WO2022203971A2

WO2022203971A2 - Method and apparatus for in-situ detection of damage occurring to an optical fiber or an optical mirror

Info

Publication number: WO2022203971A2
Application number: PCT/US2022/021036
Authority: WO
Inventors: Roger S. WEIKEL; Adam HINERMAN; Erich ZELMER; Keith Glover; Avery CALHOUN; Jeffrey A. JEWELL; Mark BLOOMBERG; Daniel MERRIFIELD; Michael SNETHEN; Tim GORMAN
Original assignee: Lsp Technologies, Inc.
Priority date: 2021-03-23
Filing date: 2022-03-18
Publication date: 2022-09-29
Also published as: WO2022203971A3

Abstract

A detector is provided for in-situ detection of damage to an optical fiber, the detector comprising: a laser light detection circuitry disposed at a terminal end of an optical fiber, the fiber coupled to an operating laser pulse generation system, to perform in-situ detection of damage occurring to the fiber, wherein the circuitry is calibrated to detect an energy level of a portion of optical signals sampled from generated laser pulses propagated in the fiber, wherein the circuitry converts the energy of the detected optical signals into electrical signals for processing to monitor a level of the optical signals to indicate normal operational integrity in the fiber or an occurrence of damage to the fiber according to a change in the energy level of the detected optical signals, and outputs a binary signal to a controller to shut off the system within a defined response time if damage is detected.

Description

METHOD AND APPARATUS FOR IN-SITU DETECTION OF DAMAGE OCCURRING TO AN OPTICAL FIBER OR AN OPTICAL MIRROR

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from U.S. Provisional Patent Application No.

63/164,599, filed on March 23, 2021 and U.S. Provisional Patent Application No. 63/302,119, filed on January 23, 2022, each of which is incorporated by reference herein in its entirety.

BACKGROUND

[0002] Laser shock peening, also known as “laser peening” and “LSP,” is a substitute or complementary process for traditional shot peening that uses cold working to produce a deep (e.g., more than 1 mm) compressive residual stress layer and modify mechanical properties of materials by impacting the material with enough force to create plastic deformation. Laser peening uses amplified high energy laser pulses (e.g., pulse widths of 10-25 ns with repetition rates up to 200Hz) to generate a plasma plume and cause a rapid rise of pressure on the surface of a part.

[0003] A universal controller may be used to control a laser’ s oscillator and gain stages to output the high energy laser pulses, which are propagated through a single optical fiber or a bundle of optical fibers to a beam delivery device or to an applicator. However, the optical fiber may degrade or break over time, either due to normal wear and tear or to acute stretching, twisting, pulling, or impact during laser operations. When the optical fiber degrades or breaks, leaks from uncontained laser pulses pose safety risks to personnel, including eye damage and explosion.

[0004] Thus, there is a need to detect in real time during an operation, any occurrence of breakage or damage to any portion of an entire optical fiber transmission path, including any connections or junctions up to the laser beam delivery device at the output. Upon the detection of breakage or damage, the generation or transmission of the laser pulses will automatically cease within a short response time to prevent injuries and accidents.

SUMMARY

[0005] In one aspect, a detector is provided for in-situ detection of damage occurring to an optical fiber, the detector comprising: a laser light detection circuitry disposed at a terminal end of an optical fiber, the optical fiber coupled to an operating laser pulse generation system, to perform in-situ detection of damage occurring to the optical fiber, wherein the laser light detection circuitry is calibrated to detect an energy level of a portion of optical signals sampled from generated laser pulses propagated in the optical fiber, wherein the laser light detection circuitry converts the energy of the detected optical signals into electrical signals for processing to monitor a level of the optical signals to indicate normal operational integrity in the optical fiber or an occurrence of damage to the optical fiber according to a change in the energy level of the detected optical signals, and outputs a binary signal to a controller to shut off the laser pulse generation system within a defined response time if damage to the optical fiber is detected.

