JPWO2020081335A5 - - Google Patents

Description

(Related application)
This application claims benefits and priorities under US Provisional Patent Application No. 62 / 745,623, filed October 15, 2018, the entire disclosure of which is incorporated herein by reference. ..

In various embodiments, the present invention relates to a laser system, in particular to a laser system having a particular arrangement of slow axis collimators.

High power laser systems are used in a number of different applications such as welding, cutting, drilling and material processing. Such a laser system generally includes a laser oscillator and an optical system that focuses the laser light onto the workpiece to be machined. Laser light from a laser oscillator is coupled to an optical fiber (or simply "fiber"). Optical systems for laser systems are typically designed to generate the highest quality laser beams, or equivalently, beams with the lowest beam parameter product (BPP). BPP is the product of the divergence angle (half angle) of the laser beam and the radius of the beam at the narrowest point (ie, beam waste, minimum spot diameter). That is, if D is the focal diameter and NA is the numerical aperture, then BPP = NA × D / 2, and thus BPP can be changed by changing NA and / or D. BPP quantifies the quality of a laser beam and how small a spot can be focused, commonly expressed in millimeter-miradian (mm-mrad) units. The Gaussian beam has the lowest possible BPP obtained by dividing the wavelength of the laser beam by π (pi). The ratio of the BPP of the actual beam to the ideal Gaussian beam at the same wavelength is shown as M ² , which is a wavelength-independent measure of beam quality.

Wavelength synthesis technology (WBC) is a technology for adjusting the output power and brightness from a laser diode, a laser diode bar, a stack of diode bars, or another laser located in a one or two-dimensional array. A WBC method has been developed that synthesizes beams along an array of one or both dimensions of the oscillator. A typical WBC system includes multiple oscillators, such as one or more diode bars synthesized using dispersion elements that form a multi-wavelength beam. Each oscillator in the WBC system resonates individually and is stabilized through feedback with wavelength characteristics from a common partially reflective output coupler, filtered by dispersion elements along the dimensions of beam synthesis. Exemplary WBC systems are US Pat. No. 6,192,062, filed February 4, 2000, and US Pat. No. 6,208,679, filed September 8, 1998. , US Pat. No. 8,670,180, filed August 25, 2011, and US Pat. No. 8,559,107, filed March 7, 2011, respectively. The entire disclosure of the application is incorporated herein by reference.

Various WBC laser systems synthesize a beam oscillated by a beam oscillator along a single direction or dimension called the WBC dimension. Thus, a WBC system or "resonator" is often characterized by various coplanar elements in the WBC dimension. As disclosed in the above literature, WBC laser systems often feature diode bars or other multi-beam oscillators from which the outputs are combined into a single output beam. For space savings and efficiency, each diode bar has a fast-axis collimator and optics that rotate the beam's fast and slow axes by 90 ° in a plane orthogonal to the beam propagation direction. It may be combined with a rotator (or "optical twister"). In such a WBC system, the slow axis of the beam is in the non-WBC dimension or in the direction optically downstream of the optical rotator. Thus, a single diode bar oscillator may be all collimated in the slow axis by a single slow axis collimator (or "slow axis collimator").

In addition, in order to maximize the efficiency of the WBC resonator, the dispersion element in the WBC system is usually composed of the Littrow angle in the WBC dimension. In order to prevent the primary reflection from the dispersion element from propagating back to the oscillator, the dispersion element may be tilted in the non-WBC direction (ie, along the slow axis). However, the tilt of the dispersion element results in different compound angles in different beams incident on the dispersion element, and thus in the beam oscillated by different oscillators, the pointing error of the optical downstream slow axis of the dispersion element. (Pointing error) is triggered. Therefore, there is a need for an improved WBC system design that suppresses pointing errors and thus improves system efficiency.

The systems and techniques according to embodiments of the present invention compensate for pointing errors (eg, slow axis pointing errors) induced by tilting of the dispersion elements in the non-WBC direction or dimensions of the WBC system, for example. The non-WBC dimension is substantially orthogonal in various embodiments, unlike the WBC dimension in which the beam is synthesized. In various embodiments, such pointing errors are converted into beam smears at the dispersion element by manipulating the individual interleaving mirrors. Embodiments of the invention use arrays of "staircased", ie, slow axis collimation (SAC) lenses that differ in height and / or position (eg, vertical position) with respect to each other. And reduce or substantially eliminate beam smear. Each SAC lens is associated with a diode bar or other oscillator, and the beams from all oscillators are combined into a multi-wavelength beam on the optical downstream side.

In embodiments of the present invention, the beam oscillator (or simply "oscillator") may include a diode laser, a fiber laser, a fiber-pigtailed diode laser, etc., and may be essentially configured from it. , Or may be composed of them, and may be packaged individually or in groups as a one- or two-dimensional array. In various embodiments, the oscillator or oscillator array is a high power diode bar where each bar has a plurality of (eg, dozens) oscillators. The oscillator may have microlenses attached therein for the collimation and beam shaping of the oscillator. The conversion optics are usually confocal, placed between the oscillator and the grating (eg, the grating), collimating individual beams from different oscillators, especially in the WBC dimension (ie, the beams are synthesized). Confocals all primary rays of the beam towards the center of the grating (in any dimension or direction). The main beam diffracted by the dispersion element propagates to the partially reflective output coupler, which provides feedback to the individual oscillators, which defines the wavelength of the individual oscillators by the dispersion element. That is, the coupler reflects various beams back to the individual oscillators, thus forming an external laser cavity, and the synthesized multi-wavelength beam is used for welding, cutting, processing, processing, etc. / Or propagate to bond within one or more optical fibers.

Various embodiments of the invention are described in U.S. Patent Application No. 14 / 632,283, filed February 26, 2015, and U.S. Patent Application No. 15 /, filed June 21, 2016. As described in 188,076, they may be used in laser systems characterized by techniques that change the BPP of the output laser beam, the entire disclosure of which is incorporated herein by reference. A laser system according to an embodiment of the invention may include power and / or spectrum monitoring as described in US Patent Application No. 16 / 417,861 filed May 21, 2019. , The entire disclosure is incorporated herein by reference. Embodiments of the invention may include alignment techniques and systems as described in US Provisional Patent Application No. 62/797,438, filed January 28, 2019, the disclosure of which. The whole is incorporated herein by reference.

As used herein, an "optical element" is a lens, mirror, prism, unless otherwise specified, that directs, reflects, bends, or otherwise optically manipulates electromagnetic radiation. It may point to any of the diffraction gratings and the like. As used herein, a beam oscillator, oscillator, or laser oscillator, or laser, includes any electromagnetic beam oscillator device, such as a semiconductor element that produces an electromagnetic beam but does or does not self-resonate. These include fiber lasers, disc lasers, non-solid lasers and the like. Generally, each oscillator includes a back reflective surface, at least one optical gain medium, and a front reflective surface. The optical gain medium increases the amplitude of electromagnetic radiation. The electromagnetic radiation is not limited to any particular part of the electromagnetic spectrum and may be visible light, infrared and / or ultraviolet light. The oscillator may include or consist of substantially a plurality of beam oscillators, such as a diode bar configured to irradiate a plurality of beams. The input beam received in the embodiments herein may be a single wavelength beam or a multi-wavelength beam coupled using various techniques known in the prior art.

Although diffraction gratings are used herein as exemplary dispersion elements, embodiments of the invention use other dispersion elements such as, for example, dispersion prisms, transmission gratings, or Echelle gratings. You may. Embodiments of the invention are one or more in addition to one or more diffraction gratings, as described in U.S. Patent Application No. 15 / 410,277 filed January 19, 2017. Prism may be used, the entire disclosure of which is incorporated herein by reference.

