Mechanisms for control of resolution and throughput for optical instruments, and methods of use thereof

Abstract

The disclosure provides a system and method of use for improved configurability and control of resolution and throughput of imaging spectrometers useful for monitoring optical signals in semiconductor process tools. In one aspect a resolution and throughput control system for an optical instrument is disclosed. In one example, the resolution and throughput control system includes: (1) a payload, (2) an actuator, and (3) a movement device that alters light input for the optical instrument by controlling movement of the payload along a single axis in response to the actuator. The optical instrument can be, for example, a spectrometer.

Description

MECHANISMS FOR CONTROL OF RESOLUTION AND THROUGHPUT FOR OPTICAL INSTRUMENTS, AND METHODS OF USE THEREOFCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 63 / 614,373 filed by Mark Meloni et al. on December 22, 2023, and U.S. Provisional Application Serial No. 63 / 568,970 filed by Mark Meloni et al. on March 22, 2024, both which are entitled “MECHANISMS FOR CONTROL OF RESOEUTION AND THROUGHPUT FOR OPTICAE INSTRUMENTS, AND METHODS OF USE THEREOF” and are commonly assigned with this application and incorporated herein by reference in their entirety.TECHNICAL FIELD

[0002] This disclosure relates, generally, to optical spectroscopy systems and methods of use. For example, a system and method for improved configurability and control of resolution and throughput of imaging spectrometers used during semiconductor processing is provided herein.BACKGROUND

[0003] Optical monitoring of semiconductor processes is a well-established method for controlling processes such as etch, deposition, chemical mechanical polishing and implantation. Optical emission spectroscopy (OES) and interferometric endpoint (IEP) are two basic types of modes of operation for data collection. In OES applications light emitted from the process, typically from plasmas, is collected and analyzed to identify and track changes in atomic and molecular species which are indicative of the state or progression of the process being monitored. In IEP applications, light is typically supplied from an external source, such as a flashlamp, and directed onto a workpiece. Upon reflection from the workpiece, the sourced light carries information, in the form of the reflectance of the workpiece, which is indicative of the state of the workpiece. Extraction and modeling of the reflectance of the workpiece permits understanding of film thickness and feature sizes / depth / widths among other properties.

[0004] The industry has been adapting and applying advancements in spectroscopic systems for many years. For example, see Apparatus and Method for Enhancing Dynamic Range of Charge Coupled Device-based Spectrograph, U.S. Patent 9,386,241, incorporated herein by reference. Within the spectrometer, the image sensor is a critical element for determining data rates, optical bandwidth, optical signal detection performance, optical signal noise performance, etc. Areal charge-coupled-devices ("CCDs") are most common but have multiple performance limitations and inhibit, among other aspects, highly desirable modes of operation and rapid data rates. As described in U.S. Patent 9,386,241, complex clocking, data shifting and reading may be performed to offset certain performance issues but, for example, the effects of multiple signal mixing and cross-contamination remain due to the physical structure of the existing devices and required pixel shifting schemes.BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The features characteristic of the present invention believed to be novel are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will be best understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings wherein:

[0006] FIG. 1A is a block diagram of a process system for employing OES and / or IEP to monitor and / or control the state of a plasma or non-plasma process within a semiconductor process tool according to the principles of the disclosure;

[0007] FIG. IB is a block diagram of an example of a resolution and throughput control (RETHCO) system constructed according to the principles of the disclosure;

[0008] FIG. 1C is a block diagram of an example of a computing device operating as a controller for a RETHCO system in accordance with this disclosure;

[0009] FIGS. 2A-4B are plots of a typical IEP optical signal (spectrum) and modifications made thereto, in accordance with of the principles of this disclosure;

[0010] FIG. 5 is an image of an example of an aperture for an optical instrument that is a typical optical slit and a summary of representative positional requirements;

[0011] FIG. 6 is a pair of simplified 2D images of an example of a movement device in the form of a flexure and an actuator or actuator system, which provides capability for positional variation of a slit aperture within the requirements discussed herein;

[0012] FIGS. 7 A and 7B are 2D and 3D images, respectively, of an example of a flexure suitable for the precise control of spectrometer resolution and throughput according to the principles disclosed herein;

[0013] FIGS. 8A and 8B are 2D images of harmonic flexural modes of a flexure suitable for the precise control of spectrometer resolution and throughput according to the principles disclosed herein;

[0014] FIGS. 9 A and 9B are 2D images of a flexure and actuator system integrated with a portion of a spectrometer for controlling the discrete selection between two slit apertures or one slit aperture and a shutter (zero width aperture).

[0015] FIGS. 10A and 10B are 2D images of various slit aperture payloads which may be used with the system described herein.

[0016] FIGS. 11A and 11B arc 3D images of a portion of a spectrometer, a flexure and actuator system, and related components.

[0017] FIGS. 12A and 12B are 3D images of a differently configured flexure and actuator system, and related components.

[0018] FIGS. 13A, 13B, 13C and 13D are simplified cross-sectional images of fiber, slit aperture, and pay load combinations.

[0019] FIGS. 14A and 14B are cross-sectional images of a slit aperture and payload combination corresponding to FIG 13C.

[0020] FIGS. 15A and 15B are plan-view drawings of a slit aperture and payload combination corresponding to FIG 13C.

[0021] FIGS. 16A, 16B, and 16C are images of a slit aperture and payload combination corresponding to FIG 13C showing selection of either a slit aperture or of a shutter position.

[0022] FIGS. 17A, 17B, and 17C are images of a fiber, slit aperture, and payload combination corresponding to FIG 13C showing selection of either a slit aperture or of a shutter position.

[0023] FIGS. 18A and 18B are images of alternative fiber, slit aperture, and payload combinations corresponding to FIG 13C.

[0024] FIGS. 19A and 19B are plots of signal coupling efficiency curves for various fiber diameters and slit aperture widths.

[0025] FIGS. 20A and 20B are plots of signal coupling efficiency and signal area for a 600- micron diameter fiber coupled to 125- and 17-micron width slit apertures.

[0026] FIG. 21 illustrates a flow diagram of an example of a method for operating a RETHCO carried out according to the principles of the disclosure.DETAILED DESCRIPTION

[0027] The constant advance of semiconductor processes toward faster processes, smaller feature sizes, more complex structures, larger wafer, and more complex process chemistries places great demands on process monitoring technologies. For example, higher data rates are required to accurately monitor much faster etch rates on very thin layers where changes in Angstroms (a few atomic layers) are critical such as for fin field-effect transistor (FINFET) and three-dimensional NAND (3D NAND) structures. Wider optical bandwidth and greater signal-to-noise are required in many cases both for OES and IEP methodologies to aid in detecting small changes either / both for reflectances and optical emissions. Cost and packaging sizes are also under constant pressure as the process equipment becomes more complex and costly itself. All of these requirements seek to advance the performance of optical monitoring of semiconductor processes. The capabilities and adaptability of suitable spectrometers are critical elements of the monitoring systems.

[0028] Accordingly, the disclosure provides a system and method for controlling the resolution and throughput of optical processing equipment, such as a spectrometer or another type of optical instrument. By controlling one or more of the resolution and throughput, the disclosed featuresallow optical instruments to alter the light input that is received for processing. As such, the optical instruments can advantageously adapt to the type of light that is being received for processing.

[0029] A resolution and throughput control (RETHCO) system is disclosed that controls the light input for optical instruments. In examples disclosed herein the RETHCO system includes a payload, an actuator system (or simply actuator), and a movement device that alters light input for an optical instrument by controlling movement of the payload along a single axis in response to the actuator. Examples of an actuator and movement device used as an example herein include a cam and a flexure. An example of an optical instrument used herein is a spectrometer.

[0030] A RETHCO system can also include a controller that alters the light input by controlling the movement of the payload relative to the aperture of the optical instrument. The controller can operate the actuator to cause payload movement via the movement device to obtain a desired light input corresponding to a processing input. The processing input can be received, for example, from a processing chamber, via a user input, or via the optical instrument itself. The processing input can be received before, during, or after a processing stage that is being monitored by the optical instrument. Processing inputs are further discussed herein with respect to, for example, FIG. IB and FIG. 1C.

