Abstract:
The present application is directed to a novel spectrometer configured with a built-in attenuated total reflectance (ATR) and accessory compartment. In particular, an arranged sample analysis compartment provided by the spectrometer performs attenuated total reflectance analysis of a sample and includes a crystal, a tip configured to press the sample against the crystal, and a detector configured to detect light after reflection within the crystal. As part of the configuration, an actuator moves an optical element between a first position wherein the optical element receives modulated light and reflects the modulated light toward the crystal and a second position wherein the optical element does not receive the modulated light so as to instead allow an additionally configured optical component to receive the modulated light.

Description:
BACKGROUND 
     Fourier transform infrared (FTIR) spectrometers are utilized to perform accurate and efficient identification of the chemical composition of a sample. Such spectrometers typically incorporate an interferometer such as a Michelson interferometer that has a beamsplitter and a moving mirror. The interferometer modulates the beam from a source to provide an output beam in which the intensity of the radiation at various wavelengths is varied. The light may be in the near ultraviolet (UV), visible (Vis), near-infrared (NIR), mid-infrared (MIR), and/or far-infrared (FIR) wavelength ranges, and thus, is not limited to the infrared spectral region. The output beam is focused and passed through or reflected from a sample, after which the beam is collected and focused onto a detector. The detector provides a time varying output signal which contains information concerning the wavelengths of absorbance or reflectance of the sample. For example, the intensity of the output light at the one or more wavelengths is compared to the intensity of the input light at the one or more wavelengths to determine characteristics of the sample, such as the absorbance, the transmittance, the fluorescence, the reflectance, etc. Fourier analysis is performed on the output signal data to yield the measured characteristics that provide information about the identity of the components within the sample, their relative concentrations, and possibly other features of the sample. 
     Conventional FTIR spectrometers include a sample chamber in which a sample is held in a position to be exposed to the light from the interferometer. The sample may take various physical states, i.e., a liquid, a solid, or a gas, and solid samples may have various physical characteristics. For example, a solid material to be analyzed may be in the form of a block or sheet of material (e.g., polymer plastics), in the form of powders or granulates, or in specific formed shapes (e.g., pharmaceutical tablets, pills and capsules). 
     Multifunctional FTIR spectrometers perform transmission or reflection measurements, or both, on a variety of samples, including liquids and powders as well as shaped solid samples such as pharmaceutical pills and tablets. The various samples can be tested utilizing the same spectrometer system without modification of the spectrometer and without the addition or rearrangement of sample compartments and sample holders. The spectrometer includes a plurality of sample holders configured within a transmission or reflection measurement system. 
     Attenuated total reflectance (ATR) is a sampling technique used in conjunction with infrared spectroscopy that enables samples to be examined directly in the solid, liquid, or gas state without further preparation. ATR uses a property of total internal reflection resulting in an evanescent wave. Light is passed through a crystal in such a way that it reflects at least once off the internal surface in contact with the sample. This reflection forms the evanescent wave which extends into the sample. The penetration depth into the sample is determined by the wavelength of light, the angle of incidence, and the indices of refraction for the crystal and the medium being probed. The number of reflections may be varied by varying the angle of incidence. The beam is collected by a detector as it exits the crystal. Example materials for ATR crystals include germanium, zinc selenide, and diamond. 