An embodiment of the present invention couples a multi-wavelength output beam to an optical fiber. In various embodiments, the optical fiber is surrounded by a plurality of clad layers surrounding a single core, a plurality of discrete core regions (or "cores") within one clad layer, or a plurality of clad layers. Has multiple cores. In various embodiments, the output beam may be guided to the workpiece for applications such as cutting, welding, and the like.

Arrays, bars and / or stacks of laser diodes as described in the general description below may be used in connection with embodiments of the innovation described herein. Laser diodes may be packaged individually or in groups, generally in a one-dimensional array / array (diode bar) or two-dimensional array (diode bar stack). A diode array stack is generally a vertical stack of diode bars. Laser diode bars or arrays generally achieve substantially higher power and cost efficiency than comparable single broad area diodes. High power diode bars typically accommodate an array of broad area oscillators and generate tens of watts with relatively low beam quality. Despite the high power, its brightness is often lower than that of broad area laser diodes. Due to the very high power generation of hundreds or thousands of watts, the high power diode bars may be stacked to produce a high power stack diode bar. The laser diode array may be configured to irradiate the beam into free space or into the fiber. Fiber coupled diode laser arrays may be conveniently used as pumping sources for fiber lasers and fiber amplifiers.

Diode laser bars are a type of semiconductor laser that include a one-dimensional array of broad area oscillators, or alternatives, a subarray that includes, for example, 10-20 thin striped oscillators. Broad area diode bars typically include, for example, 19-49 oscillators, each with, for example, 1 μm × 100 μm digit dimensions. Beam quality along a dimension of 1 μm, or fast-axis, generally has a diffraction limit. Beam quality along a dimension of 100 μm, or slow-axis, generally has multiple diffraction limits. Generally, diode bars for commercial use have laser cavity lengths in the order of 1 to 4 mm, are about 10 mm in the width direction, and generate tens of watts of output power. Many diode bars are operated in the wavelength range of 780 to 1070 nm, with a wavelength of 808 nm (pumped neodymium laser) and 940 nm (pumped Yb: YAG) being the most prominent. The wavelength range of 915-976 nm is used for pumping erbium-doped, ytterbium-doped high-power fiber lasers and amplifiers.

A diode stack is simply an arrangement of multiple diode bars capable of irradiating very high output power. Also called a diode laser stack, multi-bar module, or two-dimensional laser array, the most common diode stack arrangement is a vertical stack, which is an effective two-dimensional array of edge oscillators. Such a stack may be formed by attaching a diode bar to a thin heatsink and stacking this assembly to obtain a periodic array of diode bars and heatsink. There are also lateral diode stacks and 2D stacks. For high beam quality, the diode bars should generally be as close to each other as possible. On the other hand, for effective cooling, a certain minimum thickness is required in the heat sink mounted between the bars. This diode bar spacing trade-off results in the beam quality (and therefore its brightness) of the longitudinal diode stack being much lower than that of a single diode bar. However, there are several ways to significantly improve this problem, such as spatial interleaving, polarization coupling, or wavelength multiplexing of the outputs of different diode stacks. .. Various types of high power beam shapers and related equipment have been developed for this purpose. Diode stacks may provide extremely high output power (eg, hundreds or thousands of watts).

The output beam formed according to an embodiment of the present invention may be used to machine a workpiece, thus an optical technique (eg, reflectance measurement) that simply probes the surface with light. In contrast, the surface of the workpiece is physically altered and / or features are formed on or within the surface. Exemplary machining based on embodiments of the present invention includes cutting, welding, drilling, and soldering. Various embodiments of the invention do not illuminate the entire surface or substantially the entire surface of the workpiece with irradiation from a laser beam, at one or more points, or in a one-dimensional straight or curved machining path. The workpiece may be processed along with it. Such a one-dimensional path may be composed of a plurality of segments, each of which may be a straight line or a curved line.

Embodiments of the invention may modify the beam shape and / or BPP to improve or optimize performance for different types of processing techniques or different types of processed materials. Embodiments of the invention are U.S. Patent Application No. 14 / 632,283 filed February 26, 2015, U.S. Patent Application No. 14 / 747,073 filed June 23, 2015, U.S. Patent Application No. 14 / 852,939 filed September 14, 2015, U.S. Patent Application No. 15 / 188,076 filed June 21, 2016, filed April 5, 2017. Various changes in BPP and / or laser beam shape as described in U.S. Patent Application No. 15 / 479,745 and U.S. Patent Application No. 15 / 649,841 filed on July 14, 2017. Method may be used. The entire disclosure of each is incorporated herein by reference.

In certain embodiments, embodiments of the present invention feature a laser system, wherein the laser system comprises a plurality of beam oscillators, each of which oscillates one or more beams, a dispersion element, a plurality of collimators, and a plurality of inters. It includes a leaving mirror and a partially reflective output coupler, which is essentially configured or composed of it. The dispersion element receives the beam and synthesizes the beam into a multi-wavelength beam in the wavelength synthesis (WBC) dimension. The plurality of collimators are arranged on the optical downstream side of the beam oscillator and on the optical upstream side of the dispersion element. Each collimator receives one or more beams from a beam oscillator and collimates the one or more beams in the non-WBC dimension. The plurality of interleaving mirrors may be arranged on the optical downstream side of the beam oscillator and on the optical upstream side of the dispersion element. The plurality of interleaving mirrors may be arranged optically downstream of the plurality of collimators. The plurality of collimators may be arranged on the optical downstream side of the plurality of interleaving mirrors. Each interleaving mirror reflects one or more beams from the beam oscillator towards the dispersion element. The partially reflective output coupler receives a multi-wavelength beam from a dispersion element, transmits the first portion of the multi-wavelength beam as an output beam, and reflects back the second portion of the multi-wavelength beam toward the dispersion element. The dispersion element is tilted at a non-zero angle in the non-WBC dimension, so that the primary reflection of the beam from the dispersion element is directed away from the beam oscillator, resulting in pointing errors in the multi-wavelength beam. One or more interleaving mirrors are tilted at a non-zero angle in the non-WBC dimension to reduce pointing errors in the multi-wavelength beam, resulting in beam smear in the non-WBC dimension with a dispersive element. The optical axes of the two or more collimators are displaced relative to each other in the non-WBC dimension, reducing beam smear due to the tilted interleaving mirrors.

Embodiments of the invention may include one or more of the following in any combination type. The non-WBC dimension may correspond to the slow axis of the beam and / or the slow axis of the beam oscillator. The non-WBC dimension may correspond to the fast axis of the beam and / or the fast axis of the beam oscillator. The dispersion element may include a diffraction grating (eg, a transmission diffraction grating or a reflection diffraction grating), and may be composed essentially of it, or may be composed of it. The at least one beam oscillator may include a diode bar or other oscillator configured to oscillate a plurality of discrete beams, and may be configured essentially from it, or it may be configured from it. In the first beam oscillator, (i) the tilt of the dispersion element in the non-WBC dimension may result in a pointing error with a first angle, and (ii) the interleaving mirror associated with the first beam oscillator is a second. It may be tilted at an angle in the non-WBC dimension. The second angle may be substantially the same as the first angle.

