High-power laser pulse delivery
Patent Information
- Application Number
- JP2025505413
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-08-03
- Filing Date
- 2022-09-07
- Publication Date
- 2025-09-02
Smart Images
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Abstract
Description
[Technical Field]
[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of European Patent Application No. 22382755.1, filed August 3, 2022.
[0002] The present disclosure relates to a delivery system for delivering one or more high-power laser pulses, and further to a method and computer program for operating a delivery system for delivering one or more high-power laser pulses. [Background technology]
[0003] Optical fibers are glass strands capable of transmitting signals in the form of light waves. The signals can be modulated messages or pulses conforming to what is essentially data information transmitted from one location to another, forming optical fiber communications. The signals can also be pulses or trains of pulses of predetermined characteristics that are sent to endpoints for a wide range of applications. These systems share the optical fiber physical path and therefore share the inherent problems of light propagation through that medium, such as attenuation, dispersion, and nonlinear effects. These effects can reduce the amount of bandwidth in communications applications and compromise the specifications of the pulses sent after a few meters in pulse delivery applications.
[0004] Delivery systems are known for delivering pulses or pulse trains to a delivery end (or endpoint) via an optical fiber path. Pulse requirements at the endpoint may include certain power, duration, and / or shape parameters, and meeting these requirements may be important to ensure good system performance. When the pulse duration is ultrashort (e.g., in the picosecond or femtosecond range), dispersion and nonlinear effects can have detrimental effects, which may result in poor system performance. As the length of optical fiber through which the pulses are to be carried increases, it may become more difficult to meet the minimum requirements or specifications of the delivery end.
[0005] Radiation-based (e.g., THz-based) measurement systems are suitable solutions for accurately determining the thickness of multilayer materials, for example, in a non-contact and non-destructive manner. Such techniques have proven highly suitable for industrial applications in the automotive and aerospace industries. These systems can also be used to detect defects or imperfections other than material thickness, such as deformations, excessive holes, discontinuities, etc.
[0006] Such radiation-based systems experience difficulties associated with the propagation of ultrashort laser pulses in optical fibers over long distances, as the long path traversed or traveled by the laser pulse can cause distortions in the temporal shape and / or spectrum of the laser pulse. Thus, it can be difficult to simultaneously meet radiation-based measurement requirements, such as accuracy / performance and laser transmission over long distances. [Prior art documents] [Patent documents]
[0007] [Patent Document 1] (See International Search Report) Summary of the Invention [Problem to be solved by the invention]
[0008] It is an object of the present disclosure to provide new methods, systems, and computer programs aimed at improving upon prior art methods of delivering high power laser pulses. [Means for solving the problem]
[0009] In one aspect, a delivery system for delivering one or more high-power laser pulses is provided. The delivery system includes a pulse generator and a first pulse provider, the first pulse provider including a first optical fiber path, a first pulse amplifier, and a first delivery end. The pulse generator is configured to generate a first low-power laser pulse having a predefined power output to avoid or minimize distortion of the first low-power laser pulse along the first pulse provider. An initial section of the first optical fiber path is configured to carry the first low-power laser pulse from the pulse generator to the first pulse amplifier. The first pulse amplifier is configured to amplify the first low-power laser pulse to generate a first high-power laser pulse having a predefined power output to operate a first end component connectable to the first delivery end. A final section of the first optical fiber path is configured to carry the first high-power laser pulse from the first pulse amplifier to the first delivery end. The first pulse amplifier is disposed at a location along the first optical fiber pathway corresponding to a distal location relative to the pulse generator or a proximal location relative to the first delivery end.
[0010] Minimizing laser pulse distortion may refer to the goal of causing predictable pulse distortion below a distortion threshold or within a distortion range. Amplifying a pulse may refer to increasing the power of a pulse on demand by driving end components with the amplified pulse. For example, a pulse amplifier may be configured to amplify the power of a low-power laser pulse by between 5 and 20 times, between 10 and 20 times, or by any amount estimated to be necessary or convenient. The concepts of proximal and distal are well known in the art to which this disclosure pertains. In line with these known concepts, the proximal / distal location of a first pulse amplifier may be expressed as the first pulse amplifier being closer to the first delivery end than the pulse generator, or in other words, the length of the initial section being longer than the length of the final section. For example, the initial and final sections of a first optical fiber path may have a length ratio of, for example, 5 / 1, 4 / 1, 3 / 1, 2 / 1, 1.5 / 1, or n / 1 (where n>1). A length ratio of n / 1 may refer to an initial section having a length of n*m and a final section having a length of 1*m, with m >= 1. For example, a length ratio of 5 / 1 may refer to: This may mean that the length of the initial section is 5 (5*1) or 10 (5*2) or 15 (5*3) etc. and the length of the final section is 1 (1*1) or 2 (1*2) or 3 (1*3) etc.
[0011] These delivery systems are able to operate much better than prior art systems aimed at the same or similar purpose because the low-power laser pulse (or pulse train) traverses most of the optical fiber path and is amplified at a point in the optical fiber path proximal or near the delivery end. Low-power laser pulses have proven less susceptible to distortion due to dispersion and / or nonlinear effects inherent in propagation through optical fiber, and therefore higher-power laser pulses of better quality can ultimately be delivered. The fact that the low-power laser pulse is amplified at or near the end of the optical fiber path allows the high-power laser pulse to arrive at the delivery end more accurately than prior art systems of the same or similar type.
[0012] The delivery system may further comprise a first pulse conditioner configured to modify or condition the first low-power laser pulse or the first high-power laser pulse, or both, to compensate for dispersion and / or nonlinear effects of the first pulse provider. Dispersion and nonlinear effects may increase due to factors such as long length, high pulse power, etc. The fact that the low-power laser pulse (or pulse train) traverses a large portion of the optical fiber path may reduce dispersion and nonlinear effects, thus enabling the minimum requirements of the delivery end to be met in a better way.
[0013] The first pulse conditioner can be included in the pulse generator, the first pulse amplifier, or the first optical fiber path. When the first pulse conditioner is included in the first optical fiber path, the first pulse conditioner can include an optical fiber portion having a dispersion parameter opposite to the dispersion parameter of all or a portion of the remaining optical fiber in the first optical fiber path.
