Laser diode-based temperature controlled systems, subsystems and methods

Abstract

A system, subsystem and method for controlling the temperature of an LD stack including at least one LD bar of at least one laser diode (LD) emitter to achieve a desired temperature of the LD stack and a corresponding emission wavelength of the LD emitter of the stack, using a thermal unit (TU) for temperature control of the LD bar / stack, a measuring device for detecting an updated ambient temperature in the area of ​​the LD bar, and a master controller for controlling the operation of the TU to achieve the desired temperature and the corresponding emission wavelength. At least one side of the TU is in direct thermal contact with a corresponding side of each LD stack, forming a contact surface area S1 between the TU and the LD stack. The size of S1 corresponds to the size of the entire contact surface area S2 of the TU facing the LD stack, which reduces the temperature control speed.

Description

[Technical field]

[0001] The present disclosure relates generally to systems, methods, units and / or devices based on laser diode emitters with temperature control, and more particularly to systems, methods, units and / or devices that enable stabilization and control of the temperature of a stack or bar of laser diode emitters. [Background technology]

[0002] In many systems that use one or more laser diodes, it is often necessary to achieve and / or stabilize the temperature in the region of the laser diode in order to achieve optimal or desired optical performance of the diode, such as a desired output wavelength.

[0003] Many laser diodes output light of different wavelengths or different wavelength bands at different temperatures and can have a typical sensitivity of 0.27 nm (nanometers) in wavelength for every 1 degree Celsius change.

[0004] Diode-pumped solid-state laser (DPSSL) systems typically use a solid-state gain medium with specific spectral absorption characteristics to generate optimal pump gain (hereafter "optimal lasing"). To enable optimal lasing, a light source is used, typically comprising a diode stack including one or more laser diode emitters, such as one or more light emitting diodes (LEDs), that can output light at one or more wavelengths that correspond to one or more absorption lines / wavelengths of the gain medium.

[0005] However, the wavelength or wavelength band output by a laser diode emitter is extremely sensitive to temperature and temperature changes (temperature change gradients) and can deviate significantly from the desired output optical characteristics, such as the desired output wavelength. If the temperature of a region of the laser diode stack deviates from the desired temperature or desired temperature range, the performance of the DPSSL system will be significantly degraded, including reduced gain, output power / energy, and degradation of throughput beam quality. It is therefore critical to maintain or achieve temperature stability of the laser diode over the entire operating temperature range of the DPSSL system.

[0006] Many DPSSL systems often need to be powered up for a while before they can actually be put into operation. It takes time (e.g., by heating / cooling the laser diode) to reach the desired temperature for optimal gain from the ambient temperature in the environment of the particular DPSSL system. This can take tens of seconds to minutes, depending on the difference between the desired temperature for optimal gain and the actual environmental temperature around the diode and / or the total mass of the diode and its mount that needs to be heated / cooled. Therefore, the power up time of the diode needs to be planned in advance for the actual required operation time of the DPSSL system based on the time required to bring the laser diode up to the desired operating temperature. Since the DPSSL system often needs to be kept in standby mode, the desired temperature (optimal mode) needs to be maintained to make the DPSSL system operational at any given time with unknown / unforeseen required operation timings, which causes unavoidable power consumption and inefficiencies in the system due to the significant amount of material that needs to be maintained at a specific desired temperature that is tens of degrees different from the environmental (ambient) temperature. Summary of the Invention

[0007] An aspect of the disclosed embodiment relates to a laser diode subsystem that includes at least the following:

[0008] (i) An LD assembly including at least one LD stack including at least one laser diode (LD) bar, each LD bar including at least one LD emitter, and the at least one LD emitter of each LD bar has at least one emission wavelength (WL) when operated at a corresponding desired operating temperature Td.

[0009] (ii) A temperature control subsystem that includes at least the following:

[0010] A thermal unit (TU) configured to control a temperature of at least one LD emitter of a corresponding LD stack.

[0011] At least one measurement device configured to detect at least one updated temperature-related parameter value of at least one LD emitter of the LD stack, the at least one updated temperature-related parameter value being associated with an updated ambient temperature Ta in a region of the at least one LD emitter.

[0012] a master control device operatively associated with the TU and the at least one measurement device, for controlling operation of the TU based on the detected updated temperature-related parameter value and at least one desired operating temperature Td of the at least one LD emitter, and at least one side of the TU in direct contact with a corresponding side of each LD stack of the laser diode assembly to provide direct thermal contact between the TU and each LD stack and form a contact surface area S1 between the TU and the corresponding TU stack.

[0013] According to some embodiments, the size of the contact surface area S1 may be smaller or equal to the overall size of the contact surface area S2 of the TU facing the LD stack, i.e., S1≦S2, and the ratio “R” of S1:S2 is adapted to reduce the mass heated or cooled by the TU in order to increase the temperature control speed by reducing the time to adjust the temperature of at least one LD emitter from an updated ambient temperature Ta to a desired operating temperature Td, which corresponds to a desired emission wavelength (WL) of the at least one emitter.

[0014] Aspects of the disclosed embodiments further relate to a diode-pumped solid-state laser (DPSSL) system including at least:

[0015] (i) An LD assembly including at least one LD stack including at least one laser diode (LD) bar, each LD bar including at least one LD emitter, each LD emitter being configured to emit light of at least one oscillation wavelength (WL) under at least one corresponding oscillation desired operating temperature Td.

[0016] (ii) Solid state (SS) gain medium.

[0017] (iii) a thermal unit (TU) configured to control the temperature of the LD stack.

[0018] (iv) at least one measurement device configured to detect at least one updated temperature-related parameter value of at least one LD emitter, the updated temperature-related parameter value being related to an updated ambient temperature Ta in a region of the at least one LD bar, and at least one desired operating temperature Td of the at least one LD emitter of each LD bar corresponding to an absorption performance of the gain medium.

[0019] (iv) a master controller operatively associated with the TU and the at least one measurement device, for controlling operation of the TU based on the detected updated temperature-related parameter value and at least one desired operating temperature Td of the at least one LD emitter, at least one side of the TU in direct contact with a corresponding side of each LD stack of the laser diode assembly to provide direct thermal contact between the TU and each LD stack, forming a contact surface area S1 between the TU and the corresponding LD stack.

[0020] According to some embodiments, at least one side of the TU may be in direct contact with a corresponding side of each LD stack of the laser diode assembly, providing direct thermal contact between the TU and each LD stack and forming a contact surface area S1 between the TU and the corresponding LD stack.

[0021] Additionally or alternatively, the system may be designed such that the size of the contact surface area S1 is less than or equal to the overall size of the contact surface area S2 of the TU facing the LD stack, i.e., S1≦S2 (the ratio “R” of S1:S2 is less than or equal to 1, i.e., R≦1), thereby reducing the mass heated or cooled by the TU and increasing the temperature control speed by reducing the time to adjust the temperature of the at least one LD emitter from the updated ambient temperature Ta to a desired operating temperature Td, which corresponds to a desired emission wavelength (WL) of the at least one emitter.

[0022] Another aspect of the disclosed embodiments relates to a temperature control method, the method including at least the following:

[0023] A laser diode assembly is provided that includes at least one LD stack including at least one laser diode (LD) bar, where each LD bar includes at least one LD emitter, and each LD emitter is configured to emit light of at least one emission wavelength (WL) when under at least one corresponding oscillation desired operating temperature Td.

[0024] Providing a thermal unit (TU) configured to control a temperature of the at least one LD emitter.

[0025] Providing at least one measuring device.

[0026] Detecting at least one updated temperature-related parameter value of the at least one LD emitter, the updated temperature-related parameter value being associated with an updated ambient temperature Ta in a region of the at least one LD emitter using the at least one measurement device.

[0027] Controlling operation of the TU based on the detected updated temperature-related parameter value and at least one desired operating temperature Td of the at least one LD emitter, wherein at least one side of the TU is in direct contact with a corresponding side of each LD stack of the laser diode assembly to provide direct thermal contact between the TU and each LD stack and form a contact surface area S1 between the TU and the corresponding LD stack. [Brief description of the drawings]

[0028] The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.

[0029] For simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, dimensions of some elements may be exaggerated relative to other elements for clarity of presentation. Furthermore, reference numbers may be repeated among the figures to indicate corresponding or similar elements. Reference to previously presented elements is implicit without necessarily further recitation to the figure or description in which they were presented. The figures are listed below.

[0030] [Figure 1A]1A shows a schematic diagram of a laser diode subsystem with fast temperature control of the temperature of a laser diode assembly according to some embodiments, FIG 1A shows a schematic diagram of a laser diode subsystem with a controllable thermal unit (TU) in direct contact with a laser diode stack or a laser diode bar or bars; [Figure 1B] 1A and 1B show schematic diagrams of a laser diode subsystem with fast temperature control of the temperature of a laser diode assembly according to some embodiments. FIG. 1B shows an exemplary ratio between the surface area S2 of the contact TU side bonded to the opposite side of the laser diode stack and the contact surface area S2 representing the overall area of ​​contact between the TU and the laser diode stack.

[0031] [Diagram 2] FIG. 2 shows a schematic diagram of a diode-pumped solid-state laser system that uses a laser diode subsystem as part of it for temperature control of a laser diode stack of a laser diode assembly, according to some embodiments.

[0032] [Diagram 3] FIG. 2 is a block diagram that generally illustrates optional modules operable by a master controller of a laser diode subsystem in accordance with some embodiments.

[0033] [Figure 4] 3 shows a schematic diagram of a laser diode subsystem according to another embodiment.

[0034] [Figure 5A] 5A shows an isometric view of a laser diode subsystem having two thermistors for measuring the laser diode emitter stack temperature according to another embodiment. [Figure 5B]5A and 5B show a front view of a laser diode subsystem having two thermistors for measuring the laser diode emitter stack temperature according to another embodiment.