All of the interleaving mirrors may be tilted at a non-zero angle in the non-WBC dimension. Two or more or all of the non-zero tilt angles of the interleaving mirrors may differ from each other. At least two interleaving mirrors may be tilted at different angles in the non-WBC dimension. All but one interleaving mirror may be tilted at a non-zero angle in the non-WBC dimension. The interleaving mirror associated with the central beam oscillator does not have to be tilted at a non-zero angle in the non-WBC dimension (ie, the interleaving mirror associated with the central beam oscillator does not have to be tilted at a non-WBC dimension at approximately zero angle). It may be placed (eg, orthogonal to the incident beam). The two or more interleaving mirrors need not be tilted at a non-zero angle in the non-WBC dimension. A second collimator and / or an optical rotator that rotates one or more beams by approximately 90 ° may be associated with each beam oscillator. Each collimator may be a slow axis collimator and / or each second collimator may be a fast axis collimator. Each collimator may be a fast axis collimator and / or each second collimator may be a slow axis collimator. The plurality of interleaving mirrors may be arranged optically downstream of the plurality of collimators. The optical distance between each collimator and the dispersion element may be approximately the same. The heights of the two or more collimators may be different. The heights of the two or more collimators may be approximately the same. The height of all collimators may be approximately the same. The laser system may include one or more folding mirrors. The one or more folded mirrors may be arranged optically downstream of the dispersion element and optically upstream of the output coupler.

In another aspect, embodiments of the present invention feature a laser system, which comprises a plurality of beam oscillators, each oscillating one or more beams, a dispersion element, a plurality of collimators, and partial reflection. It includes, and is essentially constructed from, or is composed of a type output coupler. The dispersion element receives the beam and synthesizes the beam into a multi-wavelength beam in the wavelength synthesis (WBC) dimension. The plurality of collimators are arranged on the optical downstream side of the beam oscillator and on the optical upstream side of the dispersion element. Each collimator receives one or more beams from a beam oscillator and collimates the one or more beams in the non-WBC dimension. The partially reflective output coupler receives a multi-wavelength beam from a dispersion element, transmits the first portion of the multi-wavelength beam as an output beam, and reflects back the second portion of the multi-wavelength beam toward the dispersion element. The dispersion element is tilted at a non-zero angle in the non-WBC dimension, so that the primary reflection of the beam from the dispersion element is directed away from the beam oscillator, resulting in pointing errors in the multi-wavelength beam. The optical axes of the two or more collimators are displaced relative to each other in the non-WBC dimension, reducing pointing errors due to the tilted dispersion elements.

Embodiments of the invention may include one or more of the following in any combination type. The non-WBC dimension may correspond to the slow axis of the beam and / or the slow axis of the beam oscillator. The non-WBC dimension may correspond to the fast axis of the beam and / or the fast axis of the beam oscillator. The dispersion element may include a diffraction grating (eg, a transmission diffraction grating or a reflection diffraction grating), and may be composed essentially of it, or may be composed of it. The at least one beam oscillator may include a diode bar or other oscillator configured to oscillate a plurality of discrete beams, and may be configured essentially from it, or it may be configured from it. The WBC dimensional collimator is a dispersion element and may result in beam smear in the non-WBC dimension. A second collimator and / or an optical rotator that rotates one or more beams by approximately 90 ° may be associated with each beam oscillator. Each collimator may be a slow axis collimator and / or each second collimator may be a fast axis collimator. Each collimator may be a fast axis collimator and / or each second collimator may be a slow axis collimator. The optical distance between each collimator and the dispersion element may be approximately the same. The heights of the two or more collimators may be different. The heights of the two or more collimators may be approximately the same. The height of all collimators may be approximately the same. The laser system may include one or more folding mirrors. The one or more folded mirrors may be arranged optically downstream of the dispersion element and optically upstream of the output coupler.

In yet another aspect, embodiments of the present invention feature a method of aligning a laser system. A laser system receives (i) multiple beam oscillators, each configured to oscillate one or more beams, and (ii) the beam, and produces the beam in the wavelength synthesis (WBC) dimension, a multi-wavelength beam. Receives a multi-wavelength beam from the dispersion element to be synthesized in (iii), transmits the first part of the multi-wavelength beam as an output beam, and reflects the second part of the multi- wavelength beam toward the dispersion element . It includes, and is essentially composed of, or is composed of a partially reflective output coupler, which returns. The beam oscillated by a plurality of beam oscillators is combined into a multi-wavelength beam by a dispersion element. Pointing errors occur in multi-wavelength beams in the non-WBC dimension. Beam smear occurs in the dispersion element in the non-WBC dimension so as to reduce the pointing error of the multi-wavelength beam. Beam smear is reduced without increasing the pointing error of the multi-wavelength beam.

Embodiments of the invention may include one or more of the following in any combination type. In the non-WBC dimension, pointing errors may occur in the multi-wavelength beam by tilting the dispersion element at a non-zero angle. In the non-WBC dimension, beam smear may occur by tilting one or more interleaver mirrors at a non-zero angle. The interleaver mirror may be located on the optical downstream side of the beam oscillators and on the optical upstream side of the dispersion element. Beam smear may be reduced by displacing the optical axes of two or more collimators with respect to each other in the non-WBC dimension. Two or more collimators are arranged on the optical downstream side of the beam oscillator and on the optical upstream side of the dispersion element. The two or more collimators may be slow axis collimators. The two or more collimators may be fast axis collimators. The non-WBC dimension may correspond to the slow axis of the beam and / or the slow axis of the beam oscillator. The non-WBC dimension may correspond to the fast axis of the beam and / or the fast axis of the beam oscillator. The beam may be rotated approximately 90 degrees before synthesizing the beam into a multi-wavelength beam. The beam may be collimated in the WBC dimension and / or the non-WBC dimension.

In another aspect, embodiments of the present invention feature a method of aligning a laser system. A laser system receives (i) multiple beam oscillators, each configured to oscillate one or more beams, and (ii) the beam, and produces the beam in the wavelength synthesis (WBC) dimension, a multi-wavelength beam. Receives a multi-wavelength beam from the dispersion element to be synthesized in (iii), transmits the first part of the multi-wavelength beam as an output beam, and reflects the second part of the multi- wavelength beam toward the dispersion element . It includes, and is essentially composed of, or is composed of a partially reflective output coupler, which returns. The beam oscillated by a plurality of beam oscillators is combined into a multi-wavelength beam by a dispersion element. The primary reflection from the dispersion element is suppressed from propagating back to the plurality of beam oscillators. Pointing errors in multi-wavelength beams are reduced.

Embodiments of the invention may include one or more of the following in any combination type. Suppressing the primary reflection from the dispersion element propagating back to multiple beam oscillators may include tilting the dispersion element at a non-zero angle in the non-WBC dimension, and is then essential. It may be configured in, and it may be configured in it. Pointing errors may be reduced by displacing the optical axes of two or more collimators with respect to each other in the non-WBC dimension. Two or more collimators are arranged on the optical downstream side of the beam oscillator and on the optical upstream side of the dispersion element. The two or more collimators may be slow axis collimators. The two or more collimators may be fast axis collimators. The non-WBC dimension may correspond to the slow axis of the beam and / or the slow axis of the beam oscillator. The non-WBC dimension may correspond to the fast axis of the beam and / or the fast axis of the beam oscillator. The beam may be rotated approximately 90 degrees before synthesizing the beam into a multi-wavelength beam. The beam may be collimated in the WBC dimension and / or the non-WBC dimension.