[0014] The initial section or the final section, or both, of the first optical fiber path may have an oversized length for multiple intended (or unintended) applications of the delivery system. Such an oversized length may enable the delivery system to be used in different applications (having the same or similar manufacturing specifications) that require more or less distance between the pulse generator and the first delivery end. Having an optical fiber path with an oversized length provides great flexibility in the use of the delivery systems disclosed herein, since the same delivery system may be used for multiple applications that require (very) different distances between the pulse generator and the delivery end. For example, delivery systems for different (and possibly disparate) applications may be structurally uniform, and cheaper multi-purpose delivery systems may be designed and manufactured accordingly. In some examples, the oversized optical fiber may be retractable and extendable, or spoolable and deployable (unwindable), so that the remaining optical fiber may remain retracted or retracted and may be deployed or stretched as needed or desired.
[0015] The initial section of the first optical fiber path may be stretchable, for example, by including or incorporating a free-dispersion fiber section therein, which may include fiber sections with opposite dispersion parameters. If the original length of the optical fiber path is not sufficient for a given application, the stretchability of the optical fiber may add further flexibility to the delivery system according to the present disclosure, since the stretchability of the optical fiber may enable the same delivery system to be used for an unexpected application requiring a longer distance (either completely or substantially) between the pulse generator and the delivery end. Implementations with such optical fiber stretchability may involve connections or couplings between different optical fiber sections, which may cause dispersion and nonlinear effects in the laser pulse(s) or laser pulse train(s) as they are transported through the interconnected optical fiber sections. In delivery systems according to the present disclosure, the fact that a large portion of the optical fiber path (from the pulse generator to approximately the delivery end) is traversed or traveled by the low-power laser pulse(s) may be important in implementations with different optical fiber sections connected to each other. Because low-power pulses are much less susceptible to dispersion and especially nonlinear effects than high-power pulses, a delivery system according to the present disclosure having interconnected optical fiber sections can be implemented more easily and optimally, and therefore less expensive, than prior art delivery systems. In this type of implementation, an existing delivery system configured to operate at a given distance between the pulse generator and the delivery end can be adapted to operate at a longer distance between the pulse generator and the delivery end in a very easy and inexpensive manner.
[0016] In implementations, the first low-power laser pulse and the first high-power laser pulse can be femtosecond or ultrashort laser pulses. Additionally or alternatively, the first low-power laser pulse and the first high-power laser pulse can have wavelengths between 1500 nm and 1600 nm. Additionally or alternatively, all or a portion of the first optical fiber pathway can be polarization maintaining, for example, to avoid or minimize possible polarization-related dispersion effects.
[0017] A delivery system using what may be referred to as a double-supply approach may further include a second pulse provider including a second optical fiber path, a second pulse amplifier, and a second delivery end. In such a double-supply approach, the pulse generator may be further configured to generate second low-power laser pulses having a predefined power output to avoid or minimize distortion of the second low-power laser pulses along the second pulse provider. An initial section of the second optical fiber path may be configured to carry the second low-power laser pulses from the pulse generator to the second pulse amplifier. The second pulse amplifier may be configured to amplify the second low-power laser pulses to generate second high-power laser pulses having a predefined power output to operate a second end component connectable to the second delivery end. A final section of the second optical fiber path may be configured to carry the second high-power laser pulses from the second pulse amplifier to the second delivery end. Still in a dual-feed implementation, the second pulse amplifier may be located along the second optical fiber path at a location corresponding to either a distal location relative to the pulse generator or a proximal location relative to the second delivery end. The second pulse provider may have the same configuration as the first pulse provider.
[0018] The dual-feed approach of delivery systems may allow them to be used in applications requiring the delivery of laser pulse(s) or pulse train(s) to two end components. For example, such delivery systems may be ideal for implementing radiation-based applications requiring a radiation emitter and a radiation receiver. A particular application of this type may be, for example, a THz radiation-based application aimed at inspecting materials or objects with the aim of detecting thickness, holes, discontinuities, irregularities, general defects, etc.
[0019] According to a dual-feed implementation, the pulse generator may include a dual output laser system configured to generate both the first low-power laser pulse and the second low-power laser pulse. Alternatively, the pulse generator may include a splitter configured to split a single or primary low-power laser pulse generated by the pulse generator into a first and a second version of the single or primary low-power laser pulse, the first version corresponding to the first low-power laser pulse and the second version corresponding to the second low-power laser pulse, or vice versa.
[0020] Still according to the dual-feed approach, the delivery system may further comprise a synchronizer configured to synchronize the delivery of the first and second low-power laser pulses with each other. Such synchronization may be based on timing the delivery of one of the first and second low-power laser pulses so that, in use, the first and second high-power laser pulses arrive at the first and second delivery ends, respectively, at a predetermined time difference from each other. The synchronizer may include a repetition rate controller configured to control or modulate the repetition rate of the first and second low-power laser pulses. The repetition rate controller may be integrated into a system having two synchronized lasers and / or may use techniques such as ASOPS (Asynchronous Optical Sampling System) and / or ECOPS (Electronically Controlled Optical Sampling System). Alternatively, the synchronizer may include a mechanical delay line configured to time the delivery of one of the first and second low-power laser pulses. Thus, the mechanical delay line may be disposed in only one of the first and second optical fiber paths. Those skilled in the art should know how this synchronization can be implemented depending on the particular intended application.
[0021] In (some) examples, the lengths of both the first optical fiber path and the second optical fiber path may be adjustable and / or tunable by adding or subtracting substantially the same amount of optical fiber length.
[0022] A provider system for providing high-power laser pulses may also be provided herein, comprising one delivery system with a dual-supply approach and another delivery system also with a dual-supply approach. Thus, such a provider system may correspond to what may be referred to as a quadruple-supply approach. A provider system with any number of delivery systems with a dual-supply approach may correspond to what may be referred to as a multiple-supply approach, which may be defined or obtained by extending the same or similar principles as those described for the quadruple-supply approach. Thus, provider systems with sextuple, octuple, ..., n-fold supply approaches may also be included within the scope of the present disclosure. Such multiple-supply approaches may cover a multitude of (unforeseen) applications.