[0035] [Figure 6] 1 is a flowchart outlining a method for controlling the temperature of a laser diode assembly based on real-time high speed measurement of one or more parameter values ​​related to updated temperatures of a laser diode bar / stack of a laser diode subsystem, according to some embodiments.

[0036] [Figure 7A] The absorption characteristics of the Nd:YAG gain medium (FIG. 7A) are shown. [Figure 7B] For example, the emission spectrum of a laser diode emitter is shown (FIG. 7B) when the emitter temperature is 70 degrees Celsius.

[0037] [Figure 8A] 8A shows the simulated / calculated performance of a time-dependent laser diode bar using a laser diode subsystem of some embodiments, illustrating the time-related response rate of the subsystem. FIG. 8A shows the calculated time-dependent power consumption behavior of the TEC. [Figure 8B] 8A and 8B show simulated / calculated performance of a time-dependent laser diode bar using laser diode subsystems of some embodiments, illustrating the time-related response rate of the subsystem. FIG. 8B shows the calculated behavior of the temperature of the bar over time.

[0038] [Figure 9A] 9A shows a calculated correlation of gain medium absorption based on bar / emitter temperature and emitter wavelength. According to some embodiments, FIG. 9A shows gain medium absorption performance in relation to bar / emitter temperature. [Figure 9B]Calculated correlation of gain medium absorption based on bar / emitter temperature and emitter wavelength is shown in Figure 9B, which shows the gain medium absorption performance in relation to the emission wavelength of the bar / emitter. [Figure 9C] A calculated correlation of gain medium absorption based on bar / emitter temperature and emitter wavelength is shown in Figure 9C, which shows a simulation relating expected and measured output energy from a solid-state (in this case Nd:YAG) laser cavity versus pump laser diode emitter temperature. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] A temperature controller, such as a thermoelectric cooler (TEC), can be used to heat, remove heat, and / or cool a laser diode assembly that includes one or more laser diode stacks.

[0040] A TEC is a semiconductor device that includes two thermally conductive plates, i.e., a hot plate and a cold plate, with a gap / distance between the plates in which alternating N-type and P-type semiconductor elements (e.g., alternating N / P pillars) are disposed.

[0041] In accordance with some aspects of the present disclosure, it is an object of one or more embodiments of the disclosed invention to improve the temperature control speed of a laser diode assembly to reach a desired operating temperature Td of the laser diode emitter of the laser diode assembly in the shortest time (at the highest heating / cooling rate) from an ambient temperature Ta, and to achieve a desired emission wavelength (WL) of the emitter corresponding to the desired operating temperature Td in the shortest time.

[0042] As used herein, the term "lasing wavelength" may refer to the wavelength intensity peak of the light emitted from a laser diode emitter.

[0043] The disclosed laser diode subsystem embodiments may be configured to allow for faster heating and / or cooling of the laser diode emitter, in particular, but not necessarily, when the absolute temperature difference between the desired operating temperature Td of the laser diode assembly and the (estimated / measured) ambient temperature Ta of the laser diode emitter required to achieve the corresponding desired emission wavelength of the emitter is high (e.g., 50 or 60 degrees Celsius or more). This allows for complete deactivation of the laser diode assembly (and optionally other parts of the system in which it is integrated) in particular when the laser diode assembly is not required for operation. This improves energy consumption efficiency while allowing for sufficiently fast achievement of the desired operating temperature Td (to achieve the desired emission wavelength) by heating / sinking / cooling the laser diode emitter from an ambient temperature Ta that is much higher or lower than the desired operating temperature Td, e.g., heating the laser diode emitter to 50 degrees Celsius lower than the desired operating temperature Td in less than one or two seconds under the ambient temperature Ta. Thus, the laser diode assembly / emitter can be quickly made operational at the optimum / desired operating temperature Td only when actual work / laser processing is required, and kept inactive (off) when not required.

[0044] The terms "ambient temperature" or "updated ambient temperature" may be used interchangeably herein and may refer to the temperature in the vicinity of a laser diode assembly or one or more of its laser diode emitter bars or stacks, and may also refer to the temperature of the environment surrounding a laser diode assembly / stack / bar / emitter even when the laser diode emitters are not operational (deactivated / disabled / off).

[0045] The term "desired operating temperature" as used herein may refer to a temperature value Td corresponding to a desired emission wavelength WL of a laser diode emitter, with a known / measured correlation between the emitter's temperature and the peak of emitted wavelength intensity. This means that the desired operating temperature Td is estimated at which the emitter will output light at a desired peak of emitted wavelength intensity for any desired requirement (which of course depends on the emission wavelength vs. temperature behavior of the particular emitter used).

[0046] To achieve optimal (e.g., maximum) temperature control speed, (i) the laser diode assembly may be directly contacted with at least one side or surface of a thermal unit such as a hot plate of the TEC. For example, the outer surface of the hot plate of the TEC may be glued / bonded / soldered to the side of the laser diode stack / bar of the laser assembly. (ii) The hot plate and / or the overall size (e.g., surface area) may be reduced to match the opposing surface area or footprint area / volume of the laser diode stack. This results in a ratio R between the contact area S1 of the laser diode contacting the TEC and the overall surface area S2 of the TEC plate side facing / bonding to the laser diode stack / bar as close to 1:1 as possible. For example, a minimum ratio of 1:2 or 1:4, i.e., R≧0.5 or R≧0.25 (i.e., the contact surface area S1 occupies 50% or more or 25% or more of the surface area of ​​the TU side bonding to the laser diode stack / bar, as close as possible to 100% surface area match (R=1)).

[0047] To achieve fast temperature control, the latest ambient temperature Ta should also be measured by a measurement device with fast sensing speed and / or output signal / data transmission speed, such as a thermistor. This allows fast heating / cooling of the laser diode assembly based on the measurement related to the latest ambient temperature and avoids overheating / undercooling due to misreading or delay of the ambient temperature Ta. A fast determination (e.g., calculation) of the temperature difference ΔT between the updated ambient temperature Ta and the (known) desired operating temperature Td, i.e., ΔT=Td-Ta or ΔT=Ta-Td, may also be required. For example, hardware and / or software means capable of fast processing / analysis of the data / signals of the received measurement device(s) may be required.

[0048] Aspects of the disclosed embodiments relate to a laser diode subsystem that includes at least: (i) a laser diode assembly having at least one laser diode stack including at least one laser diode bar (LDB) including at least one laser diode emitter, where the laser diode emitter of each LDB may have at least one desired operating temperature Td; (ii) a temperature control subsystem configured to rapidly measure and rapidly control the temperature of the laser diode assembly using a thermal unit (TU) such as a TEC, heater, heat sink, etc.; and (iii) one or more measurement devices configured to directly or indirectly measure an ambient temperature Ta in the region of the laser assembly.

[0049] According to some embodiments, at least one side of the TU is in direct contact with a corresponding side of each laser diode stack / bar of the laser diode assembly, and the TU is in direct thermal contact with each laser diode stack / bar. The size of the TU corresponds to the size of the laser diode assembly, reducing the mass heated and / or cooled by the TU and increasing the temperature control speed for changing the temperature from the measured / determined updated ambient temperature Ta to the desired operating temperature Td in the most efficient manner (e.g., reduced / minimized temperature control time and reduced / minimized overall power consumption operating time and / or energy consumption of the emitter and / or TU).

[0050] According to some embodiments, the temperature control subsystem may also include or be associated with a master controller operatively associated with the TU and the measurement device, and controls operation of the TU to reach at least one desired operating temperature Td of the at least one laser diode emitter based on updated temperature-related parameter values ​​detected by the measurement device.

[0051] According to some embodiments, direct contact between the sides of the TUs that are bonded to the laser diode stacks / bars may be made by soldering one side of each laser diode stack to a bonding side of the TU using a solder material that may have a similar or the same coefficient of thermal expansion (CTE) as at least one side of the TU that connects to at least one diode stack of the diode assembly and / or as at least one side of each laser diode stack that connects to the TU.

[0052] According to some embodiments, each laser diode stack may further comprise a spacer separating the diode bars in each laser diode stack from each other. The spacer may be positioned such that the bonding (contact) side of the TU is also in direct contact with the spacer of the respective laser diode stack.

[0053] In some embodiments, the TU directly connects each laser diode stack such that light emitted from each laser diode emitter of each LDB of the diode stack is directed in a direction that is angled relative to the plane of at least one TU connection side, forming a non-zero angle (e.g., between 30 degrees and 150 degrees) between the surface or plane of each TU connection side and the direction of the emitted light from each laser diode.

[0054] According to some embodiments, the entire operation of the laser diode subsystem may be automated.

[0055] According to some aspects of the disclosed embodiments, the laser diode subsystem may be operable as part of a DPSSL system that uses a laser diode assembly (located within a gain / lasing cavity) to illuminate a fixed gain medium made of a YAG-based material, such as a YAG-based material doped with one of neodymium (Nd), ytterbium, thulium (Tm), holmium (Ho), or erbium (Er), e.g., Nd:YAG, Yb:YAG, Ym:YAG, Ho:YAG, Er:YAG.

[0056] The Nd:YAG gain medium has at least two optimal absorption wavelengths ML1 / WL2 (WL1=795 nm and WL2=808 nm) in the infrared (1R) region. Correspondingly, the laser diode emitter (hereinafter also abbreviated as "emitter") of the laser diode assembly may be configured to emit light at corresponding wavelengths WL1 and WL2, which are achieved at different temperatures Td1 or Td2. This may allow for more efficient operation, such as faster acquisition of the desired temperature Td1 / Td2 (e.g., Td1=20 degrees Celsius, Td2=68 degrees Celsius to achieve the corresponding wavelengths WL1 and WL2 of the Nd:YAG related emitter). Also, the power consumption of the thermal unit is more economical in terms of time and energy due to the temperature control to reach either the desired operating temperature Td1 or Td2 closer to or faster reaching the ambient temperature Ta corresponding to one of the absorption wavelengths WL1 or WL2 of the gain medium. This allows the DPSSL to operate efficiently over a very wide range of environmental temperatures (e.g., above 100 degrees Celsius).