[0006] In another aspect, a method is provided for in-situ detection of damage occurring to an optical fiber, the method comprising: disposing a laser light detection circuitry at a terminal end of an optical fiber, the optical fiber being coupled to an operating laser pulse generation system, where the laser light detection circuitry is configured to perform steps, the steps comprising: (i) detecting in-situ to the optical fiber, an energy level of a portion of optical signals sampled from generated laser pulses propagated in the optical fiber; (ii) converting the energy of the detected optical signals into electrical signals for processing to monitor a level of the optical signals to indicate normal operational integrity in the optical fiber or an occurrence of damage to the optical fiber according to a change in the energy level of the detected optical signals; and (iii) outputting a binary signal to a controller to shut off the laser transmission system within a defined response time if damage to the optical fiber is detected.

[0007] In another aspect, a detector for in-situ detection of damage occurring to an optical mirror is provided, the detector comprising: a housing having a proximal end and a distal end; wherein the proximal end receives a cable for transmitting a signal; wherein the distal end includes a viewing port and at least one of: one or more attenuator and a photodiode; and one or more circuit board comprising circuitry contained within the housing between the proximal end and the distal end, wherein the circuitry is operably connected to the cable.

BRIEF DESCRIPTION OF THE FIGURES

[0008] The accompanying figures, which are incorporated in and constitute a part of the specification, illustrate various example systems and are used merely to illustrate various example aspects. In the figures, like elements bear like reference numerals.

[0009] FIG. 1 illustrates an example location of a beam delivery device at a terminal end of an optical fiber.

[0010] FIG. 2 illustrates a laser beam delivery device with an integrated laser light detection circuitry.

[0011] FIG. 3A depicts a principle of in-situ detection with feedback control.

[0012] FIG. 3B depicts a principle of in-situ detection with feedback control.

[0013] FIG. 4A illustrates an in-situ detection of damage occurring to an optical fiber.

[0014] FIG. 4B illustrates an in-situ detection of damage sending a feedback control signal to the laser pulse generation system.

[0015] FIG. 5 is an example of a schematic of a laser light detection circuitry.

[0016] FIG. 6 is a hardware implementation of a laser light detection circuitry. [0017] FIG. 7 illustrates the components used in a laser light detection circuitry.

[0018] FIG. 8 illustrates optical signal detection and conversion of the optical signals into logic signal output for laser generation feedback control.

[0019] FIG. 9 illustrates a scheme of optical pulse latching in normal operation and damage occurrence.

[0020] FIG. 10 illustrates an output stage outputting a signal level usable in a controller.

[0021] FIG. 11 illustrates hardware or software logic to indicate normal optical fiber operation or damage occurrence detection in the optical fiber.

[0022] FIG. 12 illustrates a scheme of pulse latching and pulse stretching to monitor optical signal energy levels for a determination of optical fiber integrity.

[0023] FIG. 13A illustrates an in-situ detection of damage occurring to a mirror with a reflective coating.

[0024] FIG. 13B illustrates an in-situ detection of damage occurring to a mirror with a reflective coating.

[0025] FIG. 14 illustrates an example laser light detector.

DETAILED DESCRIPTION

[0026] FIG. 1 illustrates an example location of a beam delivery device 102 at a terminal end of an optical fiber, as part of a laser pulse generation system 100. System 100 may include a laser peening system. FIG. 2 illustrates a laser beam delivery device 202 with an integrated laser light detection circuitry 204. Laser light detection circuitry 204 may be configured to be housed within a tubular housing coaxially mounted at the terminal end of the optical fiber. System 100 may effect an in-situ (in place) detection of damage occurring to an optical fiber, including the use of a calibrated detector with laser light detection circuitry 204 disposed at a terminal end of an optical fiber. The optical fiber may be coupled to an operating laser pulse generation system (such as an LSP system) to perform in-situ detection of damage occurring to an optical fiber (i.e., real time detection during operation). In an example, the detector itself may be an accessory attached at the terminal end of the optical fiber (e.g., adjacent to delivery device 102, 202). In another example, the detector may simply be circuitry 204 (i.e., a printed circuit board or an integrated circuit chip package) incorporated within delivery device 102, 202 with field programmable memory to receive calibrations.