     SUMMARY 
     In an illustrative embodiment, a spectrometer for analyzing a sample is provided. The spectrometer includes, but is not limited to, a base plate, a light source, an interferometer, an accessory compartment, a sample analysis device, a first optical element, a second optical element, and an actuator. The light source is mounted to the base plate and configured to transmit light. The interferometer is mounted to the base plate to receive light from the light source and to form modulated light. The accessory compartment is configured to accept a sample analysis accessory device and includes a first wall, a second wall, and a third wall extending from the base plate. The third wall extends between the first wall and the second wall. The first wall includes a first light port configured to accept first light. The sample analysis device is mounted to the base plate and separated from the accessory compartment by the first wall. The sample analysis device is configured to perform attenuated total reflectance analysis of a sample and includes a crystal configured to receive second light, a tip configured to press the sample against the crystal, and a detector configured to detect third light after reflection of the second light within the crystal. The first optical element is mounted to the base plate and is configured to receive and to reflect the modulated light toward the first light port to form the first light. The second optical element is mounted to the base plate. The actuator is mounted to the second optical element and is configured to move the second optical element between a first position and a second position. In the first position, the second optical element is configured to receive the modulated light and to reflect the modulated light toward the crystal to form the second light such that the first optical element does not receive the modulated light. In the second position, the second optical element does not receive the modulated light thereby unblocking the first optical element from receiving the modulated light. 
     Other principal features and advantages of the invention will become apparent to those skilled in the art upon review of the following drawings, the detailed description, and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Illustrative embodiments of the invention will hereafter be described with reference to the accompanying drawings, wherein like numerals denote like elements. 
         FIG. 1  depicts a block diagram of a spectroscopy system in accordance with an illustrative embodiment. 
         FIG. 2  depicts a perspective view of a spectrometer in accordance with an illustrative embodiment. 
         FIG. 3  depicts a right side perspective view of the spectrometer of  FIG. 2  without cover plates over an accessory compartment. 
         FIG. 4  depicts a left side perspective view of the spectrometer of  FIG. 2  without cover plates over an accessory compartment. 
         FIG. 5  depicts a top view of the spectrometer of  FIG. 2  without any cover plates. 
         FIG. 6  depicts a side view of a portion of the bench compartment of the spectrometer of  FIG. 2  in accordance with an illustrative embodiment. 
         FIG. 7  depicts a top view of an ATR compartment of the spectrometer of  FIG. 2  in accordance with an illustrative embodiment. 
         FIG. 8  depicts a left side view of the ATR compartment of  FIG. 7  in accordance with an illustrative embodiment. 
         FIG. 9  depicts a back view of the ATR compartment of  FIG. 7  with a flipper mirror in a down position in accordance with an illustrative embodiment. 
         FIG. 10  depicts a back view of the ATR compartment of  FIG. 7  with a flipper mirror in an up position in accordance with an illustrative embodiment. 
         FIG. 11  depicts a back bottom perspective view of components of the ATR compartment of  FIG. 7  in accordance with an illustrative embodiment. 
         FIG. 12  depicts a left side bottom perspective view of components of the ATR compartment of  FIG. 7  in accordance with an illustrative embodiment. 
         FIG. 13  depicts a top view of a portion of the bench compartment of the spectrometer of  FIG. 2  in accordance with a second illustrative embodiment. 
         FIG. 14  depicts a top view of the spectrometer of  FIG. 13  without any cover plates. 
         FIG. 15  depicts a top view of a portion of the bench compartment of the spectrometer of  FIG. 2  in accordance with a third illustrative embodiment. 
         FIG. 16  depicts a top view of the spectrometer of  FIG. 15  without any cover plates. 
     
    
    
     DETAILED DESCRIPTION 
     As understood by a person of skill in the art, Fourier transform infrared (FTIR) spectroscopy is a measurement technique where, instead of recording the amount of energy absorbed in each individual spectral range, the energy across the entire spectra is collected by a single detector. The light source emits broadband infrared energy that is directed into an interferometer, such as a Michelson interferometer, which splits the light. The light that comes out of the interferometer is directed into a sample compartment of a sample analysis device. The light interacts with the sample and is either transmitted through or reflected off of the surface of the sample depending on the type of analysis performed by the sample analysis device. After exiting the sample compartment, the light reaches a detector and is measured to produce a sample analysis signal. Using the Fourier transform, the sample analysis signal is transformed from the frequency domain to the time domain to obtain spectral information about the sample. Typically, the FTIR spectrometer includes a laser for internal calibration of the interferometer. 