These and other objectives, along with the advantages and features of the invention disclosed herein, will be further clarified by reference to subsequent description, accompanying drawings and claims. Further, it will be appreciated that the features of the various embodiments described herein are not mutually exclusive and may exist as various combinations and sequences. As used herein, the term "substantially" means ± 10%, and in certain embodiments ± 5%. The term "substantially constructing" means excluding other materials that contribute to function, unless otherwise defined herein. However, such other materials may be present in trace amounts, either together or individually. In the present specification, the terms "radiation" and "light" are used interchangeably unless otherwise specified. As used herein, "downstream" or "optically downstream" is used to indicate the relative position of the second element after the light beam hits the first element, where the first element is the second element. On the other hand, it is "upstream" or "optically upstream". As used herein, the "optical distance" between two elements is the distance between the two elements in which the light beam actually travels, and the optical distance is the physical distance between the two elements. It may be, but not necessarily due to reflections from the mirror, or other changes in the propagation direction experienced by the light traveling from one element to the other. Distances used herein may be considered as "optical distances" unless otherwise specified.

In drawings, similar reference symbols generally indicate the same part through different drawings. Furthermore, it is emphasized that the drawings are not necessarily scaled and generally show the principles of the invention. In subsequent discussions, various embodiments of the invention will be described with reference to subsequent drawings.

Schematic diagram of a wavelength synthesis technology (WBC) resonator according to an embodiment of the present invention. Schematic diagram of dispersion elements and various beams in the WBC dimension according to embodiments of the present invention. Schematic of Dispersive Elements and Various Beams in Non-WBC Dimension According to Embodiments of the Invention Schematic of Dispersive Elements and Various Beams in Non-WBC Dimension According to Embodiments of the Invention Schematic of Dispersive Elements and Various Beams in Non-WBC Dimension According to Embodiments of the Invention Graph of beam pointing error in non-WBC dimension induced by tilt of dispersion element according to embodiment of the present invention Graph of beam smear in the dispersion element when the pointing error shown in FIG. 3A is reduced to substantially zero by the embodiment of the present invention. Graph of lens arrangement used to reduce beam smear in FIG. 3B to approximately zero according to embodiments of the present invention. Graph of relative displacement of two differently arranged lenses according to an embodiment of the present invention based on the curve shown in FIG. Graph of residual beam smear caused by the lens arrangement shown in FIG. 5A according to an embodiment of the present invention. Graph of simulated difference in beam smear of diode bar left and right edge oscillators with respect to central oscillator in one of the lens displacement arrangements shown in FIG. 5A according to embodiments of the present invention. Graph of simulated difference in pointing error of diode bar left and right edge oscillators with respect to central oscillator in one of the lens displacement arrangements shown in FIG. 5A, according to embodiments of the present invention. Schematic diagram of the WBC resonator in the non-WBC direction according to the embodiment shown in FIG. 2A according to the embodiment of the present invention. Schematic diagram of the WBC resonator in the non-WBC direction according to the embodiment shown in FIG. 2B according to the embodiment of the present invention. Schematic diagram of the WBC resonator in the non-WBC direction according to the embodiment shown in FIG. 2C according to the embodiment of the present invention. Schematic diagram of the WBC resonator in the non-WBC direction according to the embodiment shown in FIG. 2D according to the embodiment of the present invention. Perspective view of an exemplary interleaving mirror tilted as shown in FIG. 7C according to an embodiment of the invention.

FIG. 1 shows nine different diode bars in the illustrated embodiment (in the present specification, the "diode bar" is any multi-beam oscillator, i.e., multiple beams oscillated from a single package. The various elements of the WBC resonator 100 that synthesize the beam oscillated from the oscillator) are shown schematically. Embodiments of the invention may be used with less than nine or more oscillations. According to embodiments of the present invention, each oscillator may oscillate a single beam, or each oscillator may oscillate a plurality of beams. The view in FIG. 1 is along the WBC dimension, i.e., the dimension in which the beam from the bar is combined. The exemplary resonator 100 features nine diode bars 105, each diode bar 105 comprising an array of oscillators along the WBC dimension (eg, a one-dimensional array), which is essentially configured or configured from it. Will be done. Each oscillator in the diode bar 105 has greater divergence in one direction (known as the "fast axis" arranged perpendicular to the WBC dimension), and vertical (the "slow axis" along the WBC dimension). It oscillates an asymmetric beam with smaller divergence in).

In various embodiments, each diode bar 105 is associated with a fast axis collimator (FAC) / optical twister microlens assembly (eg, mounted or otherwise optically coupled). The Fast Axis Collimator (FAC) / Optical Twister Microlens Assembly collimates the fast axis of the oscillated beam while rotating the fast and slow axes of the beam by 90 °, so that the slow axis of each oscillated beam is , Orthogonal to the WBC dimension downstream of the microlens assembly. The microlens assembly converges the main ray of the oscillator from each diode bar 105 towards the dispersion element 110. Suitable microlens assemblies are US Pat. No. 8,553,327, filed March 7, 2011, and US Pat. No. 9,746,679, filed June 8, 2015. The entire disclosure of each is incorporated herein by reference.

Embodiments of the invention presented herein relate both the FAC lens and the optical twister (eg, a microlens assembly) to each beam oscillator and / or the oscillated beam, thus a SAC lens (discussed below). ) Affects the beam in the non-WBC dimension. In other embodiments, the oscillated beam does not rotate and the FAC lens may be used to change the pointing error in the non-WBC dimension. Therefore, it will be understood herein that a SAC lens generally refers to a lens having power in the non-WBC dimension, and such a lens may include a FAC lens in various embodiments. .. Thus, in various embodiments, for example, embodiments in which the oscillated beam is not rotated and / or embodiments in which the fast axis of the beam is in the non-WBC dimension, the FAC lens is described herein. As such, it may be used as a SAC lens (ie, it may be stepped).

As shown in FIG. 1, the resonator 100 also features a set of SAC lenses 115, one SAC lens 115 associated with and one diode bar 105 receiving a beam from it. Each SAC lens 115 collimates the slow axis of the beam oscillated from a single diode bar 105. After collimation on the slow axis by the SAC lens 115, the beam propagates to a set of interleaving mirrors 120 that divert the beam 125 towards the dispersion element 110. The arrangement of the interleaving mirror 120 allows the free space between the diode bars 105 to be reduced or minimized. Upstream of the dispersion element 110 (which may include, may be essentially composed of, or may be composed of, for example, a diffraction grating such as the transmission grating shown in FIG. 1), the lens 130 is a diode bar. It may be selectively used to collimate a subbeam from 105 (ie, an oscillated ray other than the main ray). In various embodiments, the lens 130 may be disposed from the diode bar 105 at an optical distance substantially equal to the focal length of the lens 130. It should be noted that in the usual embodiment, the overlap of the main rays in the dispersion element 110 is mainly due to the turning of the interleaving mirror 120, not the focusing ability of the lens 130.

As shown in FIG. 1, the lenses 135 and 140 are US Pat. No. 9,256,073 filed on March 15, 2013 and US Pat. No. 9, filed on June 23, 2015. , 268, 142, have formed an optical telescope for the promotion of optical cross-talk, the entire disclosure of which is herein. Incorporated by reference. The resonator 100 may include one or more optical folding mirrors 145 for diversion of the beam, so that the resonator 100 may be housed in a smaller physical footprint. The dispersion element 110 combines the beam from the diode bar 105 into a single multi-wavelength beam 150, which propagates to the partially reflective output coupler 155. The coupler 155 transmits a part of the beam as an output beam of the resonator 100, and together, the other part of the beam is used as a dispersion element 110 and feedback for stabilizing the oscillation wavelength of each beam. Reflects back from the diode bar 105.

