Method and device for determining a force applied to a sample in optical recording technology

Abstract

An optical measurement system for inspecting a sample. The measuring system comprises an internal reflection element, an objective table, an optical assembly, a base and a sensor. The internal reflective element has a contact surface. The objective table is located below the internal reflection element. The stage and the internal reflective element are configured to apply a force to the sample. The optical assembly includes a light source and a light detector. The optical assembly is configured to scan the sample by directing source light from the light source toward the contact surface and detecting source light optically interacting with the contact surface by the light detector. The base is configured to support the optical assembly and the internal reflective element. The sensor is mounted on the base and is configured to detect a force applied to the sample by the internal reflective element and the stage.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims priority and the benefit of U.S. Provisional Application No. 63 / 222,525, filed Jul. 16, 2021, the disclosure of which is incorporated herein by reference in its entirety for any and all purposes. Technical Field

[0003] The present disclosure generally relates to spectroscopy, and more particularly, to optical interrogation systems and methods for determining contact forces on a sample. Background Art

[0004] Attenuated total reflection (ATR) is an optical interrogation technique commonly used in conjunction with infrared spectroscopy (e.g., Fourier transform infrared spectroscopy (FTIR)) that can directly examine samples in solid, liquid, or gaseous states. In particular, ATR utilizes the total internally reflected light generated at the interface of a configured internal reflection element (IRE) and a coupled sample plane. In operation, a light beam (e.g., infrared light) passes through the IRE crystal in such a way that it reflects at least once on the inner surface in contact with the sample. This reflection forms an evanescent wave that extends into the sample, typically up to about 2 micrometers, the exact value of which is determined by the wavelength of the light, the angle of incidence and refractive index of the IRE crystal, and the sample medium being interrogated. Subsequently, the reflected light beam carrying the spectral information of the sample is interrogated using, for example, a single pixel, linear array, or two-dimensional array detector for analysis.

[0005] The samples (mainly solid samples to be interrogated by ATR as the interrogation technique) can have many different shapes and sizes. To achieve effective optical coupling, a force is applied to such samples through a configured stage mechanism, which is designed to provide tight contact with optical components such as diamond, silicon, or germanium (Ge) ATR elements. Conventional stages contain pressure mechanisms that include mechanical screws, levers, sliders, and actuators for applying pressure to a given sample.

[0006] However, during typical ATR measurements, a repeatable and controllable force needs to be applied to the sample to precisely control the signal-to-noise ratio in the ATR measurement.

[0007] The foregoing background discussion is only intended to assist the reader. It is not intended to limit the innovations described herein. Thus, the foregoing discussion should not be regarded as indicating that any particular element of the existing systems is not suitable for use with the innovations described herein, nor is it intended to indicate that any element is essential in implementing the innovations described herein. Summary of the Invention

[0008] The ATR measurement system described herein largely meets the above requirements. The ATR measurement system enables the objective lens, ATR, and the structure associated with the support to move with low resistance on the bearings. The system can be in contact with sensitive sensors (e.g., load cells, strain gauges) that are electrically attached to a low-noise circuit and an operational amplifier. The range of the load cell (and / or strain gauge) is limited, thus enabling accurate and repetitive measurement of low forces. Before failure, the deflection of the sensor is very small, thus maintaining the optical alignment.

[0009] The ATR measurement system can measure the force and / or pressure at the tip of the ATR. The sensor can be combined with a high-precision low-noise analog electronic circuit, enabling the user to measure the force more precisely.

[0010] Traditional systems use sensors with lower sensitivity, which rely on additional forces applied to the stage that supports the sample and the sample weight. Since the deflection on the stage needs to be limited, the strain should be designed to be lower. This affects the percentage of strain that the strain gauge can measure. When exposed to low strain, there may be linearity and accuracy issues in force measurement. When applying the sensor to the upper assembly, large strain may not allow a rigid optical path. Sensor settings often operate with the material at approximately 50% strain; these sensors are generally not linear or accurate at 10% strain. Therefore, for microscope applications, high-precision sensors may be too flexible, while the more rigid sensor designs suitable for microscopes may not be accurate under typical ATR loads.

[0011] The ATR measurement system described herein includes a load cell located on the optical side of the system, which is connected to the base. The system includes a hinge connection, which basically allows the sensor to measure almost all forces at the ATR contact. The measurement range of the sensor is limited, so the force to be measured should be within this measurement range. By applying a fixed, constant load to the stage (e.g., above) that supports the sample, the entire load of the optical assembly can be supported by a fastener (e.g., from below). At this time, the articulated beam can be positioned relative to the sample (e.g., vertically), but it can return to the same position on the fastener. The sensor can be calibrated or zeroed. The sensor can be configured to repeatedly and accurately report the load applied by the ATR crystal to the sample during measurement.