     With reference to  FIG. 1 , a block diagram of a spectrometry system  100  is shown in accordance with an illustrative embodiment. In the illustrative embodiment, spectrometry system  100  may include a spectrometer  102  and an interfaced computing device  120  to which spectrometer  102  may be connected. Spectrometer  102  need not connect to interfaced computing device  120 . If connected, spectrometer  102  and interfaced computing device  120  may be connected directly or through a network. The network may be any type of wired and/or wireless public or private network including a cellular network, a local area network, a wide area network such as the Internet, etc. Spectrometer  102  may send and receive information to/from interfaced computing device  120 . For example, spectrometer  102  may send results obtained for a sample for storage on interfaced computing device  120 . As another example, spectrometer  102  may receive software updates from interfaced computing device  120  and/or receive commands from interfaced computing device  120 . The commands may control operation of one or more components of spectrometer  102 . Interfaced computing device  120  may include a computing device of any form factor such as a personal digital assistant, a desktop computer, a laptop computer, an integrated messaging device, a cellular telephone, a smart phone, a pager, etc. without limitation. 
     Spectrometer  102  may include an input interface  104 , a button  106 , an output interface  108 , a display  110 , a computer-readable medium  112 , a control application  114 , a communication interface  116 , and a processor  118 . Different and additional components may be incorporated into spectrometer  102 . Input interface  104  provides an interface for receiving information from the user for entry into spectrometer  102  as known to those skilled in the art. Input interface  104  may use various input technologies including, but not limited to, a keyboard, a pen and touch screen, a mouse, a track ball, a touch screen, a keypad, one or more buttons including button  106 , etc. to allow the user to enter information into spectrometer  102  or to make selections presented in a user interface displayed on display  110 . Spectrometer  102  may have one or more input interfaces that use the same or a different input interface technology. 
     Output interface  108  provides an interface for outputting information for review by a user of spectrometer  102 . For example, output interface  108  may include an interface to display  110 , a speaker, a printer, etc. Display  110  may be a thin film transistor display, a light emitting diode display, a liquid crystal display, or any of a variety of different displays known to those skilled in the art. Spectrometer  102  may have one or more output interfaces that use the same or a different interface technology. The same interface may support both input interface  104  and output interface  108 . For example, a touch screen both allows user input and presents output to the user. Display  110 , the speaker, and/or the printer further may be accessible to spectrometer  102  through communication interface  116 . 
     Computer-readable medium  112  is an electronic holding place or storage for information so that the information can be accessed by processor  118  as known to those skilled in the art. Computer-readable medium  112  can include, but is not limited to, any type of random access memory (RAM), any type of read only memory (ROM), any type of flash memory, etc. such as magnetic storage devices (e.g., hard disk, floppy disk, magnetic strips, . . . ), optical disks (e.g., CD, DVD, . . . ), smart cards, flash memory devices, etc. Spectrometer  102  may have one or more computer-readable media that use the same or a different memory media technology. Spectrometer  102  also may have one or more drives that support the loading of a memory media such as a CD or DVD. 
     Communication interface  116  provides an interface for receiving and transmitting data between devices using various protocols, transmission technologies, and media as known to those skilled in the art. Communication interface  116  may support communication using various transmission media that may be wired or wireless. Spectrometer  102  may have one or more communication interfaces that use the same or a different communication interface technology. Data and messages may be transferred between spectrometer  102  and interfaced computing device  124  using communication interface  116 . 
     Processor  118  executes instructions as known to those skilled in the art. The instructions may be carried out by a special purpose computer, logic circuits, or hardware circuits. Thus, processor  118  may be implemented in hardware, firmware, or any combination of these methods and/or in combination with software. The term “execution” is the process of running an application or the carrying out of the operation called for by an instruction. The instructions may be written using one or more programming language, scripting language, assembly language, etc. Processor  118  executes an instruction, meaning that it performs/controls the operations called for by that instruction. Processor  118  operably couples with output interface  108 , with input interface  104 , with computer-readable medium  112 , and with communication interface  116  to receive, to send, and to process information. Processor  118  may retrieve a set of instructions from a permanent memory device and copy the instructions in an executable form to a temporary memory device that is generally some form of RAM. Spectrometer  102  may include a plurality of processors that use the same or a different processing technology. 