[0027] FIGS. 3A and 3B depict example in-situ detection systems 306, 308 with feedback control. An in-situ detection system 306 may include a laser pulse generation system 310 providing a light energy that is sensed by a laser light detector 312. Laser light detector 312 may in turn send electrical energy (e.g., a signal) to a control system 314. An in-situ detection system 308 may replace laser pulse generation system 310 with any light source 316.

[0028] The laser light detection circuitry (e.g., circuitry 204) in laser light detector 312 may detect an energy level of a portion of optical signals sampled from generated laser pulses propagated in the optical fiber of laser pulse generation system 310. The sampled optical signal may be a reflected signal or may be passed through a filter or attenuator output to avoid the detector being damaged from a direct beam. The laser light detection circuitry (e.g., circuitry 204) in laser light detector 312 may convert the energy of the detected optical signals into electrical signals for processing by control system 314. The electrical signals may be used to monitor an energy level of the optical signals to indicate normal operational integrity in the optical fiber or an occurrence of damage to the optical fiber according to a change in the energy level to the detected optical signals. The laser light detection circuitry (e.g., circuitry 204) in laser light detector 312 may output a binary signal (optionally an analog signal) to control system 314 (e.g., a UCC controller) to shut off laser pulse generation system 310 within a defined response time if damage to the optical fiber is detected.

[0029] FIGS. 4A and 4B illustrate in-situ detection systems 406. Systems 406 detect damage occurring to an optical fiber. System 406 includes a laser light generator 410, which generates laser light and passes the laser light through a laser optical fiber 420. Laser optical fiber 420 terminates in a tool 422. Tool 422 may include a beam delivery device 402, which may take the form of a pen. Beam delivery device 402 may include a laser light detector 412.

[0030] Laser light detector 412 includes laser light detection circuitry capable of identifying a break in laser optical fiber 420, as described above. Laser light detector 412 monitors the optical signals sampled from generated laser pulses propagated in laser optical fiber 420, and sends an electrical signal 424 (e.g., an on/off signal) to a control system 414 (FIG. 4A) or a safety PLC 426 (FIG. 4B). Laser light detector 412 may send an “on” electrical signal 424 to control system 414 or safety PLC 426 confirming that laser optical fiber 420 is not broken and that system 406 is safe to operate. Laser light detector 412 may send an “off’ electrical signal 424 to control system 414 or safety PLC 426 confirming that laser optical fiber 420 is broken and that system 406 is not safe to operate. Where system 406 is not safe to operate, control system 414 or safety PLC 426 may prevent system 406 from generating laser light until system 406 has been inspected and/or repaired.

[0031] FIG. 5 is an example of a schematic of a laser light detection circuitry. In one aspect, the photodiode circuit (e.g., InGAS photodiode) converts light energy into an electrical current. This current may enter a “comparator” circuit (e.g., LTC6752HMS8-2#PBF) that outputs a high signal when the photodiode pulse is above a set threshold and a low signal when the photodiode pulse is below the set threshold. The threshold is set by two resistors, R1 and R2. The output may then enter a “pulse stretcher” circuit, which converts the pulse width to a width sufficient for the rest of the circuit to detect the pulse. This pulse, now compared and stretched, may then enter the “latching” circuit (built in with LTC6752HMS8-2#PBF). When the latching circuit “sees” a pulse from the pulse stretcher, the latching circuit output becomes high and stays high until it “sees” a reset pulse. For the reset pulse, a constantly running timer (e.g., ALD555SAL) may send a pulse to the latching circuit at a set frequency (set by resistors and capacitors). The resulting output from the latching circuit may enter an “output driver,” which converts the signal up to 24VDC and/or 3mA, which is typically easily read by PLCs.

[0032] Because the latching circuit output regularly resets to a low value due to the result pulse timer, the system may have a de facto built-in diagnostic as follows: if the latching circuit output is constantly low, a fiber break is indicated; and if the latching circuit output is constantly high, it indicates that there is something wrong with the circuit/setup as normal operations should exhibit the signal periodically becoming low and then high again. The latching circuit output signal being high, periodically becoming low, and then high again, indicates that the system is functioning normally and that the laser optical fiber is not broken.