[0012] According to one aspect of the present disclosure, a measurement system for inspecting a sample is provided. The measurement system may include an internal reflection element, a stage, an optical assembly, a base, and a sensor. The internal reflection element may include a contact surface configured to contact the sample. The stage may be located adjacent to the internal reflection element (e.g., axially below). At least one of the stage and the internal reflection element may be configured to apply a force to the sample when the sample is placed on the stage and the contact surface contacts the sample. The optical assembly may include a light source and a light detector. The optical assembly may be configured to scan the sample by guiding source light from the light source to the contact surface and detecting the source light optically interacting with the contact surface through the light detector. The base may be configured to support the optical assembly and the internal reflection element. The sensor may be mounted on the base and configured to detect the force applied to the sample by at least one of the internal reflection element and the stage.

[0013] According to another aspect of the present disclosure, a method for inspecting a sample with a measurement system is provided. The method may include: placing a sample on a stage; contacting the sample through a contact surface of an internal reflection element, the internal reflection element being positioned adjacent to the stage (e.g., axially above); applying a force to the sample with at least one of the contact surface of the stage and the internal reflection element; and detecting the force applied to the sample through a sensor. The sensor may be mounted on a base. The base may be configured to support an optical assembly adjacent to the stage (e.g., vertically above). The optical assembly may include a light source and a light detector. The optical assembly may be configured to scan the sample by guiding source light from the light source to the contact surface and detecting the source light optically interacting with the contact surface through the light detector.

[0014] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Additionally, the claimed subject matter is not limited to solutions that address any or all disadvantages noted in any part of this disclosure. Brief Description of the Drawings

[0015] The above summary and the following detailed description of the exemplary embodiments of the present application will be better understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the present application, exemplary embodiments of the present disclosure are shown in the drawings. However, it should be understood that the present application is not limited to the precise arrangements and instrumentalities shown. In the drawings:

[0016] Figure 1The figure shows a top view of an ATR measurement system according to one aspect of the present disclosure.

[0017] Figure 2 Shows Figure 1 A side view of the ATR measurement system shown in

[0018] Figure 3 The figure shows a schematic diagram of an ATR measurement system according to one aspect of the present disclosure.

[0019] Figure 4 Shows a side schematic diagram of a part of an ATR measurement system according to one aspect of the present disclosure.

[0020] Figure 5 Shows according to one aspect of the present disclosure, Figure 1 A close-up side view of the load measurement component of the ATR measurement system shown in

[0021] Figure 6 Shows a schematic diagram of a controller according to one aspect of the present disclosure.

[0022] Figure 7 The figure illustrates a method of inspecting a sample using a measurement system according to one aspect of the present disclosure. Detailed Description

[0023] Certain terms used in this specification are for convenience only and are not restrictive. The words "axial", "radial", "circumferential", "outward", "inward", "upper", and "lower" denote directions in the referenced drawings. As used herein, when used to describe dimensions, shapes, orientations, distances, spatial relationships, or other parameters, the term "substantially" and its derivatives and words with similar meanings encompass the stated dimensions, shapes, orientations, distances, spatial relationships, or other parameters, and may also encompass ranges that are 10% more and 10% less than the stated parameter, including ranges that are 5% more and 5% less than the stated parameter, 3% more and 3% less than the stated parameter, and 1% more and 1% less than the stated parameter. All ranges disclosed herein include the stated endpoints and can be combined independently (e.g., a range "from 2 grams to 10 grams" includes the endpoints, 2 grams and 10 grams, and all intermediate values). This term encompasses the above-listed words, their derivatives, and words with similar meanings.

[0024] In Fourier transform infrared (FTIR) spectroscopy, an unknown substance is irradiated with broad-spectrum infrared light, which can be absorbed by the sample of interest. The wavelength range of the light source irradiation is approximately 0.7 micrometers to 25 micrometers. The light intensity as a function of wavelength is measured before and after interaction with the sample, and the absorbance caused by the sample is calculated. At specific frequencies corresponding to the vibration frequencies of the molecular bonds in the sample, the light is absorbed by the sample in different amounts. Since the bonds of each molecule are different, the FTIR absorption spectrum of each molecule is also different. Therefore, a spectral "fingerprint" can be generated by recording the absorbance of light as a function of wavelength.

[0025] For a typical ATR / FTIR instrument, traditional pressure devices use drive screws, levers, and wedges to generate force and / or pressure on the material, and this mechanism requires manual movement by the user. Manual movement is one way to apply force, but the user (e.g., the tester) can manipulate a joystick to raise the stage, or software can be used to raise the stage to a specific position relative to the internal reflection element (IRE). However, this traditional manual (e.g., knob-driven) movement of the mechanism is often large and cumbersome, and it is also difficult to operate in a way that can repeatedly apply a contact force or according to desired properties such as desired spectral characteristics. When testing hard samples, if the force is increased by only a few micrometers, the manual method can be very difficult, time-consuming, or both, to ensure that the interface pressure is at the preferred level.