[0031] In the following description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized. It is also to be understood that structural, procedural and system changes may be made without departing from the spirit and scope of the present invention. The following description is, therefore, not to be taken in a limiting sense. For clarity of exposition, like features shown in the accompanying drawings are indicated with like reference numerals and similar features as shown in alternate embodiments in the drawings are indicated with similar reference numerals. Other features of the present invention will be apparent from the accompanying drawings and from the following detailed description. It is noted that, for purposes of illustrative clarity, certain elements in the drawings may not be drawn to scale.

[0032] With specific regard to monitoring and evaluating the state of a semiconductor process within a process tool, FIG. 1A illustrates a block diagram of process system 100 utilizing OES and / or IEP to monitor and / or control the state of a plasma or non-plasma process within a process tool. The shown and described components are simplified for expedience and are commonly known. Semiconductor process tool 110 generally encloses wafer 120 and possibly process plasma 130 in a typically partially evacuated volume which may include various process gases. Process tool 110 may include one or multiple optical interfaces 140, 141 and 142 to permit observation into the chamber at various locations and orientations. Interfaces 140, 141 and 142 may include multiple types of optical elements such as, but not limited to, optical filters, lenses, windows, apertures, fiber optics, etc.

[0033] For IEP applications, light source 150 may be connected with interface 140 directly or via fiber optical cable assembly 153. As shown in this configuration, interface 140 is oriented normal to the surface of wafer 120 and often centered with respect to the same. Light from light source 150 may enter the internal volume of process tool 110 in the form of collimated beam 155. Beam 155 upon reflection from the wafer may again be received by interface 140. In common applications, interface 140 may be an optical collimator. Following receipt by interface 140, the light may be transferred via fiber optic cable assembly 157 to spectrometer 160 for detection and conversion. Sourced and detected light may include, for example, the wavelength range from DUV to NIR and wavelengths of interest may be selected from any subrange therein. For larger substrates or where understanding of wafer non-uniformity is a concern additional normally oriented interfaces, not shown, may be used.

[0034] For OES applications, interface 142 may be oriented to collect light emissions from plasma 130. Interface 142 may simply be a viewport or may additionally include other optics such as lenses, mirrors and optical wavelength filters. Fiber optic cable assembly 159 may direct any collected light to spectrometer 160. Multiple interfaces may be used separately or in parallel to collect OES related optical signals. For example, interface 141 may be located to collect emission from near the surface of wafer 120 while interface 142 may be located to view the bulk of the plasma, as shown in FIG. 1. Other interfaces, not shown, may be located up / down-stream of theplasma / wafer interface. Light directed to the spectrometer 160 via either the fiber optic cable assemblies 157 or 159 can be received via an aperture (not shown) of the spectrometer 160 for processing. FIGS. 2A, 2B, 3A, 3B, 4A, and 4B illustrate examples of light directed to the spectrometer 160 from semiconductor processing and FIG. 5 illustrates an example of an aperture that would be used by the spectrometer 160 to receive the light.

[0035] In many semiconductor processing applications, it is common to collect both OES and IEP optical signals and this collection provides multiple problems for using spectrometer 160. Typically OES signals are continuous in time whereas IEP signals may be either / both continuous or discrete in time. The mixing of these signals causes numerous difficulties as process control often requires the detection of small changes in both the OES and IEP signals and the inherent variation in either signal can mask the observation of the changes in the other. It is not advantageous to support multiple spectrometers for each signal type due to cost, complexity, inconvenience of signal timing synchronization, calibration and packaging.

[0036] Advantageously, the spectrometer 160 includes a RETHCO system 165 that alters the light input received by the spectrometer 160 from the fiber optic cable assemblies 157 and 159. The RETHCO 165 cooperates with the aperture of the spectrometer 160 to alter the light input to optimize the resolution and throughput of the light for processing. RETHCO 165 may be used with either or both of the inputs provided by fiber optic cable assemblies 157 and 159.

[0037] As indicated in FIG. 1A, optical signals (also referred to herein as light), after detection and conversion to electrical signals, are typically amplified and digitized within a subsystem of spectrometer 160, and passed to signal processor 170. Optimizing the resolution and the throughput of the light improves the accuracy of the spectrometer 160 for the detecting and the converting and also the further processing by the signal processor 170. Signal processor 170 may be, for example, an industrial PC, PLC or other system which employs one or more algorithms to produce output 180 such as an analog or digital control value for example representing the intensity of a specific wavelength or the ratio of two wavelength bands. Signal processor 170 may alternatively be integrated with spectrometer 160. Without being too specific, an OES algorithm analyzes emission intensity signals at predetermined wavelength(s) and determines trendparameters that relate to the state of the process and can be used to access that state, for instance end point detection, etch depth, etc. For IEP applications, an algorithm may analyze entire spectra to determine a film thickness. For example, see System and Method for In-situ Monitor and Control of Film Thickness and Trench Depth, U.S. Patent 7,049,156, incorporated herein by reference. Output values 180 may be transferred to process tool 110 via communication link 185 for monitoring and / or modifying the production process occurring within the process tool.

[0038] FIG. IB illustrates a block diagram of an example of a RETHCO system 190 constructed according to the principles of the disclosure. The RETHCO system 190 provides an example of the RETHCO system 165 of FIG. 1A. The RETHCO system 190 includes a controller 191, an actuator 192, a movement device 193, and a pay load 194. The controller 191 directs operations of one or more components of the RETHCO 190 in response to a processing input to provide a desired light input for an optical instrument. The processing input provides processing information for light that is actively being processed or will be processed by the optical instrument. The processing information can include processing stage data, operating modes, optical data determined from the received light, and feedback data received from processing the light. The processing information can be received from a processing chamber, from a user input, from a signal processor, from the optical instrument receiving the light, or another component or system of a processing system, such as processing system 100. For example, the feedback data can be received from the spectrometer 160 or signal processor 170 of the processing system 100. The controller 191 instructs the actuator 192 to control movement of the movement device 193 to obtain the light input for the optical instrument based on the processing input. The controller 191 can instruct the actuator 192 by generating and sending operating signals to the actuator 192 to control the movement. The operating signals can initiate movement of the actuator and stop movement of the actuator when the desired light input is obtained. The controller 191 can determine the operating signals according to one or more algorithms. FIGS. 13 illustrates example of methods that correspond to one or more algorithms for generating the operating signals.

[0039] The actuator 192 causes the movement device 193 to move in response to the instructions from the controller 191, wherein the movement of the movement device 193 causesmovement of the pay load 194, such as movement for the pay load 194 along a single axis. The movement of the movement device 193 can be along another axis or axes from the single axis movement of the pay load 194. As noted above, the actuator 192 can receive operating signals that direct movement of the actuator. For example, the actuator 192 can include a cam and a motor, such as a stepper motor, that drives the cam to turn and cause the movement of the movement device 193. Instead of a cam, the actuator 192 can include a scissor device that causes movement of the movement device 193 in response to the operating signals. The actuator 192 can also be another type of mechanical device and can be controlled in various ways including pneumatically, hydraulically, magnetically, electrically, or capacitively.

[0040] The movement device 193 alters light input for the optical instrument by controlling movement of the payload 194 along a single axis in response to the actuator 192. For example, the actuator 192 can displace a portion of the movement device 193 that causes movement of the payload 194 along the single axis. The movement device 193 can be a flexure, such as the parallelogram flexure of FIGS. 6-9B and FIGS. 11 A to 12B.

[0041] The pay load 194 is moved relative to the aperture of the optical instrument to alter the light input for the optical instrument. The pay load 194 can include one or more discrete openings that can be moved to within the aperture opening to alter the light input. Additionally, the payload 194 can include one or more shutter regions that can be moved to block the aperture and prevent light from entering the optical instrument. The pay load 194 may not include any openings and be moved to partially block the aperture or to completely cover the aperture as in shutter mode. Several examples for payload 194 are provided by the different payloads disclosed herein. FIGS. 10A to 10B include examples of a payload that include discrete openings that can be moved within the opening of an aperture to control the light input. As noted in FIGS. 10 and 10B, FIGS. 7A, 7B, 9A, 9B, and 11 A to 12B also show examples of payloads that can be used.