[0057] According to some embodiments, the laser diode subsystem may be configured to enable fast temperature measurements, fast temperature difference determinations, and fast temperature control within a few seconds (e.g., up to 2 seconds) for a DPSSL system using a Nd:YAG based gain medium with optimal absorption corresponding to the output wavelengths WL1 (795 nm) and WL2 (808 nm) of the laser diode emitters and corresponding to desired operating temperatures Td1 (20° C.) and Td2 (68° C.) for an ambient temperature Ta ranging from either of the desired operating temperatures Td1 / Td2 up to 50° C.

[0058] For example, if the DPSSL system is in an environment where the ambient external temperature can range from (-30) to (+70) degrees Celsius, the master controller will determine (based on the measured / determined accurate updated ambient temperature Ta) which of the desired operating temperatures Td1 or Td2 is closer to the updated ambient temperature and heat / cool the laser diode stacks / bars to the closest determined desired operating temperature.

[0059] According to some embodiments, the TU may be configured for passive cooling only, for example by passive heat removal (natural removal of heat, optionally via a TEC plate and / or a heat sink / heat spreader, or by applying a minimal current to it), and active heating only. In this case, a DPSSL system based on an embodiment of a Nd:YAG gain medium and a laser diode assembly may only need to heat the laser diode stack / bar at an ambient temperature in the range of (-30) to (+70) degrees Celsius to reach the nearest desired operating temperature of 20 / 68 degrees Celsius, or the desired operating temperature Td1 / Td2 that is reached in the shortest time. For example, for an ambient temperature Ta of 70°C, only 2 degrees Celsius of heat removal or cooling is required to reach the desired operating temperature Td2=68°C, which can be achieved quickly. In a specific example where the ambient temperature is in the range of 100 degrees Celsius, i.e., within the range of (-30)°C to (+70)°C, the maximum temperature difference ΔTmax required to reach the nearest / fastest desired operating temperature of 20°C or 68°C by heating / cooling is +50 degrees Celsius.

[0060] According to some embodiments, when the heat removal or cooling rate Vc is much slower than the heating rate Vh, i.e., Vc << Vh, a given decision-making process may include determining which desired operating temperature Td1 / Td2 is achieved faster, taking into account the difference between the cooling / heat removal rate and the heating rate and the temperature difference ΔT. In some cases, cooling / heat removal is only performed when the ambient temperature Ta exceeds the desired operating temperature Td2 that is higher, and a decision is made to heat the laser diode stack / bar to the nearest desired operating temperature Td1 / Td2 at a temperature below the maximum desired operating temperature Td2. For example, when the ambient temperature Ta is in the range from (-30°C) to (+67°C) (including a temperature close to the lowest desired operating temperature Td1), all heating may be required, and an ambient temperature Ta that exceeds the lowest operating temperature Td1 = 20°C may require heating to reach a higher operating temperature Td2 = 68°C, and an ambient temperature Ta < Td1 = 20°C that is below the desired operating temperature Td1 may require heating to reach the lowest desired operating temperature Td1 = 20°C. When the ambient temperature Ta is equal to either of the desired operating temperatures Td1 / Td2, TU may not be required to stabilize the operating temperature unless it is detected that the temperature has deviated from the desired operating temperature.

[0061] According to some embodiments, the laser diode assembly may include a laser diode emitter, TU, a main control device, and one or more power supplies for supplying power to the one or more measurement devices.

[0062] According to some embodiments, some or all of the laser diode emitter, TU, the main control device, and the one or more measurement devices may be individually powered such that they can operate (supply power to) the laser diode emitter and / or TU only as needed, while enabling the continuous / periodic operation of the measurement device and the main control device.

[0063] In some embodiments, the master controller is configured to individually control the operation of the TUs and the diode emitters, and may optionally also be configured to control the operation of one or more measurement devices.

[0064] According to some embodiments, one or more parameters may affect and therefore may be designed to optimize the temperature control rate, such as the ratio R of the overall or partial size, mass and / or dimensions of the TU to the overall or partial size, mass and / or dimensions of the footprint of the laser diode assembly / stack / bar or diode assembly. Thus, the design of the laser diode subsystem may be such that one or more of these ratios are minimized or reduced. The materials of at least the contacting parts of the TU and the laser diode assembly may also affect the thermal heating / removal rate and thus the temperature control rate, and may be considered in the design of the laser diode subsystem to optimize (reduce / minimize) the temperature control rate.

[0065] The master controller may be implemented as or include a printed circuit board (PCB) and may be located near, external to, or remote from the laser diode assembly. The printed circuit board may be connected to and in communication with the TU and at least one measurement device.

[0066] According to some embodiments, the TU side may be coupled to the laser diode stack / bar by soldering. The soldering material may have high thermal conductivity. Furthermore, the soldering material used to connect the TU to the laser diode stack / bar may have a melting point that allows the TU and the stack / bar to be soldered sequentially (stepwise).

[0067] According to some embodiments, the mass of the stack / bar or the entire laser diode assembly can be reduced to less than 1 gram.

[0068] According to some embodiments, by using a TEC as at least a portion of the TU in contact with the laser diode stack / bar, the power density of the TEC can be at least typically 15 W / cm for heating. 2 It can be said that:

[0069] According to some embodiments, the TEC (hot and cold) plates may be fabricated from a material such as Aluminum Nitride (AlN) that has a coefficient of thermal expansion (CTE) that corresponds (matches) the CTE of the spacers placed between the laser diode stacks / bars or laser diode emitters, eliminating or reducing physical damage, such as detachment of the TU from the laser diode assembly, when the laser diode subsystem is subjected to extreme ambient temperatures or experiences high temperature changes (high temperature gradients).

[0070] According to some embodiments, one or more of the measurement devices may have high speed measurement characteristics, for example being capable of measuring temperature related parameter values ​​at speeds of a few tenths of a second.

[0071] According to some embodiments, the ambient temperature of this relevant parameter value may be measured using a device or electrical circuit that manipulates (eg, biases) the input current supplied to the laser diode emitter.

[0072] According to some embodiments, the DPSSL system may be carried as a payload on a manually, automatically / autonomously, and / or remotely operated manned or unmanned vehicle.

[0073] Reference is now made to FIG. 1A, which illustrates a schematic of a laser diode subsystem (LDS) 1000 according to some embodiments.

[0074] The LDS 1000 may include:

[0075] A laser diode assembly (LDA) 1100 may include one or more laser diode stacks, each having one or more laser diode bars of one or more laser diode emitters.

[0076] A thermal control subsystem 1200, which includes:

[0077] (i) A thermal unit (TU) 1210 configured to heat and cool and / or remove heat from the laser diode stack of the LDA 1100.

[0078] (ii) a measurement device 1220, located in the vicinity of the laser diode stack of the LDA 1100 and configured, such as a thermistor, to measure a parameter value related to the ambient temperature Ta of the laser diode stack of the LDA 1100;

[0079] (iii) a master controller 1230 communicatively associated with the thermal unit 1210, the measurement device 1220, and optionally the LDA 1100;

[0080] According to some embodiments, the TU 1210 may include an electronically controllable TEC 1211 and, optionally, a heat spreader, such as a heat sink 1212.

[0081] The TEC1211 may include a first plate (hot plate) and a second plate (cold plate) with alternating N-type and P-type semiconductor element media disposed between the two plates.

[0082] The first and second plates of the TEC 1211 may be constructed of a material with high thermal conductivity to rapidly transfer heat to the LDA 1100.

[0083] A TU surface 12 (e.g., a surface of a first plate of TEC1211) may be coupled to a corresponding LDA surface 11 of LDA1100 to form a "contact area" S1 between them (e.g., by soldering them together using a thermally conductive solder material). The contact area S1 may be equal to or slightly smaller than the area of ​​the corresponding (opposing) LDA surface 11, such that the entire footprint of LDA1100 or a large portion of it is in direct thermal contact with the TU surface 12, and the ratio S1:S2 of the contact surface area S1 to the TU surface area S2 is as close to 1:1 as possible (e.g., about 1:1.5 in this example), but does not exceed an upper (maximum) ratio threshold of, for example, 1:1.4 or 1:2.

[0084] Minimizing the difference between the TU surface area S2 and the area of ​​the LDA surface 11 forming the contact area S1 allows for faster temperature control. Since the size of the TU surface 12 of the first plate of the TEC1211 (TU surface area S2 and optionally mass / volume, etc.) is close to the size of the LDA surface 11, the heat does not spread significantly from the contact area S1. Thus, the heat generated in the TEC1211 is directly and quickly transferred from the TEC1211 to the LDB of the LDA1100, which heats up in a more efficient way that focuses most of the energy on the LDA1100, avoiding or reducing the transfer of heat to other elements or components. The heat rejected from the LDA1100 is quickly removed or actively cooled by the TEC1211 when used for LDA cooling, and the rejected heat is directly channeled from the LDA1100 to the first plate of the TEC1211 and from there to the second plate of the TEC1211.

[0085] According to some embodiments, t-connector receptacles, such as connector receptacles 23 and 24, may be used to connect the LDA 1100 to the TU 1210. Connector receptacles 23 and 24 may be configured to be received in their sockets or openings 23a and 24a to accommodate fastening and / or electrical connectors or connectors.

[0086] According to some embodiments, connector receptacles 23 and 24, and / or corresponding connectors (not shown), are constructed of a low thermal conductivity material and may be used to mechanically and / or electrically connect LDA 1100 to other elements, devices, power sources, etc.

[0087] According to some embodiments, the size, mass, geometry, and / or configuration of the LDA1100 may be designed in a customized manner to further improve temperature control efficiency, such as by using a more compact / smaller configuration that stacks all emitters tighter and more compactly, by using smaller spacers or no spacers at all, by reducing the mass of the LDA1100 by selecting a lighter TU material with similar thermal properties, by removing most of the holding plates of standard used laser diode stacks, by reducing the total number and / or size of electrical connectors, etc.