[0033] The photodiode may operate over a range of optical frequencies. The photodiode may be configured to detect laser pulses operating at a defined range of modulation frequency with a defined duration of response time and a defined range of power level to indicate the normal operational integrity in the optical fiber and the occurrence of damage to one or more junctions in the optical fiber.

[0034] The comparator circuit may comprise a first comparator which outputs a high logic pulsed signal when the converted electrical signals output from the photodiode exceeds a reference threshold, and otherwise, the first comparator outputs a low logic pulsed signal. The comparator circuit may comprise a second comparator which functions as a pulse stretcher by stretching a pulse width of the high logic pulsed signal or the low logic pulsed signal to detectable pulse width by a set reset (“SR”) latching circuit. [0035] For the reset pulse, the constantly running timer may be a timer chip that periodically sends a timing pulse at a set frequency to the SR latching circuit.

[0036] The timed SR latching circuit may be configured to output negative going pulses for negative logic. The reset period may be 40ms. The PNP type higher logic output voltage may be 4.5V to 26 V.

[0037] The SR latching circuit may output a binary logic at a first logic state and remains at the first logic state upon detecting the high logic pulsed signal. The SR latching circuit may change the first logic state to a second logic state to reset the SR latching circuit upon detecting the low logic pulsed signal. The SR latching circuit may reset and output a low logic state when the photodiode fails to detect a light source, the low logic state indicating a loss of laser power in the optical fiber caused by damage occurred to at least a connector junction of the optical fiber.

[0038] The laser light detection circuitry may configured to perform at least two functions, the functions comprising: (1) detecting laser pulses that operate in an optical frequency range of 1050-1065 nanometers (nm) with a pulse width of 20 nanoseconds (ns) at 1 microjoule (uJ); (2) operating at a pulse input frequency of 1-200 Hz; (3) detecting with a response time of no more than 200 ms; and (4) detecting a minimum emitted light energy of 100 millijoules (mJ) and a minimum loss in emitted energy of 40 mJ.

[0039] The laser pulse generation system may comprises laser transmission shutters, which may be optical locks that block a beam path to prevent laser radiation from leaving the system. The laser light detection circuitry may be configured to detect at least two or more of: (1) a photodiode responsivity threshold at lOmV/W +/- 20%; (2) a detection response time between 6-11 milliseconds after the laser turns on; (3) a detection response time between 16- 42 milliseconds after the laser turns off; (4) a longest period between negative-going pulse between 37-294 milliseconds; (5) that laser transmission shutters are shut if the optical power output detected is below 26W; (6) that the laser transmission shutters are shut if the optical power output detected is sporadic between 26W-27W; and (7) that the laser transmission shutters are opened if the optical power output detected is above 28W.

[0040] The controller may be configured to shut off the laser transmission system within 300 milliseconds if damage to the optical fiber is detected.

[0041] FIG. 6 illustrates a hardware implementation of a laser light detection circuitry.

[0042] FIG. 7 illustrates key components used in a laser light detection circuitry, as described in detail above. The components include a photodiode connected to a comparator/pulse stretcher, which in turn is connected to an SR latching circuit, generating an output signal to a safety PLC. Other key components may include a power supply and filtering components.

[0043] FIG. 8 illustrates optical signal detection and conversion of the optical signals

(latching circuit output signal 870, photodiode signal 872, and stretched output signal 876) into an SPLC logic signal output 874 for laser generation feedback control. Also illustrated are varying negative going pulses 878.

[0044] FIG. 9 illustrates a scheme of optical pulse latching in normal operation and damage occurrence. The upper plot illustrates optical pulse latching in normal operation. The lower plot illustrates optical pulse latching in a damage occurrence, such as a optical fiber break scenario. The input may include a photodiode square wave.

[0045] FIG. 10 illustrates an output stage outputting a signal level usable in a controller. The output signal may be converted to 24VDC and/or 3mA for analysis by the PLC.