[0042] FIG. 1C illustrates a block diagram of an example of a computing device operating as a controller 196 for a RETHCO system in accordance with this disclosure. The controller 196 includes one or more communications interface, represented by interface 197, one or more memory or data storage, represented by memory 198, and one or more processors represented by processor199. The components of the controller 196 can be communicatively coupled via conventional connections. The interface 197 includes the necessary hardware, software, or combination thereof to receive and send data, such as for communicating analog or digital electrical signals. Examples of the data include processing inputs that are received and operating signals that are sent. The interface 197 can be a conventional interface that communicates via various communication systems, connections, busses, etc., according to protocols, such as standard protocols or proprietary protocols (e.g., interface 197 may support I2C, USB, RS232, SPI, or MODBUS). Data can be received by the controller 196 via the interface 197 and stored in the memory 198 for processing by the processor 199. A user interface, such as a keyboard, touch screen, keypad, etc, can be used to input data to the controller 196 via the interface 197. For example, look-up tables, predetermined light input settings, and other data can be manually input into the controller 196 via the interface 197, stored in the memory 198, and processed by the processor 199. The memory 198 is configured to store the various software and digital data aspects related to the controller 196. Additionally, the memory 198 is configured to store a series of operating instructions corresponding to an algorithm or algorithms that direct the operation of the processor 199 when initiated to, for example, direct the operation of a RETHCO system to alter the light input for an optical instrament. The directing may include instructing an actuator to move a movement device and therefore a payload to obtain the desired light input. The memory 198 can be a non-transitory computer readable medium (e.g., flash memory and / or other media).

[0044] The processor 199 is configured to direct the operation of the RETHCO system. As such, the processor 199 includes the necessary logic to communicate with the interface 197 and the memory 198 and perform the functions described herein to obtain a desired light input for an optical instrument.

[0045] Memory 198 and processor 199 may act upon stored instructions and algorithms such as provide control of actuator 192, movement device 193, and payload 194. Algorithms may include, for example, instructing a stepper motor to increase a step count and rotate a cam until a flexure moves a payload to achieve a specific position, a predetermined signal level change, or an alteration of the resolution of the spectrometer.

[0046] FIGS. 2A-4B are plots of a typical IEP optical signal (spectrum) and modifications made thereto by one or more elements or methods disclosed herein. Specifically, FIG. 2A is a plot 200 of a typical OES (optical emission spectrum) optical signal (spectrum) collected from a semiconductor process plasma, in accordance with one embodiment of this disclosure. For the following discussion reference will be made to individual spectral features (lines) such as line 230 which is indicated. Line 230 generally represents the well-known hydrogen emission line at 656 nm. Proximate to line 230, but not specifically indicated, also exist emission lines from bromine that is also used within the process monitored and producing the observed plasma. The relationship between the observations of hydrogen and bromine will be detailed more in discussion of the following figures and discussion of a problem addressed by one or more embodiments of the current disclosure.

[0047] FIG. 2B is a plot 250 of a magnified portion of the spectrum of plot 200 showing further details of the hydrogen line and locally convolved bromine lines. Monitoring of the intensity of line 230 may be suitable for processes where differentiation of the hydrogen and bromine is not required. This may include certain higher power etch process like dielectric mask “open” etch processes.

[0048] FIG. 3A is a plot 300 of a magnified portion of the spectrum of plot 200 showing details of a different hydrogen line 330 and different bromine lines 335 and 340. Monitoring of the intensity of lines 330, 335, and 340 may be suitable for processes where differentiation of the hydrogen and bromine is required. This may include certain etch process where lower power and precise control is required. The spectrum of plot 300 was collected with identical resolution and throughput conditions as the spectrum of plot 200. Although the individual lines are visually separated, automated processing can be challenging since signal-to-noise is small due to low throughput. Altering the throughput and relatedly the resolution, as discussed herein, can provide improved signal-to-noise and therefore improved process control capability.

[0049] FIG. 3B is a plot 350 of a magnified portion of a spectrum showing the changes in the spectrum that result from altering the resolution and throughput of the spectrometer. The decrease in resolution increased the spectral bandwidth which results in greater convolution of the threelines but also results in greater overall signal and improved signal-to-noise which improves process control capability.

[0050] FIG. 4A is a plot 400 of a magnified portion of a spectrum 430 showing the changes in the spectrum that result from further altering the resolution and throughput of the spectrometer. The further decrease in resolution further increases the spectral bandwidth which results in greater convolution of the three lines but also results in greater overall signal and improved signal-to-noise which improves process control capability. However, the further increased spectral convolution may have an adverse effect in the process capability to detect changes between the hydrogen and bromine lines.

[0051] FIG. 4B is a plot 450 of a magnified portion of a spectrum 430 showing the changes in the spectrum that result from again further altering the resolution and throughput of the spectrometer. In this case, although the signal levels are greatly increased, differentiation of the hydrogen lines is greatly decreased due to the high spectral convolution and process control capability is actually reduced.

[0052] These above examples simplify and showcase the resolution and throughput trade-off and the need for adaptation and configurability. It should also be noted that regardless of the alteration of the resolution and throughput, a signal offset remains and depending upon the resultant signal levels may have more or less an effect upon the signal-to-noisc and the process capability.

[0053] FIG. 5 is an image of an example of an aperture for an optical instrument that is a typical optical slit 500 and a summary of representative positional requirements. Slit 500 as the input aperture to a spectrometer generally controls the resolution and optical throughput of the system. Slit 500 is generally made from a thin metal plate with an actual slit aperture which allows the transmission of light from some external source, e.g., fiberoptical cable, and passes that light into the spectrometer for processing, collection, and conversion. Location and positional tolerances, stability, and repeatability of the slit aperture are critical for consistent operation of a spectrometer. Typically for a fixed slit substrate, these requirements are met with reasonablecaution. For the systems and methods discussed herein, where all or a portion of the slit aperture may be moved there is added complexity.

[0054] Each of the six degrees of freedom for a slit aperture will be described as follows. Translating motion in the X-axis direction contributes to defocus of the image of the slit on the imaging sensor within the spectrometer causing variation in optical resolution. Motion in this direction greater than ±0.001” (±25 pm) can be problematic. In the case of an underfilled uniform slit aperture, translating motion in the Y -axis direction may provide limited adverse contributions spectrometer performance. Motion should be limited due to non-ideality of slit apertures but variation on the order of ±0.004” (±100 pm) may be acceptable. Translating motion in the Z-axis direction contributes to image shift and wavelength calibration shift on the imaging sensor within the spectrometer causing variation in optical resolution. Motion in this direction greater than ±0.001 (±25 pm) can be problematic.

[0055] Rotating motion about the X-axis direction contributes to image shift and wavelength calibration shift on the imaging sensor within the spectrometer causing variation in optical resolution. Rotating motion about the X-axis couples to translations in the YZ plane. A rotation of approximately ±1° of the slit aperture about its centerline equates to approximately ±35 pm of Z- axis translation with similar resultant calibration shift. Rotating motion about the Y-axis direction contributes to both image shift and defocus on the imaging sensor within the spectrometer causing variation in optical resolution and calibration. Rotating motion about the Y-axis couples to translations in the XZ plane. A rotation of approximately ±1° of the slit aperture about its centerline equates to approximately 1-10 pm of X-axis and / or Z-axis translation with similar’ resultant calibration and resolution shifts. Rotating motion about the Z-axis direction contributes to defocus on the imaging sensor within the spectrometer causing variation in optical resolution. Rotating motion about the Z-axis couples to translations in the XY plane. A rotation of approximately ±1° of the slit aperture about its centerline equates to approximately ±35 pm of X-axis translation with similar resultant resolution shifts.

[0056] FIG. 6 shows a pair of simplified 2D images of an example of a movement device in the form of a flexure 610 and an actuator system or simply actuator 620, which provides capabilityfor positional variation of a slit aperture within the requirements discussed herein above. The flexure 610 is a parallelogram flexure and the actuator 620 is a cam. Image 600 shows the combination flexure and actuator in a position where the cam provided the least displacement of the flexure and results in the flexure retracting as indicated. This position is at a first limit of the stroke of the flexure. This may be termed an “open” or “retracted” position. Image 650 shows the combination flexure and actuator in a position where the cam provided the most displacement of the flexure and results in the flexure extending as indicated. This position is at a second limit of the stroke of the flexure. This may be termed an “closed” or “extended” position.