In various embodiments, the dispersion element 110 is oriented so that the diffraction angle is the same as the incident angle in order to obtain high diffraction efficiency at the retrow angle, i.e., at least in the WBC dimension. Since the oscillators of each diode bar 105 need to be slightly spatially separated in the WBC dimension, the beam from any single oscillator is the incident of the other beam oscillated from the other oscillator. It is incident on the dispersion element 110 at a slightly different angle from the angle. That is, usually, from each diode bar, at most one oscillator actually oscillates the beam that hits the dispersion element 110 at the retrow angle, and the other beams are at slightly different angles from the retrow angle. Referring to FIG. 2A, at non-retrow angles, various beams from the diode bar 105 incident on the dispersion element 110 can cause problems in feedback. FIG. 2A shows the retrow angle (θ) for the central beam 205 in the WBC dimension (eg, the beam is the beam from the center of the oscillator 105 (or one of them in a beam oscillator that oscillates an even beam)). ) Shows the dispersion element 200. The beam 210 and the beam 215 are beams incident on the dispersion element 200 at an angle different from the retrow angle (eg, adjacent beams and / or beams separated from the central beam 205). The line 220 indicates a perpendicular line of the dispersion element 200. As mentioned above, the dispersion element 200 combines beams 205, 210 and 215 into a single output beam 225 propagating towards an output coupler (not shown in FIG. 2A). The feedback 230 is received by the output coupler and separated by the dispersion element 200 into individual elements, each propagating back to one oscillator. For example, the feedback 235 is a feedback component propagating back to the oscillator associated with the beam 215.

FIG. 2A shows the primary reflection 240 of the dispersion element 200, propagating back to the oscillator of the beam 215 in the illustrated example. The primary reflection 240 competes with the desired feedback beam 235, thus resulting in instability in wavelength stabilization of the beam 215, or stabilization of the beam 215 at the wrong wavelength. This results in the power of the WBC resonator becoming unstable and / or even reduced. (The exemplary embodiments of the invention are herein from dispersion elements such as diffraction gratings that have problems, i.e., form instability in the desired feedback beam and / or oscillation and / or power. Although described in particular by primary reflections, however, by embodiments of the present invention, the principles, techniques, and systems described herein have higher dimensional reflections with problems (eg, second). It may also be applied in the case of secondary reflection, tertiary reflection, etc.).

The wavelength λ1 of the desired feedback 235 and the competing wavelength λ2 of the primary reflection from the dispersion element 200 may be specified by Equations 1 and 2 below.

In the above, as shown in FIG. 2A, p is the linear density of the dispersion element 200 (that is, the line per unit length), and the angle (θ + Δθ) is the incident angle of the beam 215. These equations 1 and 2 show that the wavelength λ1 and the wavelength λ2 are always different unless Δθ = 0, as in the exemplary central beam 205 of FIG. 2A.

In order to avoid contention of feedback resulting from the primary reflection from the dispersion element, embodiments of the present invention include a slight tilt of the dispersion element 200 in the non-WBC direction, as shown in direction 245 in FIG. 2A. When the dispersion element 200 is tilted at an angle δ, the primary reflection 240 is directed against feedback from the non-tilted dispersion element, as shown in FIG. 2B, which is a view of FIG. 2B along arrow A. Propagate at an angle of 2δ. In FIG. 2B, along the non-WBC dimension, the incident beams 205, 210, 215 overlap and the dashed line 250 indicates the untilted orientation of the dispersion element 200. (The illustrated embodiment of the invention describes a dispersion element oriented in the retrow state in the WBC dimension, but this is not always the case. In various embodiments, the dispersion element is in the WBC dimension. In, may be tilted or oriented at a non-retrow angle, and embodiments of the present invention reduce the problem of tilting the dispersion element in the non-WBC direction.)

However, as shown in FIG. 2B, the tilt of the dispersion element 200 can result in dispersion in the diffracted beam 225 in the non-WBC direction. The dispersion is caused by a small composite angle between the incident beam and the surface of the tilted dispersion element 200. This dispersion or pointing error of the beam in the non-WBC direction can result in unstable wavelength stabilization and unstable WBC resonator power.

As shown in FIG. 2C, in various embodiments of the invention, the pointing error of the wavelength dispersion (ie, diffracted) beam reflects the beam towards the dispersion element (ie, mirror 120 of FIG. 1). Through the adjustment of individual interleaving mirrors, it may be converted to the whole beam smear ΔS at the dispersion element in the non-WBC direction. Beam smear degrades beam quality by (ΔS / S × 100)% in the non-WBC dimension. Here, S is the beam size at the dispersion element in the non-WBC dimension. In various embodiments, the SAC lens (eg, the SAC lens 115 in FIG. 1) is placed in the non-WBC direction, i.e., in the slow axis of FIG. 1 (out of the paper) so as to minimize the resulting beam smear ΔS. It may be adjusted (eg, converted) individually. (Similarly, SAC lenses with central optical axes arranged at different desired levels may be used; i.e., SAC lenses may have different sizes, with each central optical axis being a staircase. ) Is placed at the desired level, so the reference for displacement or adjustment of the SAC lens will be understood to be equivalent to the use of a SAC lens with an optical axis at the desired level or position.) FIG. 2D is interleaving. The adjustment of the tilt of the mirror 120 shows the optimized case where the pointing error of the beam is minimized, and the resulting beam smear is due to the displacement of the SAC lens 115 in the non-WBC direction (eg, the slow axis of FIG. 1). , Minimized.

3A, 3B, 4, 5A, and 5B show numerical exemplary results according to embodiments of the present invention and based on the WBC resonator 100 of FIG. Illustratively, the dispersion element 110 is tilted on the slow axis by 10 mrad and is configured at a retrow angle (in the WBC dimension) at a central wavelength of 975 nm, with other angles of incidence on the dispersion element within ± 3 ° of the retrow angle. .. Illustratively, each SAC lens 115 is assumed to collimate the slow axis of the beam of the associated diode bar 105, thus at the dispersion element 110, the size of the slow axis beam is approximately 3.5 mm and is slow. The divergence of the axis is approximately 4 mrad.

FIG. 3A corresponds to the case shown in FIG. 2B. FIG. 3A is a graph of pointing errors of beams from various diode bars 120 in the non-WBC direction induced by a 10 mrad tilt of the dispersion element 110 of the resonator 100 of FIG. FIG. 3B corresponds to the case shown in FIG. 2C. FIG. 3B is a graph of beam smear at the dispersion element 110 when the pointing error shown in FIG. 3A is reduced to approximately zero by individual adjustments of the various interleaving mirrors 120. In this example, the central diode bar 105 (ie, diode bar # 5 in FIG. 1) has a pointing error of approximately zero, and thus the interleaving mirror 120 associated with the diode bar 105 (ie, its diode bar 105). Note that the interleaving mirror 120) that receives the beam from does not need to be tilted to compensate for the pointing error. Thus, embodiments of the present invention are not all interleaving mirrors 120, but one or more interleaving mirrors 120 (eg, all but one interleaving mirror 120, eg, a central oscillator such as a diode bar). Includes an embodiment in which all interleaving mirrors 120) other than the interleaving mirrors 120 associated with the above are tilted to compensate for pointing errors. (In the present specification, a "central" oscillator, such as a diode bar, is an oscillator in the array or line of oscillators, with approximately the same number of oscillators located on either side of it, eg, one of the central oscillators. The number of oscillators on one side of the central oscillator may be the same as each other, and in other oscillators, the number of oscillators on one side of the central oscillator is the number of oscillators on the other side of the central oscillator. More than one, two, or three or more.) A pointing error of approximately ± 0.4 mrad in the non-WBC direction (FIG. 3A) corresponds to approximately 20% of slow axis divergence in the dispersion element. In the WBC resonator 100, it can cause significant power loss. Smear due to reduced pointing error (FIG. 3B), ie beam displacement at the dispersion element at a slow axis of approximately ± 0.4 mm, can degrade beam quality at the slow axis by 20% or more.

