Complementary security system for laser-induced breakdown spectroscopy

Abstract

In the operation of analytical devices and in particular laser-induced breakdown spectroscopy (LIBS) devices, a number of advantages can be obtained by using complementary safety mechanisms, e.g. safety mechanisms that control the operation or firing of a laser. Such complementary safety mechanisms can prevent the laser from operating in a larger number of unsafe situations (even if one or more detected conditions are safe based on the non-activation of their associated safety mechanism) and allow operation in a larger number of safe situations (even if one or more detected conditions are unsafe based on the activation of the associated safety mechanism) than single safety mechanisms acting alone.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 533,354, filed July 17, 2017. The contents of that application are incorporated herein by reference in their entirety. Technical Field

[0003] This invention relates to complementary safety mechanisms for devices incorporating laser-induced breakdown spectroscopy (LIBS) apparatus (such as portable (e.g., handheld) analytical devices). The combination of safety mechanisms provides detection of a variety of safety-related conditions to improve overall performance. Background Technology

[0004] The analytical technique of first forming a sample using a high-energy plasma that, upon cooling, produces a characteristic emission spectrum is well-known. More specifically, during this cooling process, electrons in atoms and ions in excited electronic states within the plasma return to their lower energies, or ground states, resulting in radiative emission at discrete wavelengths corresponding to the energy level changes. Each element in the periodic table is associated with a unique spectral emission line detectable in the visible portion of the electromagnetic spectrum. Therefore, the emitted light from the plasma can be collected and coupled to a spectrometer to resolve the spectral distribution of the emission from elements in the sample. The intensity of each spectrum can be used to determine the concentration of each associated element.

[0005] In laser-induced breakdown spectroscopy (LIBS), a high-temperature plasma is formed after a short-pulse laser beam is focused onto the sample surface. This short-pulse laser beam has sufficient power density to ablate a small portion of the sample, or remove it through both thermal and non-thermal conversion. The sample can theoretically be solid, liquid, or gaseous; however, in the last case, the concept of a "surface" does not exist, and the laser is focused onto a sample containing gas. Regardless of the state of matter, optical emission from the resulting plasma plume is collected using appropriate light-collecting optics, and the spectral distribution of the optical emission (i.e., intensity relative to wavelength) is detected by a spectrometer and converted into electronic form for analysis by a processor. Therefore, the spectral distribution information obtained by the spectrometer can reveal the atomic and molecular composition of the portion of the sample to which the laser beam was directed, each component having its own characteristic optical emission spectrum.

[0006] LIBS provides a simple, reliable, and rapid method particularly suitable for analyzing metal samples by resolving their elemental composition. Concentrations can be accurately determined over a wide range, extending down to the parts per million (ppm) level. For these reasons, LIBS has found wide applicability in metal production industries such as foundries and steel manufacturing, in analyzing wire (e.g., copper-clad steel wire) to ensure compliance with compositional standards, in characterizing scrap metals for classification purposes, and in many other applications.

[0007] A known drawback of LIBS measurement devices is that their bulky structure limits their applicability for field use. Traditionally, LIBS has been limited to laboratory conditions. However, recent efforts have attempted to reduce the form factor of LIBS devices, as evidenced by US 7,394,537 and US 7,821,634. Given these advances toward the commercialization of portable (e.g., handheld) LIBS devices, allowing users in the field direct access to on-site compositional analysis of samples, numerous safety-related concerns have become a reality. The most obvious hazard to users of portable LIB devices or nearby bystanders is accidental exposure to the laser output, and particularly eye exposure. To this end, US 2015 / 0103334 discloses a "eye-safe" handheld LIBS device; however, the specific laser described to achieve this safety feature may significantly affect the device's performance. Furthermore, the designation of "eye-safe" may lead to a lack of additional safety precautions included in the device and / or borne by the user.

[0008] Some safety mechanisms can be used to detect potentially unsafe conditions and temporarily disable the laser in a LIBS device. However, some safety mechanisms are incompatible with certain sample types or test conditions and may not operate satisfactorily, thus unduly preventing the LIBS device from operating when it is actually safe to do so. Therefore, improvements to analytical devices using lasers remain necessary, particularly regarding the safety of such devices operated in the field. Summary of the Invention

[0009] An aspect of the invention relates to the discovery that the combination of safety mechanisms is complementary and significantly reduces the likelihood that the laser in a portable (e.g., handheld) laser-induced breakdown spectroscopy (LIBS) device is excited in an unsafe manner, such as being emitted in a way that endangers the user or bystander, particularly if pointed into their eyes. Ensuring safety is complicated by the variety of sample types that can be used for potential analysis with such devices under various test conditions, where some safety mechanisms may identify a sample type or test condition as unsafe even when a safe operating condition is actually present. For example, sample types can include conductive or non-conductive samples, substantially transparent or opaque samples, and / or samples with pores or voids. The possible variations in sample types (particularly regarding differences in their material state, opacity, conductivity, size, and surface characteristics) make some safety mechanisms not only incompatible but also potentially problematic. In this example, small samples, samples with holes, or samples with circular surfaces may not have the ability to form an hermetically sealed barrier with the sample chamber of the LIBS device to maintain a minimum threshold of chamber pressure. However, they may have the ability to form an opaque barrier with the sample chamber, such that the amount of light in the sample chamber is below a minimum threshold (e.g., indicating that the laser pulse will not escape into an open environment that could potentially cause harm). Therefore, while a second complementary safety system based on the light level in the chamber would allow safe operation of the device, a single safety mechanism that activates to prevent laser emission based on a lower measured chamber pressure will prevent operation of the device because the second complementary safety system will not activate (e.g., activate to prevent operation) when the light level in the chamber is below a threshold. Thus, by utilizing the complementary second safety mechanism, operation of the device can be permitted due to the identification of safety conditions. However, it should be understood that if both the pressure-based safety mechanism and the light-based safety mechanism are activated, operation of the device is prevented.

[0010] In an alternative instance, if a substantially transparent sample is used, which allows laser pulses to be transmitted with sufficient power to cause harm, the same first pressure-based safety mechanism can form an hermetically sealed seal above the permissible threshold, but if a second light-based safety mechanism is activated due to the detection of light (e.g., ambient light transmitted through the transparent sample), the device properly blocks the laser emitted due to unsafe conditions.