[0046] FIG. 11 illustrates hardware or software logic to indicate normal optical fiber operation or damage occurrence detection in the optical fiber. The logic may be used for safety PLC integration. The logic detects signals that are at a high value, while debouncing inputs that are at a low value. The result is a reduction in system reaction time by about two times the laser pulse repetition rate.

[0047] FIG. 12 illustrates a scheme of pulse latching and pulse stretching to monitor optical signal energy levels for a determination of optical fiber integrity. The input may be a photodiode signal. The output may be a square waveform. The output may be delayed. The output may have a pulse width of more than 100 ns. The detection threshold may be determined by resistors or voltage input. The output signal may be amplified to the supply voltage.

[0048] FIGS. 13A and 13B illustrate an in-situ detection of damage occurring to a mirror 1334 with a reflective coating.

[0049] A laser light detector 1312 may be a component of a laser beam generation system, wherein the laser beam generation system may include an oscillator configured to generate a laser beam 1332, mirror 1334 having a front and back side with a reflective coating on one of the front side or the back side, a laser beam block 1336, and a control system. The control system may be operably connected to a signal and power cable.

[0050] As illustrated in FIG. 13A, laser light detector 1312 (such as that illustrated in

FIG. 14) is oriented between mirror 1334 and laser beam block 1336. Laser light detector 1312 may have a field of view 1340 focused upon laser beam block 1336. Laser beam 1332 directed to mirror 1334 is expected to reflect (as illustrated, for example, 90 degrees). However, where mirror 1334’ s reflective coating has been damaged or otherwise fails, some or all of laser beam 1332 may pass through mirror 1334 and intersect laser beam block 1336. Any laser light passing through mirror 1334 due to damage to mirror 1334, illustrated as mirror leakage 1338, may be sensed by laser light detector 1312 upon a surface of laser beam block

1336 [0051] As illustrated in FIG. 13B, laser light detector 1312 (such as that illustrated in

FIG. 14) is oriented between mirror 1334 and laser beam block 1336. Laser light detector 1312 may have field of view 1340 focused upon a back side of mirror 1334, opposite the front side of the mirror that is initially contacted by laser beam 1332. Where mirror 1334’ s reflective coating has been damaged or otherwise fails, some or all of laser beam 1332 may pass through mirror 1334. Any laser light passing through mirror 1334 due to damage to mirror 1334, illustrated as mirror leakage 1338, may be sensed by laser light detector 1312 upon the back side of mirror 1334.

[0052] Where mirror 1334’ s reflective coating is intact, then transmitted loss of laser beam 1332 passing through mirror 1334 (illustrated as mirror leakage 1338) is so low that laser light detector 1312 may not detect the transmitted loss (mirror leakage 1338); almost ah of laser beam 1332 is reflected. When the reflective coating becomes degraded, the transmitted loss (mirror leakage 1338) increases to a level where the transmitted loss (mirror leakage 1338) can be detected by laser light detector 1312. Laser light detector 1312 is connected to a laser beam generation system’s control system, and generates a signal when the transmitted loss is detected. This generated signal may be used to interrupt the output of the laser and/or alert operators of the laser beam generation system to the damage, failure, and/or degrading of mirror 1334’ s reflective coating.

[0053] FIG. 14 illustrates an example laser light detector 1412. Laser light detector

1412 may be used to detect damage to a mirror (e.g., mirror 1334) with a reflective coating. Laser light detector 1412 may include a housing 1450 having a proximal end 1460 and a distal end 1462. Proximal end 1460 may receive a signal and power cable 1452. Distal end 1462 may include a viewing port 1454, one or more attenuator 1458, and/or a photodiode 1456. One or more circuit board 1404 may be oriented within housing 1450 between proximal end 1460 and distal end 1462. [0054] When laser light detector 1412 is used to detect damage to a mirror (e.g., mirror

1334) with a reflective coating, viewing port 1454’ s orientation establishes the field of view 1340 of laser light detector 1312 described above in reference to FIGS. 13A and 13B. That is, the size, direction, orientation, angle, and the like of viewing port 1454 on housing 1450 establishes what laser light detector 1412 is able to observe through viewing port 1454.