In various embodiments of the invention, beam smear in the non-WBC direction (eg, slow axis) is reduced in the slow axis by the individual displacement of the SAC lens shown in FIG. FIG. 4 is a graph (modeled by ZEMAX simulation) of the displacement of the SAC lens 115 required to reduce the beam smear of FIG. 3B to approximately zero. Assuming that the various SAC lenses 115 are approximately the same size and shape, the displacement of the individual SAC lenses corresponds to the same amount of displacement of the SAC lens on the central optical axis. As shown in FIG. 4, the SAC lens 115 is each provided by a diode bar 105 associated with the SAC lens 115 (even in embodiments where the spacing of the oscillators 105 in the WBC dimension is substantially constant, as shown in FIG. 1). It may be displaced by different amounts. However, in other embodiments, this "staircase" of SAC lens displacement is displaced or displaced to approximately the same level in the non-WBC dimension (eg, slow axis) as one or more other proximal SAC lenses. It may include one or more SAC lenses to be arranged. Such an arrangement may be difficult to achieve highly reliable lens conversion adjustment in a confined space without causing other problems such as induction of apex roll, so SAC. It may be desirable in embodiments where the physical space around the lens is limited.

FIG. 5A shows the relative displacement of the SAC lens in two arrangements (or “stairs”) according to an embodiment of the invention, based on the ideal curve shown in FIG. In each embodiment, the overall height (ie, the maximum difference in displacement) is the same, approximately 0.7 mm. Since either embodiment does not completely correspond to the ideal curve of FIG. 4, there is a residual beam smear in the slow axis, as shown in FIG. 5B. The table below summarizes the lens displacements in the two cases shown as staircase 1 and staircase 2.

As shown, the staircase 1 includes a SAC lens that has less different lens displacements, i.e., is displaced at approximately the same height regardless of the increase in residual smear. In contrast, the staircase 2 has different lens displacements in each lens, corresponding closer to the ideal case of FIG. 4, resulting in less residual smear. As shown in FIG. 5B, the total range of the remaining amount smear in the two cases is approximately 0.09 mm and 0.03 mm, respectively, and the beam quality deterioration of the slow axis of approximately 2.6% and 0.9%, respectively. Corresponds to. In the embodiment of the present invention, the residual beam smear on the slow axis due to the tilt adjustment of the interleaving mirror is reduced to less than about 3 mm, less than about 2 mm, less than about 1 mm, less than about 0.5 mm, less than about 0.1 mm, or about 0. Reduce to a level of less than 05 mm. In the embodiment of the present invention, the slow axis beam deterioration due to the tilt adjustment of the interleaving mirror is reduced to less than about 10%, less than about 8%, less than about 5%, less than about 3%, less than about 2%, or about 1%. Reduce to less than a level.

Note that the residual smear in FIG. 5B shows the behavior of only the central oscillator of each diode bar 105. That is, FIG. 5B may correspond to an example in which each diode bar 105 is replaced with an oscillator that oscillates only a single beam. However, in various embodiments, each diode bar 105 has a plurality of oscillators and thus oscillates a plurality of beams. In various embodiments, the diode bar 105 or other beam source containing the plurality of oscillators is, for example, more than 8, more than 10, more than 20, more than 30, more than 40, between 10 and 50. Alternatively, it may have any number of oscillators (and corresponding beams), such as between 19 and 46. As mentioned above, the beam from the non-central oscillator on each bar may exhibit different pointing errors (and the resulting beam smear) due to slightly different angles of incidence on the dispersive elements. In various embodiments of the invention, the SAC lens and the interleaving mirror for each diode bar are optically arranged and tilted with respect to the central oscillator of the diode bar. Therefore, it may be desirable to consider pointing errors and beam smears associated with other oscillators in each diode bar. 6A and 6B are graphs of simulated differences in smear and pointing errors in the left and right edge oscillators of each diode bar with respect to the central oscillator of the bar. Residual smear caused by the use of staircase 1 in FIG. 5B is assumed. In the simulation, a bar width of 9.4 mm (ie, the distance between the left and right edge oscillators) is used. As shown, the maximum difference in beam smear compared to the central oscillator is less than 0.6 μm and the maximum difference in pointing error is less than 0.05 mrad, both of which have a negligible effect on the performance of the WBC resonator 100.

7A-7D are schematic views of the resonator 100 in the non-WBC direction, corresponding to the cases described with respect to FIGS. 2A-2D, respectively. Each of FIGS. 7A-7D includes a single diode bar 105, a SAC lens 115, a diode bar 105, a dispersion element 110, and an interleaving mirror 120 associated with the output coupler 155. Other elements of the resonator 100 are omitted for simplicity. In FIG. 7A, the resonator beam 150 propagates from the diode bar 105 to the output coupler 155 and is shown by the solid line. In the case of FIG. 7A, since the dispersion element 110 is not tilted, the resonator beam 150 overlaps the center line 700 orthogonal to the output coupler 155, and the primary beam reflection in the non-WBC dimension is detrimental. It may interfere with the feedback beam from the output coupler 155 (ie, by propagating back to the oscillator). Black spots on the interleaving mirror 120 indicate points where the resonator beam hits the mirror 120 and is reflected towards the dispersion element 110.

As shown in FIG. 7B, when the dispersion element 110 is tilted in the non-WBC direction (eg, slow axis) by the angle δ, a pointing error with an angle α is induced in the resonator beam 150. The pointing error angle α (mrad) is substantially proportional to the inclination angle δ of the dispersion element 110 and the grid line density p (lines / μm) of the dispersion element. The pointing error angle is approximately proportional to the tangent of the off-Littrow incident angle Δθ (in the WBC direction) of the beam (described above with respect to FIG. 2A). These relationships may be expressed by the following equation 3.

In various embodiments of the invention, the dispersion element 110 is an angle of 5 mrad or less, an angle of 10 mrad or less, an angle of 15 mrad or less, an angle of 20 mrad or less, an angle of 25 mrad or less in the non-WBC direction (ie, slow axis). , Or may be tilted at an angle of 30 mrad or less. The slope may be at least 1 mad, at least 2 mad, at least 3 mad, or at least 5 mad in various embodiments.

As shown in FIG. 7C, the tilt of the interleaving mirror 120 may be adjusted by an angle β in the non-WBC dimension (eg, slow axis), thus leading to unstable wavelength stabilization pointing errors. Eliminate the angle α. In various embodiments of the invention, the slope δ of the dispersion element 110 is greater than the pointing error angle α (eg, approximately 10-fold or 100-fold larger). Further, in various embodiments of the present invention, the interleaving mirror tilt β is substantially the same as the pointing error angle α.

As described herein, correction of pointing errors in the non-WBC direction caused by tilting of the dispersion element usually results in increased beam smear in the non-WBC direction at the dispersion element. In FIG. 7C, this beam smear is indicated by ΔS. As shown in FIG. 7D, the quantity T displaces the SAC lens 115 in a non-WBC dimension (eg, slow axis) (ie, so that the beam does not hit the longitudinal center and / or optical axis of the SAC lens 115). This results in an offset of the beam position of the quantity ΔS'in the interleaving mirror 120. As shown in FIG. 7D, this offset ΔS'in the interleaving mirror is, in various embodiments, f is the focal length of the SAC lens 115 and D is between the SAC lens 115 and the interleaving mirror 120. It is the optical distance, L is the optical distance between the SAC lens 115 and the dispersion element 110, and ε is the remaining beam smear in the dispersion element 110, as shown in Equation 4 below.