[0011] A single safety mechanism may not provide sufficient protection against unsafe laser radiation. For example, a spectral feedback-based safety mechanism can be used to monitor the received spectral distribution and automatically stop laser operation if no sample spectrum is detected. However, when used alone, such a safety mechanism may not provide adequate protection against unwanted laser radiation due to the high speed of laser timing relative to the spectral feedback loop. Therefore, aspects of the present invention relate to the discovery of a safety system with two or more safety mechanisms that address practical considerations associated with portable (e.g., handheld) LIBS devices. These considerations include, in particular, the generally relative commercial needs for: (i) flexibility in handling a wide range of sample types encountered in the analytical field; and (ii) a safety system that does not significantly hinder this objective but also provides a high level of protection to the user and those nearby. Therefore, embodiments of the present invention relate to safety systems and methods (e.g., implemented using software or hardware components) in which two or more safety mechanisms are “complementary,” meaning that they can be combined to act in contrast to these individually acting mechanisms to: (i) increase the chance that the laser will not be improperly locked in a safe situation (when it is safely emitted), as in the particular sample types described herein; (ii) increase the chance that the laser will not be excited in an unsafe situation; or preferably (iii) a combination of both (i) and (ii). According to more specific embodiments, the combined use of complementary safety mechanisms can: (i) allow safe operation of the laser for a given “measurement challenge” (e.g., sample type), even if one or more of the safety mechanisms are activated (e.g., based on the detection of potentially unsafe conditions) and / or (ii) prevent unsafe operation of the laser if a particular subset of the safety mechanisms is activated, regardless of whether any of the remaining one or more safety mechanisms are activated.

[0012] According to one aspect, this disclosure relates to the use of two or more safety mechanisms (sometimes referred to as “interlocking features”) in an apparatus as described herein. Such safety interlocking features may include pneumatic interlocking features, optical interlocking features, inductive sensing features, mechanical proximity sensing features, optical proximity sensing features, or spectral feedback sensing features, as known in the art or as described herein. The selection or use of any particular safety interlocking feature may be determined by the apparatus (such as a LIBS instrument) and / or the material to be analyzed (such as a gas, liquid, or solid). Each interlocking feature may be defeated in different ways due to incompatibility with certain sample types. According to this disclosure, the combined use of safety interlocking features (some of which may be defeated in specific ways) provides a high level of certainty that the apparatus will operate in a manner that will not cause harm to an individual. According to one aspect, the apparatus is programmed to select one or more suitable available safety mechanisms within the apparatus. According to one aspect, the apparatus is programmed to select two or more suitable available safety mechanisms within the apparatus. According to this aspect, redundancy or backup or multiple uses of the safety mechanisms improve the safety of the operator or other persons in the vicinity of the apparatus.

[0013] Other aspects of the invention relate to the significant advantage of interpreting multiple detected conditions, each of which, in isolation, may be potentially unsafe. While each individual detected condition (depending on its measured value) may potentially activate a particular safety mechanism, a specific combination of detected conditions activating one or more safety mechanisms can be associated with a given measurement challenge (e.g., sample type) that does not pose a safety hazard. Thus, when such a specific combination of conditions is detected, laser operation in a portable LIBS device can be advantageously permitted. Otherwise, a given measurement challenge could actually pose a safety hazard, such that the detection of the associated combination of conditions could prevent laser operation.

[0014] Therefore, a further aspect of the invention relates to implementing two or more complementary safety mechanisms in a LIBS device in such a way that limitations inherent in a first safety mechanism can be partially or completely remedied by a second safety mechanism. These limitations may more specifically relate to a safety mechanism failing to function as desired for a given sample type. In some embodiments, the LIBS device may be configured to receive information associated with a specific measurement challenge, such as sample type, at the device's user interface. The received information may result in one or more safety mechanisms being disabled, while the remaining safety mechanisms are active. In other embodiments, the LIBS may be configured to provide an output (such as at the device's user interface) requesting confirmation of the measurement challenge, and is further configured to receive confirmation (or non-confirmation) of the measurement challenge before allowing laser operation. Thus, such user input for confirmation can act as an electronic overlay of a temporary safety mechanism that prevents laser operation while awaiting this confirmation. In yet another embodiment, the LIBS device may be configured to activate a temporary, mechanical safety mechanism (e.g., a trigger lock), optionally in conjunction with an indication of providing a measurement challenge (e.g., displayed on the user interface). The temporary safety mechanism may be configured to be manually overlaid by the user upon confirmation of the measurement challenge.

[0015] These and other aspects, embodiments, and advantages will become apparent from the following detailed description. Attached Figure Description

[0016] Figure 1 An embodiment of a handheld laser-induced breakdown spectroscopy (LIBS) device is shown.

[0017] Figure 2 The operation of a representative room-based safety mechanism is demonstrated, which detects the light intensity within the sample chamber of the LIBS device.

[0018] Figure 3 The operation of a representative sample position-based safety mechanism is demonstrated, which detects the distance between the sample and the plane of the sample chamber exit.

[0019] Figure 4-7 It demonstrates the possible operating modes of representative security systems.

[0020] The accompanying drawings should be understood as illustrations of embodiments of the invention and / or the principles involved. As will be apparent to those skilled in the art upon which this disclosure is known, other analytical apparatuses, methods, and associated computer program products will have corresponding components, steps, and instructions, partially determined by their specific purpose. Operating modes should be understood to be generally applicable and do not exclude intervention, pre- or post-intervention, sub-steps, user-initiated actions, and / or device outputs. Similar reference numerals denote corresponding parts throughout several views of the drawings. Detailed Implementation

[0021] Complementary security agencies

[0022] As described above, aspects of the present invention relate to the numerous advantages gained in analytical devices, and particularly in laser-induced breakdown spectroscopy (LIBS) devices, through the use of complementary safety mechanisms that control the operation or emission of a laser. These complementary safety mechanisms work synergistically because, compared to individual safety mechanisms acting alone, the combination prevents laser operation in a greater number of unsafe conditions (e.g., even if one or more detected conditions do not activate the associated safety mechanism) and allows operation in a greater number of safe conditions (e.g., even if one or more detected conditions do activate the associated safety mechanism).

[0023] According to a particular embodiment, laser operation of the LIBS device may be blocked when any one of two or more security mechanisms is activated. According to another particular embodiment, laser operation of the LIBS device may be blocked when at least one of two or more security mechanisms is not activated, for example, when a combination of detected conditions (and the corresponding combination of activated security mechanisms) is associated with a given measurement challenge, such as an unpermitted measurement challenge, as described below. According to yet another particular embodiment, the LIBS device may include three or more security mechanisms, and laser operation may be blocked when any two or more security mechanisms are activated. According to yet another particular embodiment, the LIBS device may include three or more security mechanisms, and laser operation may be blocked when a combination of detected conditions is associated with a measurement challenge, such as an unpermitted measurement challenge as described below, which does not activate at least one of the three or more security mechanisms. According to yet another particular embodiment, laser operation may be permitted when at least one of two or more security mechanisms is activated, for example, when a combination of detected conditions is associated with a measurement challenge (e.g., a permissible measurement challenge), as described below. In any of these embodiments, the determination of whether laser operation is permitted or prohibited may be based on conditions detected upon receipt of a user input signal (such as pressing a trigger of the device to initiate analysis) (e.g., within 5 seconds, 2 seconds, or 1 second) (e.g., detected parameters in the sample chamber and / or the detected position of the sample).