[0023] In an example according to what may be referred to as a dual THz feed approach, the first end component may be a THz emitter and the second end component may be a THz receiver, or vice versa, the THz emitter and the THz receiver fitted with a THz measurement header connectable to the delivery system. In particular, a THz measurement system may be provided comprising a delivery system according to the dual THz feed approach and a connectable THz measurement header connected to the delivery system.
[0024] According to what may be referred to as a quadruple THz feed approach, a feed system may be provided that includes a first delivery system with a dual THz feed approach and a second delivery system also with a dual THz feed approach. In particular, a THz measurement system may be provided that includes one of the above feed system, a THz measurement header connected to the first delivery system and connectable with the first delivery system, and a THz measurement header connected to the second delivery system and connectable with the second delivery system. The same or similar considerations discussed with respect to multiple feed or n-fold feed approaches may be extrapolated to such THz feed approaches.
[0025] In a further aspect, a method is provided for operating a delivery system (for delivering one or more high-power laser pulses) including a pulse generator and a first pulse provider, the first pulse provider including a first optical fiber path, a first pulse amplifier, and a first delivery end, the first pulse amplifier being disposed at a location along the first optical fiber path corresponding to a distal location relative to the pulse generator or a proximal location relative to the first delivery end. Such a method of operating a delivery system includes operating the pulse generator to generate a first low-power laser pulse having a power predefined to avoid or minimize distortion of the first low-power laser pulse along the first pulse provider, the first low-power laser pulse being conveyed from the pulse generator to the first pulse amplifier through an initial section of the first optical fiber path. The method of operating a delivery system further includes operating a first pulse amplifier to amplify the first low-power laser pulse to generate a first high-power laser pulse having a predefined power output, and operating a first end component connectable to the first delivery end, wherein the first high-power laser pulse is transported from the first pulse amplifier to the first delivery end through a final section of the first optical fiber path.
[0026] In yet a further aspect, computer programs are provided that include program instructions for causing a system or computing system to perform methods of operating a delivery system for delivering one or more high-power laser pulses, such as those described elsewhere in this disclosure, which may be embodied on a storage medium and / or carried on a carrier signal.
[0027] In yet a further aspect, there is provided a computing system for operating a delivery system to deliver one or more high-power laser pulses, the computing system comprising a memory and a processor, the computing system embodying instructions stored in the memory and executable by the processor, the instructions including one or more functions for performing a method of operating the delivery system, such as those described elsewhere in this disclosure.
[0028] Non-limiting examples of the present disclosure are described below with reference to the accompanying drawings. [Brief explanation of the drawings]
[0029] [Figure 1] FIG. 1 is a block diagram that schematically illustrates a delivery system for delivering one or more high-power laser pulses, according to an example. [Figure 2] FIG. 10 is a block diagram that schematically illustrates a delivery system for delivering one or more high-power laser pulses, according to a further example. [Figure 3] FIG. 10 is a block diagram that schematically illustrates a delivery system for delivering one or more high-power laser pulses, according to a still further example. [Figure 4] FIG. 10 is a block diagram that schematically illustrates a delivery system for delivering one or more high-power laser pulses, according to a still further example. [Figure 5] FIG. 10 is a block diagram that schematically illustrates a delivery system for delivering one or more high-power laser pulses, according to a further example. [Figure 6] FIG. 10 is a block diagram that schematically illustrates a delivery system for delivering one or more high-power laser pulses, according to a still further example. [Figure 7] 1 is a flowchart that schematically illustrates a method of operating a delivery system for delivering one or more high-power laser pulses, in accordance with an example. DETAILED DESCRIPTION OF THE INVENTION
[0030] 1 is a block diagram that schematically illustrates a delivery system 100 for delivering one or more high-power laser pulses 114, according to an example. As generally shown in the figure, the delivery system 100 may include several modules or units, or groups of modules or units, such as a pulse generator 102 and a first pulse provider 115. The first pulse provider 115 may include various modules or units, such as first optical fiber paths 103, 107 covering first lengths 104, 108, a first pulse amplifier 105, and a first delivery end 109. The delivery system 100 may correspond to a single-delivery approach, in the sense that only one high-power laser pulse (or pulse train) can be or is delivered.
[0031] The first optical fiber pathway 103, 107 may include an initial optical fiber section 103 connecting the pulse generator 102 and the pulse amplifier 105, and a final optical fiber section 107 connecting the pulse amplifier 105 and the first delivery end 109. The first pulse amplifier 105 may be located at a position along the first optical fiber pathway 103, 107 that corresponds to a distal position relative to the pulse generator 102 or a proximal position relative to the first delivery end 109. In other words, the first pulse amplifier 105 may be located much closer to the first delivery end 109 than the pulse generator 102.
[0032] The pulse generator 102 may include a laser pulse generator 101 configured to generate a first low-power laser pulse 111 having a predefined power so as to avoid or minimize distortion of the first low-power laser pulse 111 along the first pulse provider 115. As shown, the first low-power laser pulse 111 will propagate (at low power) through most of the first optical fiber pathway 103, 107 by virtue of the proximal location of the first pulse amplifier 105 relative to the first delivery end 109. Ideally, the predefined power of the first low-power laser pulse 111 may be as low as possible, for example, taking into account the minimum power at which the module(s) or unit(s) compatible with the pulse generator 102 and / or the first pulse provider 115 can operate. The initial optical fiber section 103 of the first optical fiber path can be configured to deliver the first low-power laser pulse 111 (from the pulse generator 102 to the first pulse amplifier 105) with intentionally little or negligible distortion, thanks to the targeted predefined low power, even if the first low-power laser pulse 111 ends up traveling a substantially long distance 104.
[0033] The first pulse amplifier 105 may be configured to amplify the first low-power laser pulse 111 to generate a first high-power laser pulse 113 having a predefined power to operate a first end component 110 connectable to the first delivery end 109. Since the pulse power that may be required for any given end component 110 to be operated, and therefore the low-to-high power amplification performed by the first pulse amplifier 105, is known, details on this matter will not be provided herein. For example, the first pulse amplifier 105 may be configured to amplify the power of the first low-power laser pulse 111 by between 5 and 10 times, or between 10 and 20 times, or according to any other suitable ratio depending on the first end component 110 to be operated. The final optical fiber section 107 of the first optical fiber pathway may be configured to carry the first high-power laser pulse 113 from the first pulse amplifier 105 to the first delivery end 109 with little, negligible, or minimal deformation 114 of the first high-power laser pulse 113 due to at least the proximal location of the first pulse amplifier 105 relative to the first delivery end 109. The first delivery end 109 may be configured, when connected to the first end component 110, to deliver the first high-power laser pulse 113 to the first end component 110.