[0055] One or more circuit board 1404 may comprise circuitry. The circuitry may be operably connected to signal and power cable 1452. Signal and power cable 1452 may provide electrical energy to laser light detector 1412 and signals to and from circuit board 1404. The signals to circuit board 1404’ s circuitry may cause the operation of laser light detector 1412, including the detection of the transmitted loss (e.g., mirror leakage 1338) of the laser beam (e.g., laser beam 1332) through a mirror (e.g., mirror 1334). When laser light detector 1412 is used to detect damage to a mirror (e.g., mirror 1334) with a reflective coating, the signals from circuit board 1404’ s circuitry, upon detection of transmitted loss (e.g., mirror leakage 1338) of the laser beam (e.g., laser beam 1332), may be used to interrupt the output of the laser and/or alert operators of the laser beam generation system to the damage, failure, and/or degrading of the mirror’s reflective coating. Circuit board 1404’ s circuitry may be configured to convert the energy of the observed laser beam (e.g., mirror leakage 1338) to indicate a failure of the mirror’s (e.g., mirror 1334) reflective coating and output a binary signal to the controller to shut off the laser beam generation system within a defined response time. Signal and power cable 1452 may be operably connected to a control system of a laser beam generation system.

[0056] To the extent that the term “includes” or “including” is used in the specification or the claims, it is intended to be inclusive in a manner similar to the term “comprising” as that term is interpreted when employed as a transitional word in a claim. Furthermore, to the extent that the term “or” is employed (e.g., A or B) it is intended to mean “A or B or both.” When the applicants intend to indicate “only A or B but not both” then the term “only A or B but not both” will be employed. Thus, use of the term “or” herein is the inclusive, and not the exclusive use. See Bryan A. Garner, A Dictionary of Modern Legal Usage 624 (2d. Ed. 1995). Also, to the extent that the terms “in” or “into” are used in the specification or the claims, it is intended to additionally mean “on” or “onto.” To the extent that the term “substantially” is used in the specification or the claims, it is intended to take into consideration the degree of precision available in manufacturing. To the extent that the term “selectively” is used in the specification or the claims, it is intended to refer to a condition of a component wherein a user of the apparatus may activate or deactivate the feature or function of the component as is necessary or desired in use of the apparatus. To the extent that the term “operatively connected” is used in the specification or the claims, it is intended to mean that the identified components are connected in a way to perform a designated function. As used in the specification and the claims, the singular forms “a,” “an,” and “the” include the plural. Finally, where the term “about” is used in conjunction with a number, it is intended to include ± 10 % of the number. In other words, “about 10” may mean from 9 to 11.

[0057] As stated above, while the present application has been illustrated by the description of embodiments and aspects thereof, and while the embodiments and aspects have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art, having the benefit of the present application. Therefore, the application, in its broader aspects, is not limited to the specific details, illustrative examples shown, or any apparatus referred to. Departures may be made from such details, examples, and apparatuses without departing from the spirit or scope of the general inventive concept.

Claims

CLAIMS What is claimed is:

1. A detector for in-situ detection of damage occurring to an optical fiber, the detector comprising: a laser light detection circuitry disposed at a terminal end of an optical fiber, the optical fiber being coupled to an operating laser pulse generation system, to perform in-situ detection of damage occurring to the optical fiber, wherein the laser light detection circuitry is calibrated to detect an energy level of a portion of optical signals sampled from generated laser pulses propagated in the optical fiber, wherein the laser light detection circuitry converts the energy of the detected optical signals into electrical signals for processing to monitor a level of the optical signals to indicate normal operational integrity in the optical fiber or an occurrence of damage to the optical fiber according to a change in the energy level of the detected optical signals, and outputs a binary signal to a controller to shut off the laser pulse generation system within a defined response time if damage to the optical fiber is detected.