[0026] Figure 1 and 2 A perspective view and a side view of an ATR measurement system 100 according to aspects of the present disclosure are shown. The measurement system 100 can include an optical assembly 101, a base 200, a load measurement assembly 300, and a manual sliding mechanism 187 that can accurately position the ATR crystal. The base 200 can support the optical assembly 101 and the load measurement assembly 300. As further described herein, the load measurement assembly 300 can be connected to the optical assembly 101. The ATR crystal slider 187 can be positioned adjacent to (e.g., below) the optical assembly 101 and can be configured to fixedly position the ATR crystal in contact with the sample material 190 thereon (see Figure 4 ). As further described herein, the optical assembly 101 can be configured to optically interrogate the sample material 190.

[0027] Figure 3 A schematic diagram of an ATR measurement system 100 according to an aspect of the present disclosure is illustrated. The measurement system 100 can include an optical assembly 101. The optical assembly 101 can include various optical components mounted on the base, such as Figure 1 and Figure 2Base 200. The optical assembly may be located within the housing 156. The optical assembly 101 may include radiation sources 102 and 144, mirrors 104, 108, 110, 148, 118, 120, 120', 126, 126', 128 and 130, beam splitters 106 and 146, detectors and / or sensors 132 and 150, and internal reflection elements 122 (e.g., prisms). It should be understood that although a certain number of the mirrors 104, 108, 110, 148, 118, 120, 120', 126, 126', 128 and 130 are typically shown as planar in design, the mirrors and / or other optical elements may include refractive optical elements (e.g., lenses), and non-planar reflective elements may also be configured to have other predetermined curvatures to provide Figure 3 the optical path shown. For example, such elements may be configured to have a concave curvature, a convex curvature, a parabolic curvature, an elliptical curvature, or any general surface required to provide an appropriate beam configuration for any portion of the beam path guided within the system 100.

[0028] The optical assembly 101 may further include an axis 112, a bushing 114, and an actuator 116 coupled to the mirror 110, as well as an electronic processor 134, an electronic display 136 (e.g., including a flat display element such as a liquid crystal display element, an organic light emitting diode display element, an electrophoretic display element, or another type of display element capable of touch screen operation), an input device 138, a storage unit 140, and a communication interface 142. The electronic processor 134 may be in electrical communication with the light detector 132, the storage unit 140, the communication interface 142, the display 136, the input device 138, the radiation sources 102 and 144, the detector 150, and the actuator 116 via communication lines 162a-i, respectively.

[0029] System 100 can be configured to function as an FTIR spectrometer during operation. It should be understood that system 100 can be used for other types of spectroscopy, including, for example, ultraviolet, visible light, Raman, or other types of spectroscopy. Under the control of processor 134, system 100 can provide light 168 through light source 102, which can be removable for ease of replacement. Light 168 can include radiation from light source 102, which can include a radiation source. Radiation 168 can be directed by mirror 104 to impinge on beam splitter 106, which can be configured to split into beam splitting optical element 106a and phase compensation plate 106b such that the received radiation 168 can be split into two beams. Using such a configuration, an interferometer (e.g., a Michelson-type interferometer) can be formed, where the first beam 170 can be reflected from the surface of beam splitter 106, propagate along a beam path parallel to arrow 171, and impinge on fixed mirror 108. Thereafter, fixed mirror 108 can reflect the first beam 170 in the opposite direction so that it is then directed towards beam splitter 106. The second beam 172 can be transmitted through beam splitter 106 and propagate along a beam path parallel to double arrow 173. The second beam 172 can impinge on the first surface 110a of movable mirror 110, and thus also be directed towards beam splitter 106 when reflected.

[0030] The first and second beams 170 and 172 can be combined through the configuration of beam splitter 106 and associated optics, which overlap spatially with the beams to form a beam that modulates the infrared radiation beam 174 (through the operation of the configured interferometer) and is directed towards mirror 118. Thereafter, mirrors 118, 120, 120' can direct the modulated infrared radiation beam 174 towards internal reflection element 122. Once inside internal reflection element 122 (which is typically configured as a prism), the modulated infrared beam 174 can be directed towards the ATR tip or the contact surface 122a of internal reflection element 122. The contact surface 122a of internal reflection element 122 can be positioned adjacent (e.g., above) the sample 190 of interest. In some cases, sample 190 can include irregularities in the surface structure (e.g., powder). When the modulated infrared light 174 impinges on contact surface 122a, a portion of the radiation of the modulated infrared light 174 can be guided through contact surface 122a into the sample material 190 by the desired evanescent wave effect (see Figure 4 ). As part of this effect, sample 190 can ideally absorb a portion of the modulated infrared light 174, which portion represents the structure of sample material 190 and thus indicates the characteristics of said sample material.

[0031] The total internal reflection portion 176 of the modulated infrared light 174 can include a reduced amount of modulated radiation that is not absorbed by the sample 190. The reflected beam 176 can be directed through a desired surface of the internal reflection element 122 and can then be directed, for example, by mirrors 126', 126, 128, and 130 so that the system 100 interrogates via detection by the light detector 132. In particular, under the control of the processor 134, the light detector 132 can be configured to measure one or more characteristics of the sample 190 based on the reflected radiation in the beam 176.