[0057] The degree of extension or retraction of the flexure may be used to controllably position a slit aperture while maintaining the positional requirements over a ~10 year lifetime that may include tens of millions of cycle. The flexure and actuator system may also provide a repositioning time on the order of 1 second or less. The flexure and actuator system is also replaceable and may be configured to support a number of different pay loads including slits with desirable slit apertures, shutter mechanisms, and / or combinations thereof. Although the discussion herein is directed toward parallelogram flexures and cam-style actuators, it should be understood that different flexures and actuators are possible. Often in optical instruments space is limited so smaller is better.

[0058] FIGS. 7A and 7B arc 2D and 3D images, respectively, of flexure 700 suitable for the precise control of spectrometer resolution and throughput. Although, in general being monolithic, flexure 700 may be divided into multiple sections with regard to physical features and / or functionality. These sections are denoted by dashed boxes and are labeled 710, 720, 730, 740, 750 and 760. In general, flexure 700 may be a monolithic piece of materials such as 1075 or 1095 spring steel with an appropriate temper and anneal to achieve suitable elastic properties. Flexure 700 may be from approximately 1 to approximately 10 mm thick and from 50 to 100 mm on its long axis and 25 to 50 mm wide on its short axis. To support certain of the requirements discussed above flexure 700 may be manufactured via EDM (electrical discharge machining) to avoid adding stresses and distortion.

[0059] Section 710 of flexure 700 may be termed as the payload section. The function of this section is to support the slit and slit aperture, shutter flag, sensor flags and / or other items to be positioned or to be used for control of positioning. This section is connected with section 720. This section is nominally rigid. Section 720 of flexure 700 may be termed as a first fixturing section. The function of this section is to support fixturing of flexure 700 to the spectrometers and to transfer the deflection motion of the flexure to the payload section 710. A bolt or screw, including a nylon bolt, can be used in the hole of section 720 to fix the flexure to an optical instrument and still allow movement to push the payload section 710. This section is nominally rigid. Section 730 of flexure 700 may be termed as a first flexible section. The function of this section is to provide a displaceable portion of flexure 700 in response to displacement of section 740. This section is generally elastically flexible and of a cross-section much less than other portions of flexure 700. The cross-section of portions of section 730 may be on the order of 0.25 to 2 mm. The crosssection of this section is important for control of and resistance to torsional flexion of flexure 700 about its long axis. Section 740 of flexure 700 may be termed as the contact section. The function of this section is to support contact from an actuator, such as a cam, whereby displacing sections 730 and 750 with negligible internal distortion. This section is nominally rigid to minimize variations in displacement resulting from variations in the application of forces to flexure 700 by an actuator. This section is connected with sections 730 and 750. Section 750 of flexure 700 may be termed as a second flexible section. This section is similar to section 730. For symmetry of motion and stability, a symmetric design of sections 730 and 750 is important as is the symmetric application of force to section 740. Section 760 of flexure 700 may be termed as a second fixturing section. Like section 720, this section supports fixturing of flexure 700 to the spectrometers and to transfer the deflection motion of the flexure to the payload section. Bolts or screws can be used to fix the section 760 to the optical instrument via the holes shown in section 760.

[0060] Varied design of flexure 700 especially sections 730 and 740 can be employed to vary the mechanical gain of the flexure. Mechanical gain is the ratio of the displacement of the portions of flexure 700 in section 740 versus the displacement of payload section 710. The mechanical gain may range from 1:1 to 1: 16 or greater. Mechanical gain may be adjusted to control the precisionof the placement of the payload with respect to the precision of the actuator. Mechanical gain as well as other properties of flexure 700 may be altered by reconfiguration of various thicknesses and cross-sectional ratios.

[0061] Other important physical aspects of flexure 700 are those that support the positional design requirements. For example, natural harmonic oscillations that are near operating frequencies (<1 to -1000 Hz) should be avoided. Optimization of designs may be supported by FEA (finite element analysis) such as by COMSOL Multiphysics. FIGS. 8A and 8B show 2D images of harmonic flexural modes of a flexure suitable for the precise control of spectrometer resolution and throughput. Image 800 shows greatly exaggerated in-plane displacements for the lowest eigenmode of the flexure. This occurs at near 3500 Hz with a submicron displacement. Image 850 shows the greatly exaggerated out-of-plane displacements for the lowest eigenmode in this direction. This mode occurs at a natural frequency of multiple KHz and with a nominal submicron displacement. FEA may also be used to compute and verify elastic deformation limits and regions of high / low stress in the flexure. The flexure should operate within the elastic portion of the stress / strain curve of the material selected to avoid deviation and drift of the flexure positioning.

[0062] FIGS. 9A and 9B are 2D images of a flexure and actuator system integrated with a portion of a spectrometer for controlling the discrete selection between two slit apertures or one slit aperture and a shutter (zero width aperture). In FIGS. 9A and 9B an elliptical profile cam 910 is utilized to cause displacement of the flexure 920 (symmetrically in vertical directions) and resultant displacement of the payload 930 (toward the left). Other cam profiles may be used to vary the displacement / velocity vs cam angle relationship to for example provide a linear or nonlinear displacement with cam rotation angle. Cam 910 may be for example made from stainless steel or another material with good wear properties. Cam 910 may have minor / major axes lengths of 5 and 7 mm and should be thicker than the thickness of flexure 920. Cam 910 provides contact forces to displace contact portions of flexure 920. To avoid backlash and vibration in the cam / flexure system, flexure 920 should be preloaded against cam 910 with loads ranging from a few ounces to a few pounds.

[0063] As cam 910 rotates and causes the displacement of the payload section of the flexure, a portion of the flexure may altematingly abut to stop features 940 and 950. As shown in FIG. 9A, when cam 910 is contacting the flexure with its minimum displacement, the flexure is contacting stop 940. As shown in FIG. 9B, when cam 910 is contacting the flexure with its maximum displacement, the flexure is contacting stop 950. This action permits the discrete positioning of two locations for slit apertures. This is commonly referred to as “fixed” stops or “hard” stops. “Fixed” stops may be used advantageously with the cam / flexure system as the flexure provides compliance to over-running the stop supporting loading of the flexure / payload against the stop for stability. A “fixed” stop configuration also generally precludes the need for active control using position sensors, cam axis rotation encoders or other devices. “Fixed” stops may also be used advantageously with a cam which is driven by a stepper motor with torque / stall sensing capabilities. A suitable stepper motor driver chip may be for example, the Texas Instruments DRV8889 device. The screws noted in FIG. 7A that are used for fixing sections 720 and 760 a e visible in FIGS. 9 A and 9B.

[0064] FIGS. 10A and 10B are 2D images of a various slit aperture payloads which may be used with the system described herein. Payload 1000 includes a slit with three different apertures 1020, 1022, and 1024. Payload 1050 includes a slit with two different apertures 1060, 1064, and a shutter region 1062. As an alternative to the discrete slit selections provided by payloads 1000 and 1050, a payload may support continuous slit widths but including a portion, but not the entirety, of the slit aperture.

[0065] FIGS. 11A and 11B are 3D images of a portion of a spectrometer, a flexure and actuator system, and related components. Flexure 1110 may be connected with portion of spectrometer optical assembly 1120 by means of screws 1125 or other suitable fastening methods. Screws 1125 immovably retain a first end of flexure 1110 with respect to spectrometer optical assembly 1120. Stepper motor 1130 acting as a means for actuating cam 1135 may also be connected to spectrometer optical assembly 1120 via screws or other fasteners. Screw 1140 may also be used to retain flexure 1110 to spectrometer optical assembly 1120 but in a slideable manner allowing operation of the flexure but inhibiting motion in other degrees of freedom. Retainer 1160guides and positions a fiberoptical cable assembly (not shown) to spectrometer optical assembly 1120 and therefore with respect to clearance aperture plate 1170. A slit payload such as shown in FIGS. 10A-10B may be located proximate clearance aperture plate 1170 except on the side opposite retainer 1160. Clearance aperture plate 1170 may act to avoid physical contact between a slit payload (not shown) and a fiberoptical cable assembly (not shown) which may be inserted into retainer 1160. Sensors 1180 and 1181 may be used in coordination with sensor flags 1190 and 1191 to control or provide feedback upon the positioning of a slit pay load. Alternatively, an axis encoder (not shown) or other system may be utilized to control or provide feedback for the slit payload positions.