[0024] As alternatives and equivalents to "security mechanism", the terms "locking" and "interlocking" may be used. These terms are recognized in the art and are descriptive components having the ability to lock or prevent the operation of a LIBS device (e.g., prevent laser operation) by receiving or detecting a measured condition (e.g., above or below a threshold of the condition) when activated.

[0025] This document describes numerous safety mechanisms, and particularly concerns the types of conditions detected as the basis for activating these mechanisms. As described herein, it is assumed that the detection of unsafe conditions by a safety mechanism (e.g., having values ​​above or below a threshold, depending on the specific case) causes the corresponding safety mechanism to be “activated.” Specific safety mechanisms described below include “room environment-based” safety mechanisms, “sample location-based” safety mechanisms, and “spectral feedback-based” safety mechanisms. These specific safety mechanisms are to be understood as categories of safety mechanisms encompassing a number of possible, specific devices with sensors and other associated components that function by detecting a given condition. It should also be understood that these specifically described safety mechanisms are exemplary and not exhaustive, allowing the invention to be implemented with other safety mechanisms or in other ways using combinations of the safety mechanisms described herein. Furthermore, the use of "two or more" safety mechanisms according to aspects of the invention can be satisfied by two safety mechanisms of the same type (i.e., within the same category), such as a first room environment-based safety mechanism activated when the detected parameter in the sample chamber is a measured pressure below a threshold pressure, and a second room environment-based safety mechanism activated when the detected parameter in the sample chamber is a measured light intensity exceeding a threshold light intensity. In some embodiments, a subset of the safety mechanisms may be disabled in the use of an apparatus combined with measurement challenges that adversely affect said subset.

[0026] Representative Examples

[0027] Embodiments of the present invention relate to a portable (e.g., handheld) laser-induced breakdown spectroscopy (LIBS) device comprising: a laser configured to guide a laser beam through a sample chamber and to an exit configured to engage (e.g., adjacent to) a surface of a sample to be analyzed. Thus, typically, the laser beam is guided onto the surface of the sample. The device may further include a spectrometer for determining the spectral distribution of the sample's emission upon exposure to energy from the laser beam. Advantageously, the device may have two or more safety mechanisms selected from the group consisting of: (i) a room environment-based safety mechanism that receives (e.g., in some cases, can prevent laser operation or emission according to the following) detected parameters in the sample chamber; (ii) a sample location-based safety mechanism that receives the detected location (or detection of non-existence) of the sample (e.g., in some cases, can prevent laser operation or emission according to the following) (i.e., "detected location" includes the detection of a non-existent sample); and (iii) a spectral feedback-based safety mechanism that receives the spectral distribution from the spectrometer (e.g., in some cases, can prevent laser operation or emission according to the following).

[0028] A further embodiment of the invention relates to a portable (e.g., handheld) device for performing laser-induced breakdown spectroscopy (LIBS) on a sample. The device includes two or more complementary safety mechanisms that receive two or more of the following: (i) a detected parameter within the sample chamber; (ii) the detected location of the sample (e.g., relative to the sample chamber, such as the plane of the chamber's outlet or relative to some other part of the device); and (iii) the distribution of the spectrum emitted from the sample. Certain combinations of the received conditions (i), (ii), and (iii) (e.g., subsets of all possible combinations) can be represented in the form of a matrix of multiple such combinations. Advantageously, each of these combinations in the matrix can be associated with a corresponding measurement challenge. Typically, each combination of received conditions (e.g., conditions that activate some safety mechanisms but not others) is uniquely associated with a specific measurement challenge, but this is not a requirement of the invention. It is also possible that certain combinations of received conditions are associated with two or more different measurement challenges (not unique), in which case additional information can be used to resolve the unique measurement challenge. Regardless of whether the association is unique, once the measurement challenge is resolved, laser operation within the device can be blocked or allowed based on the nature of the measurement challenge (e.g., permissible or not permissible) and the specific operating configuration of the device.

[0029] A further embodiment of the invention relates to a non-transitory computer-readable medium having a computer program embodied thereon. The computer program includes instructions for causing a processor to perform the following operations: (a) receiving inputs (e.g., input signals) from two or more complementary safety mechanisms, wherein the inputs indicate two or more of the following: (i) a detected parameter within the sample chamber; (ii) the detected location of the sample; and (iii) the distribution of a spectrum emitted from the sample. The inputs can be received by the non-transitory computer-readable medium from various sensors / transducers used in LIBS devices for detecting conditions as described herein. These transducers include sample chamber pressure transducers, sample chamber light intensity transducers, sample proximity transducers (e.g., sample inductive proximity transducers), spectral distribution transducers, etc., all of which are capable of converting the associated detected condition into a signal (e.g., an electrical signal) indicating the condition (e.g., converting the detected sample chamber pressure into an electrical signal, the detected sample chamber light intensity into an electrical signal, the detected sample proximity into an electrical signal, or the detected spectral distribution (or the absence of such a distribution) into an electrical signal). The instructions may further cause the processor to execute (b), which associates the input with the measurement challenge based on a storage matrix of combinations of (i), (ii) and (iii) associated with the corresponding (e.g., potential or speculative) measurement challenge.

[0030] The instruction may optionally further cause the processor to execute (c) an output that provides the following: (1) the output blocks or allows laser operation, depending on the measurement challenge; or (2) the output, in the form of a temporary safety mechanism requiring further action or input from the user (e.g., user input confirming the measurement challenge), to allow laser operation. Thus, in the case of an output in the form of a temporary safety mechanism, the instruction may further cause the processor to execute (d) an input that receives further input, such as at the user interface, indicating confirmation or non-confirmation of the measurement challenge, and (e) an output that blocks or allows laser operation, depending on the further input. In this way, laser operation may be influenced by user input after assessing the potential association between the detected conditions and the measurement challenge.

[0031] In an alternative embodiment, in step (a) of the step performed by the processor, further input is received at the user interface, indicating that the user has entered a measurement challenge. In this case, the processor performs an alternative step (c) that provides an output to block or allow laser operation, depending on whether the measurement challenge (associated with a combination of detected conditions) is the same as the user-input measurement challenge. For example, if a stored, permissible measurement challenge (e.g., a poor gas seal combined with a good optical seal) is associated with a combination of detected conditions, the output could allow laser operation based on a match between the permissible measurement challenge and the user-input measurement challenge. In this way, laser operation may be influenced by user input before the potential association between the detected conditions and the measurement challenge is evaluated.