[0088] According to some embodiments, the laser diode subsystem 1000 may be positioned such that the emitter of its LDA 1100 emits light in a direction (e.g., as shown by arrow E in FIG. 1A) that is angled (e.g., perpendicular) to the plane of the contact surface area S1.

[0089] According to some embodiments, the LDA 1100 may be of low mass, such as less than 1 gram.

[0090] 2 shows a schematic diagram of a diode-pumped solid-state laser (DPSSL) system 2000 according to some embodiments. The DPSSL system 2000 includes at least the following:

[0091] A laser diode subsystem 2100 including at least: (i) an LDA 2110 having a laser diode stack including a single laser diode bar 2111 of multiple laser diode emitters 2112, (ii) one or more temperature measurement devices 2130 such as a thermistor, (iii) a temperature control subsystem including a TEC 2120, and (iv) a main controller 2140 that can be implemented using a PCB.

[0092] The gain medium 2200 may be an element such as a Nd:YAG rod having one or more primary optimum absorption wavelengths WL1=795 nm and WL2=808 nm, configured to output a light beam at a wavelength or in a narrow wavelength band different from the emission wavelength of the emitter 2112, and may optionally also include:

[0093] An optical setup 2001 including one or more optical elements and / or optical devices configured to direct and optionally focus light from the laser diode emitter 2112 to the gain medium 2200 to optimally illuminate the gain medium 2200. This can be done, for example, by creating a light spot (also referred to herein as a "spot") that can be absorbed by the gain medium 2200. The spot can be configured by the optical setup 2001 to (a) be of a desired size, (b) impinge on the gain medium 2200 at a desired designated gain medium region / surface / spot, and / or (c) impinge on the gain medium 2200 at a desired beam propagation direction angle.

[0094] The master controller 2140 may be configured to receive temperature-related data / signals in real-time, ongoing or periodic from a measurement device 2130, which may be located in the vicinity of the laser diode bar 2111, process the received data / signals to determine a real-time updated ambient temperature Ta of the laser diode bar 2111, determine (e.g., calculate) a temperature difference ΔT between the updated ambient temperature Ta and the desired operating temperature Td, and control the TEC 2120 to heat or remove heat / cool the laser diode bar 2111.

[0095] According to some embodiments, as shown in FIG. 2, the TEC 2120 may include a first (hot) plate 2125a and a second (cold) plate 2125b made of a thermally conductive material, and an NP semiconductor layer 2127 located between the first and second plates 2125a, 2125b.

[0096] One side of the first (hot) plate 2125a that does not face the NP semiconductor layer 2127 (which may be flat) is in direct contact with the opposing side of the laser diode bar 2111 and has a surface area magnitude similar to that of the laser diode bar 2111, such that at least the majority of the surface area of ​​the entire laser diode bar 2111 that is in direct contact with the first (hot) plate 2125a is covered / encased by the surface area of ​​the side of the first (hot) plate 2125a.

[0097] The direct contact of the TEC 2120 first (hot) plate 2125a, their similar size of surface areas (e.g., a ratio between the surface area of ​​the first plate 2125a and the surface area of ​​the laser diode bar 2111 of about 1:1.5), combined with a design in which the surface area of ​​the first (hot) plate 2125a envelops (completely covers) at least a majority of the corresponding surface area of ​​the laser diode bar 2111, improves power consumption and temperature control speed. The increased temperature regulation / control speed results in significantly improved energy consumption management, especially in cases where the updated ambient temperature Ta deviates significantly from the desired operating temperature Td, sometimes resulting in a temperature difference of as much as 70 degrees Celsius. For example, to reduce power consumption, when the DPSSL system 2000 does not need to emit a laser beam, the emitter 2112 and optionally the entire DPSSL system 2000 may be set to remain inactive and activated / briefly operated (e.g., within a few seconds) only before optimal DPSSL laser beam emission is required, thereby overcoming such a large temperature difference ΔTs in a minimum time such as within a second or two. The updated ambient temperature Ta in these cases may be the natural temperature of the outside / environment, where the (closest) desired operating temperature Td is known and may not be altered, and the temperature control subsystem 2120 is set to adjust the smaller temperature difference after the desired operating temperature Td is achieved, versus a temperature stabilization maintenance operating mode in which the DPSSL system 2000 outputs a laser beam for a longer period of time.

[0098] 3 is a block diagram that generally illustrates optional modules operable by a master controller, such as master controller 2140, of laser diode subsystem 2100, in accordance with some embodiments. Master controller 2140 may include:

[0099] A communications module 2141 configured to receive data / signals from one or more measurement devices, such as the measurement device 2130 of the temperature control subsystem 2120 of the laser diode subsystem 2100, the received signals indicating an updated ambient temperature Ta of the laser diode stack / bar / emitter of the laser diode assembly.

[0100] A processing and control unit 2142 (a) processes (in real time) the received measurement data / signals, (b) based thereon, determines an updated ambient temperature Ta of the laser diode emitter / bar, (c) determines (calculates) an updated temperature difference ΔT between the updated ambient temperature Ta and the (selected) desired operating temperature Td, and (d) based on the determined temperature difference and the (selected) desired operating temperature Td, automatically operates the TU of the laser diode subsystem 2100, and optionally also the laser diode emitter 2112, to achieve the determined desired operating temperature Td.

[0101] A memory device 2143 for storing operational commands / instructions / plans, data received from measurement devices, and / or determined values ​​such as updated ambient temperature and / or temperature difference.

[0102] A power source, such as one or more batteries and / or power supplies, that provides power to one or more devices, such as the main controller 2140 itself, the measurement device 2130, the TEC of the temperature control subsystem 2120, the laser diode (LD) emitter 2112, and devices of the optical setup 2001.

[0103] 4 shows a schematic diagram of a laser diode subsystem 4000 according to another embodiment. The laser diode subsystem 4000 may include:

[0104] A laser diode assembly (LDA) 4100 may include one or more laser diode stacks, each having one or more laser diode bars of one or more laser diode emitters.

[0105] The thermal control subsystem 4200 may include at least one TU including a TEC having two thermally conductive plates including a first plate 4211 and a second plate 4112, and optionally a heat sink thermally coupled to the second plate 4112 of the TEC 4210.

[0106] According to some embodiments, the LDA 4100 may include one or more connections, such as connection 4001, for connecting to a measurement device, such as one or more thermistors 4301.

[0107] Other electrical connection means may be used, such as connection 4002 for electrically connecting the TEC 4210 to a main controller (not shown) and / or one or more power supply means.

[0108] According to some embodiments, the first plate 4211 of the TEC 4210 may be integrally connected or drilled into one or more connector receptacles, such as connector receptacles 41 and 42, and may be configured and arranged to be received into those sockets or openings to accommodate fastening and / or electrical connectors, and may be made of a very low thermal conductivity material.

[0109] The first plate 4211 of the TEC4210 may be thermally coupled to the underside of the LDA4100, for example, by soldering the LDA4100 to the first plate 4211 of the TEC4210 using a thermally conductive solder material, such that the contact surface area of ​​the contact side of the LDA4100 and the contact surface area of ​​the TEC's first plate 4211 (equal to contact area S1) is close to the TU contact surface area S2.

[0110] 5A and 5B show schematic diagrams of a laser diode subsystem 5000 having two thermistors 5301 and 5302 for improving the accuracy of temperature measurements of the LDA 5100 in accordance with another embodiment.

[0111] The laser diode subsystem 5000 may include:

[0112] A laser diode assembly (LDA) 5100 may include one or more laser diode stacks, each having one or more multiple laser diode bars of one or more laser diode emitters.

[0113] The thermal control subsystem 5200 may include at least one TU including two thermally conductive plates, i.e., a first plate 5211 and a second plate 5212 having an NP semiconductor layer 5213 therebetween, and optionally a heat sink 5220 thermally coupled to the second plate 5212 of the TEC 5210.

[0114] A thermistor 5301 arranged and configured to directly measure the temperature Ta of the LDA5100, and a thermistor 5302 arranged and configured to measure the temperature TU.

[0115] Electrical connectors 5001 and 5002 for connecting the TEC 5210 and / or thermistors 5001 and 5002, for example, to a power supply and / or other electrical system components.

[0116] The first plate 5211 of the TEC5210 may be thermally coupled to the underside of the LDA5100, for example by soldering the LDA5100 to the first plate 5211 of the TEC5210 using a thermally conductive soldering material, such that the surface area of ​​the contact side of the LDA5100 and the contact surface area of ​​the first plate 5211 of the TEC (equal to contact area S1) is equal in size to the TU contact area S2.

[0117] According to some embodiments, as shown in Figures 5A and 5B, one of the thermistors, such as the first thermistor 5301, may be placed adjacent to the LDA 5100 to measure the ambient temperature Ta(LDA) of the LDA 5100, while the other (second) thermistor 5302 may be placed adjacent to one of the TEC plates, such as the second plate 5212, to measure the ambient temperature Ta(TU) of the TEC 5210. This configuration also allows measuring / calculating the ambient temperature difference ΔTa between the TU (e.g., the TEC 5210) and the LDA 5100 (ΔTa=Ta(LDA)-Ta(TU) or ΔTa=Ta(TU)-Ta(LDA)). This allows measuring / determining the performance of the TU / TEC 5210, such as, for example, the heating / cooling rate, maximum / minimum heat transfer capacity, etc.

[0118] FIG. 6 is a schematic flow chart illustrating a method for automatic control of temperature of a laser diode assembly based on real-time, automated, and rapid measurement of one or more parameter values ​​related to updated temperatures of laser diode bars / stacks of a laser diode subsystem, in accordance with some embodiments.

