation zone. Also, the at least one semiconductor-based narrowband radiation-emitting device element is formed as an array of more than one surface-emitting laser diode device. In one form, the array comprises an X by Y matrix of surface emitting laser diode devices where both X and Y are greater than one (1). In one form, the array is in the form of an engineered array of more than one surface emitting laser diode device, such that relative geometric positions have been determined to provide better irradiation of a given target to be irradiated, taking into account the combined irradiation output pattern of the laser diode devices. In at least one form, devices of at least two different device types are included in the array, the device types defined by at least one of: different wavelengths are generated, made from different wafer substrate chemistries, have different physical sizes, and different power outputs. The array of at least two different device types may be characterized as being three or more different device types. In at least one form, the different device types included in the array can produce at least two different wavelengths that are centered within 100nm of each other or more than 150nm of each other.

Also, it should be appreciated that the irradiation array used to generate radiant energy associated with a target in accordance with the present invention includes a semiconductor irradiation array, wherein devices are not mounted flush with any edge of the board on which the array is mounted. In one form, the mounting plate is configured as a highly thermally conductive substrate having at least one layer to conduct heat and one layer to conduct supply current. The array is comprised of surface emitting semiconductor laser devices, wherein the axis of optical photon output of the array of devices is substantially perpendicular to the large plane of the mounting substrate. In one form, the mounting plate is also configured to be thermally coupled to at least one of: a water jacket cooling system, a thermal radiation fin arrangement, a state change cooler, a compressed media cooler, and a thermoelectric cooler.

In addition, the device may be positioned on the substrate in a variety of ways. For example, rows and columns of devices may be provided where the devices are all oriented in the same manner, i.e., the length (or width) directions of all devices are parallel. The rows or columns may also be offset (as in fig. 3 (b)). Further, alternating devices in a row and/or column can be rotated, for example, 90 ° so that the length (or width) directions of adjacent devices are orthogonal to each other. In at least one application, this rotation of the alternating device allows for a more uniform field of irradiation.

Also, the array may be formed on a circuit board or cooling substrate so that any number of surface emitting devices may be formed thereon. An exemplary array would have eight (8) surface emitting devices thereon. Also, the array may be an array of integrated chips of a plurality of devices fabricated as a unit on a wafer level.

With respect to the optional lens arrangement 525 as mentioned above, it will be appreciated that such a lens handling arrangement may take a variety of forms, but in at least one form it is a simplified lens handling arrangement when compared to arrangements known with respect to laser diode applications. In this regard, the surface emitting nature of the device allows the emitting surface to be directed towards the target area, that is, the emission is orthogonal to the plane of the mounting substrate. This reduces the need for complex optics systems. Thus, in many cases, a simple cylindrical lens placed in front of the device, for example, will be sufficient for lens processing applications. In this regard, a single cylindrical lens for multiple devices or a separate lens for each device may be implemented. Also, since surface emitting devices typically have a larger facet area and smaller power density, less expensive lens arrangements and materials may be implemented. These advantages are desirable in DHI applications where a large surface area emitting at a precise wavelength is satisfactory. The high energy density that is often desirable in laser applications is not necessary in DHI applications.

Of course, while a variety of configurations are possible, in one form one of a lens treatment arrangement or a reflector arrangement is superimposed between the array and the target for the purpose of improving the irradiance pattern at the point where the irradiance reaches the intended target. In other forms, the geometric arrangement of the surface emitting laser diode devices is arranged such that the irradiance output pattern does not require any refractive, diffractive or reflective devices to be superimposed between the laser diode devices and the irradiation target.

The gantry region 530 and the irradiation or target region 540 can also take a variety of forms. In one form, the gantry region includes a conveyor or rotating disk to move the target into the region to be irradiated 540. The shelf region 530 may also be a retaining plate or other support element. In some forms, the stage region may be fixed, but the array (and lens, if included) is moved relative to the target. Of course, the configuration varies with the application.

Those skilled in the art will appreciate that the system 500 of FIG. 3 may take a variety of forms and implementations. For example, the system 500 may take the form of a system for heating a preformed plastic bottle during a blow molding process. In another form, the system 500 may be positioned in an oven for baking various types of food items.