[0032] Alternatively, the use of non-transitory computer-readable media may be optional when one or more security mechanisms within a security apparatus are operating without the use of a computer program. For example, a light intensity transducer may be able to directly prevent laser emission without the use of a computer program. In this example, the activation of the light intensity transducer may always be associated with an unacceptable measurement challenge, and therefore, there is no need to computationally compare the activation information with a matrix. Typically, this direct coupling between the security mechanism and the laser results in significantly faster response times to prevent emission while performing computations and sending instructions from the processor.

[0033] Figure 1 A handheld LIBS device 100 with a handle 12 and a user interface 14 is shown, through which information about the analysis can be input from the user and the user can receive information. Such information includes input and reception of detected conditions, safe or unsafe situations (e.g., based on combinations of detected conditions), and / or measurement challenges as described herein. As shown, for ease of use, the user interface 14 can be pivoted from the upper plane of the device. Operation of the device 100 (including operation of the laser 16) can be at least partially initiated or dependent on mechanical actions by the user, such as pressing a trigger 18. That is, pressing the trigger 18 can provide a user input signal received by the device to initiate the analysis. This mechanical action, or another mechanical action, can further provide one or more signals to complementary safety mechanisms 15a-d and associated sensors 17a-d to detect one or more conditions within the sample chamber 20 or elsewhere within or around the device 100. Based on the detected conditions and optional further input from the user, the press trigger 18 (or possibly a second press if the user requests and provides further input after the first press trigger) can operate or activate the laser 16 before or after evaluating the conditions determined by the sensors 17a-d.

[0034] Some embodiments of the LIBS device 100 may also include one or more elements for adjusting the output of the laser 16 (not shown), such as elements for randomizing the wavefront phase of the laser beam to eliminate "hot spots" of higher laser power at the beam point. For example, a transmission optical element divided into randomly distributed regions of varying optical thickness (e.g., half the laser wavelength) is often referred to as a random phase plate that can effectively disperse hot spots.

[0035] like Figure 2 As shown, laser 16 is configured to guide laser beam 19 through window 23 into sample chamber 20, which is at least partially defined by the wall of seal 25 (e.g., sample chamber 20 may also include additional space defined by the wall in the nose of device 100 between seal 25 and window 23). Beam 19 then interacts with sample 50 at sample plane 30. In the described embodiment, seal 25 may comprise a flexible tubular structure configured to engage with surface 32 of sample 50 and create an hermetically and light-tight seal. For example, seal 25 may comprise a "skirt-like" structure made of an elastic material substantially conforming to the characteristics of surface 32, which forms an hermetically and light-tight seal under a small degree of pressure.

[0036] Furthermore, in some embodiments, the apparatus 100 may include an optical fiber 35 that transmits light emitted by the plasma generated by the sample 50 when subjected to the laser beam 19. Specifically, the optical fiber 35 is coupled to a spectrometer 40 that detects the emitted spectral signal, which is transmitted to a non-transitory computer-readable medium to resolve elements and / or compounds present in the sample 50. Regarding the LIBS apparatus, certain desired testing conditions (e.g., for detecting light elements such as carbon) require the sample chamber 20 to have an inert atmosphere for accurate spectral detection, which may be maintained at an argon pressure slightly above ambient pressure. An argon supply 45 may be used to supply this argon pressure to the sample chamber 20.

[0037] Although device 100 is shown with four safety mechanisms 15a-d and four associated sensors 17a-d for determining various conditions inside and / or outside the chamber 20 (and possibly outside device 100), other representative devices may typically have two to ten safety mechanisms, typically two to eight, and typically three to six. As described herein, these safety mechanisms 15 are preferably combinations of two or more of the following: chamber environment-based safety mechanisms 15a, 15b; sample location-based safety mechanism 15c; and spectral feedback-based safety mechanism 15d. A fault indicator 21 (such as a warning light) may be used to indicate that at least one of the safety mechanisms 15 has been activated. One or more fault indicators may also be specific, i.e., fault indicator 21a may indicate the activation of a specific safety mechanism, such as safety mechanism 15a. Figure 1 In the specific device shown, four fault indicators 21a-21d are dedicated to safety mechanisms 15a-d and can be marked to warn the user of specific unsafe conditions or potential unsafe conditions that have been detected. Alternatively, such general and / or specific information relating to the activation of one or more safety mechanisms can be received by displaying appropriate information on the user interface 14.

[0038] Safety mechanisms based on indoor environment

[0039] The chamber environment-based safety mechanism can be activated based on parameters measured within the sample chamber 20 of the device, or to indicate the detection of unsafe conditions. Representative parameters are chamber pressure and light intensity. Regarding pressure, some LIBS applications typically require the sample chamber 20 to be maintained in an inert atmosphere, such as with argon. When the measured pressure is below a threshold pressure, a chamber pressure interlock configured to measure the degree of positive pressure (e.g., overpressure) within the chamber 20 can be activated. Alternatively, when the measured pressure is above the threshold pressure, a chamber pressure interlock configured to measure the degree of negative pressure (e.g., vacuum) within the chamber 20 can be activated. Threshold pressures can be absolute pressures (e.g., set at + / -15 psia, + / -15.5 psia, + / -16 psia, + / -16.5 psia, etc.), but preferably, the threshold pressure is relative to ambient pressure and is therefore expressed as "gauge pressure" (above or below ambient pressure) (e.g., set at + / -0.1 psig, + / -0.25 psig, + / -0.5 psig, + / -1 psig, etc.), where "psig" is used to specify pressure in pounds per square inch (gauge pressure). For example, by using relative threshold pressures, variations in altitude and other factors affecting ambient pressure, as well as desired conditions of "positive" pressure present in the sample chamber, such as slight overpressure from an inert gas (e.g., argon), can be automatically taken into account. In some cases, the threshold pressure differential can be user-controlled or individually input if a given level of overpressure (relative to ambient pressure) is desired.

[0040] According to some embodiments, a chamber pressure interlock can be activated when the measured pressure is below a low threshold pressure or above a high threshold pressure. The measured pressure (e.g., in the range of 0 to 5 psig) can be converted into a proportional voltage by a pressure sensor / transducer, which is input to programming instructions for the device's processor (CPU).