[0119] The method may include:

[0120] Detecting at least one updated temperature related parameter value of the laser diode assembly: 61, where the updated temperature related parameter is related to an updated ambient temperature Ta of the laser diode assembly / stack / diode.

[0121] Determining an updated temperature Ta based on the detected updated temperature-related parameter values, and determining an updated difference ΔT between the updated ambient temperature Ta and the (closest / selected) desired operating temperature Td: 62.

[0122] Based on the determined updated temperature difference ΔT and the (closest / selected) desired operating temperature Td, determining one or more updated control actions required to control TU and to achieve the determined desired operating temperature Td in an optimal manner (e.g., within the shortest time): 63.

[0123] Controlling the operation of the TU of the laser diode subsystem, and optionally the operation of the LD emitter, based on the determined desired operating temperature Td: 64.

[0124] According to some embodiments, all of the process steps 61-64 may be performed automatically, either on an ongoing or periodic basis.

[0125] Referring to Figure 7A which shows the absorption lines of the Nd:YAG gain medium, it is clear that the Nd:YAG gain medium exhibits the highest absorption at wavelengths WL1 = 795 nm and WL2 = 808 nm.

[0126] FIG. 7B shows the spectral behavior of the laser diode emitter at a temperature of (for example) 70 degrees Celsius, using a current draw of, for example, 170 A (amperes), or the design operating current of the laser diode. At this temperature Td=70°C, the emission WL peak is shown to be at 808 nm, with a relatively narrow emission band of about 3 nm. Considering a shift of 0.27 nm from the emission WL peak, for every degree Celsius, this LD emitter is expected to output an intensity peak at 794.5 nm at 20°C (50°C difference from Td). This is calculated as 808 (nm) - 0.27 (nm / °C) x 50°C = 794.5 nm. The emission wavelength of light of about 795 nm emitted by this LD emitter is well absorbed by the Nd:YAG gain medium, so the DPSSL system can produce significant pumping gain.

[0127] 8A and 8B show the estimated (simulated) performance of the time-dependent laser diode bar of the temperature control subsystem without checking with the control circuit / feedback subsystem (time-related behavior of power consumption and temperature), which shows the estimated time-related response rate of the laser diode subsystem when using the laser diode subsystem according to some embodiments. The bar is shown to heat up from an ambient temperature Ta of (-40)°C to (+23)°C to about +63°C in less than about 2 seconds (about 1 second), and then stabilize to a value close to the value of the desired operating temperature Td (+20°C) in just over 1 second (FIG. 8B). Accordingly, the main power consumption of about 10W (watts) to heat the LD bar is made within the first second, and the power consumption is then dramatically reduced to about 2W to stabilize the temperature Td and / or once it is reached or exceeded when the LD bar is deactivated (using power only to maintain the desired operating temperature Td).

[0128] This simulation was performed without continuous feedback and control measures, so the performance is lower than would be expected if a control feedback loop / circuit were used. A control feedback loop / circuit would continuously measure the temperature difference between the LDA ambient temperature Ta and the desired operating temperature Td, and continuously or nearly continuously adjust the temperature to achieve the desired operating temperature Td. Thus, in this case, the system was able to reach the exact value of the desired operating temperature Td (+20)°C within about 2 seconds.

[0129] The power consumption behavior correlated with the temperature change behavior of FIG. 8B is shown in FIG. 8A and shows that with a substantial temperature difference of about 60° C., the initial heating of the emitter from the ambient temperature Ta to just above the desired operating temperature Td required a power consumption of about 10 W in only about 1.5 seconds (less than 2 seconds). After the initial heating, stabilization of the desired operating temperature Td requires much less energy / power consumption, with the power consumption remaining substantially stable at about 2 W. Again, this is due to the very low mass of the diode bar.

[0130] 9A-9C show calculated correlations for gain medium absorption.

[0131] This is based on the temperature of the bar / emitter and the emission wavelength of the emitter, according to some embodiments.

[0132] FIG. 9A shows the gain medium absorption performance related to the bar / emitter temperature.

[0133] FIG. 9B shows the gain medium absorption performance in relation to the lasing wavelength of the bar / emitter.

[0134] Figure 9C shows the integrated dependence (straight line) of the output power performance on the gain medium absorption efficiency and the emitter / bar temperature. Figure 9C also shows the measured output energy from the oscillator as a function of the pump diode temperature (dashed line). The measured output energy is very close and correlates well with the theoretical calculation, proving the feasibility of the proposed concept. Simulations to generate the estimated absorption performance shown in Figures 9A-9B were performed for LD emitters targeted for oscillation at desired oscillation wavelengths of 795 nm and 808 nm at corresponding desired operating temperatures of Td1 = 20°C and Td2 = 68°C, corresponding to the optimum absorption WL of a cylindrical Nd:YAG gain medium doped with 0.7% Nd and having a cylinder diameter of 4 nm. The simulations used a beam tracing program / method known as Tracc-prp to calculate the dependence of the gain medium absorption efficiency on the temperature of the LD emitter over an overall temperature range of 100°C (between -30°C and +70°C). Figures 9A-9C show the strong dependence and correlation between the absorption efficiency dependence on the temperature of the emitter and the oscillation WL of the LD emitter, and the strong absorption of the gain medium at the optimum / desired WL of 808 nm and 795 nm achievable when the desired operating temperatures of the corresponding emitters are reached at Td1 = 20°C and Td2 = 68°C.

[0135] Example.

[0136] Example 1 is a laser diode subsystem that includes at least the following:

[0137] (i) A laser diode assembly including at least one LD including at least one laser diode (LD) bar, each LD bar (LDB) including at least one LD emitter, and the at least one LD emitter of each LDB has at least one oscillation wavelength (WL) when operated at the same corresponding desired operating temperature Td.

[0138] (ii) A temperature control subsystem that includes at least the following:

[0139] A thermal unit (TU) configured to control the temperature of the at least one LD emitter.

[0140] At least one measurement device configured to detect at least one updated temperature-related parameter value of at least one LD emitter of the laser diode assembly, the updated temperature-related parameter value being associated with an updated ambient temperature Ta in a region of the at least one LD emitter.

[0141] A master controller operatively associated with the TU and operatively associated with the at least one measurement device, for controlling operation of the TU based on the detected updated temperature-related parameter value and at least one desired operating temperature Td of the at least one LD emitter.

[0142] Here, at least one side of the TU is in direct contact with a corresponding side of each LD stack of the laser diode assembly, providing direct thermal contact between the TU and each LD stack, the size of the TU corresponds to the size of the laser diode assembly, and the mass to be heated or cooled is minimized, and the temperature control speed is improved by shortening the time required for adjusting the temperature of the at least one LD emitter from the updated ambient temperature Ta to the desired operating temperature Td, thereby achieving the oscillation WL of the at least one LD emitter corresponding to the desired operating temperature Td.

[0143] In Example 2, the content of Example 1 may include a case where the overall size of the TU and / or the ratio between the dimensions of the TU corresponds to the overall size and / or dimensions of the diode assembly or the footprint of the diode assembly.

[0144] In Example 3, the content of Example 2 may include that the ratio R of the contact surface area S1 between the TU and at least one diode stack of the diode assembly to the overall TU contact surface area S2 of at least one side of the TU in direct contact with at least one laser diode stack of the diode assembly is 1:4 or more, i.e., S1 / S2=R≧0.25.

[0145] In Example 4, the content of Example 3 may include that the ratio R between the contact surface area S1 and the total contact surface area S2 of the TU is equal to or greater than 1:2, i.e., R≧0.5.

[0146] In Example 5, the contents of any one or more of Examples 1 to 4 may include that direct contact between the TU and at least one laser diode stack is made by soldering one side of each laser diode stack to one side of the TU using a soldering material.

[0147] In Example 6, the content of Example 5 may include that the soldering material has a similar or the same coefficient of thermal expansion (CTE) as at least one side of the TU that connects to at least one diode stack of the diode assembly and / or at least one side of each laser diode stack that connects to the TU.

[0148] In Example 7, the contents of any one or more of Examples 1 to 6 may include, wherein each laser diode stack of the diode assembly includes a plurality of diode bars, each laser diode bar includes a plurality of emitters, each laser diode stack further includes a spacer separating the diode bars in each laser diode stack from each other, and at least one side of the TU is in direct contact with the spacer of the diode stack.

[0149] In Example 8, the contents of any one or more of Examples 1 to 7 may include that a TU is directly connected to each laser diode stack, such that light emitted from each respective diode of the diode stack is directed in a direction that is angled with respect to at least one TU connection side, forming a non-zero angle between a surface or plane of each TU connection side and the direction of light emitted from each laser diode.

[0150] In Example 9, the content of Example 8 may include that a non-zero angle formed between a plane or surface on the TU side connecting to at least one diode stack and a direction of light emitted from each laser diode is 30 to 150 degrees.

[0151] In Example 10, the contents of any one or more of Examples 1 to 9 may include that the laser diode subsystem further includes one or more connectors for securing the TU to the diode assembly, and at least one of the one or more connectors is made of a thermally and / or electrically non-conductive material.

[0152] In an eleventh embodiment, any one or more of the contents of the first to tenth embodiments may include that the TU includes a thermoelectric cooler (TEC).

[0153] In Example 12, any one or more of the contents of Examples 1 to 11 may include that the TU includes a TEC and a heat spreader including one or more heat conducting elements.

[0154] In Example 13, any one or more of the contents of Examples 1 to 12 may include that at least one measurement device of the temperature control subsystem includes one or more temperature sensors, at least one of which is located near the diode assembly.

[0155] In Example 14, the subject matter of Example 13 may include, where at least one of the one or more temperature sensors has a response time of less than 2 seconds.

[0156] In Example 15, the contents of any one or more of Examples 1 to 14 may include the laser diode subsystem further including at least one printed circuit board (PCB), and the TU being carried by the PCB or directly attached to the PCB.