     Control application  114  performs operations associated with controlling, maintaining, updating, etc. the operation of spectrometer  102 . Some or all of the operations described herein may be controlled by instructions embodied in control application  114 . The operations may be implemented using hardware, firmware, software, or any combination of these methods. With reference to the example embodiment of  FIG. 1 , control application  114  is implemented in software (comprised of computer-readable and/or computer-executable instructions) stored in computer-readable medium  112  and accessible by processor  118  for execution of the instructions that embody the operations of control application  114 . Control application  114  may be written using one or more programming languages, assembly languages, scripting languages, etc. 
     With reference to  FIG. 2 , a perspective view of spectrometer  102  is shown in accordance with an illustrative embodiment. The components of spectrometer  102  are mounted within or to a housing  200  and may be arranged in a variety of manners. As used in this disclosure, the term “mount” includes join, unite, connect, associate, insert, hang, hold, affix, attach, fasten, bind, paste, secure, bolt, screw, rivet, solder, weld, glue, form over, layer, and other like terms. The phrases “mounted on” and “mounted to” include any interior or exterior portion of the element referenced. As used herein, the mounting may be a direct mounting between the referenced components or an indirect mounting through intermediate components between the referenced components. 
     Housing  200  may include a plurality of walls that surround one or more of the components of spectrometer  102 . For example, housing  200  may include a top bench compartment wall  202 , a top detector wall  204 , a top accessory compartment wall  206 , a top ATR compartment wall  208 , a front detector wall  210 , a front accessory compartment wall  212 , a front ATR compartment wall  214 , a left side wall  400  (shown with reference to  FIG. 4 ), a right side wall  216 , a base plate  500  (shown with reference to  FIG. 5 ), and a back wall  502  (shown with reference to  FIG. 5 ). In an illustrative embodiment, electrical connectors that may embody an interface for input interface  104 , output interface  108 , and communication interface  116  are mounted in back wall  502 . In the illustrative embodiment, button  106  is mounted on top ATR compartment wall  208  and triggers the operation of spectrometer  102  either on or off. Thus, measurements may be initiated by selecting button  106  that triggers initiation of a measurement sequence by one or more components of spectrometer  102  under control of control application  114 . 
     In the illustrative embodiment, a bench compartment is housed generally between top bench compartment wall  202 , base plate  500 , left side wall  400 , right side wall  216 , and back wall  502 . In the illustrative embodiment, a detector compartment is housed generally between top detector wall  204 , base plate  500 , left side wall  400 , the bench compartment, an accessory compartment  300  (shown with reference to  FIG. 3 ), and front detector wall  210 . In the illustrative embodiment, accessory compartment  300  is housed generally between top accessory compartment wall  206 , floor plate  302  (shown with reference to  FIG. 3 ), the bench compartment, the detector compartment, an ATR compartment, and front accessory compartment wall  212 . In the illustrative embodiment, the ATR compartment is housed generally between top ATR compartment wall  208 , base plate  500 , the bench compartment, accessory compartment  300 , front ATR compartment wall  214 , and right side wall  216 . Other compartment arrangements are possible. In the illustrative embodiment, right side wall  216  includes a first light port  218 , front detector wall  210  includes a detector output port  220 , and an ATR arm  222  is mounted to top ATR compartment wall  208  for rotational movement of ATR arm  222  toward and away from top ATR compartment wall  208 . ATR arm  222  may include an ATR knob  224 . 