[0041] On the other hand, room light interlocking can be activated in response to a measured light intensity in the room exceeding a threshold light intensity (e.g., at an optical wavelength and / or possibly other wavelengths). Similar to room pressure interlocking, the threshold condition can be an absolute condition or otherwise relative to ambient (surrounding) conditions. Figure 2A specific chamber-light interlock is illustrated, wherein an external light source 202 (i.e., located outside the sample chamber 20) provides at least a portion of the measured light intensity, which can be more specifically measured by a camera 17b, acting as a sensor for determining the chamber-light interlock parameter. The camera can be a miniature camera that can be used to capture images of the sample 50. According to this embodiment, the camera 17b can detect excessive “leakage” of light from the external light source 202, which causes the measured light intensity to exceed a threshold intensity and activates the chamber-light interlock. Specifically, the camera 17b can measure light entering the sample chamber 20 through a seal 25 positioned peripherally relative to the window 23. Again, the seal 25 is configured to provide a seal with respect to the surface 32 of the sample 50 such that the sample chamber 20 is substantially opaque when positioned sufficiently close to the sample plane 30. For example, the camera 17b measures the light intensity in the sample chamber 20 (e.g., light passing through the window 27 from the sample chamber 20), and a non-transitory computer-readable medium calculates differential light intensity based on measurements from at least two time points. In one embodiment, the difference between an on state at a first time point and an off state at a second time point can be repeated (e.g., flickering) of light source 202. However, it should be understood that since only a measurable difference in light intensity needs to be calculated, it may not be necessary to use an off state. Furthermore, the light may originate from a source other than light source 202. In the described example, timely modulation of the light intensity from light source 202 using a known pattern substantially improves the ability to distinguish signals and identify differential light intensity. In this case, activation of room light interlock may occur when the measured differential light intensity exceeds an allowable threshold for differential light intensity.

[0042] In an alternative embodiment, the chamber light interlock can utilize a light source 206 equipped with a camera 17b (e.g., as a miniature flash for capturing an image of surface 32) to check for light leakage. For example, the light source 206 communicates optically with the sample chamber 20 (e.g., through a window, not shown), and a simple implementation of the chamber light interlock can involve calculating the average intensity of pixels obtained from the camera image to provide a value for the measured light intensity inside the chamber (e.g., the image itself may be unrelated to the interlock function). In the case of measured differential light intensity, the camera flash can be gated, for example, at known intervals. By comparing the resulting bright and dark images, it can be determined whether an opaque seal exists on surface 32 of sample 50, based on the chamber being “bright” when the flash is on and “dark” when the flash is off. In other words, if sample 50 is not present, light will not be reflected back from surface 32 to camera 17b, and the image will appear darker. In this way, using differential intensity as the detected parameter makes the interlock substantially insensitive or completely insensitive to the intensity of ambient light. According to more complex implementation schemes, other types of image analysis, such as sample texture analysis, can be performed using camera 17b to verify the presence of sample 50 in the optical path of beam 19 passing through window 23.

[0043] It should be understood that light sources 202 and 206 may include any suitable light source known in the relevant art, such as an LED light source. Furthermore, light sources 202 and 206 may each include one or more lights organized in any arrangement (e.g., light source 202 may include multiple lights arranged in a ring around the outer diameter of the seal 25).

[0044] The pressure sensor 17a for chamber pressure interlocking can also be present in the sample chamber 20 to provide a specific device with a complementary safety mechanism as described herein. In this case, the combination of external light source 202 or internal light source 206 with camera 17b can provide chamber light interlocking 15b to complement chamber pressure interlocking 15a. Figure 1 For example, a transparent glass sample placed against the seal 25 in the optical path of the beam 19 passing through window 23 may not activate the chamber light interlock 15b (e.g., due to the transparency of the glass), but may still activate the chamber pressure interlock 15a. Therefore, one or both of these safety mechanisms 15a, 15b can be used to advantageously prevent unwanted laser emission. Other safety interlocks can also be used to address certain limitations of chamber environment-based safety mechanisms. Such limitations may arise if chamber sealing and / or pressurization are not possible, such as in cases of insufficient sample size, surface irregularities, and / or porosity.

[0045] Safety mechanism based on sample location

[0046] The sample location-based safety mechanism can be activated based on a detected condition (i.e., the location of sample 50 exceeds a threshold distance), providing an indication that the sample is too far from sample chamber 20 or is not present at all. The threshold distance can be the distance from a portion of sample chamber 20 (e.g., sample plane 30) to sample chamber 50, or it can be the distance from another portion of device 100 to said sample chamber. The sample location-based safety mechanism or sample proximity interlock can be mechanical or optical and can be activated when the presence of sample material at a relevant location of the associated sensor is not detected, where this location is typically offset from window 23 (laser output aperture). The sample proximity interlock can include a proximity sensor based on the detection of a number of possible phenomena associated with the presence of a sample. In one embodiment, the sensor can specifically be an inductive proximity sensor. In this type of sensor, a time-varying current is established in a coil via an oscillating circuit. The amplitude of the oscillation depends on: 1) a drive circuit that can be fixed; 2) the design of the coil that can be fixed; and 3) the physical environment around or near the coil, which can vary depending on the presence or absence of magnetic or conductive materials. For example, when a conductive metal is placed near the coil, the emitted electromagnetic field induces a current in the metal. The generation of these currents depletes the energy of the oscillating circuit driving the coil, and the amplitude of the oscillation decreases. Inductive proximity sensors monitor the amplitude of these oscillations, and when a change is detected, the sensor circuitry indicates the presence of a conductive sample. Electrically driven sensing circuits are sometimes referred to as eddy current damped oscillators (ECKO).

[0047] The proximity indication signal of an inductive proximity sensor can be discrete or continuous (increasing as the distance between the metal sample and the coil decreases). Discrete inductive sensors typically have a fixed electrical threshold and are physically adjusted with respect to the metal to produce an indication when the metal reaches a fixed distance. Discrete inductive sensors can have a fixed threshold or a programmable threshold, for example, established via a digital-to-analog converter (DAC). Continuous inductive sensors can be integrated using an analog-to-digital converter (ADC).

[0048] As an alternative to inductive proximity sensors, another type of sensor that can be used for sample proximity interlocking is a mechanical proximity sensor (or mechanical proximity switch), in which electrical contact is made or broken by movement of a switching assembly in response to the position of the sample. Mechanical proximity sensors may include limit switches. Another type of sensor is a magnetic proximity sensor (or magnetic proximity switch), in which electrical contact is made or broken based on the presence of a magnetic field in response to the position of the sample. This sensor can be mechanical (reed switch) or solid-state (Hall sensor). Yet another type of sensor is a capacitive proximity sensor (or switch) that monitors the signal amplitude of a circuit incorporating an inductive capacitor. When a material with a dielectric constant different from air approaches the inductive capacitor, the amplitude of the driving signal changes. Yet another type of sensor is a photoelectric proximity sensor (or photoelectric proximity switch), in which a beam of electromagnetic radiation is reflected from the sample to detect its position. Yet another type of sensor is an ultrasonic proximity sensor (ultrasonic proximity switch), in which ultrasonic waves are reflected from the sample to detect its position.