[0032] As described above, the configured mirrors 108 and 110 together with the beam splitter 106 advantageously form an interferometer. In operation, by translating the mirror 110 in the left-right direction (e.g., double arrow 164) before each measurement, an interferogram containing information (e.g., sample absorption information) can be formed by multiple measurements of the radiation in the reflected beam 176. The processor 134 can be configured to apply one or more mathematical transforms (e.g., Fourier transform) to the interferogram to obtain the sample absorption information.

[0033] The mirror 110 can be coupled to the shaft 112, the bushing 114, and the actuator 116. The shaft 112 can move freely within the bushing 114, and a viscous fluid is typically disposed between the shaft 112 and the bushing 114 to enable relative movement between the two. Thus, when the actuator 116 receives a control signal from the processor 134 via the communication line 162i, the mirror 110 can move.

[0034] To measure the position of the mirror 110, the light source 144, the beam splitter 146, the mirror 148, and the detector 150 can be configured to measure the position of the mirror 110. These components can be arranged to form a second interferometer (e.g., a Michelson-type interferometer). During the operation of the mirror position measurement, the light source 144 (e.g., a monochromatic emission source (laser)) can receive a control signal from the processor 134 via the communication line 162g and can generate a radiation beam 178. As an example of the desired light source, the light source 144 can be a configured vertical cavity surface emitting laser (VCSEL) that generates radiation having a center wavelength of 850 nm. However, it should be understood that the source 144 can also include a variety of other sources, such as laser diodes, light emitting diodes, etc., that are capable of having radiation between 400 nm and approximately 1200 nm.

[0035] The light beam 178 can be incident on the beam splitter 146, and the beam splitter can divide the radiation beam 178 into a first beam 180 and a second beam 182. The first light beam 180 can be reflected from the surface of the beam splitter 146 and can be incident on the second surface 110b of the mirror 110. The second surface 110b can be positioned relative to the first surface 110a of the mirror 110. The first light beam 180 can be reflected from the surface 110b and return to the beam splitter 146. The second light beam 182 can be emitted through the beam splitter 146, reflected by the mirror 148, and return to the beam splitter 146. The beam splitter 146 can combine (e.g., spatially overlap) the reflected light beams 180 and 182, and the spatially overlapped light beam 184 can be directed to the detector 150. The detector 150 can receive a control signal from the processor 134 via the communication line 162k and can be configured to measure the intensity of the combined light beam 184. The combined light beam 184 can provide an interference pattern containing the desired optical position information. Therefore, the monitoring light beam 184 can accurately determine the position (and velocity and tilt, if needed) of the mirror 110 by calculating the peaks and valleys of the amplitude of the light beam 184.

[0036] On the one hand, the processor 134 can compare the absorption information with the reference information (e.g., reference absorption information) stored in the storage unit 140 to determine the characteristics of the unknown sample. For example, after performing a Fourier transform on the received reflected light beam 176, the processor 134 can determine whether the absorption information of the sample matches any one or more of multiple sets of reference absorption information of multiple substances, and the reference absorption information is stored in the storage unit 140 as database records or even comes from a database remotely located via wireless communication.

[0037] If a match is found (e.g., the sample absorption information and the reference information of a specific substance are sufficiently consistent), the sample 190 is considered to be identified by the processor 134. The processor 134 can send an electronic signal along the communication line 162d to the display 136, and this signal indicates to the system operator the successful identification of the sample 190 and provides the name of the identified substance. If the processor 134 does not find a match between the sample absorption information and the reference information, the processor 134 can send an electronic signal to the display 136, and this electronic signal indicates to the system operator that the sample 190 has not been successfully identified, or that an effective optical coupling is not provided between the ATR contact surfaces 122a due to, for example, insufficient force applied by the contact member 191.

[0038] The communication interface can receive and transmit signals from / to the processor 134 via the communication line 162c. The communication interface 142 can include a wireless transmitter / receiver unit, which can be configured to transmit signals from the processor 134 to other devices, and receive signals from other devices and transmit the received signals to the processor 134. For example, the communication interface 142 can allow the processor 134 to communicate with other devices via a wireless network including a plurality of devices connected to a network and / or via a direct connection to another device. The processor 134 can establish a secure connection (e.g., an encrypted connection) to one or more devices to ensure that signals can only be sent and received by devices approved for use on the network.

[0039] The light source 102 can be configured as a replaceable component. The light source 102 can include a broadband radiation source configured to provide infrared radiation such that the system 100 can operate as an infrared spectrometer. The infrared radiation provided by the source 102 can include a wavelength distribution having a center wavelength of approximately 10 micrometers. Generally, the light source 102 can include a variety of light sources known to those skilled in the art, including a heated infrared source selected from any custom or conventional known light sources used in the art, such as but not limited to a wire, a metal, or a ceramic element heated to emit a continuous band of light radiation.