[0066] FIGS. 12A and 12B are 3D images of a differently configured flexure and actuator system, and related components. In this configuration flexure 1210 which is actuated by cam 1215 and stepper motor 1217 contains payload 1220 which includes only a shutter flag and does not include a slit or slit apertures as in previous examples herein. Upon activation and motion of flexure 1210, payload 1220 may be positioned to obscure all or part of the aperture within slit 1230. Relatedly, payload 1220 may be configured as a partial slit and slit aperture and slit 1230 may be also configured as a partial slit and slit aperture whereby the relative motion of 1220 and 1230 slit apertures of various and continuously variable slit aperture widths may be achieved. FIG 12A shows shutter payload 1220 “retracted” and not obscuring the slit aperture with slit 1230. FIG 12B shows shutter payload 1220 “advanced” and obscuring the slit aperture with slit 1230. The shown configuration may include less features and components as previous examples, for example, no position sensors or sensors flags may be required and step counting may be used with the inclusion of a homing routine. Payload 1220 can also be used with the systems of FIGS. 9A and 9B. Similarly, the payloads having discrete openings can be used in the systems of FIGS. 12A and 12B.

[0067] FIGS. 13A, 13B, 13C and 13D are simplified cross-sectional images of fiber, slit aperture, and payload combinations for dual aperture system that may be used with optical instruments as disclosed herein. The selection of fiber, slit aperture and payload combination involves various trade-offs regarding complexity, actuation and positional requirements, generalperformance, reliability, and cost. FIG. 13A shows a first combination 1300 including a single moving slit, or payload 1310, and a single fiber 1305 for illumination. Payload 1310 includes a wide slit aperture 1312 and a narrow slit aperture 1314. Wide slit aperture 1312 may have a width of approximately 50 microns or greater. Narrow slit aperture 1314 may have a width of 5 microns or greater. The relative positions of wide slit aperture 1312 and narrow slit aperture 1314 may be exchanged and any combination of slit aperture width is possible within the design capability of the optical instrument including the slit apertures. Payload 1310 may be positioned by means of various devices, systems and mechanisms as disclosed herein. Typically combination 1300 requires critically accurate positioning and repeatability of positioning for both slit apertures 1312, 1314, since in many optical instruments, such as spectrometers, slit aperture location is directly related to wavelength calibration and resolution at the micron level. Payload 1310 may also be positioned into a location intermediate either of slits 1312 and 1314 to a location without an aperture and used to provide a shuttering function. Payload 1310 corresponds to payload 1050 described above that also has two different apertures 1060, 1064, and a shutter region 1062.

[0068] FIG. 13B shows a second combination 1325 including a pay load 1335 and a fixed position slit substrate 1340 illuminated by a single fiber 1330. Payloadl335 includes a wide access aperture 1337 and a narrow slit aperture 1339. Wide access aperture 1337 may have a width of approximately 50 microns or greater and should be wider than wide slit aperture 1342. Narrow slit aperture 1339 may have a width of 5 microns or greater. The relative positions of wide access aperture 1337 and narrow slit aperture 1339 may be exchanged and any combination of slit aperture and access aperture width is possible within the design capability of the optical instrument including the slit apertures. Payload 1335 may be positioned by means of various devices, systems and mechanisms as disclosed herein. Slit 1340 includes wide slit aperture 1342. For high resolution or high light level operation, Pay load 1335 is positioned so that slit aperture 1339 is located between fiber 1330 and wide slit aperture 1342. Light exiting fiber 1330 is apertured by slit aperture 1339 and passes, generally without effect, through wide slit aperture 1342. For low resolution or low light level operation, pay load 1335 is positioned so that wide access aperture 1337 is located between fiber 1330 and wide slit aperture 1342. To provide a shuttering function,pay load 1335 is positioned intermediate to or beyond either of slit aperture 1339 and access aperture 1337 and light exiting fiber 1330 is blocked from entering wide slit aperture 1342. Compared to combination 1300, combination 1325 requires fewer accurate positions of moving components since one of the two slit apertures is fixed and the other is moving. Furthermore, the “stacking” of the two slit apertures may have an adverse influence on instrument resolution since both slit aperture planes cannot be conjugate to the detector plane at the same time depending upon the instrument depth of focus. In combinations 1300 and 1325 a clearance aperture plate, such as clearance aperture plate 1170, can be positioned between the fiber 1305 and payload 1310 and between fiber 1330 and pay load 1335. A clearance aperture plate allows isolating a moveable payload from contacting a fixed fiber. In one alternative, a gap / space between the fiber and the moveable payload can be used.

[0069] FIG. 13C shows a third combination 1350 including a fixed slit substrate 1360 and a moving selector pay load 1365 illuminated by dual fibers 1355 and 1357. Slit 1360 includes a wide slit aperture 1362 and a narrow slit aperture 1364. Wide slit aperture 1362 may have a width of approximately 50 microns or greater and should generally be wider than narrow slit aperture 1364. Narrow slit aperture 1364 may have a width of 5 microns or greater. The relative positions of wide slit aperture 1362 and narrow slit aperture 1364 may be exchanged and any combination of slit aperture and access aperture width is possible within the design capability of the optical instrument including the slit apertures. Moving selector payload 1365 may be positioned by means of various devices, systems and mechanisms as disclosed herein. Moving selector payload 1365 includes at least one access aperture 1367 which should be wider than wide slit aperture 1362. For high resolution or high light level operation, moving selector pay load 1365 is positioned so that access aperture 1367 is located to permit light exiting from fiber 1355 to pass through slit aperture 1364 to further enter into the optical instrument. For low resolution or low light level operation, moving selector payload 1365 is positioned so that access aperture 1367 is located to permit light exiting from fiber 1357 to pass through slit aperture 1362 to further enter into the optical instrument. To provide a shuttering function, moving selector payload 1365 is positioned so that access aperture 1367 is not aligned with neither slit aperture 1362 nor slit aperture 1364 and light exiting bothfiber 1355 and 1357 is blocked from entering the optical instrument. The inclusion of two or more access apertures into moving selector payload 1365 may provide increased flexibility of positioning and / or control and support selection of more than one fiber and slit aperture combination. Compared to combinations 1300 and 1325, combination 1350 requires fewer accurate positions of moving components since both of the two slit apertures 1362, 1364, are fixed. Furthermore, although there is “stacking” of the slit 1360 and moving selector pay load 1365, both slits reside on the same conjugate plane and are not subject to variable defocus. As detailed herein below the positioning of the access apertures in the moving selector payload requires considerably less precision and accuracy than if an actual slit substrate containing any apertures, which is closer to the optical fiber, was to be positioned. This combination may require twice as much optical fiber to be provided as combinations 1300 and 1325. .

[0070] FIG. 13D shows a fourth combination 1375 including a fixed slit substrate 1385 and two moving selector payloads 1390 and 1395 illuminated by dual fibers 1380 and 1382. Slit 1385 includes a wide slit aperture 1387 and a narrow slit aperture 1389. Wide slit aperture 1387 may have a width of approximately 50 microns or greater and should generally be wider than narrow slit aperture 1389. Narrow slit aperture 1389 may have a width of 5 microns or greater. The relative positions of wide slit aperture 1387 and narrow slit aperture 1389 may be exchanged and any combination of slit aperture and access aperture width is possible within the design capability of the optical instrument including the slit apertures.

[0071] Moving selector payloads 1390 and 1395 may be positioned by means of various devices, systems and mechanisms as disclosed herein. Moving selector payload 1390 includes at least one access aperture 1392 which may be wider than wide slit aperture 1387. Moving selector payload 1395 includes at least one access aperture 1397 which may be wider than narrow slit aperture 1389. For high resolution or high light level operation, moving selector payload 1390 is positioned so that access aperture 1392 and moving selector payload 1395 is positioned so that access aperture 1397 are located to permit light exiting from fiber 1380 to pass through slit aperture 1389 to further enter into the optical instrument.