[0049] Figure 3 A representative sample position-based security mechanism is illustrated, wherein a sample proximity sensor 17c is positioned to sense whether a distance D from sample 50 to sample plane 30 exceeds a threshold distance for activating the security mechanism. The sample proximity sensor 17c can be any proximity sensor of the types described above. Those skilled in the art, as will understand from this disclosure, will appreciate that the functionality of certain sensor types, and therefore the sample proximity interlock as a whole, may be affected by certain sample materials. For example, inductive proximity sensors require metallic samples (e.g., samples that are substantially conductive), and magnetic proximity sensors require magnetic samples. Photoelectric proximity sensors require samples with sufficient reflectivity. Therefore, such limitations of sample position-based security mechanisms can be compensated for using additional complementary security mechanisms.

[0050] Spectral feedback-based security agency

[0051] A spectral feedback-based safety mechanism can be activated when the spectral distribution determined by the spectrometer indicates an incorrect sample or the absence of a sample. In one embodiment, a spectral interlock can prevent unsafe emission of the laser into the air, resulting in a recorded spectrum resembling a “dark spectrum.” For example, a dark spectrum can be obtained for one or more initial emission of the laser, where the representative emission rate is typically less than 200 milliseconds, typically less than 100 milliseconds, and typically less than 50 milliseconds. Alternatively, a spectral interlock can prevent unsafe emission of the laser at biological tissue, which returns the spectral characteristics of the tissue. In some embodiments, one or more dedicated sensors may be included for tissue detection, which may include, but are not limited to, near-infrared (NIR) sensors capable of detecting proteins or sensors capable of detecting water, such as certain types of optical sensors. In these cases, laser operation may be blocked after these initial emission. As mentioned above, a spectral interlock can be insufficient on its own because at least one laser pulse is required to obtain the raw spectrum for analysis. However, according to some embodiments, this time can be reduced by utilizing the common characteristics of the dark spectrum, such as limiting intensity values ​​to a narrower range and significantly greater featurelessness compared to the normal spectrum. Spectral feedback mechanisms require at least one laser emission to collect the spectrum and may therefore be insufficient as a sole safety mechanism; however, they can provide a valuable secondary safety mechanism in certain types of testing. For example, if a user is testing a thin film (e.g., aluminum foil), all interlocks initially pass through, but after a certain number of laser emissions, the sample is ablated, creating a hole. This hole is small enough not to activate either a camera-based interlock or a pressure interlock, yet the laser passes through and causes harm. In this case, the spectral feedback interlock is triggered after a single exposure to the open air, whereas without interlocks, there could be hundreds or even thousands of exposures.

[0052] Measurement Challenges

[0053] Certain sample types may have characteristics and / or may present certain test conditions that can be associated with a “measurement challenge,” which activates one or more safety mechanisms regardless of whether the test conditions are actually safe or unsafe. For example, an unsafe characteristic of a sample type includes samples that are at least partially transparent (e.g., translucent), allowing sufficient laser power to be transmitted that could be potentially harmful. In this case, a pressure-based, room-environment-based safety mechanism can detect an appropriate level of pressure and allow the device to operate, while a second-light-based, room-environment-based safety mechanism can detect light intensity exceeding a threshold and will be activated to block laser emission.

[0054] In this regard, aspects of the invention relate to handheld devices that can be effectively adapted to such measurement challenges, thereby increasing the scope of use and flexibility of said handheld devices, and importantly, doing so without negatively impacting their safety. A “measurement challenge” may include a “permissible measurement challenge,” which indicates a safe condition in which laser operation should be permitted when one or more safety mechanisms are activated. A measurement challenge may also include a “disallowed measurement challenge,” which indicates an unsafe or at least problematic test condition (e.g., inactivation and improper permission of operation) in which laser operation should not be permitted when one or more safety mechanisms are “beaten” by the measurement challenge. As described above, each safety mechanism is “activated” when it measures one or more parameters indicating an unsafe test condition (e.g., exceeding a certain threshold).

[0055] Furthermore, one or more of the safety mechanisms can also be used for data quality purposes regarding certain measurement challenges. For example, some sample types require an inert atmosphere within the sample chamber for accurate detection, such as those containing light elements (e.g., carbon). Therefore, for applications where the detection of light elements is desired, chamber pressure interlocking is highly advantageous in determining if the sample chamber has overpressure conditions indicating the presence of inert gas (e.g., indicating poor chamber sealing and / or gas supply failure). In this example, for data quality purposes, utilizing chamber pressure interlocking is highly desirable, even if, from a safety perspective, the chamber pressure interlocking might be compromised by the sample type. Therefore, when activated for data quality purposes, chamber pressure interlocking can prevent laser emission, even when other safety mechanisms indicate that the conditions are safe for emission.

[0056] In the embodiments described herein, certain safety mechanisms can be active during each measurement challenge and enable the safety mechanisms to prevent operation of the device whenever they are activated. For example, a chamber light interlock can be continuously operable to prevent laser emission when activated. In the same or alternative instances, a spectral detection interlock can be continuously active and prevent further laser excitation when no sample is detected. In either instance, the safety mechanism may not be covered. For a chamber light interlock, this may be due to the fact that if a condition exists where sufficient light is detected in the sample chamber, the likelihood of the laser beam being released into the environment and causing harm is high. Similarly, with respect to a spectral detection interlock, if no sample is detected, there may be unsafe conditions and / or one or more elements of the device may be problematic, where continuing laser emission is pointless if no data can be collected.

[0057] Advantageously, certain combinations of sample type characteristics and / or test conditions detected by safety agencies can be readily associated with certain measurement challenges. Such combinations can serve as the basis for a device to identify the presence of these associated measurement challenges. For example, if a chamber pressure interlock is satisfied but a chamber light interlock is activated, the device can determine the presence of a substantially transparent sample that forms an hermetically sealed seal with the device but allows light to pass through it.

[0058] In one instance, a measurement challenge involving a substantially transparent or at least semi-transparent sample can represent a safety hazard if the laser beam penetrates the sample with sufficient power to cause harm. As described elsewhere, chamber pressure interlocks may be defeated to improperly permit operation, thus rendering the device reliant on inductive and / or chamber optical interlocks for safety. In this instance, if either the chamber optical interlock or the inductive interlock is activated, the device prevents any laser emission.

[0059] In another example, the measurement challenge involves the sample's electrical conductivity. If the user expects to test a sample that is essentially non-conductive (e.g., nonmetal), an inductive interlock will activate and inappropriately prevent the device from operating. Therefore, for such measurement challenges, the inductive interlock can be switched off or activated, with the signal ignored by the device to support signals from both the chamber optical interlock and the chamber pressure interlock. Again, if either the chamber optical interlock or the chamber pressure interlock is activated, the device will prevent any excitation of the laser.