[0034] Delivery system 100 may further comprise other modules or units, such as, for example, a first pulse conditioner, which may comprise one or more conditioner modules 112, 106. Conditioner module 112 may be associated with, coupled to, or included in pulse generator 102 and may be configured to modify or condition first low-power laser pulse 111 to compensate for dispersion and / or nonlinearity effects due to propagation through initial optical fiber section 103 having a known, defined length 104. In the particular scenario shown, first low-power laser pulse 111 is shown wider at the output of conditioner module 112 than at the input of first pulse amplifier 105. This is intended to indicate that the adjuster module 112 can explicitly modify or adjust the first low-power laser pulse 111 such that dispersion and / or nonlinear effects due to the optical fiber pathway 103 (having a known, defined length 104) result in the first low-power laser pulse 111 with appropriate minimum or optimum specifications (e.g., width) at the input of the first pulse amplifier 105. These appropriate minimum or optimum specifications can be sought and induced in the manner described above in order for the first pulse amplifier 105 to perform minimally or optimally.
[0035] Conditioner module 106 may be associated with, coupled to, or included in first pulse amplifier 105 and may be configured to modify or condition first high-power laser pulse 113 to compensate for dispersion and / or nonlinear effects due to transmission through final optical fiber section 107. In the particular scenario shown, two versions or generations of first high-power laser pulse 113, 114 are shown. Pulse generation 113 corresponds to that output by conditioner module 112, and pulse generation 114 corresponds to that received at first delivery end 109. Pulse generation 113 is shown broader than pulse generation 114. This width difference is intended to reflect that the adjuster module 106 can explicitly modify or adjust the first high-power laser pulse 113 such that dispersion and / or nonlinear effects due to the optical fiber pathway 107 (having a known, defined length 108) result in the first high-power laser pulse 114 at the first delivery end 109 with appropriate minimum or optimum specifications (e.g., width). These appropriate minimum or optimum specifications can be sought and induced in the manner described above for the first end component 110 to perform minimally or optimally.
[0036] Adjuster module(s) or unit(s) may be uniquely or additionally located at any point in the first optical fiber path 103, 107 for the same purpose of compensating for dispersion and / or nonlinearity effects. Any pulse conditioning, such as that described herein, may be primarily aimed at ensuring that the first high-power laser pulse 114 arrives at the first delivery end 109 meeting the minimum operational specifications of the first end component 110. Since it is known how the laser pulse(s) may be tailored depending on the optical fiber path(s) and / or components (within the first pulse provider 115) to be traversed or traveled by the laser pulse(s) and depending on the requirements of the first end component 110, specific details regarding this are not provided herein. In a particular example, the adjuster module(s) located in the first optical fiber path 103, 107 may include an optical fiber portion having a dispersion parameter opposite to that of all or a portion of the remaining optical fiber in the first optical fiber path 103, 107. The first end component 110 may be, for example, a THz-based component such as a THz emitter or a THz receiver, which may require an appropriate laser pulse (or pulse train) to operate.
[0037] The initial optical fiber section 103 or the final optical fiber section 107 (in the first optical fiber path), or both, may have oversized lengths for multiple intended (or unexpected) uses of the delivery system 100. In particular, the initial optical fiber section 103 or the final optical fiber section 107, or both, may be retractable and extendable, or spoolable and deployable (rewindable). In this manner, the length 104 of the first section 103 may be adaptable to the intended or desired distance between the pulse generator 102 and the first pulse amplifier 105 (with or without the conditioner module 112), and / or the length 108 of the second section 107 may be adaptable to the intended or desired distance between the first pulse amplifier 105 and the first delivery end 109 (with or without the conditioner module 106). The delivery system 100 may require larger or smaller lengths of the initial optical fiber section 103 and / or the final optical fiber section 107, for example, due to larger or smaller sizes of objects to be inspected in radiation-based applications. Inspection of aircraft may require longer lengths than, for example, automobiles or motorcycles. With the proposed adaptable excess length approach, the same delivery system 100 can be used for different applications in a very flexible and versatile manner. In the particular example according to FIG. 1 , only the initial optical fiber section 103 is shown oversized with a reelable / reeled remaining fiber path 116. Ideally, the remaining fiber can be reeled 116 in a location proximal to the pulse generator 102, for example, to remain protected within a cabinet housing the pulse generator 102.
[0038] The first low-power laser pulse 111 and the first high-power laser pulses 113, 114, whose representation in the figure is a schematic time pulse trace (obtained, for example, using an autocorrelator), may be femtosecond laser pulses. Minimum specifications that must be met at the launch point 109 for the connectable end component 110 to perform properly may include, for example, a pulse duration between 50 fs and 150 fs, and / or a pulse wavelength between 1500 nm and 1600 nm. In (some) examples, all or part of the first optical fiber paths 103, 107 may be polarization-maintaining to minimize polarization-related dispersion effects.
[0039] FIG. 2 is a block diagram that schematically illustrates a delivery system 200 for delivering one or more high-power laser pulses according to a further example. FIG. 2 is similar to FIG. 1, except that it further includes a free-dispersion fiber section. Numeral references identifying the same or similar elements from FIG. 1 may be reused in FIG. 2 and its following description. The delivery system 200 may also correspond to a single-feed approach, in the sense that only one high-power laser pulse (or pulse train) is delivered. The delivery system 200 may include the same or similar pulse generator 102 as that of FIG. 1, and the first pulse provider 208 may be different from the first pulse provider 115 of FIG. 1. The figure illustrates that the fiber section 103 may be stretchable (and may be stretched or elongated accordingly, as needed or desired), for example, by including or incorporating a free-dispersion fiber section including fiber portions with opposite dispersion parameters. In the particular example shown, length 104 of fiber section 103 is extended to longer length 207 by adding additional fiber sections 204, 205, and 206. As shown, longer length 207 may result from adding length 104 (of fiber section 103) and lengths 201-203 (of fiber sections 206, 205, and 204, respectively). To make this fiber extension non-dispersive, fiber sections 204 and 206 may have one dispersion parameter, and fiber section 205 may have another dispersion parameter opposite that of sections 204 and 206. In this way, based on selecting appropriate lengths 201-203, the dispersion due to fiber sections 204 and 206 and the dispersion due to fiber section 205 may compensate for each other, such that the dispersion of the entire added fiber portions 204-206 may be zero or negligible. Unlike FIG. 1, the first low-power laser pulse 111 is shown twice in FIG. 2 with substantially the same width as it is transported through optical fiber portions 206, 205, and 204 that match the free-dispersion fiber sections used to extend the original optical fiber section 103.