[0157] In Example 16, the contents of any one or more of Examples 1 to 15 may include that the at least one measurement device, the TU, and the laser diode assembly are all disposed within a diode-pumped solid-state laser (DPSSL) system that also includes a laser diode assembly and a solid-state gain medium, and at least one desired operating temperature Td of the at least one LD emitter of each LD bar corresponds to an absorption characteristic of the gain medium.

[0158] In the seventeenth embodiment, any one or more of the contents of the first to sixteenth embodiments may include a case where the main control device is configured at least as follows.

[0159] Receiving updated temperature data in real time or near real time from the at least one measurement device, the updated temperature data indicative of at least an updated ambient temperature parameter value Ta of the diode assembly.

[0160] Determining an updated ambient temperature Ta based on the received updated temperature data.

[0161] Determine the updated temperature difference ΔT.

[0162] The updated temperature difference ΔT is the difference between the desired operating temperature value Td and the determined updated ambient temperature value and is determined in real-time or near real-time relative to the time the updated temperature data is received.

[0163] In real time, or near real time, one or more updated control actions required to control TU are determined in relation to the time at which the corresponding updated temperature difference ΔT was determined to most quickly achieve the desired operating temperature Td or to achieve a deviation from the desired operating temperature Td that is less than a predetermined temperature deviation threshold TDth.

[0164] Controlling the TU in real time or near real time based on the determined one or more control actions relative to a determination time of the corresponding one or more control actions.

[0165] In Example 18, the contents of any one or more of Examples 1 to 17 may include that the main control device includes at least the following.

[0166] A communications module for transmitting at least data to and from the TU via one or more communications links and for receiving at least data from the at least one or more measurement devices.

[0167] A processing and control module processes the data received from the at least one measurement device, determines one or more updated temperature control actions based on the processing results, and controls a temperature of the laser diode assembly based on the determined one or more updated control actions.

[0168] Memory unit.

[0169] In Example 19, the contents of any one or more of Examples 1 to 18 may include that each desired operating temperature Td of each LD bar is associated with a corresponding desired oscillation wavelength (WL) of at least one corresponding LD emitter of the corresponding LD bar.

[0170] In Example 20, any one or more of the contents of Examples 1 to 19 may include that all of the LD emitters of each LDB have at least one desired operating temperature Td.

[0171] In Example 21, the content of Example 20 may include that all the LD emitters of each LDB are light-emitting diodes (LEDs).

[0172] In Example 22, the content of any one or more of Examples 1 to 21 may include that the laser diode subsystem is configured to adjust a temperature of at least one LD emitter from its updated ambient temperature Ta to a desired operating temperature Td such that an absolute value of a temperature difference ΔT between the updated ambient temperature Ta and the at least one desired operating temperature Td is up to 60 degrees Celsius within a maximum adjustment time of 2 seconds.

[0173] In Example 23, any one or more of the contents of Examples 1 to 22 may include that the master controller is located outside and / or remote from the laser diode assembly.

[0174] In Example 24, the contents of any one or more of Examples 1 to 23 may include that the main control device includes a printed circuit board (PCB) connected to the TU and the at least one measurement device, and the PCB is disposed proximate to the laser diode assembly.

[0175] In Example 25, any one or more of Examples 1 to 23 may include, wherein the laser diode assembly has a mass of 1 gram or less.

[0176] Example 26 is a diode-pumped solid-state laser (DPSSL) system that includes at least the following:

[0177] A DPSSL device containing at least the following:

[0178] (i) A laser diode assembly including at least one LD stack including at least one laser diode (LD) bar, each LD bar including at least one LD emitter, each LD emitter configured to emit light of at least one lasing wavelength (WL) when under at least one corresponding light emission desired operating temperature Td.

[0179] (ii) Solid state (SS) gain medium.

[0180] (iii) a thermal unit (TU) configured to control the temperature of the LD stack.

[0181] (iv) at least one measurement device configured to detect at least one updated temperature-related parameter value of the at least one LD emitter, the updated temperature-related parameter value being associated with an updated ambient temperature Ta in a region of the at least one LDB, the SS gain medium, the at least one measurement device and TU, and the laser diode assembly are all disposed within the DPSSL device, and at least one desired operating temperature Td of the at least one LD emitter of each LD bar corresponds to an absorption characteristic of the gain medium.

[0182] a master controller operatively associated with the TU and operatively associated with the at least one measurement device for controlling operation of the TU based on the detected updated temperature-related parameter value and at least one desired operating temperature Td of the at least one LD emitter, wherein at least one side of the TU is in direct contact with a corresponding side of each LD stack of the laser diode assembly such that there is direct thermal contact between the TU and each laser diode stack, and a size of the TU corresponds to a size of the laser diode assembly, and improves a temperature control speed by reducing a time to adjust the temperature of the at least one LD emitter from the updated ambient temperature Ta to a desired operating temperature Td, thereby achieving an oscillation WL of the at least one LD emitter corresponding to the desired operating temperature Td corresponding to the at least one absorption characteristic of the SS gain medium.

[0183] In Example 27, the subject matter of Example 26 may include, wherein the gain medium includes one of the following: an yttrium aluminum garnet (YAG) based material, a doped YAG material doped with one of neodymium (Nd), ytterbium (Yb), thulium (Tm), holmium (Ho), and erbium (Er).

[0184] Example 28 is a method for temperature control, the method including at least the following:

[0185] A laser diode assembly is provided that includes at least one LD stack including at least one laser diode (LD) bar, where each LD bar includes at least one LD emitter, and each LD emitter is configured to emit light of at least one oscillation wavelength (WL) when under at least one corresponding light emission desired operating temperature Td.

[0186] Providing a thermal unit (TU) configured to control a temperature of the at least one LD emitter.

[0187] Providing at least one measuring device.

[0188] Detecting at least one updated temperature-related parameter value of the at least one LD emitter, the updated temperature-related parameter value being associated with an updated ambient temperature Ta in a region of the at least one LD emitter using the at least one measurement device.

[0189] Controlling operation of the TU based on the detected updated temperature-related parameter value and at least one desired operating temperature Td of the at least one LD emitter, wherein at least one side of the TU is in direct contact with a corresponding side of each laser diode stack of the laser diode assembly to provide direct thermal contact between the TU and each LD stack, and a size of the TU corresponds to a size of the laser diode assembly, minimizing the mass of the laser diode, and shortening the time to adjust the temperature of the at least one LD emitter from the updated ambient temperature Ta to the desired operating temperature Td, thereby improving the temperature control speed and achieving an oscillation WL of the at least one LD emitter corresponding to the desired operating temperature Td.

[0190] In Example 29, the content of Example 28 may include the following:

[0191] (a) receiving, in real time or near real time, updated temperature data from at least one measurement device, the updated temperature data indicative of at least an updated ambient temperature parameter value, Ta, of the diode assembly;

[0192] (b) determining, in real time or near real time relative to the time of receipt of the updated temperature data, an updated temperature difference ΔT between the desired operating temperature value Td and the updated ambient temperature value Ta, ΔT=Td-Ta or ΔT=Ta-Td;

[0193] (c) determining, in real time or near real time, one or more updated control actions required to control TU relative to the time of the corresponding determination of the updated temperature difference ΔT, to most quickly achieve the desired operating temperature Td or to reduce the deviation from the desired operating temperature Td to less than a predetermined temperature deviation threshold TDTh.

[0194] (d) controlling the TU in real time or near real time based on the determined one or more control actions relative to a determination time of the corresponding one or more control actions;

[0195] In Example 30, any one or more of the contents of Examples 28 to 29 may include a case where steps (a) to (d) are performed automatically using a master controller.

[0196] In Example 31, any one or more of the contents of Examples 28 to 30 may include that steps (a) to (d) can be performed in real time or in real time.

[0197] In Example 32, the contents of any one or more of Examples 28 to 31 may include that the overall size and / or dimension ratio of the TU corresponds to a ratio between the overall size and / or dimension of the diode assembly, or the overall size and / or dimension of the footprint of the diode assembly.

[0198] In Example 33, the content of Example 32 may include that the ratio R of the contact surface area S1 between the TU and at least one diode stack of the diode assembly to the overall TU contact surface area S2 of at least one side of the TU in direct contact with at least one laser diode stack of the diode assembly is 1:4 or greater, i.e., S1 / S2=R≧0.25.

[0199] In Example 34, the content of Example 33 may include that the ratio R between the contact surface area S1 and the total contact surface area S2 of the TU is 1:2 or more, i.e., R≧0.5.

[0200] In Example 35, any one or more of the contents of Examples 28 to 34 may include that direct contact between the TU and at least one laser diode assembly is made by soldering one side of each laser diode stack to one side of the TU using a soldering material.

[0201] In Example 36, the content of Example 35 may include that the solder material has a similar or the same coefficient of thermal expansion (CTE) as at least one side of the TU that connects to at least one diode stack of the diode assembly and / or at least one side of each laser diode stack that connects to the TU.

[0202] In Example 37, the contents of one or more of Examples 28 to 26 may include that a TU is in direct contact with each laser diode stack, and light emitted from each of the LD emitters of each LD bar is directed in an angled direction with at least one TU connection surface, forming a non-zero angle between a surface or plane of each TU connection surface and a direction of emitted light from each laser diode.

[0203] In Example 38, the content of Example 37 may include that a non-zero angle formed between a surface or plane of the TU connecting to at least one diode stack and the direction of light emitted from each laser diode is 30 to 150 degrees.

[0204] In Example 39, any one or more of the contents of Examples 28 to 38 may include that the TU is configured with a thermoelectric cooler (TEC).

[0205] In Example 40, any one or more of the contents of Examples 28 to 39 may include a case where the TU includes a TEC and a thermal spreader including one or more heat conducting elements.

[0206] In Example 41, any one or more of the contents of Examples 28 to 40 may include that at least one measurement device of the temperature control subsystem includes one or more temperature sensors, and at least one temperature sensor is located near the laser diode assembly.