In the embodiment of the present invention, since the remaining beam smear is reduced to substantially zero and, as described above, β is substantially the same as the pointing error angle α, the displacement T of the SAC lens is the following equation 5 May be represented by.

In various embodiments of the present invention, the optical distance L from the SAC lens 115 to the dispersion element 110 is substantially the same for all different oscillators. Thus, according to various embodiments of the invention, the SAC staircase, i.e., the SAC lens offset / displacement, is such that the subscript k is each beam oscillator, i.e. k = 1, 2,. .. .. , N, where n is the number of beam oscillators, may be substantially indicated by Equation 6.

As is clear from this equation, a smaller distance from the SAC lens 115 to the interleaving mirror 120 requires a larger SAC lens offset. In an embodiment in which the optical distance D from the SAC lens 115 to the interleaving mirror 120 is approximately the same for each beam oscillator, the SAC step offset follows a linear or substantially linear relationship proportional to Δθ _k . Another embodiment of the invention, as shown in FIGS. 4 and 5A, is a substantially parabolic SAC lens, at least in part, in that T _k is inversely proportional to D _k in such embodiments. Including stairs. According to embodiments of the present invention, the optical distance D between the various SAC lenses and the corresponding interleaving mirrors may vary, so that the shape of the SAC lens staircase is linear (or substantially). Not limited to linear) or parabolic (or substantially parabolic), the SAC lens staircase does not have to increase monotonically and is stepwise (eg, 1, 2, or 3 or more in displacement). May increase (with steps).

Embodiments of the present invention may also include a SAC lens staircase in a WBC resonator without an interleaving mirror. In such an embodiment, the SAC lens staircase may be defined as abbreviated as Equation 7.

In such an embodiment, the displacement of the array of SAC lenses substantially eliminates the pointing error caused by the tilt of the dispersion element, but may result in uncompensated beam smear of the residue in the dispersion element. Such beam smear may be substantially calculated as in Equation 8.

For example, the same as above, but excluding the use of interleaving mirrors, numerical examples result in overall beam smear in dispersion elements of 0.9 mm and above, and correspond to beam quality degradation of 25% and above in the slow axis.

FIG. 7E shows a perspective view of an exemplary interleaving mirror 120 tilted as shown in FIG. 7C. The solid line corresponds to the incident beam and is shown with respect to the center line 700 of FIG. 7C. As shown, the interleaving mirror 120 is tilted (ie, rotated) in the non-WBC (eg, slow axis) dimension, and the incident beam is interleaved at an angle β in the non-WBC (eg, slow axis) direction. It is reflected from the leaving mirror 120.

In various embodiments of the invention, the offset displacement of the SAC lens is approximately 5% or less of the focal length, or approximately 3% or less of the focal length. For example, in a numerical example using a SAC lens having a focal length of 50 mm, the maximum displacement of the SAC lens staircase may be limited to about 2.5 mm or less or about 1.5 mm or less. In various embodiments of the invention, the offset displacement of the SAC lens may be at least about 0.1%, at least about 0.2%, at least about 0.5%, or at least about 1% of the focal length. good.

In embodiments of the present invention, the total height of the SAC lens staircase (ie, the range of displacement of the SAC lens array) is centered (or only in various embodiments) with the dispersion element (WBC direction). In) it may be reduced by setting it to an angle smaller than the retrow angle. Such embodiments may exhibit slightly lower diffraction efficiencies and slightly lower dispersion power of the dispersion element. In the numerical examples provided above, setting the tilt angle of the dispersion element 1 ° smaller than the retrow angle reduces the overall height of the SAC lens staircase from approximately 0.7 mm to approximately 0.4 mm.

In various embodiments, the SAC lens staircase may be implemented by displacement of one or more SAC lenses in the WBC resonator (eg, longitudinal displacement orthogonal to the beam incident direction). In other embodiments, the different SAC lenses may have different heights in the slow axis direction, so that the center point (eg, the optical axis) of each lens is located at an appropriate level. In such embodiments, the bases of the various SAC lenses may (but not necessarily) be substantially coplanar, and the center of the SAC lens may be offset by the desired amount. The lens. In various embodiments, the position (eg, the base position) and the height of the two or more SAC lenses may vary within the staircase.

In various embodiments, the various SAC lenses are placed on a substantially planar platform, and the SAC lenses vary on the base, for example by spacers of various heights or thicknesses, or lens bases. It is placed at a high height. In other embodiments, the various SAC lenses and the bases thereof may have substantially the same dimensions and shape, and the common platform itself may allow the SAC lenses to be properly positioned. Regions with different heights (eg, mesas or other protrusions) may be defined. In various embodiments, the displacement of one or more SAC lenses may be adjusted after installation on a common platform, for example, through one or more actuators.

In various embodiments, for subsequent modifications through mirror tilt and / or lens displacement, as described in US Provisional Patent Application No. 62 / 797,438, filed January 28, 2019. In addition, beam smear and / or pointing errors of various beams may be detected by a detection system that demultiplexes the beam for inspection of the individual beam components of the overlapping beams, and the entire disclosure thereof. Is incorporated by reference herein. For example, beam smear and / or pointing errors may be detected and the tilt and / or displacement of the individual components is adjusted by a human operator or computer controlled control system (and mechanical regulators such as actuators, worm gears, etc.). It may be, and thus minimize the observed beam smear and / or pointing error.

The terms and expressions used herein are used as descriptive terms without limitation and are intended to exclude the equivalent of the features shown and described in the use of such terms and expressions. However, it is acknowledged that various modifications are possible within the scope of the invention described in the claims.

Claims (50)