[0040] FIG. 3 is a block diagram that schematically illustrates a delivery system 300 for delivering one or more high-power laser pulses according to yet another example. Such a delivery system 300 may correspond to what is referred to herein as a dual-feed approach, in the sense that two (first and second) high-power laser pulses (or pulse trains) are separately delivered to respective end components 304, 305. Such end components 304, 305 may be, for example, a THz emitter and a THz receiver, respectively, forming what is known as a THz measurement header. The delivery system 300 may include a single laser pulse generator 301 and two (first and second) pulse suppliers 302, 303 for supplying corresponding (first and second) high-power laser pulses (or pulse trains) to the respective connectable or connected (first and second) end components 304, 305. Thus, the apparatus shown in this figure may correspond to a THz-based measurement system with a dual-feed approach. The pulse providers 302, 303 may have the same, similar or compatible configurations aimed at providing respective (first and second) high-power laser pulses (or pulse trains) to respective connectable or connected (first and second) end components 304, 305 in an appropriate manner to operate, for example, corresponding THz measurement headers. The end components 304 and 305 may be operated appropriately by providing first and second high-power laser pulses (or pulse trains) that meet the corresponding minimum specifications of said end components 304 and 305.
[0041] The pulse generator 301 may be configured to generate first and second low-power laser pulses (to be delivered and regulated via the respective first and second pulse providers 302, 303) according to either a direct generation approach or a split-based generation approach. The direct generation approach may be based, for example, on a dual-output laser system (not shown) configured to directly generate both the first and second low-power laser pulses. The split-based generation approach may be based, for example, on a splitter (not shown) configured to split a single or primary low-power laser pulse (e.g., generated by a laser pulse generator in the pulse generator) into first and second versions of the primary low-power laser pulse. Thus, the first version may correspond to the first low-power laser pulse and the second version may correspond to the second low-power laser pulse, or vice versa.
[0042] The delivery system 300 may further comprise other modules, such as, for example, adjuster(s) (not shown), a synchronizer (not shown), etc. The synchronizer may be included in the pulse generator 301 and may be configured to synchronize the delivery of the first and second low-power laser pulses with one another. This synchronization may be performed so that, in use, the first and second high-power laser pulses arrive at the first and second delivery ends 304, 305, respectively, at a predetermined time difference from one another. The synchronizer may include, for example, a repetition rate controller or, alternatively, a mechanical delay line. The repetition rate controller may be configured to control or modulate the repetition rate of the first and second low-power laser pulses. The mechanical delay line may be configured to time the delivery of one of the first and second low-power laser pulses with respect to the other.
[0043] Because the performance of a delivery system using a dual-feed approach may depend on the simultaneous achievement of minimum specifications for the first and second end components, achieving optimal performance may be more difficult than with a delivery system using a single-feed approach. However, like the single-feed approach, implementations using a dual-feed approach can minimize inherent dispersion and nonlinear effects due to the propagation of low-power laser pulses along the majority of the corresponding optical fiber path.
[0044] Thus, a new scenario is provided, which may be useful for deploying the technology in industrial situations requiring both precision and long optical fiber path distances. For example, a THz system for controlling the layer thickness of a car body coating may typically require distances of more than 30 meters and precision in the 1 micrometer range. Such a THz system may be implemented using low-power optical fiber path lengths of more than about 20 meters and (as a result) high-power optical fiber path lengths of less than about 10 meters. The delivery system according to the present disclosure may enable long-distance propagation of laser pulses under appropriate performance and precision conditions to provide optical pulses of optimal or minimum specifications at corresponding THz antennas.
[0045] FIG. 4 is a block diagram that schematically illustrates a delivery system 400 for delivering one or more high-power laser pulses, according to yet another example. The particular example shown also supports a dual-feed approach, since it can be configured to operate two connectable (or optionally connected) end components 404, 405 (e.g., forming a THz measurement header). In the illustrated scenario, the synchronizer 406 can be external to the pulse generator 401, which can be similar to the pulse generator 102 of FIGS. 1 and 2 , with the difference that the pulse generator 401 can output two laser pulses instead of one. Thus, the pulse generator 401 can include a pulse generator 407 configured to generate first and second low-power laser pulses, and, in some examples, first and second adjuster modules 408, 409 for appropriately adjusting the first and second low-power laser pulses, respectively. The first and second pulse providers 402, 403 included in the delivery system 400 may also be the same as or similar to the pulse providers described elsewhere in this disclosure. In the particular example shown, the pulse providers 402, 403 may be the same as or similar to those in FIG. 2. As shown, the synchronizer 406 may be configured to time the delivery of one of the first and second low-power laser pulses through the pulse provider 403 to create a predetermined time difference between the delivery of one and the other.
[0046] The possibility of upgrading a dual-feed system originally manufactured with a specific original length to cover a longer optical fiber path may offer further opportunities in industrial situations. The upgrade can be implemented by adding additional free-dispersion optical fiber sections, as shown in pulse feeders 402 and 403. To precisely illustrate the advantages of the dual-feed delivery system 400, the following THz-based example can be considered. A THz measurement system for controlling the layer thickness of body coatings in a factory manufacturing small and medium-sized vehicles was initially designed and manufactured to cover the maximum expected distance, e.g., 20 meters. However, as the factory began to manufacture larger vehicles requiring a new distance, e.g., 30 meters or more, it decided to upgrade the original system to accommodate the new scenario.