In this regard, with reference to fig. 3(b) and 3(c), an example of an implementation of the device of fig. 3(a) is illustrated. It will be appreciated that the device or system illustrated in fig. 3(b) and 3(c) is merely exemplary in nature and may take a variety of other forms. As mentioned above, target 535 is shown in fig. 3 (c). This object may take many forms, including the form of plastic preformed bottles or food items such as pizzas. It should also be appreciated that changes to the target object may require changes to the system that should be immediately apparent after studying the invention (e.g., changes to the transport system or gantry area).

More specifically, FIG. 3(b) illustrates an exemplary form of array 520. As shown, the array 520 has a plurality of surface emitting devices 522 disclosed thereon. Each surface emitting device includes an emitting surface or region, such as shown at 524. The array 520 shown in fig. 3(b) illustrates that a substantially emitting surface can be realized on the circuit board to emit radiation towards the article. As shown, the array 520 will allow for uniform output to be emitted toward a target traveling in a direction perpendicular to the long side of each of the devices 522. Devices such as device 522 will be arranged or controlled in a variety of ways. For example, each set of two or three devices arranged in columns as shown may be considered and controlled as separate transmission regions. In other embodiments, zone control may not be a priority, however, the efficiency of configuration and cooling may determine the type. As mentioned above, improved performance is obtained because a device such as 522 may be arranged on a circuit board or cooling substrate to output energy in a direction perpendicular to the emission surface. These improvements may not be obtained using edge-emitting laser diodes, as should be apparent in light of the disclosure herein.

Referring now to fig. 3(c), the array 520 is shown in an orientation whereby the emitting surface emits radiation toward an article 535 residing within a heating zone 540 on the gantry region 530. For purposes of this illustration, it should be noted that the direction of travel of the item 535 enters/leaves the page, as indicated by the dots. In connection with the array 520, a lens or lens arrangement 525 is also shown. The lens 525 may take a variety of configurations. However, the use of surface emitting devices allows the lens processing device 525 to assume a relatively simple and inexpensive configuration. In this regard, the lenses may be simple cylindrical lenses formed as bars sized to advantageously spread the energy emitted from the array 520. It should be appreciated that the lens arrangement 525 is merely an optional feature for any given application. It should also be appreciated that the relative position of the lens 525 from the surface of the array may determine the pattern experienced at the output or target 535. This pattern is a function of the arrangement of devices 522 on lens array 520, for example. Those skilled in the art will appreciate the manner in which the lens may distribute and focus energy as desired. In either case, the use of surface emitting devices allows greater flexibility in the use and configuration of lenses, as the more favorable energy spreading of surface emitting devices allows the placement of the lens arrangement closer to the emitting surface. This cannot be achieved using edge-emitting devices for at least the following reasons: edge emitting devices can generate too much heat and create hot spots on or in the lens that would not be conducive to proper performance.

Array 520 is also shown with cooling lines 529 and cooling fins 528. The simplicity of the arrangement of the cooling means illustrates a further advantage of using surface emitting devices whereby the devices emit in a direction perpendicular to the emitting surface and the largest plane of the substrate or mounting entity. This allows for a simplified cooling arrangement as shown herein.

A protective shield 526 is also shown. The protective shield 526 may take a variety of forms. However, in at least one form, the protective shield 526 is made of a material that will be transparent at the desired wavelength but also protects the array from undesirable wear.

Referring now to fig. 3(d), a graph 550 is shown. In the graph, the percentage of output experienced at the target is plotted against the distance D across at least two zones of the target. As shown, line A illustrates a system utilizing a surface emitting device. In this regard, line A shows a sharp decrease from 100% output experienced to 0% output experienced at the boundary or edge of a region. Using an edge emitting device, output B is expected. This is a more gently sloping curve. This illustrates one advantage of using a surface emitting device whereby at least one direction of output is collimated-such that a flat gently sloping curve or gaussian dip (such as the dip shown at line B) is not experienced. In this regard, it is expected that the output of an array using surface emitting devices will be more linear in nature, while the radiation output of edge emitting devices tends to be more elliptical and gaussian. In this way, the use of surface emitting devices allows for better zone control of the output. Furthermore, it will be appreciated that a higher number of smaller arrays may be used for finer region control for larger arrays, whereby larger regions or less precise regions are desired.