[0040] Figure 4 A side view of the stage or platform 186 and the internal reflection element 122 according to one aspect of the present disclosure is illustrated. The stage 186 can be positioned adjacent to the optical assembly 101 (e.g., below it) and can be configured to support the sample material 190 thereon. The internal reflection element 122 can include a contact surface 122a positioned to contact the sample 190. As shown, the sample 190 can include powder represented by circles. It should be understood that the sample 190 can include a solid or a liquid. Light from the light source 102 can enter the internal reflection element 122 and be reflected from the surface 122b to the contact surface 122a, and can exit the internal reflection element 122 by being reflected from the surface 122c.

[0041] The edge of the internal reflection element 122 opposite the contact surface 122a can be supported (e.g., from above relative to the platform 186) and mounted directly or indirectly to the housing 156. The internal reflection element 122 can be rigidly mounted, so that movement of the internal reflection element 122 can also cause movement of the optical assembly 101. A coating (not shown), such as a metal (e.g., gold), can be applied to the internal reflection element 122 to achieve stable coupling with the bottom of the housing 156, thereby further providing support for the internal reflection element 122 (e.g., from above). The support provided by the housing 156 can enable the internal reflection element 122 to withstand significant applied forces during operation without shifting from its mounting position.

[0042] The force component 250 can be connected to the stage 186 (e.g., from below with respect to the optical component 101). The force application component 250 can include an actuator 202 and a translation member 205. The actuator 202 can include, for example, a motor (such as a DC motor) or a solenoid, an electromagnetic solenoid, or other types of force actuators that can be moved in a controlled manner (such as a piezoelectric drive mechanism, a linear motor, a rotary motor, a pneumatic or hydraulic actuator, etc.). The translation member 205 can be connected to the stage 186 to control the movement of the stage 186 in the vertical directions V and V' and / or the rotational direction (not labeled). The translation member 205 can include a screw mechanism, a cam, or other mechanisms to control the linear and / or rotational movement of the stage 186. In one aspect, the stage 186 and the sample 190 can be positioned adjacent to the internal reflection element 122 (e.g., vertically below).

[0043] During interrogation, the operator can control the actuator 202 to translate the stage 186 in the vertical direction V such that the sample 190 contacts the contact surface 122a of the internal reflection element 122. The stage 186 can be controlled to be raised and / or rotated into position. When the sample 190 contacts the contact surface 122a, at least one of the stage 186 and the internal reflection element 122 can apply a force to the sample 190. The movement of the stage 186 can bring the contact surface 122a into close contact with the sample material 190 to achieve effective coupling of the evanescent wave and improve the signal-to-noise ratio in the measurement of the reflected radiation beam 176. The housing 156 of the optical component 101 can ensure that the internal reflection element 122 remains in the same position on the stage 186.

[0044] The contact force applied to the sample 190 by the stage 186 and / or the internal reflection element 122 can be a desired fixed force that is an optionally user-selected force, or a desired force controlled by spectrometer feedback based on the spectrometer characteristics of the sample 190. For example, the user can select the fixed force to be applied and can control the stage 186 to apply the fixed force to the sample 190. Alternatively, the force applied to the sample 190 by the stage 186 and / or the internal reflection element 122 can depend on, for example, the photodetector 132 at the detection end of the beam path (see Figure 3) feedback. When a force is applied to sample 190, the optical assembly 101 can simultaneously and continuously query the signal strength provided by the photodetector 132. If the signal strength (e.g., sample spectral feature strength) provides a reasonable signal, the stage 186 can be controlled to stop, and the force applied to sample 190 can be maintained. If the signal is unreasonable, the stage 186 can continue to increase the force and / or can apply pressure to sample 190 until the maximum allowable force is applied or until an acceptable signal strength is obtained. Once there is sufficient contact force and / or pressure for a reasonable signal, this operation causes the stage 186 to stop moving. It should be understood that other operations (e.g., movement of the internal reflection element) can be used to apply force and / or pressure to sample 190.

[0045] Figure 5 A close-up side view of a load measurement assembly 300 connected to a base 200 according to one aspect of the present disclosure is shown. The load measurement assembly 300 can be further connected to a front-end assembly 302. The front-end assembly 302 can include a plate member 304 rigidly connected to the base 200. The connection between the front-end assembly 302 and the base 200 can define a cantilever connection. The plate member 304 can extend from the base 200 in a direction substantially perpendicular to the vertical directions V and V'. The plate member 304 can be configured to deflect in the vertical directions V and V'. The plate member 304 can include steel, aluminum, titanium, composite material, or polymer material. The plate member 304 can be rigidly fixed to and at least partially support the optical assembly 101. The optical assembly 101 and the internal reflection element 122 can define a fixed constant load adjacent to (e.g., above) the sample 190. It should be understood that the plate member 304 can include more than one plate, a beam, multiple beams, and / or other structures that are configured to support the optical assembly 101 and are also configured to deflect based on the force and / or pressure applied to the internal reflection element 122.