[0072] For low resolution or low light level operation, moving selector payload 1390 is positioned so that access aperture 1392 and moving selector pay load 1395 is positioned so that access aperture 1397 are located to permit light exiting from fiber 1382 to pass through slit aperture 1387 to further enter into the optical instrument. To provide a shuttering function, moving selector pay loads 1390 and 1395 are positioned so that access apertures 1392 and 1397 are not aligned with either slit aperture 1387 or slit aperture 1389 and light exiting both fiber 1380 and 1382 is blocked from entering the optical instrument. Compared to combinations 1300, 1325, and 1350, combination 1375 more readily permits selection of either slit aperture or the shutter function by binary action such as by using a cantilever flexure where typically only two positions are controllable. In combinations 1300, 1325, and 1350, each of the respective single payloads require three positions to use the respective slit apertures and provide a shutter function. Therefore, a stepper motor drive or other driver is needed to move the payloads to more than two positions.

[0073] FIGS. 14A and 14B are cross-sectional images of a slit aperture and payload combination corresponding to FIG 13C, wherein the moveable payload is located on the non-fiber side of a fixed slit aperture. FIG. 14A shows an example of the combination corresponding to FIG 13C wherein the moving selector payload 1420 is positioned with respect to the slit substrate 1410 and a wide slit aperture (not indicated) and light 1430 is thereby permitted to enter into the instrument. FIG. 14B shows an example of the combination corresponding to FIG 13C wherein the moving selector payload 1420 is positioned with respect to the slit 1410 and a narrow aperture (not indicated) and light 1480 is thereby permitted to enter into the instrument.

[0074] FIGS. 15A and 15B are plan-view drawings of a slit aperture and pay load combination corresponding to FIG 13C. Payload 1500 may be formed from a flat rectangular metal plate large enough to structurally support the required access aperture(s). For example, payload 1500 may be 10 x 10 mm and 0.01 mm thick. Access aperture region 1530 is enlarged and detailed in FIG. 15B. Slit 1525 may be formed from a flat rectangular metal plate large enough to structurally support the required slit aperture(s). For example, slit 1525 may be 10 x 20 mm and 0.01 mm thick. Slit aperture region 1545 is enlarged and detailed in FIG. 15B. Access aperture region 1530 includes a wide access aperture 1535 and a narrow access aperture 1537. Slit aperture region 1545 includesa wide slit aperture 1547 and a narrow slit aperture 1549. Slit aperture 1547 may be for example 125 microns wide by 3 mm tall and slit aperture 1549 may be for example 25 microns wide by 3 mm tall. Access aperture 1535, may be designed to allow passage of light from slit aperture 1547 and may therefore be wider and taller than slit aperture 1547. For example, access aperture 1535 may be 225 microns wide and 5 mm tall. Access aperture 1537 may be designed to allow passage of light from slit aperture 1549 and may therefore be wider and taller than slit aperture 1549. For example, access aperture 1537 may be 125 microns wide and 5 mm tall. Payload 1500 and slit 1525 correspond to, for example, payload 1420 and fixed slit aperture 1410 of FIGS. 14A and 14B.

[0075] The relative widths of associated access apertures and slit aperture may be chosen to support ease of positioning of a moving payload with respect to a desired slit aperture. As defined above for this example the access aperture are each 100 microns wider than their respective slit apertures. This allows for a nominal positioning variation of + / - 50 microns without adverse effects upon the passage of light through the combination of slit aperture and access aperture. The relative distance between slit apertures may defined with respect to desired properties such as manufacturability and crosstalk. For example, material between slit apertures 1547 and 1549 must be able to support the mechanical function of the apertures without excess flexibility or distortion. Additionally depending upon the configuration of fibers illuminating the slit apertures, the slit apertures may be closer or farther apart to control stray light and / or crosstalk between the signals provided by the fibers. The relative distance between access apertures may be defined with respect to the same requirements as for the slit apertures but may also include allowances for shutter functionality. As shown in FIG. 15B, the distance between access apertures is much larger than the distance between slit apertures to allow for a shutter region between the positions associated with selecting of either slit aperture. Distances between access apertures is subject to available motion in the direction required for selection of the slit apertures provided by the chosen actuator and mechanism.

[0076] FIGS. 16A, 16B, and 16C are images of a slit aperture and payload combination corresponding to FIG 13C showing selection of either a slit aperture or of a shutter position. FIG.16A shows a portion of flexure 1610 supporting and positioning selector payload 1620 and aligning wide access aperture 1630 with wide slit aperture 1635. Alignment of access aperture 1630 with slit aperture 1635 may be achieved in this example by contacting stop feature 1640 and flexure integrated stop 1645. Stops 940 and 950 of FIGS. 9A and 9B provides examples of stops that correspond to stops 1640 and 1650. FIG. 16B shows a portion of flexure 1610 supporting and positioning selector pay load 1620 and aligning narrow access aperture 1632 with narrow slit aperture 1637. Alignment of access aperture 1632 with slit aperture 1637 may be achieved in this example by contacting stop feature 1650 and flexure integrated stop 1655. The wide access aperture 1630 and the narrow access aperture 1632 are represented by gray in FIGS. 16A to 16C and integrated with the pay load 1620. The wide slit aperture 1635 and the narrow slit aperture 1637 are represented by black in FIGS. 16A to 16C and are fixed. FIG. 16C shows a portion of flexure 1610 supporting and positioning selector payload 1620 and positioning selector payload 1620 such that neither slit aperture is aligned with its corresponding access aperture. This provides a so-called shutter position and blocks light entering into the instrument. In this example, positioning of selector payload 1620 is not achieved by contact between stops but via step counting of a stepper motor actuating the flexure, a position sensor (not shown), or other means. In FIGS. 16A, 16B, and 16C, payload 1620 corresponds to payload 1420 and / or 1365.

[0077] FIGS. 17A, 17B, and 17C arc images of a fiber, slit aperture, and payload combination corresponding to FIG 13C showing selection of either a slit aperture or of a shutter position. FIG. 17A shows two rows of 200-micron optical fibers 1700 and 1710, which can represent fibers 1357 and 1355, in a nested arrangement. Slit apertures 1720 and 1730 are each generally aligned with a single row of the optical fibers, i.e., slit aperture 1720 is aligned with fiber row 1700 and slit aperture 1730 is aligned with fiber row 1710. In this example, slit aperture 1720 is shown darked to indicate that a selector payload aperture (not shown) is aligned with slit aperture 1720 to allow light to enter into the instrument via fiber row 1700. FIG. 17B shows portions of two rows of 200 micron optical fibers 1700 and 1710 in a nested arrangement. Slit apertures 1720 and 1730 are each generally aligned with a single row of the optical fibers, i.e., slit aperture 1720 is aligned with fiber row 1700 and slit aperture 1730 is aligned with fiber row 1710. In this example, slit aperture1730 is shown darked to indicate that a selector payload aperture (not shown) is aligned with slit aperture 1730 to allow light to enter into the instrument via fiber row 1710. FIG. 17C shows portions of two rows of 200 micron optical fibers 1700 and 1710 in a nested arrangement. Slit apertures 1720 and 1730 are each generally aligned with a single row of the optical fibers, i.e., slit aperture 1720 is aligned with fiber row 1700 and slit aperture 1730 is aligned with fiber row 1710. In this example, neither slit aperture is shown darked to indicate that no selector payload aperture (not shown) is aligned with any slit aperture and light is not allowed to enter into the instrument.

[0078] FIGS. 18A and 18B are images of alternative fiber, slit aperture, and payload combinations corresponding to FIG 13C.