2. The detector according to claim 1, wherein the laser light detection circuitry comprises a photodiode that operates over a range of optical frequencies, wherein the photodiode is configured to detect laser pulses operating at a defined range of modulation frequency with a defined duration of response time and a defined range of power level to indicate the normal operational integrity in the optical fiber and the occurrence of damage to one or more junctions in the optical fiber.

3. The detector according to claim 1, comprises: a first comparator which outputs a high logic pulsed signal when the converted electrical signals output from the photodiode exceeds a reference threshold, otherwise, outputs a low logic pulsed signal , a second comparator which functions as a pulse stretcher by stretching a pulse width of the high logic pulsed signal or the low logic pulsed signal to detectable pulse width by a SR latching circuit; a timer chip that periodically sends a timing pulse at a set frequency to the SR latching circuit, wherein the SR latching circuit outputs a binary logic at a first logic state and remains at the first logic state upon detecting the high logic pulsed signal, and changes the first logic state to a second logic state to reset the SR latching circuit upon detecting the low logic pulsed signal.

4. The detector according to claim 3, wherein the SR latching circuit resets and outputs a low logic state when the photodiode fails to detect a light source, wherein the low logic state indicates a loss of laser power in the optical fiber caused by damage occurred to at least a connector junction of the optical fiber.

5. The detector according to claim 3, wherein the timed SR latching circuit is configured to output negative going pulses for negative logic, and the reset period is 40ms, and the PNP type higher logic output voltage is 4.5 V to 26 V.

6. The detector according to claim 2, wherein the laser light detection circuitry is configured to perform at least two functions, the functions comprising: detecting laser pulses that operate in an optical frequency range of 1050-1065 nanometers (nm) with a pulse width of 20 nanoseconds (ns) at 1 microjoule (uJ), operating at a pulse input frequency of 1-200 Hz, detecting with a response time of no more than 200 ms, detecting a minimum emitted light energy of 100 millijoules (mJ) and a minimum loss in emitted energy of 40 mJ.

7. The detector according to claim 1, wherein the laser pulse generation system comprises laser transmission shutters, and wherein the laser light detection circuitry is configured to detect at least two or more of: a photodiode responsivity threshold at lOmV/W +/- 20%, a detection response time between 6-11 milliseconds after the laser turns on; a detection response time between 16-42 milliseconds after the laser turns off; a longest period between negative-going pulse between 37-294 milliseconds, that the laser transmission shutters are shut if the optical power output detected is below 26W, that the laser transmission shutters are shut if the optical power output detected is sporadic between 26W-27W, that the laser transmission shutters are opened if the optical power output detected is above 28 W.

8. The detector according to claim 1, wherein the controller is configured to shut off the laser transmission system within 300 milliseconds if damage to the optical fiber is detected.

9. The detector according to claim 1, wherein the laser light detection circuitry is configured to be housed in a tubular housing coaxially mounted at the terminal end of the optical fiber.

10. The detector according to claim 1, wherein the operating laser pulse generation system comprises a laser peening system.

11. A method for in-situ detection of damage occurring to an optical fiber, the method comprising: disposing a laser light detection circuitry at a terminal end of an optical fiber, the optical fiber being coupled to an operating laser pulse generation system, where the laser light detection circuity is configured to perform steps, the steps comprising:

(i) detecting in-situ to the optical fiber, an energy level of a portion of optical signals sampled from generated laser pulses propagated in the optical fiber;

(ii) converting the energy of the detected optical signals into electrical signals for processing to monitor a level of the optical signals to indicate normal operational integrity in the optical fiber or an occurrence of damage to the optical fiber according to a change in the energy level of the detected optical signals; and

(iii) outputting a binary signal to a controller to shut off the laser transmission system within a defined response time if damage to the optical fiber is detected.

12. The method according to claim 11, wherein the laser light detection circuitry comprises a photodiode that operates over a range of optical frequencies, wherein the photodiode is configured to detect laser pulses operating at a defined range of modulation frequency with a defined duration of response time and a defined range of power level to indicate the normal operational integrity in the optical fiber and the occurrence of damage to one or more junctions in the optical fiber.