[0046] The load measurement assembly 300 can include a sensor 306, a deflection assembly 308, and a controller 310 (see Figure 6)。The deflection assembly 308 can be mounted to the base 200. The sensor 306 can be mounted to the deflection assembly 308. The controller 310 can be located on the base 200 or other structures of the ATR measurement system 100. Alternatively, the controller 310 can be located remotely from the measurement system 100 and be configured to communicate with the measurement system 100 via a communication interface (not shown). At least a portion of the deflection assembly 308 can be configured to deflect based on forces and / or pressures applied to the sample 190 by the internal reflection element 122 and / or the stage 186. As further described below, the sensor 306 can be configured to detect the deflection of the deflection assembly 308. The sensor 306 can further be configured to provide a signal to the controller 310 indicative of the deflection of the deflection assembly 308. The controller 310 can be configured to determine the forces and / or pressures applied to the sample 190 based on the signal indicative of deflection received from the sensor 306.

[0047] The deflection assembly 308 can include a projection member 312, a hinge beam 314, and a support member 316. It should be understood that the deflection assembly 308 can also include a plate member or beam 304, or other structures configured to facilitate the load measurement described herein. The support member 316 can be fixedly connected to the base 200 by fasteners 318. The fasteners 318 can include, for example, screws, rivets, clamps, and / or other types of fasteners. The support member 316 can include a hinge support surface 320 configured to connect a hinge 322 thereto. The support member 316 can include a first hole and a second hole (not visible in the figure) that extend through (or at least partially through) the support member 316 to the hinge support surface 320. In one aspect, both the first and second holes can extend in a substantially horizontal direction H and H'. The horizontal directions H and H' are substantially perpendicular to the vertical directions V and V'. The first hole can be configured to receive a hinge beam retaining element 324. As further described below, the hinge beam retaining element 324 can be used to adjust the position of the hinge beam 314. The second hole can be configured to receive a first bearing element 326. As further described below, the first bearing element 326 can be configured to substantially prevent rotational movement of the hinge beam 314.

[0048] The support member 316 can further include a projection support surface 328 that defines a third hole (not visible). The third hole can be configured to receive a second bearing element 330. As further described below, the second bearing element 330 can be configured to substantially prevent rotation of the projection member 312. In one aspect, the projection support surface 328 can be substantially parallel to the hinge support surface 320.

[0049] The articulated beam 314 may include a rear hinge surface 332 and a front hinge surface 334. In one aspect, the rear hinge surface 332 may be substantially parallel to the front hinge surface 334. The rear hinge surface 332 may be connected to the hinge 322 such that the articulated beam is hinge-connected to the support member 316. The articulated beam 314 may be configured to rotate relative to the support member 316 about the hinge 322. The hinge 322 may include, for example, a pin joint or other type of hinge. It should be understood that the hinge 322 may include (or be replaced by) another component configured to allow rotation, such as a flexure beam, a flexure element, or other similar components. In one aspect, the rotation of the articulated beam 314 about the hinge 320 may be substantially perpendicular to the vertical directions V and V'. During operation, the rear hinge surface 332 may be configured to abut against the first bearing element 326 and / or the articulated beam retaining element 324 connected to the support member 316.

[0050] The sensor 306 may be connected to the front hinge surface 334 of the articulated beam 314 such that the sensor 306 is hinge-connected to the base 200 through the hinge 322. The sensor 306 may be configured to abut against the projection surface 336 of the projection member 312. The sensor 306 may be configured to sense the movement and / or deflection of the projection member 312. The sensor may include a load sensor, a strain gauge, a force-sensitive resistor, or other type of force sensor or transducer configured to detect a load.

[0051] The projection member 312 may be fixedly connected to the plate member 304 of the front end assembly 302 by a fastener 338. The projection member 312 may extend at least partially in the vertical direction V from the plate member 304. The projection member 312 may include a projection surface 336. The projection surface 336 may face the front hinge surface 334 of the articulated beam 314. During operation, the movement and / or deflection of the projection surface 336 may be sensed by the sensor 306. As further described below, the projection surface 336 may further be configured to abut against the second bearing element 330 positioned within the support member 316.

[0052] Figure 6A schematic diagram of a controller 310 according to an aspect of the present disclosure is shown. As shown, the controller 310 may include a processor 350 and a memory 352. It should be understood that the controller 310 may also include a processor 134, a display 136, a storage unit 140, a communication interface 142, or other computing components. The memory 352 may store data provided to the controller 310 from the sensor 306, which indicates the deflection of the deflection assembly 308. The memory 352 may also store executable code that includes algorithms for determining the force and / or pressure applied to the sample 190 by the internal reflection element 122 and / or the stage 186. The memory 352 may include random access memory (RAM), or read-only memory (ROM), or both. The controller 310 may be connected to the actuator 202 of the force assembly 200. The controller 310 may send a signal to the actuator 202 to adjust the height of the stage 186 to affect the force and / or pressure applied to the sample 190.