     With reference to  FIG. 3 , a right side perspective view of spectrometer  102  is shown in accordance with an illustrative embodiment with top accessory compartment wall  206  and front accessory compartment wall  212  removed to show accessory compartment  300 . With reference to  FIG. 4 , a left side perspective view of spectrometer  102  is shown in accordance with an illustrative embodiment with top accessory compartment wall  206  and front accessory compartment wall  212  removed to show accessory compartment  300 . Accessory compartment  300  may be defined by top accessory compartment wall  206 , front accessory compartment wall  212 , floor plate  302 , a left accessory compartment wall  304 , a back accessory compartment wall  306 , and a right accessory compartment wall  402  (shown with reference to  FIG. 4 ). In the illustrative embodiment, left accessory compartment wall  304  includes a second light port  308  through which light can be provided from accessory compartment  300  to the detector compartment depending on a type of sample analysis accessory device mounted within accessory compartment  300 . Though not shown, accessory compartment  300  includes one or more electrical connectors that may provide power to the sample analysis accessory device mounted within accessory compartment  300 , may receive signals from the sample analysis accessory device mounted within accessory compartment  300 , and/or may send signals to the sample analysis accessory device mounted within accessory compartment  300 . The signals may be sent/received by spectrometer  102  and/or by interfaced computing device  124 . Illustrative sample analysis accessory devices include a gas chromatography (GC) IR (GC-IR) device, a near IR (NIR) integrating sphere device, a NIR or mid-IR (MIR) fiber optic probe, a thermogravimetric analysis (TGA) device, an IR microscope, an FT-Raman device, a diffuse reflectance device, a single-bounce or multiple-bounce ATR device, a single-bounce or multiple-bounce horizontal ATR (HATR) device, a specular reflectance device, a grazing incidence angle reflectance device, a photoacoustic device, a liquid chromatography device, a photoelastic modulation (PEM) device, etc. 
     In the illustrative embodiment, right accessory compartment wall  402  includes a third light port  404  through which light can be provided from/to the ATR compartment to/from accessory compartment  300  depending on the type of sample analysis accessory device mounted within accessory compartment  300 . In the illustrative embodiment, left side wall  400  includes a fourth light port  406  and a fifth light port  408 . A fewer or a greater number of input and output ports may be included in the walls of spectrometer  102 . First light port  218 , fourth light port  406 , and fifth light port  408  receive or transmit light exterior of spectrometer  102  as defined by base plate  500 . 
     With reference to  FIG. 5 , a top view of spectrometer  102  is shown in accordance with an illustrative embodiment with front accessory compartment wall  212 , top bench compartment wall  202 , top detector wall  204 , top accessory compartment wall  206 , and top ATR compartment wall  208  removed to show an interior of spectrometer  102 . In an illustrative embodiment, the detector compartment includes a plurality of detectors and an optical element (not shown) positioned to receive a light beam  510  from accessory compartment  300 . For example, in the illustrative embodiment, the detector compartment includes a first detector  504 , a second detector  506 , and a third detector  508 . For illustration, first detector  504  may be a deuterated triglycine sulfate (DTGS) detector, second detector  506  may be a deuterated, L-alanine doped triglycine sulfate (DLaTGS) detector, and third detector  508  may be a nitrogen-cooled mercury-cadmium-telluride (MCT) detector though of course other types of detectors and arrangements of detectors may be used. The optical element may be mounted to an actuator, which moves the optical element to reflect the received light beam  510  to the selected detector. The actuator may be used to control translational and/or rotational movement of the optical element. Illustrative actuators, as used herein, include an electric motor, a servo, stepper, or piezo motor, a pneumatic actuator, a gas motor, etc. The actuator further may move the optical element to reflect the received light beam  510  through detector output port  220  and to an externally mounted detector. In an illustrative embodiment, the optical element is an elliptical mirror. 
     In an illustrative embodiment, the ATR compartment includes an ATR  512 , which includes ATR arm  222  and an optical element  514  positioned to reflect/receive a light beam  516  to/from accessory compartment  300  through third light port  404 . Optical element  514  further may be positioned to reflect/receive a light beam  548  to/from the bench compartment. 