Multiple beam oscillators, each oscillating one or more beams,
A dispersion element that receives the beam and synthesizes the beam into a multi-wavelength beam in the wavelength synthesis (WBC) dimension.
A plurality of collimators arranged on the optical downstream side of the plurality of beam oscillators and the optical upstream side of the dispersion element,
Here, each of the plurality of collimators receives one or a plurality of beams from the plurality of beam oscillators and collimates to the non-WBC dimension.
A plurality of interleaving mirrors arranged on the optical downstream side of the plurality of beam oscillators and the optical upstream side of the dispersion element,
Here, each of the plurality of interleaving mirrors reflects one or more beams from the beam oscillator toward the dispersion element.
A partially reflective type that receives the multi-wavelength beam from the dispersion element, transmits the first portion of the multi-wavelength beam as an output beam, and reflects the second portion of the multi-wavelength beam toward the dispersion element. With the output coupler,
Equipped with
The dispersion element is tilted at a non-zero angle in the non-WBC dimension, whereby the primary reflection of the beam from the dispersion element is directed away from the plurality of beam oscillators and the multi-wavelength. Bringing a pointing error to the beam,
One or more of the interleaving mirrors is tilted at a non-zero angle in the non-WBC dimension so as to reduce the pointing error of the multi-wavelength beam, thereby the dispersion element. Brings beam smear in the non-WBC dimension,
The optical axes of the two or more collimators are displaced relative to each other in the non-WBC dimension, which reduces beam smear due to the tilted interleaving mirrors.
Laser system. The laser system of claim 1, wherein the non-WBC dimension corresponds to the slow axis of the beam. The laser system of claim 1, wherein the non-WBC dimension corresponds to the fast axis of the beam. The laser system according to claim 1, wherein the dispersion element has a diffraction grating. The laser system of claim 1, wherein the at least one beam oscillator has a diode bar configured to oscillate a plurality of discrete beams. In the first beam oscillator
The tilt of the dispersion element in the non-WBC dimension results in a pointing error with a first angle.
The laser system of claim 1, wherein the interleaving mirror associated with the first beam oscillator has a second angle in the non-WBC dimension. The laser system according to claim 6, wherein the second angle is substantially equal to the first angle. The laser system of claim 1, wherein all interleaving mirrors are tilted at a non-zero angle in the non-WBC dimension. The laser system of claim 1, wherein the at least two interleaving mirrors are tilted at different angles in the non-WBC dimension. The laser system of claim 1, wherein all but one interleaving mirror is tilted at different angles in the non-WBC dimension. 10. The laser system of claim 10, wherein the interleaving mirror associated with the central beam oscillator is not tilted at a non-zero angle in the non-WBC dimension. The laser system of claim 1, wherein the two or more interleaving mirrors are not tilted at a non-zero angle in the non-WBC dimension. The laser system of claim 1, further comprising (i) a second collimator and (ii) an optical rotator that rotates one or more beams by approximately 90 ° in connection with each beam oscillator. 13. The laser system of claim 13, wherein each collimator is a slow axis collimator and each second collimator is a fast axis collimator. The laser system according to claim 1, wherein the plurality of interleaving mirrors are arranged on the optical downstream side of the plurality of collimators. The laser system according to claim 1, wherein the optical distance between each collimator and the dispersion element is substantially equal. The laser system according to claim 1, wherein two or more collimators have different heights. The laser system according to claim 1, wherein the heights of two or more collimators are substantially equal. The laser system according to claim 1, wherein the heights of all collimators are substantially equal. The laser system according to claim 1, further comprising one or more folded mirrors arranged optically downstream of the dispersion element and upstream of the output coupler. Multiple beam oscillators, each oscillating one or more beams,
A dispersion element that receives the beam and synthesizes the beam into a multi-wavelength beam in the wavelength synthesis (WBC) dimension.
A plurality of collimators arranged on the optical downstream side of the plurality of beam oscillators and the optical upstream side of the dispersion element,
Here, each of the plurality of collimators receives one or a plurality of beams from the plurality of beam oscillators and collimates to the non-WBC dimension.
A partially reflective type that receives the multi-wavelength beam from the dispersion element, transmits the first portion of the multi-wavelength beam as an output beam, and reflects the second portion of the multi-wavelength beam toward the dispersion element. With the output coupler,
Equipped with
The dispersion element is tilted at a non-zero angle in the non-WBC dimension, whereby the primary reflection of the beam from the dispersion element is directed away from the plurality of beam oscillators and the multi-wavelength. Bringing a pointing error to the beam,
The optical axes of the two or more collimators are displaced relative to each other in the non-WBC dimension, thereby reducing the pointing error due to the tilted dispersion element .
Laser system. 21. The laser system of claim 21, wherein the non-WBC dimension corresponds to the slow axis of the beam. 21. The laser system of claim 21, wherein the non-WBC dimension corresponds to the fast axis of the beam. 21. The laser system of claim 21, wherein the dispersion element has a diffraction grating. 21. The laser system of claim 21, wherein the at least one beam oscillator has a diode bar configured to oscillate a plurality of discrete beams. 21. The laser system of claim 21, wherein the plurality of collimators provide beam smear in the non-WBC dimension in the dispersion element. 21. The laser system of claim 21, further comprising (i) a second collimator and (ii) an optical rotator that rotates one or more beams by approximately 90 ° in connection with each beam oscillator. 27. The laser system of claim 27, wherein each collimator is a slow axis collimator and each second collimator is a fast axis collimator. 21. The laser system of claim 21, wherein the optical distance between each collimator and the dispersion element is approximately equal. 21. The laser system of claim 21, wherein two or more collimators have different heights. 21. The laser system of claim 21, wherein the heights of two or more collimators are approximately equal. 21. The laser system of claim 21, wherein all collimators have substantially equal heights. 21. The laser system of claim 21, further comprising one or more folded mirrors arranged optically downstream of the dispersion element and upstream of the output coupler. It ’s a way to align the laser system.
The laser system is
(I) A plurality of beam oscillators configured to oscillate one or more beams, respectively.
(Ii) With a dispersion element that receives the beam and synthesizes the beam into a multi-wavelength beam in the wavelength synthesis (WBC) dimension.
(Iii) The multi-wavelength beam is received from the dispersion element, the first portion of the multi-wavelength beam is transmitted as an output beam, and the second portion of the multi-wavelength beam is reflected back toward the dispersion element. , Partial reflection type output coupler,
Equipped with
The method is
Combining the beam oscillated by the plurality of beam oscillators with the multi-wavelength beam by the dispersion element,
Introducing a pointing error to the multi-wavelength beam in the non-WBC dimension.
To reduce the pointing error of the multi-wavelength beam, to bring beam smear at the dispersion element in the non-WBC dimension.
To reduce the beam smear without increasing the pointing error of the multi-wavelength beam,
Including, how. 34. The method of claim 34, wherein the pointing error is brought to the multi-wavelength beam by tilting the dispersion element at a non-zero angle in the non-WBC dimension. The one or more interleaving mirrors are arranged on the optical downstream side of the plurality of beam oscillators and on the optical upstream side of the dispersion element.
34. The method of claim 34, wherein tilting one or more interleaving mirrors in a non-WBC dimension at a non-zero angle results in beam smear. The two or more collimators are arranged on the optical downstream side of the plurality of beam oscillators and on the upstream side of the dispersion element.
34. The method of claim 34, wherein the beam smear is reduced by displacing the optical axes of two or more collimators with respect to each other in the non-WBC dimension. 37. The method of claim 37, wherein the two or more collimators are slow axis collimators. 37. The method of claim 37, wherein the two or more collimators are fast axis collimators. 34. The method of claim 34, wherein the non-WBC dimension corresponds to the slow axis of the beam. 34. The method of claim 34, wherein the non-WBC dimension corresponds to the fast axis of the beam. 34. The method of claim 34, further comprising rotating the beam by approximately 90 ° prior to synthesizing the beam into a multi-wavelength beam. It ’s a way to align the laser system.
The laser system is
(I) A plurality of beam oscillators configured to oscillate one or more beams, respectively.
(Ii) With a dispersion element that receives the beam and synthesizes the beam into a multi-wavelength beam in the wavelength synthesis (WBC) dimension.
(Iii) The multi-wavelength beam is received from the dispersion element, the first portion of the multi-wavelength beam is transmitted as an output beam, and the second portion of the multi-wavelength beam is reflected back toward the dispersion element. , Partial reflection type output coupler,
Equipped with
The method is
Combining the beam oscillated by the plurality of beam oscillators with the multi-wavelength beam by the dispersion element,
Suppressing the primary reflection from propagating back from the dispersion element to the plurality of beam oscillators.
To reduce the pointing error of the multi-wavelength beam and
Including, how. Suppressing the primary reflection from propagating back from the dispersion element to the plurality of beam oscillators comprises tilting the dispersion element at a non-zero angle in the non-WBC dimension. Item 43. The method according to item 43. The two or more collimators are arranged on the optical downstream side of the plurality of beam oscillators and on the upstream side of the dispersion element.
43. The method of claim 43, wherein by displacing the optical axes of two or more collimators with respect to each other in the non-WBC dimension, pointing errors are reduced. The method of claim 45, wherein the two or more collimators are slow axis collimators. The method of claim 45, wherein the two or more collimators are fast axis collimators. 43. The method of claim 43, wherein the non-WBC dimension corresponds to the slow axis of the beam. 43. The method of claim 43, wherein the non-WBC dimension corresponds to the fast axis of the beam. 43. The method of claim 43, further comprising rotating the beam by approximately 90 ° prior to synthesizing the beam into a multi-wavelength beam.