[0047] 4 illustrates a specific, potentially modifiable implementation 400 according to the present disclosure. A pulse generator 401 may output two low-power laser pulses via first and second optical fiber paths of respective pulse providers 402, 403. Adjuster modules 409, 408 in the pulse generator 401 may compensate for dispersion and nonlinear effects of light propagation through the low-power sections of the first and second optical fiber paths (in the pulse providers 402, 403). Synchronization may be performed by a mechanical delay unit 406 in the second optical fiber path (in the pulse provider 403). This implementation may correspond to a TDS-THz system, where the first end component 404 is a THz emitter antenna and the second end component 405 is a THz receiver / detector antenna.
[0048] As shown, two free-dispersion fiber sections can be included in the low-power sections of both the first and second optical fiber paths (within pulse providers 402, 403). Both additional free-dispersion fiber sections can have the same length to match the lengths of the first and second optical fiber paths. Even if the pulse generator 401 and the modules in pulse providers 402 and 403 were originally properly manufactured and adjusted to the nominal specifications of the original system, slight, but potentially significant, mistunes can appear in the high-power laser pulses at antennas 404, 405.
[0049] An advantage of the delivery system 400 is that it can keep dispersion and nonlinear effects below acceptable levels and balanced with one another. For example, if a mistune is expressed in a pulse duration that is slightly different from the (minimum or optimal) specification of the antennas 404, 405, the magnitude and sense of that difference can be balanced and / or approximately the same in both antennas 404, 405. This is an important advantage compared to prior art THz systems operating over long distances, where dispersion and nonlinearities may affect the laser pulses passing through the first and second pulse providers 402, 403 in less controlled, unbalanced, or different ways. In the delivery system 400, for example, the pulse duration difference can be adjusted or tuned by changing the length of the patch cords of the first and second optical fiber paths (within the pulse providers 402, 403), for example, by lengthening or shortening the length by the same or similar amount.
[0050] FIG. 5 is a block diagram that schematically illustrates a delivery system 500 for delivering one or more high-power laser pulses, according to a further example. The particular example shown may correspond to what may be referred to as a quadruple-feed approach, since it may be configured to operate four connectable (or optionally connected) end components 506-509. End components 506 and 507 may form a first THz measurement header, and end components 508 and 509 may fit into a second THz measurement header. Thus, the device shown in this figure may correspond to a THz-based measurement system using a quadruple-feed approach, or, in other words, a dual-header approach. Delivery system 500 may include a pulse generator 501 having the same or similar configuration as other pulse generators described herein, with the difference that pulse generator 501 is capable of outputting four low-power laser pulses instead of one or two. Delivery system 500 may include two delivery systems using a dual-feed approach, such as those of FIGS. 3 and 4. In the particular example shown, pulse providers 502-505 may be the same as or similar to those in Figure 3. Delivery systems configured to deliver more than four high-power laser pulses (or pulse trains) to more than four end components, respectively, may also be provided based on the principles underlying the example of Figure 5 or any other similar example described herein. Dual-header, triple-header, quadruple-header, or generally multiple-header approach delivery systems may make it possible to provide a THz-based measurement system with several or many THz measurement headers for contactless inspection or analysis of different parts of the same object or different objects simultaneously.
[0051] FIG. 6 is a block diagram that schematically illustrates a delivery system 600 for delivering one or more high-power laser pulses, according to yet a further example. FIG. 6 is similar to FIG. 5, and therefore, numerical references identifying the same or similar elements from FIG. 5 may be reused in FIG. 6 and its following description. The difference between FIG. 6 and FIG. 5 may be in how a low-power laser pulse (or pulse train) can be generated for provision to corresponding pulse providers 502-505 to operate associated end components 506-509. Pulse generator 501 may be similar to that of FIG. 5, but in the case of FIG. 6, it is configured to output two low-power laser pulses 603, 604 instead of four. Splitter 601 may be configured or arranged to split low-power laser pulse 603 into a first version / branch 605 and a second version / branch 606 of low-power laser pulse 603, with first version / branch 605 provided to pulse provider 502 and second version / branch 606 provided to pulse provider 504. Another splitter 602 may be configured or arranged to split the low-power laser pulse 604 into a first version / branch 607 and a second version / branch 608 of the low-power laser pulse 604, with the first version / branch 607 being provided to the pulse provider 503 and the second version / branch 608 being provided to the pulse provider 505. In this configuration, only one of the low-power laser pulses 603, 604 output by the pulse generator 501 may be timed relative to the other low-power laser pulse 603, 604 at the pulse generator 501 itself. The apparatus shown in this figure may similarly correspond to a THz-based measurement system with a quadruple feed approach, or in other words, a double header approach. Delivery systems configured to feed more than four high-power laser pulses (or pulse trains) to more than four end components, respectively, may also be provided based on the principles underlying the example of FIG. 6 or any other similar examples described herein.
[0052] As used herein, the terms "module" or "unit" may be understood to refer to software, firmware, hardware, and / or various combinations thereof. Note that the modules are exemplary. Modules may be combined, integrated, separated, and / or replicated to support various applications. Also, functions described herein as being performed by a particular module may be performed by one or more other modules and / or by one or more other devices instead of, or in addition to, the functions performed by the particular described module.
[0053] The modules may be implemented across multiple devices associated with or linked to a corresponding delivery system for delivering one or more high-power laser pulses as proposed herein and / or to other components, which may be local or remote from each other. Furthermore, a module may be moved from one device and added to another device, and / or may be included in both devices associated with a corresponding delivery system for delivering one or more high-power laser pulses as proposed herein. Any software implementation may be tangibly embodied in one or more storage media, such as, for example, a memory device, a floppy disk, a compact disk (CD), a digital versatile disk (DVD), or other device capable of storing computer code.
[0054] A delivery system for delivering one or more high-power laser pulses according to the present disclosure may be implemented by computing means, electronic means, or a combination thereof. The computing means may be a set of instructions (e.g., a computer program), and the delivery system for delivering one or more high-power laser pulses may comprise a memory and a processor, embodying said set of instructions stored in the memory and executable by the processor. These instructions may include one or more functions for performing a corresponding method of operating the delivery system, such as those described with reference to the several figures.