[0060] In another example, the measurement challenge includes test conditions where the device cannot form an opaque or hermetically tight seal between the sample chamber and the sample. This can include samples with insufficient dimensions, irregular or circular surfaces, and / or holes, making it difficult or impossible to form a seal with the device, potentially leading to pressure loss and / or laser withdrawal. It should be understood that repeated laser emission can ablate material at the focal point of the laser beam and can create holes in thin samples (e.g., foil samples). In such measurement challenges, if neither opto-pressure interlock nor inductive interlock is activated, chamber opto-pressure interlock and inductive interlock can be used for safety, and chamber pressure interlock can be used to ensure data quality. In other words, if the device can form a seal with a conductive sample that satisfies both opto-pressure interlock and inductive interlock, the device can operate safely.

[0061] In a further example, the measurement challenge includes test conditions in which the sample can be moved relative to the test apparatus (e.g., during analysis). In such measurement challenges, one or more chamber optical interlocks can be used for safety, where movement results in a detectable loss of air pressure and / or light entering the sample chamber. Furthermore, a spectral detection interlock can also determine changes in spectral information indicating that the laser beam is emitting at different points (e.g., increased noise due to surface contamination). In this example, this results in the immediate shutdown of laser emission to prevent harm.

[0062] In the final example, the measurement challenge includes test conditions where the sample type includes biological tissue, such as when a user presses the device against a body surface (where chamber pressure and chamber light mechanisms may be overcome), and allows for unsafe operation of the device. From a safety perspective, preventing such operation can be crucial. Again, the device can rely on inductive interlocking to ensure safety, such that if the inductive interlocking is activated, the device can prevent laser emission.

[0063] Any measurement challenge encompassing those specifically described above can be considered a “permissible” measurement challenge, wherein detection of a combination of sample type characteristics and / or test conditions associated with the challenge can cause the device (or instructions such as software controlling device operation) to allow laser operation. Otherwise, detection of a combination of sample type characteristics and / or test conditions associated with a permissible measurement challenge can cause the device to allow laser operation, depending on additional input received from the user before or after condition detection. Detection of a combination of sample type characteristics and / or test conditions associated with a “disallowed” measurement challenge can cause the device to prevent laser operation, optionally in conjunction with providing information about the measurement challenge (e.g., in a user interface or via a fault indicator). Examples of possible measurement challenges related to the representative measurement challenges described above may include: (i) the sample is transparent or at least translucent, for example, regarding laser transmission; (ii) the sample is non-metallic; and (iii) the sample cannot seal the device outlet; (iv) the device moves relative to the sample; (v) there is no gas supply to the sample chamber; and (vi) gas is not required for the test. Based on the associated combination of detected conditions, an unacceptable measurement challenge may be associated with an unsafe situation, or alternatively with other situations where the operation or capability of the device (e.g., in providing reliable analytical results) may be impaired, such as in the case of a loss of inert gas supply according to measurement challenge (v).

[0064] Measurement challenge matrix with safety agency compatibility

[0065] Based on the foregoing description, it is understandable that numerous possible measurement challenges can influence the basis for the activation of a given security mechanism. Again, combinations of such measurement challenges can be associated with different measurement challenges, both permissible and disallowed. Therefore, in certain situations, combinations of security mechanisms or interlocks activated by associated measurement challenges can be used to identify the presence of such measurement challenges.

[0066] In the described embodiments, some safety mechanisms are incompatible with measurement challenges of samples comprising conductive or non-conductive samples, transparent or opaque samples, biological tissue, and / or samples with shapes or forms that prevent the formation of effective seals such as circular surfaces, holes, or voids. For a particular measurement challenge, each safety mechanism may be “incompatible” (I) with the measurement challenge (e.g., improperly allowing operation under unsafe conditions or preventing operation in the presence of safety test conditions); or “compatible” (C) with the measurement challenge (e.g., properly preventing operation under unsafe conditions or allowing operation in the presence of safety test conditions).

[0067]

[0068] As is evident from this table, the measurement challenges involved in the operation of various safety mechanisms can be simply characterized in binary terms, such as based on whether a given measurement challenge is compatible with the safety mechanism described herein (e.g., providing a "C" input) or incompatible with said safety mechanism (e.g., providing an "I" input). In other embodiments, the measurement challenge can be characterized in quantitative terms, such as based on the conditions actually measured (e.g., sample chamber pressure).

[0069] Operation of representative security systems

[0070] A representative security system comprising two or more complementary security mechanisms as described above can advantageously utilize information related to the detected test conditions that activate individual security mechanisms, for example in matrix form as described above, which correlates combinations of such detected conditions with corresponding measurement challenges. Figure 4 The document illustrates a simple way to utilize this information. According to this embodiment, the LIBS device receives user input (e.g., at the user interface) related to measurement challenges such as transparent samples. Given this input, the device then disables or ignores signals from certain safety mechanisms based on information stored in the device. More specifically, given the user input, a subset of those safety mechanisms, such as chamber pressure interlocks and conductive sample interlocks, are incompatible. Other interlocks (i.e., the remaining subset of safety mechanisms) can then remain enabled and effectively perform their designated safety functions.

[0071] according to Figure 5In one embodiment, the LIBS device receives inputs from two or more complementary safety mechanisms (e.g., #1, #2, #3, #4) and associates these inputs (each indicating a corresponding detected test condition as described above) with a stored matrix of combinations of these test conditions. Laser operation can be permitted if no safety mechanism is activated. Laser operation can also be permitted if the combination of detected conditions (the combination of safety mechanisms that activate the detection of these test conditions) is associated with a permissible measurement challenge. Conversely, laser operation can be prevented if at least one safety mechanism is activated, and the combination of activated safety mechanisms is not associated with any permissible measurement challenge. Figure 6 Implementation examples and Figure 5 Compared to the previous implementation, the specificity and robustness of the safety system can be further improved by adding one or more user inputs of measurement challenges (“one or more input measurement challenges”) as further received inputs. Such inputs may, for example, require the user to select from an options menu displayed on the user interface (e.g., “transparent” or “non-metallic”). This input can also be used... Figure 4 In some embodiments, this serves as the basis for disabling or ignoring signals from a subset of security agencies. Figure 6 In the case of the embodiments described, laser operation may be permitted if (i) no safety mechanism is activated; or (ii) a combination of compatible safety mechanisms is associated with one or more input measurement challenges that permit operation. On the other hand, if at least one safety mechanism is activated, and the combination of activated compatible safety mechanisms is not associated with a permitted operation for an input measurement challenge, laser operation will be prevented.