[0079] FIG. 18A shows portions of two rows of 200 micron optical fibers 1800 and 1810 in a square arrangement. Slit apertures 1820 and 1830 are each generally aligned with a single row of the optical fibers, i.e., slit aperture 1820 is aligned with fiber row 1800 and slit aperture 1830 is aligned with fiber row 1810. In this example, slit aperture 1820 is shown darked to indicate that a selector pay load aperture (not shown) is aligned with slit aperture 1820 to allow light to enter into the instrument via fiber row 1800. FIG. 18B shows a portion of a row of 600 micron optical fibers 1850. Slit apertures 1820 and 1830 are each illuminated by this single row of fibers in contrast to the examples of FIGS. 17A-17C and FIG. 18A. In this example, slit aperture 1820 is shown darked to indicate that a selector pay load aperture (not shown) is aligned with slit aperture 1820 to allow light to enter into the instrument via fiber row 1850. In general, any number of slit apertures may be aligned to one or more rows of optical fibers subject to geometric limitations and considerations of efficiency of signal coupling. FIGS. 19A and 19B are plots of signal coupling efficiency curves for various fiber diameters and slit aperture widths. FIG. 19A shows plot 1900 that presents the signal coupling efficiency for a 125 micron wide slit aperture to optical fibers of various diameters as the slit aperture is offset with respect to the center of each fiber. Curves 1920 relate to 200 micron core fibers. Curves 1930 relate to 400 micron core fibers. Curves 1940 relate to 600 micron core fibers. Within each set of curves the dashed curve represents the coupling efficiency with the buffer removed from the fiber and the solid curve represents the fiber with thebuffer not removed. As may be seen by observation of the various curves, larger core fibers are less sensitive to displacements of the slit aperture from the center of the fibers.

[0080] FIG. 19B shows plot 1950 that presents the signal coupling efficiency for a 17 micron wide slit aperture to optical fibers of various diameters as the slit aperture is offset with respect to the center of each fiber. Curves 1960 relate to 100 micron core fibers. Curves 1970 relate to 200 micron core fibers. Curves 1980 relate to 400 micron core fibers. Curves 1990 relate to 600 micron core fibers. Within each set of curves the dashed curve represents the coupling efficiency with the buffer removed from the fiber and the solid curve represents the fiber with the buffer not removed. As may be seen by comparing plot 1900 and plot 1950, the 17 micron slit aperture may be displaced considerably more than the 125 micron slit aperture before an edge of the slit aperture is displaced from the illuminating fiber. FIGS. 20A and 20B are plots of signal coupling efficiency and signal area for a 600-micron diameter fiber coupled to 125- and 17-micron width slit apertures. The specific associations of slit aperture widths, fiber diameters, and fiber to slit aperture centerline displacements can provide multiple methods for defining and controlling input signal level range for an optical instrument and the resultant dynamic range of the instrument. FIG. 20A shows plot 2000 that presents the signal coupling efficiency for 17 and 125 micron wide slit apertures to 600 micron core diameter optical fibers as the slit aperture is offset with respect to the center of the fiber. Curves 2010 relate to a 125 micron wide slit aperture. Curves 2020 relate to a 17 micron wide slit aperture. Within each set of curves the dashed curve represents the coupling efficiency with the buffer removed from the fiber and the solid curve represents the fiber with the buffer not removed. As may be seen by comparing curves 2010 and 2020, the 17 micron slit aperture and the 125 micron slit aperture may be positioned with respect to the centerline of a 600 micron core fiber to each achieve approximately 80% coupling efficiency and the varying one of both relative displacements, the relative efficiency may be adjusted. FIG. 20B shows plot 2050 that presents the signal coupling as a function of coupling area for 17 and 125 micron wide slit apertures to 600 micron core diameter optical fibers as the slit aperture is offset with respect to the center of the fiber. Curve 2060 relates to a 125 micron wide slit aperture. Curve 2070 relates to a 17 micron wide slit aperture. Each curve the coupling area with the buffer not removed. As may be seen bycomparing curves 2060 and 2070, the signal range and dynamic range of the system may be adjusted over a range greater than the nominal slit aperture width ratio (125 / 17 ~ 7.35) to much less than the nominal ratio by adjusting the relative slit aperture width in association with the relative displacement of the slit aperture centerlines to the fiber centerline.

[0081] FIG. 21 illustrates a flow diagram of an example of a method 2100 for operating a RETHCO carried out according to the principles of the disclosure. A controller, such as represented in FIGS. IB and 1C, can perform one or more of the steps of method 2100 to obtain a desired light input for an optical instrument. The steps of method 2100 represent one or more algorithms directed to obtaining a desired light input for an optical instrument to process light. The method 2100 starts in step 2105.

[0082] In step 2110, a processing input is received. The processing input can be received before, during, or after processing of the light by the optical instrument. The processing input can be automatically sent to the controller via a processing chamber, the optical instrument, a signal processor, or another component of a processing system, such as represented in FIG. 1. The processing input can also be manually input by a user.

[0083] In step 2120, a light input for the optical instrument is determined based on the processing input. The controller can use a look-up table that has been uploaded to determine the light input from the processing input. For example, the processing input can indicate a processing stage of a processing chamber and the controller can determine the light input from a look-up table using the processing stage. This can occur multiple times in response to changes of the processing stages. The controller can also calculate or determine a light input based on the processing input. For example, the controller can receive a processing input that identifies the type of light that is being processed or is expected to be processed by the optical instrument and can determine the optimal light input for processing that type of light. A look-up table can also be used in this example based on the type of light and historical data. The processing input can also indicate the light that is being processed by the optical instrument or has recently been processed by the optical instrument. In other words, one or more processors can determine the type of light being processed and provide a processing input that indicates the type light being processed. The one or moreprocessors can determine light input or the processing input based on processing information received from the optical instrument during processing of the light.

[0084] In step 2130, a control system is directed to provide the light input for the optical instrument. The control system can be a RETHCO system as disclosed herein. The controller can send operating signals to move a payload as disclosed herein to achieve the desired light input. As disclosed herein, more than one payload can be used.

[0085] In step 2140, the light input is altered upon receipt of another processing input. The processing input could indicate a shutter mode that blocks the aperture of the optical device or could indicate a change is a processing stage, light being processed, etc. The light input can be altered by the controller sending operating signals to move a payload.

[0086] In step 2150, the method ends.

[0087] A spectrometer as noted herein may advantageously incorporate a RETHCO. The spectrometer may receive optical signals from external optics and may, following integration and conversion, send data to external systems, which may also be used to control the spectrometer, such as selecting a mode of operation or controlling integration timing as defined herein. The spectrometer may include an optical interface such as an SMA or FC fiber optic connector or other opto-mechanical interface. Further optical components such as slits, lenses, filters and gratings may act to form, guide and chromatically separate the received optical signals and direct them to a sensor for integration and conversion. The RETHCO can also work with the optical components to obtain the optimum light input for processing. Low-level functions of the sensor may be controlled by elements such as an FPGA and processor. Following optical to electrical conversion signals may be directed to an A / D convertor and converted from electrical to digital signals which may then be stored in a memory for immediate or later use and transmission such as to an external systems (c.f., signal processor 170 of FIG 1A).

[0088] The changes described above, and others, may be made in the optical measurement systems and subsystems described herein without departing from the scope hereof. For example, although certain examples are described in association with semiconductor wafer processing equipment, it may be understood that the optical measurement systems described herein may beadapted to other types of processing equipment such as roll-to-roll thin film processing, solar cell fabrication or any application where high precision optical measurement may be required. Furthermore, although certain embodiments discussed herein describe the use of a common light analyzing device, such as an imaging spectrograph, it should be understood that multiple light analyzing devices with known relative sensitivity may be utilized. Furthermore, although the term “wafer” has been used herein when describing aspects of the current invention, it should be understood that other types of workpieces such as quartz plates, phase shift masks, LED substrates and other non- semiconductor processing related substrates and workpieces including solid, gaseous and liquid workpieces may be used.

[0089] The embodiments described herein were selected and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated. The particular embodiments described herein are in no way intended to limit the scope of the present invention as it may be practiced in a variety of variations and environments without departing from the scope and intent of the invention. Thus, the present invention is not intended to be limited to the embodiment shown, but is to be accorded the widest scope consistent with the principles and features described herein.

[0090] The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and / or flowchart illustration, and combinations of blocks in the block diagrams and / or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

[0091] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0092] As will be appreciated by one of skill in the ait, the present invention may be embodied as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects all generally referred to herein as a "circuit" or "module." Furthermore, the present invention may take the form of a computer program product on a computer-usable storage medium having computer-usable program code embodied in the medium.