[0055] When the delivery system for delivering one or more high-power laser pulses is implemented solely by electronic means, the controller of the system can be, for example, a complex programmable logic device (CPLD), a field programmable gate array (FPGA), or an application specific integrated circuit (ASIC).
[0056] When the delivery system for delivering one or more high-power laser pulses is a combination of electronic means and computing means, the computing means may be a set of instructions (e.g., a computer program), and the electronic means may be any electronic circuitry capable of performing the corresponding steps of the delivery method for delivering one or more high-power laser pulses proposed in this specification, such as those described with reference to other figures.
[0057] The computer program(s) may be embodied on a storage medium (e.g., a CD-ROM, a DVD, a USB drive, computer memory, or read-only memory) or may be carried on a carrier signal (e.g., on an electrical or optical carrier signal).
[0058] The computer program(s) may be in the form of source code, object code, code intermediate source and object code such as partially compiled form, or any other form suitable for use in implementing a delivery system for delivering one or more high-power laser pulses according to the present disclosure. The carrier may be any entity or device capable of carrying the computer program(s).
[0059] For example, the carrier may include a storage medium such as a ROM, e.g. a CD-ROM or a semiconductor ROM, or a magnetic recording medium, e.g. a hard disk. Further, the carrier may be a transmissible carrier such as an electrical or optical signal, which may be conveyed via electrical or optical cable or by radio or other means.
[0060] When the computer program(s) is / are embodied in a signal which may be conveyed directly by a cable or other device or means, the carrier may be constituted by such cable or other device or means. Alternatively, the carrier may be an integrated circuit in which the computer program(s) is / are embedded, the integrated circuit being adapted to perform, or for use in the performance of, the delivery method for delivering one or more high-power laser pulses as proposed herein.
[0061] Figure 7 is a flow chart that schematically illustrates a method of operating a delivery system such as that of Figures 1 and 2. Such methods of operating a delivery system may also be referred to herein as operating methods. As generally shown in the figure, the operating method may begin (e.g., at block 700) upon detecting a start condition, such as a request to begin the method. Because the operating method according to Figure 7 can be performed to control or operate a delivery system according to Figures 1 and 2, numerical references from Figures 1 and 2 may be reused in the following description of Figure 7.
[0062] The method of operation may further include (e.g., in block 701) operating the pulse generator 102 to generate a first low-power laser pulse (or pulse train) having a power predefined to avoid or minimize distortion of the first low-power laser pulse (or pulse train) along the first pulse provider 115, 208, wherein the first low-power laser pulse (or pulse train) is conveyed from the pulse generator 102 to the first pulse amplifier 105 through an initial section 103, 208 of the first optical fiber pathway. This functionality performed or performable in block 701 may be performed, for example, to operate the pulse generator 102 described above with reference to FIGS. 1 and 2 . Accordingly, the functional details, considerations, and principles described for the pulse generator 102 above may be considered to be attributable or attributeable to method block 701 as well.
[0063] The method of operation may further include (e.g., at block 702) operating first pulse amplifier 105 to amplify a first low-power laser pulse to generate a first high-power laser pulse having a predefined power to operate first end component 110 connectable to first delivery end 109, where the first high-power laser pulse is transported from first pulse amplifier 105 to first delivery end 109 through final section 107 of first optical fiber pathway. This functionality performed or performable in block 702 may be performed, for example, to operate pulse amplifier 105 described above with reference to FIGS. 1 and 2 . Accordingly, the functional details, considerations, and principles described for pulse amplifier 105 above may be considered to be attributable or attributeable to method block 702 as well.
[0064] The method of operation may further include verifying (e.g., at decision block 703) whether an exit condition is met, if so, Y (Yes), the method may end, e.g., by transitioning to end block 704, otherwise, N (No), a new iteration of the method may begin, e.g., by looping back to block 701 to generate the next initial low-power laser pulse (or pulse train). The exit condition may include, e.g., receiving a user exit request.
[0065] 7 are suitable for operating delivery devices according to a single-feed approach, they can obviously be extended to operate delivery devices according to a multiple-feed approach based on the functional principles described herein for the operating method itself and for delivery devices operable by said method. For example, elements other than pulse generators and pulse amplifiers, such as synchronizers and / or regulators, can be operated by an operating method based on the functional principles described herein for synchronizers and / or regulators, respectively.
[0066] While only a few examples are disclosed herein, other alternatives, modifications, uses, and / or equivalents thereof are possible. Moreover, all possible combinations of the described examples are also covered. Therefore, the scope of the present disclosure should not be limited by the specific examples, but should be determined solely by a fair reading of the appended claims. [Explanation of symbols]
[0067] 100,200 Transmission System 102 Pulse Generator 115,208 First pulse supplier 103,107 First optical fiber path (103 initial section, 107 final section) 105 First Pulse Amplifier 109 first delivery end 110 first end component 111 First low power laser pulse 113,114 First high-power laser pulse 112,106 Regulator module (pulse regulator) ** 300 Transmission System 301 Pulse Generator 302,303 Pulse supply 304,305 End components ** 400 Transmission System 401 Pulse Generator 402,403 Pulse supply 404,405 End components 406 Synchronous Device 408,409 Regulator module (pulse regulator) ** 500,600 Transmission System 501 Pulse Generator 502, 503, 504, 505 Pulse supply 506,507,508,509 End components 601,602 Splitter
Claims
1. 1. A delivery system for delivering one or more high power laser pulses, comprising: a pulse generator and a first pulse provider, the first pulse provider including a first optical fiber path, a first pulse amplifier, and a first delivery end; the pulse generator is configured to generate a first low-power laser pulse having a predefined power to avoid or minimize distortion of the first low-power laser pulse along the first pulse provider; an initial section of the first optical fiber pathway configured to carry the first low-power laser pulse from the pulse generator to the first pulse amplifier; the first pulse amplifier is configured to amplify the first low-power laser pulse to generate a first high-power laser pulse having a predefined power to operate a first end component connectable to the first delivery end; a final section of the first optical fiber pathway configured to carry the first high-power laser pulse from the first pulse amplifier to the first delivery end; 10. A delivery system comprising: a first pulse amplifier disposed at a location along the first optical fiber path corresponding to a distal location relative to the pulse generator or a proximal location relative to the first delivery end.