Referring to fig. 4, the apparatus 100 (or 10) may be incorporated in a cylindrical configuration to heat items such as plastic bottle preforms 610. In this form, the actual implementation may vary depending on the designer's desire to move the item 610, the array 100, or both. Movement of the irradiation source or target (by various means, such as hydraulic systems, pistons, motors, etc.) may be necessary in DHI heating applications. A reflective surface 618 and a lens arrangement 620 are also illustrated. As described above, these lens configurations may be greatly simplified and more cost effective than other known lens arrangements for laser diode applications. The lens arrangement 620 may also provide the function of isolating the laser diode array from any contaminants that may come from the environment or the target. For example, food splatter in the cooking oven will be shielded from depositing on any of the laser array apparatuses so that the lens arrangement protects the lifetime of the apparatus. If lens treatment is not necessary in some types of applications, element 620 may take the form of only a protective shield that is transparent at the wavelengths being used for the application. In some cases, both a lens handling arrangement and a protective shield may be used. One reason for doing so may be to make it possible to periodically replace the protective shield with a clean or clean protective shield. Such shields may be disposable or of the type that can be cleaned and reused. Another feature that should be present with respect to the protective shield may be an anti-reflective coating or a coating for other purposes. Some surface emitting laser diodes emit a polarized beam, so the protective shield configuration may also be adapted to use polarization for good effect.

The arrangement shown in FIG. 4 shows a further illustration of the advantage of using a surface emitting device over an edge emitting device in DHI applications. In this regard, it should be reiterated that the output of a surface emitting device is perpendicular to the largest surface of the fabricated device or mounting arrangement or entity. In this regard, this allows for improved cooling and other techniques. Thus, in fig. 4, a very compact arrangement may be achieved, which may be desirable in some applications. If edge emitting devices are used in the arrangement shown in fig. 4, it may be desirable for the circuit board to be positioned so that multiple circuit boards are used to form each array and arranged to protrude from the back side of the array. These circuit boards will be oriented in a direction parallel to the output toward the target 610. As such, the configuration of the device 600 may be much larger and more complex and cumbersome than would be necessary if a surface emitting device were used.

It should be appreciated that the operation of the presently described embodiments may vary depending on the particular implementation. However, in at least one form, the systems described herein (and variations thereof) will generally enable subsequent operation of positioning or introducing the target (e.g., by conveyors, rotating disks, hydraulic systems, etc.) and surface emitting devices (in many forms, configured in arrays) in the irradiation zone to emit narrow band radiation toward the target that matches the desired absorption characteristics of the target. This allows for the desired heating, cooking, etc. The system will be under the control of a controller or control module to provide current to a device or array of devices in the manner described herein (e.g., uniformly, in zones, at different wavelengths, at different locations, etc.). It will be appreciated that the controller, as well as other means of controlling functionality of the contemplated system, may take a variety of forms. For example, the controller may utilize a memory device or memory location that stores routines executed by a suitable processor. In this regard, the techniques of the present disclosure may be implemented and/or controlled using a variety of different software routines and/or hardware configurations.

The foregoing description provides disclosure of only certain embodiments of the invention and is not intended to limit the invention to these particular embodiments. Thus, the present invention is not limited to the above-described embodiments. Rather, it is recognized that one skilled in the art could conceive alternative embodiments that fall within the scope of the invention.

Claims (15)

1. A system for non-contact implantation of radiant energy into a target, the system comprising:

means operative to position a target in an irradiation zone that facilitates application of radiant heating into the target;

at least one semiconductor-based narrowband radiation emitting device element, the at least one narrowband radiation emitting device operative to emit radiation at a radiant heat output narrow wavelength band that matches a desired absorption characteristic of the target;

the at least one narrow band radiation emitting device is a mounted surface emitting laser diode device;

the at least one narrowband radiation emitting device is mounted to a mounting entity comprising at least one of a circuit board and a cooling substrate so as to direct a central axis of an irradiance pattern from the at least one narrowband radiation emitting device substantially orthogonally relative to a maximum plane of the mounting entity;

a mounting arrangement configured to position the at least one narrow band radiation emitting diode device so as to direct irradiation from the at least one narrow band radiation emitting diode device to a target in the irradiation zone; and

means operative to supply current to the at least one narrowband radiation emitting device.