[0093] Various aspects of the disclosure can be claimed including the apparatuses, systems, and methods disclosed herein. Aspects disclosed herein include:A. A resolution and throughput control system for an optical instrument including: (1) a payload, (2) an actuator, and (3) a movement device that alters light input for the optical instrument by controlling movement of the payload along a single axis in response to the actuator.B . A controller of a resolution and throughput control system for an optical instrument, including: (1) an interface that receives a processing input for the optical instrument, and (2) one or more processors to perform operations that include determining a light input for the optical instrument based on the processing input and directing the control system to provide the light input for the optical instrument.C. A method of operating a resolution and throughput control system for an optical instrument including: (1) receiving a processing input, (2) determining a light input condition forthe optical instrument based upon the processing input, (3) directing a control system to provide the light input for the optical instrument; and (4) altering the light input upon receipt of another processing input.

[0094] Each of aspects A, B, and C can have one or more of the following additional elements in combination: Element 1: wherein the single axis is one of six axes corresponding to six degrees of movement for the movement device and the movement device is configured to restrict movement in each of the remaining six degrees of movement. Element 2: wherein the movement device alters the light input by moving the pay load relative to an aperture of the optical instrument. Element 3: wherein the pay load includes at least one slit. Element 4: wherein the payload incudes two slits. Element 5: wherein the moving is discrete along the single axis. Element 6: wherein the moving is non-discrete along the single axis. Element 7: wherein the moving system is a parallelogram flexure. Element 8: wherein the actuator is a cam or a scissor mechanism. Element 9: wherein the actuator causes the moving by displacing the moving device in one direction. Element 10: wherein the actuator is a mechanical actuator. Element 11: wherein the mechanical actuator is controlled pneumatically, hydraulically, magnetically, electrically, or capacitively. Element 12: wherein the actuator is controlled by a stepper motor. Element 13: wherein the payload includes one or more discrete openings of different sizes. Element 14: wherein the one or more discrete openings arc slits. Element 15: wherein the payload includes a shutter region. Element 16: wherein the payload includes no openings. Element 17: further comprising a controller that directs operation of the actuator. Element 18: wherein the payload is a first pay load and the system further includes a second payload and the light input is altered by moving either the first pay load or the second pay load. Element 19: wherein the movement device is a first movement device and the system further includes a second movement device, wherein the first movement device is dedicated to moving the first payload and the second movement device is dedicated to moving the second payload. Element 20: wherein the first and second movement devices only move the first and second payloads, respectively, to two different positions. Element 21: wherein the first and second movement devices move the first and second pay loads to shutter the light input. Element 22: wherein the first or second movement devices alter the light input bymoving the first or second payloads relative to an aperture of the optical instrument. Element 23: wherein the first or second movement devices alter the light input by moving both the first and second payloads relative to an aperture of the optical instrument. Element 24: wherein the first or second movement devices alter the light input by moving at least one of the first or second payloads relative to an aperture of the optical instrument and at least one of the first and second payloads includes at least one slit. Element 25: the first or second pay loads relative to an aperture of the optical instrument and at least one of the first and second pay loads includes two slits. Element 26: wherein the optical instrument is a spectrometer.

Claims

IN THE CLAIMS:

1. A resolution and throughput control system for an optical instrument, comprising: a payload; an actuator; and a movement device that alters light input for the optical instrument by controlling movement of the payload along a single axis in response to the actuator.

2. The control system as recited in Claim 1, wherein the single axis is one of six axes corresponding to six degrees of movement for the movement device and the movement device is configured to restrict movement in each of the remaining six degrees of movement.

3. The control system as recited in Claim 1, wherein the movement device alters the light input by moving the payload relative to an aperture of the optical instrument.

4. The control system as recited in Claim 3, wherein the payload includes at least one slit.

5. The control system as recited in Claim 3, wherein the payload incudes two slits.

6. The control system as recited in Claim 1, wherein the moving is discrete along the single axis.

7. The control system as recited in Claim 1, wherein the moving is non-discrete along the single axis.

8. The control system as recited in Claim 1, wherein the moving system is a parallelogram flexure.

9. The control system as recited in Claim 1, wherein the actuator is a cam or a scissor mechanism.

10. The control system as recited in Claim 9, wherein the actuator causes the moving by displacing the moving device in one direction.

11. The control system as recited in Claim 1, wherein the actuator is a mechanical actuator.

12. The control system as recited in Claim 11, wherein the mechanical actuator is controlled pneumatically, hydraulically, magnetically, electrically, or capacitively.

13. The control system as recited in Claim 1, wherein the actuator is controlled by a stepper motor.

14. The control system as recited in Claim 1 , wherein the payload includes one or more discrete openings of different sizes.

15. The control system as recited in Claim 14, wherein the one or more discrete openings are slits.

16. The control system as recited in Claim 14, wherein the payload includes a shutter region.

17. The control system as recited in Claim 1, wherein the payload includes no openings.

18. The control system as recited in Claim 1, further comprising a controller that directs operation of the actuator.

19. The control system as recited in Claim 1, wherein the payload is a first payload and the system further includes a second payload and the light input is altered by moving either the first payload or the second payload.

20. The control system as recited in Claim 19, wherein the movement device is a first movement device and the system further includes a second movement device, wherein the first movement device is dedicated to moving the first payload and the second movement device is dedicated to moving the second payload.

21. The control system as recited in Claim 20, wherein the first and second movement devices only move the first and second payloads, respectively, to two different positions.

22. The control system as recited in Claim 21, wherein the first and second movement devices move the first and second payloads to shutter the light input.

23. The control system as recited in Claim 22, wherein the first or second movement devices alter the light input by moving the first or second payloads relative to an aperture of the optical instrument.

24. The control system as recited in Claim 22, wherein the first or second movement devices alter the light input by moving both the first and second payloads relative to an aperture of the optical instrument.

25. The control system as recited in Claim 22, wherein the first or second movement devices alter the light input by moving at least one of the first or second payloads relative to an aperture of the optical instrument and at least one of the first and second payloads includes at least one slit.

26. The control system as recited in Claim 22, wherein the first or second movement devices alter the light input by moving at least one of the first or second payloads relative to an aperture of the optical instrument and at least one of the first and second payloads includes two slits.

27. The control system as recited in Claim 1, wherein the optical instrument is a spectrometer.

28. A controller of a resolution and throughput control system for an optical instrument, comprising: an interface that receives a processing input for the optical instrument; and one or more processors to perform operations that include: determining a light input for the optical instrument based on the processing input, and directing the control system to provide the light input for the optical instrument.

29. The controller as recited in Claim 28, wherein the directing includes instructing one or more actuators of the control system to control movement of at least one movement device of the control system to obtain the light input for the optical instrument.

30. The controller as recited in Claim 29, wherein the instructing includes sending operating signals to the one or more actuators to control the movement, wherein the operating signals initiate movement of the one or more actuators and stop movement of the one or more actuators when the light input is obtained.

31. The controller as recited in Claim 30, wherein stopping movement is based on feedback signals received via the interface from the control system.

32. The controller as recited in Claim 29, wherein the at least one movement device moves one or more payloads with respect to an aperture of the optical instrument to obtain the light input.

33. The controller as recited in Claim 29, wherein the aperture includes at least one slit aperture.

34. The controller as recited in Claim 33, wherein the aperture includes two slit apertures.

35. The controller as recited in Claim 28, wherein the processing input is a processing stage of a semiconductor process.36 The controller as recited in Claim 28, wherein the processing input is optical data from a processing chamber.

37. The controller as recited in Claim 28, wherein the processing input is a predetermined setting for the light input.

38. The controller as recited in Claim 28, wherein the processing input indicates a shutter mode.

39. The controller as recited in Claim 28, wherein the processing input indicates an operating mode of a processing chamber.

40. The controller as recited in Claim 28, wherein the processing input is determined by the one or more processors based on processing information received from the optical instrument during processing of light.

41. A method of operating a resolution and throughput control system for an optical instrument comprising: receiving a processing input; determining a light input condition for the optical instrument based upon the processing input; directing a control system to provide the light input for the optical instrument; and altering the light input upon receipt of another processing input.

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