2. 10. The delivery system of claim 1, further comprising a first pulse conditioner configured to modify or condition the first low-power laser pulse or the first high-power laser pulse, or both, to compensate for dispersion and / or nonlinearity effects of the first pulse provider.
3. 3. The delivery system of claim 2, wherein the first pulse conditioner is included in the pulse generator, in the first pulse amplifier, or in the first optical fiber path.
4. 4. The delivery system of claim 3, wherein the first pulse conditioner is included in the first optical fiber path and includes an optical fiber section having a dispersion parameter opposite to the dispersion parameter of all or a portion of the remaining optical fiber in the first optical fiber path.
5. 10. The delivery system of claim 1, wherein the initial section or the final section, or both, of the first optical fiber path have a length that is oversized for multiple intended uses of the delivery system.
6. 2. The delivery system of claim 1, wherein the initial section of the first optical fiber path is extendable by including or collecting within it a free dispersion fiber section including fiber portions having opposite dispersion parameters.
7. 10. The delivery system of claim 1, wherein the first low-power laser pulse and the first high-power laser pulse are femtosecond or ultrashort laser pulses.
8. 10. The delivery system of claim 1, wherein the first low-power laser pulse and the first high-power laser pulse have wavelengths between 1500 nm and 1600 nm.
9. 10. The delivery system of claim 1, wherein all or part of the first optical fiber path is polarization-maintaining.
10. The transmission system of claim 1, a second pulse provider, the second pulse provider including a second optical fiber path, a second pulse amplifier, and a second delivery end; the pulse generator is further configured to generate a second low-power laser pulse having a power predefined to avoid or minimize distortion of the second low-power laser pulse along the second pulse provider; an initial section of the second optical fiber pathway configured to carry the second low-power laser pulses from the pulse generator to the second pulse amplifier; the second pulse amplifier is configured to amplify the second low-power laser pulse to generate a second high-power laser pulse having a predefined power output to operate a second end component connectable to the second delivery end; a final section of the second optical fiber pathway configured to carry the second high-power laser pulse from the second pulse amplifier to the second delivery end; wherein the second pulse amplifier is disposed at a location along the second optical fiber path that corresponds to a distal location relative to the pulse generator or a proximal location relative to the second delivery end.
11. 11. The delivery system of claim 10, wherein the second pulse provider has the same configuration as the first pulse provider.
12. 11. The delivery system of claim 10, wherein the pulse generator comprises a dual output laser system configured to generate both the first low-power laser pulse and the second low-power laser pulse.
13. 11. The delivery system of claim 10, wherein the pulse generator includes a splitter configured to split a single low-power laser pulse generated by the pulse generator into a first version and a second version of the single low-power laser pulse, the first version corresponding to the first low-power laser pulse and the second version corresponding to the second low-power laser pulse, or vice versa.
14. 11. The delivery system of claim 10, further comprising a synchronizer configured to synchronize delivery of the first and second low-power laser pulses with one another.
15. 15. The delivery system of claim 14, wherein the synchronizer is configured to synchronize delivery of the first and second low power laser pulses with one another based on timing delivery of one of the first and second low power laser pulses such that, in use, the first and second high power laser pulses arrive at the first and second delivery ends, respectively, at a predetermined time difference from one another.
16. 15. The delivery system of claim 14, wherein the synchronizer comprises a repetition rate controller configured to control or modulate a repetition rate of the first and second low power laser pulses.
17. 15. The delivery system of claim 14, wherein the synchronizer comprises a mechanical delay line configured to time the delivery of one of the first and second low-power laser pulses.
18. 11. The delivery system of claim 10, wherein the lengths of both the first optical fiber path and the second optical fiber path are adjustable and / or tunable by adding or subtracting substantially the same amount of optical fiber length.
19. 11. The delivery system of claim 10, wherein the first end component is a THz emitter and the second end component is a THz receiver, or vice versa, and the THz emitter and THz receiver are compatible with a THz measurement header connectable to the delivery system.
20. 20. A THz measurement system comprising: a delivery system according to claim 19; and a THz measurement header connected to and connectable to said delivery system.
21. A delivery system according to claim 10; Another delivery system according to claim 10; 1. A provider system for providing high power laser pulses, comprising:
22. 20. A first delivery system according to claim 19; A second delivery system according to claim 19; 1. A delivery system for delivering high power laser pulses, comprising:
23. 23. A THz measurement system including the supply system of claim 22, A THz measurement system, wherein the THz measurement header connectable to the first transmission system is connected to the first transmission system, and the THz measurement header connectable to the second transmission system is connected to the second transmission system.
24. 1. A method of operating a delivery system for delivering one or more high power laser pulses, the delivery system comprising a pulse generator and a first pulse provider, the first pulse provider comprising a first optical fiber path, a first pulse amplifier, and a first delivery end, the method comprising: the first pulse amplifier is disposed at a location along the first optical fiber path corresponding to a distal location relative to the pulse generator or a proximal location relative to the first delivery end; The method comprises: operating the pulse generator to generate a first low-power laser pulse having a power predefined to avoid or minimize distortion of the first low-power laser pulse along the first pulse generator, the first low-power laser pulse being conveyed from the pulse generator to the first pulse amplifier through an initial section of the first optical fiber pathway; and operating the first pulse amplifier to amplify the first low-power laser pulse to generate a first high-power laser pulse having a predefined output power to operate a first end component connectable to the first delivery end, wherein the first high-power laser pulse is transported from the first pulse amplifier to the first delivery end through a final section of the first optical fiber pathway.
25. 25. A computer program product comprising program instructions for causing a computing system to perform the method of claim 24 for operating a delivery system to deliver one or more high-power laser pulses.
26. 26. A computer program according to claim 25 embodied on a storage medium.
27. 26. The computer program of claim 25 carried on a carrier signal.
28. 1. A computing system for operating a delivery system for delivering one or more high power laser pulses, the computing system comprising: a memory; and a processor; the computing system embodying instructions stored in the memory and executable by the processor; 25. A computing system, comprising: a computing device, the instructions including functionality to perform the method of claim 24, wherein the instructions operate a delivery system to deliver one or more high-power laser pulses.