2. A system for non-contact implantation of radiant energy into a target, the system comprising:

at least one semiconductor-based narrowband radiation emitting device element, the at least one narrowband radiation emitting device operative to emit radiation at a radiant heat output narrow wavelength band that matches a desired absorption characteristic of the target;

the at least one narrow band radiation emitting device is a mounted surface emitting laser diode device;

the at least one narrowband radiation emitting device is mounted to a mounting entity comprising at least one of a circuit board and a cooling substrate so as to direct a central axis of an irradiance pattern from the at least one narrowband radiation emitting device substantially orthogonally relative to a maximum plane of the mounting entity;

a mounting arrangement configured to position the at least one narrow band radiation emitting diode device so as to direct irradiation from the at least one narrow band radiation emitting diode device to a target in an irradiation zone; and

means operative to supply current to the at least one narrowband radiation emitting device.

3. The system of claim 1 or 2, wherein the at least one semiconductor-based narrowband radiation emitting device element forms an array of more than one surface emitting laser diode device.

4. The system of claim 3, wherein the array comprises an X by Y matrix of surface emitting laser diode devices, wherein both X and Y are greater than one (1).

5. The system of claim 4, wherein devices of at least two different device types are included in the array:

the device type is defined by at least one of: different wavelengths are generated, manufactured from different wafer substrate chemistries, have different physical sizes, different power outputs, and have different device output types.

6. The system of claim 5, wherein the different device types included in the array can produce at least two different wavelengths that are centered over 150nm from each other.

7. A system according to claim 1 or 2, wherein the means operative to supply current to the at least one narrowband radiation emitting device consists of a system selectively supplyable with current by means of:

at least one current controlled power supply controllable by an intelligent controller:

the intelligent controller controlling the power supply is comprised of at least one of: programmable logic controller, control panel based on microprocessor, computer control system and embedded logic controller.

8. The system of claim 5, wherein the intelligent controller has the ability to selectively control irradiation from the at least two different device types.

9. The system of claim 3, wherein laser emission inside each laser diode device occurs in a direction parallel to a mounting plane of the device while the central axis of the output irradiance pattern is generally orthogonal to the mounting plane.

10. An irradiation array for generating radiant energy associated with a target, comprising:

a semiconductor irradiation array, wherein devices are not mounted flush with any edge of a board on which the array is mounted;

wherein the mounting plate is configured as a highly thermally conductive substrate having at least one layer to conduct heat and one layer to conduct supply current;

wherein the array is constituted by surface-emitting semiconductor laser devices;

wherein an axis of optical photon output of the array of devices is substantially perpendicular to a major plane of the mounting substrate; and the number of the first and second electrodes,

wherein the mounting plate is configured to be thermally coupled to at least one of: a water jacket cooling system, a thermal radiation fin arrangement, a state change cooler, a compressed media cooler, and a thermoelectric cooler.

11. The system of claim 10, wherein the array is an X by Y array of surface emitting devices, whereby both X and Y are greater than one.

12. The system of claim 10, wherein the array is an arrangement of surface emitting devices whereby some of the devices are rotated relative to their neighbors.

13. A method for irradiating a target item, the method comprising:

introducing a target item into the irradiation zone;

emitting radiation at a radiant heat output narrow wavelength band that matches desired absorption characteristics of the target item using a mounted surface emitting laser diode device, wherein the mounted surface emitting laser diode device is mounted to a mounting entity comprising at least one of a circuit board and a cooling substrate so as to direct a central axis of an irradiation pattern from the device substantially orthogonally with respect to a maximum plane of the mounting entity; and

irradiating the target item based on the irradiation device.

14. The method of claim 13, wherein the target item is a food item.

15. The method of claim 13, wherein the target item is a preformed plastic bottle.