[0072] Figure 7 This provides yet another alternative operation for the security system, in which, with Figure 6 Compared to the previous implementation, user input can be provided at a later time in the process, that is, in response to a request related to a potential, permissible measurement challenge being identified. Specifically, as in Figure 5 and 6In one embodiment, the device receives input from a safety mechanism. Laser operation can be permitted if no safety mechanism is activated, but laser operation can be prevented if at least one safety mechanism is activated and the combination of activated safety mechanisms is not associated with a permissible measurement challenge. On the other hand, if the combination of activated safety mechanisms is associated with a permissible measurement challenge, a temporary safety mechanism can be activated and potentially overridden based on user input. According to one embodiment, the device can provide an output of a potential, permissible measurement challenge (e.g., displayed on a user interface) and request user confirmation (e.g., accessed on the user interface) of the measurement challenge to overridden the temporary safety mechanism. For example, the user interface might display “Gas required?” and allow the user to select “Confirm” to manually overridden the temporary safety mechanism, thereby allowing laser operation. According to some embodiments, the temporary safety mechanism can be overridden by other user actions, such as unlocking a trigger security that has been locked upon detecting a permissible measurement challenge. Requests related to such actions can be output, for example, in a message displayed on the user interface, such as “Trigger locked, confirm required gas and emission safety line before unlocking.” In the absence of further user input confirming the measurement challenge, the temporary safety mechanism may prevent laser operation.

[0073] In summary, aspects of the present invention relate to security systems and methods (e.g., implemented using software and / or hardware components) wherein two or more security mechanisms are complementary, thereby increasing the chance of avoiding unsafe operation and / or increasing the chance of avoiding lock-up when safe operation is possible compared to these individually acting mechanisms. Those skilled in the art will recognize from the knowledge gained from this disclosure that various changes can be made to the disclosed apparatus and associated security systems and operating modes to obtain these and other advantages without departing from the scope of the invention. Thus, it should be understood that the features described herein are readily modified, altered, changed, or replaced. The specific embodiments shown and described herein are merely illustrative and are not intended to limit the invention as set forth in the appended claims.

Claims

1. A laser-induced breakdown spectroscopy (LIBS) apparatus comprising: a laser configured to direct a laser beam through a sample chamber to a surface of a sample, and a spectrometer configured to determine a distribution of a spectrum emitted from the sample in response to the laser beam; a user interface comprising a menu of options including a plurality of measurement challenges associated with LIBS analysis techniques, wherein the user interface is configured to receive user input indicating a measurement challenge selected from the menu; and a processor configured to associate the selected measurement challenge with two or more complementary safety mechanisms and to prevent operation of the laser when at least one of the two or more complementary safety mechanisms is activated and to permit operation of the laser for a given measurement challenge that activates at least one of the two or more safety mechanisms; wherein the two or more complementary safety mechanisms are selected from the group consisting of: a chamber pressure-based safety mechanism, a chamber light-based safety mechanism, a conductive sample-based safety mechanism, and a spectral feedback-based safety mechanism.

2. The apparatus of claim 1, wherein, including a chamber pressure-based safety mechanism, wherein the chamber pressure-based safety mechanism is activated when a detected parameter within the sample chamber is a measured pressure that is below a threshold pressure.

3. The apparatus of claim 2, wherein the threshold pressure is relative to an ambient pressure.

4. The apparatus of claim 1, wherein, including a chamber light-based safety mechanism, wherein the chamber light-based safety mechanism is activated when a detected parameter within the sample chamber is a measured light intensity that exceeds a threshold light intensity.

5. The apparatus of claim 4, wherein an external light source external to the sample chamber provides at least a portion of the measured light intensity.

6. The apparatus of claim 4, wherein the measured light intensity is a differential light intensity between an on state and an off state of a light source configured to provide light within the sample chamber, the differential light intensity being below a threshold differential light intensity.

7. The apparatus of claim 1, wherein the two or more complementary safety mechanisms include the chamber pressure-based safety mechanism activated when a detected parameter within the sample chamber is a measured pressure that is below a threshold pressure and the chamber light-based safety mechanism activated when the detected parameter within the sample chamber is a measured light intensity that exceeds a threshold light intensity.

8. The apparatus of claim 1, wherein the conductive sample-based safety mechanism comprises an inductive proximity sensor.

9. The apparatus of claim 1, wherein the conductive sample-based safety mechanism is activated when the sample is non-metallic.

10. The apparatus of claim 1, wherein the spectral feedback-based safety mechanism is activated when the spectral distribution indicates an incorrect sample.

11. The apparatus of claim 1, wherein operation of the laser is prevented when any one of the two or more safety mechanisms is activated.

12. The apparatus of claim 1, further comprising one or more fault indicators indicating activation of at least one of the two or more safety mechanisms.

13. The apparatus of claim 12, wherein the one or more fault indicators indicate the activation of a particular one of the two or more safety mechanisms.

14. The apparatus of claim 1, wherein (i) the chamber light-based safety mechanism or the chamber pressure-based safety mechanism is activated based on a detected parameter within the sample chamber, or (ii) the electrically conductive sample-based safety mechanism is activated based on a detected electrical conductivity property of the sample, and wherein the detected parameter in (i) or the detected electrical conductivity property in (ii) occurs simultaneously, respectively, upon receipt of a user input signal to initiate analysis.

15. An apparatus for performing laser-induced breakdown spectroscopy (LIBS) on a sample, the apparatus comprising two or more complementary safety mechanisms that receive two or more of: (i) a detected parameter within a sample chamber; (ii) a detected electrical conductivity property of the sample; and (iii) a distribution of spectra emitted from the sample, wherein the apparatus is configured to associate a combination of (i), (ii), and (iii) with a measurement challenge that prevents or allows operation of a laser within the apparatus, wherein the apparatus comprises a user interface comprising a menu of options including a plurality of measurement challenges associated with LIBS analysis techniques, wherein the user interface is configured to receive a user input indicating a measurement challenge selected from the menu.

16. The apparatus of claim 15, wherein the measurement challenge is selected from the group consisting of: (i) the sample is substantially transparent or translucent; (ii) the sample is non-metallic; (iii) the sample is not sealable with the apparatus; (iv) the apparatus moves relative to the sample; (v) there is no gas supply to the sample chamber; (vi) the sample is biological tissue; and (vii) combinations thereof.

17. A non-transitory computer readable medium having a computer program presented thereon, the computer program containing instructions for causing a processor to perform the steps of: (a) receiving, from a user interface, one of a plurality of measurement challenges associated with LIBS analysis techniques, wherein, the user interface is configured to receive a user input indicating a measurement challenge selected from a menu (b) receiving input from two or more complementary safety mechanisms associated with a laser-induced breakdown spectroscopy (LIBS) apparatus of any of claims 1-16, the input indicating two or more of: (i) a detected parameter within a sample chamber, (ii) a detected electrical conductivity property of a sample, and (iii) a distribution of spectra emitted from the sample; (c) associating the input with a measurement challenge based on a stored matrix of combinations of (i), (ii), and (iii) associated with respective measurement challenges; (d) providing an output that prevents or allows operation of the laser in accordance with the measurement challenge.

18. The non-transitory computer readable medium of claim 17, wherein the laser is within a laser-induced breakdown spectroscopy (LIBS) device.

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