[0053] Figure 7 A flowchart of a method 400 for inspecting a sample 190 using an ATR / FTIR measurement system 100 according to an aspect of the present disclosure is shown. In step 402, the load measurement assembly 300 may be positioned. Referring to Figure 5 , positioning the load measurement assembly 300 may include rotating the articulated beam 314 about the hinge 322 until the sensor 306 contacts the projection surface 336 of the projection member 312. The first bearing element 326 may be used to rotate the articulated beam 314 to apply a force to the rear hinge surface 332. Once the sensor 306 is positioned, the first bearing element 326 may be locked to substantially prevent the articulated beam 314 from rotating in a direction away from the projection surface 336 of the projection member 312. The sensor 306 may be approximately zeroed such that the initial force detected by the sensor is approximately zero.

[0054] It should be understood that when the optical assembly 101 and the internal reflection element 122 are fixedly connected to the front end assembly 302, the 304 may initially deflect downward in the vertical direction V' due to the load (e.g., weight) of the optical assembly 101 and the internal reflection element 122. To compensate for this initial deflection, as described above, the sensor 306 is positioned to contact the projection member 312.

[0055] In step 404, the sample 190 can be positioned on the stage 186. On the one hand, the sample 190 can be placed towards the center of the stage 186 and at least partially positioned below the internal reflection element 122. After placing the sample 190 on the stage 186, in step 406, the stage 186 can be raised in the vertical direction V until the internal reflection element 122 contacts the sample 190. In one aspect, after the internal reflection element 122 has contacted the sample 190, the sensor 306 can be approximately zeroed again (or initially).

[0056] In step 408, a contact force and / or pressure can be applied to the sample 190 by the stage 186 against the ATR tip 122a of the internal reflection element 122. The force and / or pressure can be applied to the sample 190 by repositioning (e.g., raising) the stage 186 by the actuator 202. As described above, the contact force and / or pressure applied to the sample 190 can include a desired force and / or pressure selected by the user, controlled by signal strength feedback, or determined by another method. In one aspect, after the internal reflection element 122 has applied an initial force to the sample 190, the sensor 306 can be approximately zeroed again (or initially).

[0057] In step 410, the sensor 306 can detect the initial force and / or pressure applied to the sample 190 by the stage 186 and the internal reflection element 122. The detected initial force and / or pressure can correspond to the required contact force and / or pressure described above. The detected initial force and / or pressure can be stored in the memory 352 of the storage unit 140 and / or the controller 310.

[0058] When a force is applied to sample 190, sensor 306 detects the force based on the deflections of optical component 101 and internal reflection element 122. The force applied to the sample by internal reflection element 122 can be substantially in the vertical direction V'. As the height of stage 186 is repositioned (e.g., raised) and the force applied to sample 190 increases, internal reflection element 122 and optical component 101 can deflect upward in the vertical direction V. The deflection of optical component 101 in the vertical direction V can cause front end assembly 302 to deflect in the vertical direction V. For example, plate member 304 can rotate about its rigid connection to base 200 (e.g., cantilever rotation / bending). The deflection of plate member 304 can cause projection member 312 to deflect in a direction angularly offset from the vertical direction V. In one aspect, projection member deflects substantially in the horizontal direction H. The deflection of projection member 312 can cause projection surface 336 to apply a deflection force to sensor 306. Controller 310 can use the deflection force detected by sensor 306 to determine the force applied to sample 190 by stage 186 and internal reflection element 122.

[0059] Sensor 306 can be configured to detect deflections of projection surface 336 up to about 30 microns. It should be understood that sensor 306 can be configured to detect deflections greater than about 30 microns. For example, the sensor can be located at different positions on measurement assembly 300 to measure deflections of one or more different components of measurement assembly 300. The deflection of projection member 312 can be limited by second bearing element 330 on support member 316. Second bearing element 330 can prevent damage to sensor 306 due to excessive deflection of projection member 312. For example, instead of applying all of the force applied to projection member 312 to sensor 306, at least a portion of the applied force is applied to second bearing element 330.

[0060] In step 412, sample 190 can be scanned by optical component 101 to identify sample 190. The scanning step includes directing source light from light source 102 to contact surface 122a of internal reflection element 122. Source light 102 can interact optically with contact surface 122a. Photodetector 132 detects source light 102 that has interacted optically with contact surface 122a.

[0061] Due to the application of force to sample 190, sample 190 can deform and / or deteriorate. The deterioration can affect the contact force and / or pressure applied to sample 190 by ATR tip 122a. For example, after scanning, the contact pressure can be reduced, thereby affecting measurements taken during successive scans of sample 190. As described below, the force applied to sample 190 by contact member 191 can be adjusted prior to successive scans by optical component 101.