[0207] In Example 42, the contents of any one or more of Examples 28 to 41 may include that the at least one measurement device, the TU, and the laser diode assembly are all disposed within a diode-pumped solid-state laser (DPSSL) system that also includes a solid-state gain medium, and at least one desired operating temperature Td of the at least one LD emitter of each LDB corresponds to an absorption characteristic of the gain medium.

[0208] In Example 43, the contents of any one or more of Examples 28 to 42 may include that all the LD emitters of each LD bar are configured to emit light of the same wavelength or wavelength band when at least one desired operating temperature Td is the same.

[0209] In Example 44, any one or more of the contents of Examples 28 to 43 may include performing temperature control by adjusting a temperature of at least one LD emitter from its updated ambient temperature Ta to a desired operating temperature Td, so that an absolute value of a temperature difference ΔT between the updated ambient temperature Ta and at least one desired operating temperature Td becomes lower than 70° C. within a maximum adjustment time of 2 seconds.

[0210] While the above description sets forth a limited number of exemplary embodiments, these embodiments should not be construed as imposing any limitations on the scope of the invention, but rather as illustrations of some of the ways in which the invention may be practiced.

[0211] The methods and / or processes described herein may be implemented by any one or more software, and / or hardware, components, devices, mechanisms, electronic and / or digital computerized systems, units, processing modules, devices, machines, engines, etc.

[0212] Systems, modules, units, devices, etc., or portions thereof, can be programmed to perform particular functions in response to computer readable and executable instructions, rules, conditions, etc. from programmable hardware and / or software-based execution modules that may implement one or more of the methods or processes disclosed herein. Thus, in effect, a "special purpose computer" specific to each disclosed method / process embodiment can be considered to be disclosed.

[0213] Additionally or alternatively, the methods and / or processes disclosed herein may be implemented as a computer program tangibly or intangibly embodied by a special purpose computer-readable signal medium. A computer-readable signal medium may include a propagated data signal having computer-readable program code embodied therein, for example as part of a baseband or carrier wave. Such a propagated signal may take a variety of forms, including but not limited to electromagnetic, optical, or any suitable combination thereof. A computer-readable signal medium may be any computer-readable medium that is not a non-transitory computer or machine-readable storage device, but can convey, propagate, or transmit a program used by or in connection with the devices, systems, platforms, methods, operations, and / or processes described herein.

[0214] The terms "non-transitory computer-readable storage" and "non-transitory machine-readable storage" may also include distribution media, intermediate storage media, computer execution memory, and other media or devices that may be stored for later reading by a computer program that executes an embodiment of the method disclosed herein. A computer program product may be deployed to be executed on one computer, or on multiple computers at one location, or may be distributed across multiple locations and interconnected by one or more communications networks.

[0215] The computer-readable executable instructions may be loaded into a computer, other programmable data processing device, or other device and cause the computer, other programmable device, or other device to execute a series of operational steps to generate a computer-executed process such that the computer-executed instructions perform the functions / acts specified in the flowchart and / or block diagram blocks or blocks.

[0216] The modules, devices, mechanisms, units and / or subsystems may each comprise a machine or group of machines that execute executable instructions (e.g., commands). The modules may be embodied by a circuit or controller programmed to cause the system to perform the methods, processes and / or operations disclosed herein. For example, the modules may be implemented as hardware circuits, e.g., custom VLS1 (Very Large Scale Integration) circuits or gate arrays, AS1C (Application Specific Integrated Circuits), off-the-shelf semiconductors such as logic chips, transistors, and / or other discrete components. The modules may also be implemented in programmable hardware devices, such as field programmable gate arrays, programmable array logic, programmable logic devices, and the like.

[0217] In the above disclosure, unless otherwise indicated, the terms "substantially," "about," "approximately," and the like, which identify a condition or relationship characterizing a feature or group of features of an embodiment of the invention, are understood to mean that the condition or characteristic is defined within a tolerance allowed for the operation of the embodiment in its intended use.

[0218] It is important to note that the methods / processes and / or systems / devices / subsystems / apparatus, etc. disclosed herein are not limited to the precise flow charts and / or diagrams set forth in the drawings. For example, the methods may include additional or fewer processes or steps than those set forth in the drawings. Furthermore, the method embodiments are not necessarily limited to the chronological order as described herein.

[0219] The terms “processing,” “calculating,” “calculating,” “determining,” “establishing,” “analyzing,” “asserting,” “estimating,” “deriving,” “selecting,” “inferring,” “identifying,” “detecting,” and the like refer to operations and / or transformations in a computer, computing platform, computing system, or other electronic computing device(s) that convert data represented as physical quantities (e.g., electronic or optical signals) in the computer's registers and / or memory into other data also represented as physical quantities.

[0220] Terms used in the singular will also include the plural unless expressly stated otherwise or otherwise required by context.

[0221] In the description and claims of this application, the verbs "comprise," "include," "have" and their conjugations are used to indicate that the object of the verb is not necessarily an exhaustive list of components, elements or parts of the subject of the verb.

[0222] Unless otherwise indicated, when the word "and / or" is used between the last two items of a list of options, it means that selecting one or more of the listed options is appropriate and selectable; that is, it means that all possible combinations of one or more of the specified options are possible. Furthermore, the word "and / or" is used interchangeably with the words "at least one of," "any one of," or "one or more of," which may be followed by a list of various options.

[0223] Certain features of the invention that are described for clarity in the context of separate embodiments or examples may also be provided in combination in a single embodiment. Conversely, various features of the invention that are described for brevity in the context of a single embodiment, example, and / or option may also be provided separately or in any suitable subcombination or combination in other described embodiments, examples, or options of the invention. Certain features described in the context of various embodiments, examples, and / or any implementations are not considered essential features of those embodiments, unless the embodiment, example, and / or any implementation would not function without the element.

[0224] It should be noted that the terms "in some embodiments," "according to some embodiments," "according to some embodiments of the invention," "for example," and "optionally" may be used interchangeably herein.

[0225] The number of elements shown in the figures should not be construed as limiting in any way but is for illustrative purposes only.

[0226] It should be noted that the term "operable" can encompass the meaning of the term "modified or configured." In other words, in some embodiments, a machine that is "operable" to perform a task can encompass the mere ability to perform that function (e.g., "modified"), and in other embodiments, can encompass a machine that is actually made to perform that function (e.g., "configured").

[0227] In this specification, the phrases "within the range of" and "within the range of from" are used interchangeably to refer to a first indicator digit and a second indicator digit, and are meant to include the first indicator digit and the second indicator digit, and all fractional and integer digits therebetween.

Claims

1. A laser diode subsystem including at least the following: (i) a laser diode (LD) assembly including at least one LD stack including at least one LD bar, each LD bar including at least one LD emitter, the at least one LD emitter of each LD bar having at least one emission wavelength (WL) when operated at a corresponding desired operating temperature Td; and (ii) A temperature control subsystem that includes at least the following: a thermal unit (TU) configured to control a temperature of the at least one LD emitter of a corresponding LD stack; at least one measurement device configured to detect at least one updated temperature-related parameter value of the at least one LD emitter of the LD stack, the at least one updated temperature-related parameter value being associated with an updated ambient temperature Ta in a region of the at least one LD emitter; and a master controller operatively associated with the TU and the at least one measurement device and configured to control operation of the TU based on the detected updated temperature-related parameter value and the at least one desired operating temperature Td of the at least one LD emitter; At least one side of the TU is in direct contact with a corresponding side of each LD stack of the laser diode assembly to provide direct thermal contact between the TU and each LD stack, forming a contact surface area S1 between the TU and the corresponding LD stack; The size of the contact surface area S1 is less than or equal to the size of the overall TU contact surface area S2 facing the LD stack, i.e., S1≦S2, and the ratio “R” of S1:S2 is such that less mass is heated or cooled by the TU, and the time to adjust the temperature of the at least one LD emitter from an updated ambient temperature Ta to a desired operating temperature Td corresponding to a desired oscillation wavelength (WL) of the at least one emitter is reduced to increase temperature control speed.

2. 2. The laser diode subsystem of claim 1, The ratio "R" of the contact surface area S1 to the total TU surface area S2 = S1:S2 is greater than or equal to 1:4, i.e., R >= 0.

25.

3. 3. A laser diode subsystem according to claim 1 or 2, comprising: The ratio R of the contact surface area S1 to the total TU contact surface area S2 is greater than or equal to 1 / 2, i.e., R≧0.

5.

4. A laser diode subsystem according to any one of claims 1 to 3, comprising: The direct contact between the TU and the at least one LD stack is made by soldering one side of each laser diode stack to one side of the TU using a solder material.

5. 5. The laser diode subsystem of claim 4, The solder material has a coefficient of thermal expansion (CTE) that is comparable to or the same as the at least one side of the TU that connects to the at least one diode stack of the diode assembly and / or the at least one side of each laser diode stack that connects to the TU.

6. 6. A laser diode subsystem according to claim 1, further comprising: Each LD stack of the laser diode assembly includes a plurality of LD bars, each LD bar includes a plurality of LD emitters, each LD stack further includes a spacer separating the LD bars in each LD stack from each other, and the at least one side of the TU is in direct contact with the spacer of the respective LD stack.

7. 7. A laser diode subsystem according to claim 1, further comprising: The TU is thermally coupled to each LD stack such that light emitted from each LD emitter of each LD stack of the LD assembly is directed at an angle relative to the at least one TU connection side, forming a non-zero angle between a surface or plane of each TU connection side and the propagation direction of the emitted light.

8. 8. The semiconductor laser subsystem of claim 7, The non-zero angle formed between the plane or surface of the TU side that connects to the at least one LD stack and the propagation direction of the light emitted from each LD emitter is between 30 and 150 degrees.

9. 9. A laser diode subsystem according to claim 1, further comprising: The TU further comprises one or more connectors for securing the TU to the laser diode assembly, at least one of the one or more connectors being made of a thermally and / or electrically non-conductive material.