13. The method according to claim 11, comprising: outputting by a first comparator, a high logic pulsed signal when the converted electrical signals output from the photodiode exceeds a reference threshold, otherwise, outputs a low logic pulsed signal , stretching by a second comparator which being a pulse stretcher, a pulse width of the high logic pulsed signal or the low logic pulsed signal to detectable pulse width by a SR latching circuit; sending by a timer chip, a periodic timing pulse at a set frequency to the SR latching circuit, outputting by the SR latching circuit, a binary logic at a first logic state remaining at the first logic state upon detecting the high logic pulsed signal, and changing the first logic state to a second logic state to reset the SR latching circuit upon detecting the low logic pulsed signal.

14. The method according to claim 13, wherein the SR latching circuit resets and outputs a low logic state when the photodiode fails to detect a light source, wherein the low logic state indicates a loss of laser power in the optical fiber caused by damage occurred to at least a connector junction of the optical fiber.

15. The method according to claim 13, wherein the timed SR latching circuit is configured to output negative going pulses for negative logic, and the reset period is 40ms, and the PNP type higher logic output voltage is 4.5 V to 26 V.

16. The method according to claim 12, wherein the laser light detection circuitry is configured to perform at least two functions, the functions comprising: detecting laser pulses that operate in an optical frequency range of 1050-1065 nanometers (nm) with a pulse width of 20 nanoseconds (ns) at 1 microjoule (uJ), operating at a pulse modulation frequency of 1-200 Hz, detecting with a response time of no more than 200 ms, detecting a minimum emitted light energy of 100 millijoules (mJ) and a minimum loss in emitted energy of 40 mJ.

17. The method according to claim 11, wherein the laser light detection circuitry is configured to perform at least two functions, the functions comprising: detecting laser pulses that operate in an optical frequency range of 1050-1065 nanometers (nm) with a pulse width of 20 nanoseconds (ns) at 1 microjoule (uJ), operating at a pulse input frequency of 1-200 Hz, detecting with a response time of no more than 200 ms, detecting a minimum emitted light energy of 100 millijoules (mJ) and a minimum loss in emitted energy of 40 mJ.

18. The method according to claim 11, wherein the controller is configured to shut off the laser transmission system within 300 milliseconds if damage to the optical fiber is detected.

19. The method according to claim 11, wherein the laser light detection circuitry is configured to be housed in a tubular housing coaxially mounted at the terminal end of the optical fiber.

20. The method according to claim 11, wherein the operating laser pulse generation system comprises a laser peening system.

21. A detector for in-situ detection of damage occurring to an optical mirror, the detector comprising: a housing having a proximal end and a distal end; wherein the proximal end receives a cable for transmitting a signal; wherein the distal end includes a viewing port and at least one of: one or more attenuator and a photodiode; and one or more circuit board comprising circuitry contained within the housing between the proximal end and the distal end, wherein the circuitry is operably connected to the cable.

22. The detector according to claim 21, wherein the distal end includes a viewing port, one or more attenuator, and a photodiode.

23. The detector according to claim 21, wherein the detector is a component of a laser beam generation system, the laser beam generation system comprising: an oscillator configured to generate a laser beam; a mirror having a front side and a back side, the mirror having a reflective coating on one of the front side or the back side; a laser beam block; and a control system operably connected to the cable.

24. The detector according to claim 23, wherein the detector is oriented between the mirror and the laser beam block, and wherein the viewing port is oriented to observe the laser beam block where the laser beam would intersect the laser beam block upon failure of the mirror’s reflective coating.

25. The detector according to claim 23, wherein the detector is oriented between the mirror and the laser beam block, and wherein the viewing port is oriented to observe the back side of the mirror where the laser beam would pass through the mirror upon failure of the mirror’s reflective coating.

26. The detector according to claims 24 and 25, wherein the circuitry is configured to convert the energy of the observed laser beam to indicate a failure of the mirror’s reflective coating and outputs a binary signal to the controller to shut off the laser beam generation system within a defined response time.