[0062] After the scanning step, in step 412, sensor 306 may detect the resultant force and / or pressure applied by ATR tip 122a to sample 190. Sensor 306 may send a signal indicative of the resultant force to the controller. The resultant force may be compared with the initial force to determine whether the resultant force is different from the initial force. This comparison step may be performed by processor 350 or another processor of controller 310. If the resultant force is different from the initial force, controller 310 may send a signal to actuator 202 to adjust the force applied to sample 190. Actuator 202 may increase the height of stage 186 to adjust the force applied to sample 190 from the resultant force to the initial force.

[0063] The position of sensor 306 on base 200 may ensure that the load measurement is independent of the travel of stage 186. The load applied to the ATR may be substantially equal to the load on sample 190. The position of stage 186, sample uniformity, sample weight, and stage control may all affect the load measurement. When the position of sensor 306 is adjacent to (e.g., above) stage 186 and sample 190, and when the support weight of the articulated structure including optical assembly 101 is zeroed, sensor 306 may immediately sense any force applied to the optical articulated structure along the vertical direction V.

[0064] On the one hand, the alignment of the optics may be decoupled from the preload of sensor 306. Hinge 322 may be adjusted to align the objective lens on the tilt axis. After completion, the sensor may be positioned (e.g., lowered) onto the carrier plate with minimal preload. In this configuration, sensor 306 may be substantially the only resistance to the ATR load.

[0065] It should be understood that the above description provides examples of the disclosed systems and methods. However, upon consideration, other embodiments of the present disclosure may differ in details from the above examples. For example, any embodiment disclosed herein may incorporate features disclosed in any other embodiment disclosed herein. All references to the present disclosure or its examples are intended to refer to the specific example being discussed at that time and do not imply any more general limitation on the scope of the present disclosure. All differentiating and disparaging language regarding certain features is intended to indicate a lack of preference for those features, but unless otherwise stated, they are not completely excluded from the scope of the present disclosure.

[0066] One of ordinary skill in the art will readily appreciate that, in accordance with the present disclosure, processes, machines, manufactures, compositions of matter, devices, methods, or steps that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein can be utilized, presently existing or later to be developed.

Claims

1. An attenuated total reflection (ATR) measurement system, comprising: an optical component configured to transfer a force in a first direction; a deflection component configured to: receive the force from the optical component; and redirect a portion of the force from the first direction to a second direction; and a sensor mounted to the deflection component, wherein the sensor is configured to: detect the force transferred from the deflection component in the second direction.

2. The ATR measurement system according to claim 1, wherein the first direction includes a vertical direction, and wherein the second direction is angularly offset from the first direction.

3. The ATR measurement system according to claim 2, wherein the second direction is in a direction orthogonal to the first direction.

4. The ATR measurement system according to claim 1, further comprising a base, and wherein the deflection component is mounted to the base.

5. The ATR measurement system according to claim 4, wherein the deflection component is fixedly mounted to the base such that the deflection component deflects when receiving the force from the optical component.

6. The ATR measurement system according to claim 1, wherein the sensor is hingedly mounted to the deflection component.

7. The ATR measurement system according to claim 1, wherein the sensor includes a load cell or a strain gauge.

8. The ATR measurement system according to claim 1, wherein the sensor generates a signal indicative of the force received by the sensor.

9. The ATR measurement system according to claim 1, wherein the sensor is configured to detect a deflection of the deflection component of less than about 30 microns.

10. The ATR measurement system according to claim 1, wherein the deflection component further includes a retaining element configured to translate in the second direction, thereby causing repositioning of the sensor relative to the projection surface of the deflection component.

11. A method, comprising: transferring a force in a first direction through a first component of an ATR measurement system; receiving the force from the first component through a deflection component of the ATR measurement system; redirecting a portion of the force from the first direction to a second direction through the deflection component; and detecting the force transferred from the deflection component in the second direction through a sensor mounted to the deflection component.

12. The method according to claim 11, wherein the first direction includes a vertical direction, and wherein the second direction is angularly offset from the first direction.

13. The method according to claim 12, wherein the second direction is in a direction orthogonal to the first direction.

14. The method according to claim 11, wherein the deflection component is mounted to a base.

15. The method according to claim 14, wherein the deflection component is fixedly mounted to the base such that the deflection component deflects when receiving the force from the first component.

16. The method according to claim 11, wherein The sensor is pivotally mounted to the deflection assembly.

17. The method according to claim 11, wherein, the sensor comprises a load cell or a strain gauge.

18. The method according to claim 11, wherein, the sensor generates a signal indicative of the force received by the sensor.

19. The method according to claim 11, wherein, the sensor is configured to detect a deflection of the deflection assembly of less than about 30 microns.

20. The method according to claim 11, wherein, the deflection assembly further comprises a retaining element configured to translate in the second direction, thereby causing repositioning of the sensor relative to the projection surface of the deflection assembly.

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