10. A laser diode subsystem according to any one of claims 1 to 9, comprising: The TU includes a thermoelectric cooler (TEC).

11. A laser diode subsystem according to any one of claims 1 to 10, comprising: The TU includes a TEC and a heat spreader that includes one or more heat conductive elements.

12. A laser diode subsystem according to any one of claims 1 to 11, comprising: The at least one measurement device of the temperature control subsystem includes one or more temperature sensors, at least one of which is positioned proximate to the diode assembly.

13. 13. The laser diode subsystem of claim 12, comprising: At least one of the one or more temperature sensors has a response time of less than 2 seconds.

14. A laser diode subsystem according to any one of claims 1 to 13, comprising: It further includes at least one printed circuit board (PCB), with the TU being carried by or directly attached to the at least one PCB.

15. A laser diode subsystem according to any one of claims 1 to 14, comprising: The at least one measurement device, the TU, and the LD assembly are all part of a diode-pumped solid-state laser (DPSSL) system that also includes a solid-state gain medium, and the at least one desired operating temperature Td of the at least one LD emitter of each LD bar corresponds to an absorption characteristic of the gain medium.

16. A laser diode subsystem according to any one of claims 1 to 15, comprising: The master controller is configured as follows: receiving updated temperature data in real time or near real time from the at least one measurement device, the updated temperature data indicative of at least an updated ambient temperature parameter value Ta of the diode assembly; determining an updated ambient temperature Ta based on the received updated temperature data; determining, in real time or near real time, an updated temperature difference ΔT between the desired operating temperature Td value and the determined updated ambient temperature Ta value relative to a time when the updated temperature data was received; Determine, in real time or near real time, one or more updated control actions required to control the TU in relation to the determination time of the corresponding updated temperature difference ΔT to quickly achieve the desired operating temperature Td or to achieve a deviation from the desired operating temperature below a predetermined temperature deviation threshold TDTh; and The TU is controlled in real time or near real time based on the determined one or more updated control actions relative to a determination time of the corresponding one or more control actions.

17. A laser diode subsystem according to any one of claims 1 to 16, comprising: The master controller includes at least: a communication module for transmitting and receiving at least data to and from said TU and for receiving at least data from said at least one measurement device via one or more communication links; a processing and control module for processing data received from the at least one measurement device, determining one or more updated temperature control actions based on the processing results, and controlling a temperature of the laser diode assembly based on the determined one or more updated control actions; and Memory unit.

18. A laser diode subsystem according to any one of claims 1 to 17, comprising: All the LD emitters in each LD bar have at least one same desired operating temperature Td.

19. 20. The laser diode subsystem of claim 18, All LD emitters are light emitting diodes (LEDs).

20. A laser diode subsystem according to any one of claims 1 to 19, comprising: The temperature of the at least one LD emitter is adjusted from an updated ambient temperature Ta to the desired operating temperature Td, so that the absolute value of the temperature difference ΔT between the updated ambient temperature Ta and the at least one desired operating temperature Td is up to 60 degrees Celsius within a maximum temperature adjustment time of 2 seconds.

21. A laser diode subsystem according to any one of claims 1 to 20, comprising: The master controller is located external and / or remote from the laser diode assembly.

22. A laser diode subsystem according to any one of claims 1 to 21, The master controller includes a printed circuit board (PCB) connected to the TU and / or the at least one measurement device, the PCB being located in close proximity to the laser diode assembly.

23. A laser diode subsystem according to any one of claims 1 to 22, comprising: The mass of the LD assembly and / or one LD stack and / or one LD bar is 1 gram or less.

24. A diode-pumped solid-state laser (DPSSL) system including at least: (i) a laser diode (LD) assembly including at least one LD stack including at least one LD bar, each LD bar including at least one LD emitter, each LD emitter configured to emit light of at least one oscillation wavelength (WL) under at least one corresponding oscillation desired operating temperature Td; (ii) a solid-state (SS) gain medium; and (iii) a thermal unit (TU) configured to control the temperature of the LD stack; (iv) at least one measurement device configured to detect at least one updated temperature-related parameter value of the at least one LD emitter, the updated temperature-related parameter value being related to an updated ambient temperature Ta in a region of the at least one LD bar; The at least one desired operating temperature Td of the at least one LD emitter of each LD bar corresponds to an absorption characteristic of the gain medium; and (iv) a master controller operatively associated with the TU and the at least one measurement device, the master controller controlling operation of the TU based on the detected updated temperature-related parameter value and the at least one desired operating temperature Td of the at least one LD emitter. At least one side of the TU is in direct contact with a corresponding side of each LD stack of the laser diode assembly to provide direct thermal contact between the TU and each laser diode stack, forming a contact surface area S1 between the TU and the corresponding LD stack; The size of the contact surface area S1 is less than or equal to the size of the overall TU contact surface area S2 facing the LD stack, i.e., S1≦S2, and the ratio “R” of S1:S2 is adapted to reduce the mass heated or cooled by the TU, and to increase the temperature control speed by shortening the time to adjust the temperature of the at least one LD emitter from an updated ambient temperature Ta to a desired operating temperature Td, which corresponds to a desired oscillation wavelength (WL) of the at least one emitter.

25. 25. The DPSSL system of claim 24, The gain medium is comprised of any one of the following: yttrium aluminum garnet (YAG) based materials; doped YAG materials doped with one of neodymium (Nd), ytterbium (Yb), thulium (Tm), holmium (Ho), erbium (Er).

26. A temperature control method, comprising at least the following steps: providing a laser diode assembly including at least one LD stack including at least one laser diode (LD) bar, each LD bar including at least one LD emitter, each LD emitter configured to emit light of at least one emission wavelength (WL) under at least one corresponding oscillation desired operating temperature Td; providing a thermal unit (TU) configured to control a temperature of the at least one LD emitter; providing at least one measurement device; Detecting at least one updated temperature-related parameter value of the at least one LD emitter, the updated temperature-related parameter value being associated with an updated ambient temperature Ta in a region of the at least one LD emitter using the at least one measurement device; controlling an operation of the TU based on the detected updated temperature-related parameter value and the at least one desired operating temperature Td of the at least one LD emitter; At least one side of the TU is in direct contact with a corresponding side of each LD stack of the laser diode assembly to provide direct thermal contact between the TU and each LD stack, forming a contact surface area S1 between the TU and the corresponding LD stack; The size of the contact surface area S1 is less than or equal to the size of the overall TU contact surface area S2 facing the LD stack, i.e., S1≦S2, and the ratio “R” of S1:S2 is such that it reduces the mass heated or cooled by the TU, and increases the temperature control speed by shortening the time to adjust the temperature of the at least one LD emitter from an updated ambient temperature Ta to a desired operating temperature Td, which corresponds to a desired oscillation wavelength (WL) of the at least one emitter.

27. 27. The method of claim 26, further comprising: (a) receiving, in real time or near real time, updated temperature data from the at least one measurement device, the updated temperature data indicative of at least one updated ambient temperature parameter value Ta of the diode assembly; (b) determining, in real time or near real time, an updated temperature difference ΔT between the desired operating temperature value Td and an updated ambient temperature value Ta, i.e., ΔT=Td−Ta or ΔT=Ta−Td, relative to a time at which the updated temperature data was received; (c) determining, in real time or near real time, one or more updated control actions required to control the TU relative to the determination time of the corresponding updated temperature difference ΔT to quickly achieve the desired operating temperature Td or to achieve a temperature deviation from the desired operating temperature Td that is less than a predetermined temperature deviation threshold TDTh; and (d) controlling the TU in real time or near real time based on the determined control action(s) relative to a determination time of the corresponding control action(s).

28. 28. The method of any one of claims 26 or 27, comprising: Steps (a) through (d) are performed automatically using the master controller.

29. 29. The method of any one of claims 26 to 28, comprising: Steps (a) to (d) can be performed in real time or near real time.

30. The method according to any one of claims 26 to 29, The ratio R between the contact surface area S1 and the total TU contact surface area S2 is 1:4 or greater, i.e. R≧0.

25.

31. 31. The method of claim 30, The ratio R between the contact surface area S1 and the total TU contact surface area S2 is 1:2 or greater, i.e. R≧0.

5.

32. The method according to any one of claims 26 to 31, Direct contact between the TU and the at least one laser diode assembly is made by soldering one side of each laser diode stack to one side of a TU using a soldering material.

33. 33. The method of claim 32, The solder material has a coefficient of thermal expansion (CTE) that is comparable to or the same as at least one side of the TU that connects to the at least one diode stack of the diode assembly and / or at least one side of each laser diode stack that connects to the TU.

34. The method according to any one of claims 26 to 33, comprising the steps of: The TU is directly connected to each laser diode stack, and light emitted from each LD emitter of each LD bar is directed in a direction that is angled with respect to at least one TU connection side, forming a non-zero angle between a surface or plane of each TU connection side and the direction of light emitted from each laser diode.

35. 35. The method of claim 34, The non-zero angle formed between the surface or plane of the TU side that connects to the at least one diode stack and the direction of light emitted from each laser diode is between 30 and 150 degrees.

36. The method according to any one of claims 26 to 35, comprising the steps of: The TU includes a thermoelectric cooler (TEC).

37. The method according to any one of claims 26 to 36, comprising the steps of: The TU includes a TEC and a heat spreader that is made up of one or more heat conductive elements.

38. The method according to any one of claims 26 to 37, comprising the steps of: The at least one measurement device of the temperature control subsystem includes one or more temperature sensors, at least one of which is located proximate to the laser diode assembly.

39. The method according to any one of claims 26 to 38, comprising the steps of: The at least one measurement device, the TU, and the laser diode assembly are all disposed within a diode-pumped solid-state laser (DPSSL) system that also includes a solid-state gain medium, and the at least one desired operating temperature Td of the at least one LD emitter of each LDB corresponds to an absorption characteristic of the gain medium.

Images