     In an illustrative embodiment, the bench compartment includes a light source that may include a plurality of light sources that emit light at one or more wavelengths selected for analysis of a sample. The light source may emit in the ultraviolet (UV), visible, IR, NIR, FIR, near-UV, etc. Thus, light emitted from the light source may not be visible. In the illustrative embodiment of  FIG. 5 , the light source includes a first light source  520  and a second light source  522 . For illustration, first light source  520  may be an IR source and second light source  522  may be a white light source. In an illustrative embodiment, the bench compartment further includes a Raman detector  524 . 
     An optical element  600  (shown with reference to  FIG. 6 ) may be mounted to an actuator (not shown), which moves optical element  600  to reflect light  526  received from first light source  520  or second light source  522  toward an aperture device  528 . The actuator may be used to control translational and/or rotational movement of optical element  600 . The actuator further may move optical element  600  to reflect light received from aperture device  528  toward Raman detector  524 . In an illustrative embodiment, optical element  600  is an elliptical mirror. 
     The actuator still further may move optical element  600  to reflect light received from aperture device  528  toward an optical element  530  or to receive light reflected from optical element  530  through fifth light port  408 . In an illustrative embodiment, optical element  530  is a parabolic mirror. In an illustrative embodiment, the aperture device  528  automatically sets the correct aperture size depending upon the resolution and spectral range selected for spectrometer  102 . Aperture device  528  may include an iris aperture and an iris filter wheel. 
     Aperture device  528  receives/transmits light  532  from/to an optical element  534 . In an illustrative embodiment, optical element  534  is a parabolic mirror that reflects light  536  to/from an interferometer  538 . Interferometer  538  includes a beamsplitter  540  selected based on the type of sample analysis accessory device selected for operation. Spectrometer  102  further may include an automatic beamsplitter exchanger that automatically changes the beamsplitter inserted in interferometer  538 . An optical element  542  receives light from beamsplitter  540  and reflects light  544  toward optical element  514  mounted within the ATR compartment. In an illustrative embodiment, optical element  542  is a flat mirror. Light  544  may pass through a validation wheel  546  to form filtered light  548  before reaching optical element  514 . Validation wheel  546  may be configured to test spectrometer  102  using Schott NG-11 and NIST traceable standards as understood by a person of skill in the art. With reference to  FIG. 6 , a side view of components of the bench compartment of spectrometer  102  is shown in accordance with an illustrative embodiment. 
     With reference to  FIG. 7 , a top view of ATR  512  is shown in accordance with an illustrative embodiment. ATR  512  includes a flipper mirror  700 , ATR arm  222 , an ATR puck  702 , and a platform  704 . ATR arm  222  is mounted to base plate  500 . ATR puck  702  includes a crystal. For example, in an illustrative embodiment, the crystal is a diamond and ATR puck  702  is a parallel-sided plate. As a result, in the illustrative embodiment, ATR  512  is configured to perform HAIR analysis of a sample. In other embodiments, the crystal may be formed of zinc selenide, germanium, KRS-5, etc. Platform  704  is mounted to ATR arm  222  and positioned generally flush with top ATR compartment wall  208 . 
     With reference to  FIG. 8 , a left side view of ATR  512  with flipper mirror  700  down is shown in accordance with an illustrative embodiment. ATR  512  further includes an ATR tip  800  (shown with reference to  FIG. 8 ) extending from ATR arm  222  and an optical element  802 . In an illustrative embodiment, optical element  802  is a parabolic mirror. With reference to  FIG. 9 , a back view of ATR  512  with flipper mirror  700  down is shown in accordance with an illustrative embodiment. With reference to  FIG. 10 , a back view of ATR  512  with flipper mirror  700  up is shown in accordance with an illustrative embodiment. 
     With reference to  FIG. 11 , a back bottom perspective view of additional components of ATR  512  is shown in accordance with an illustrative embodiment. With reference to  FIG. 12 , a left side bottom perspective view of the additional components of ATR  512  is shown in accordance with an illustrative embodiment. ATR  512  further includes a first optical element  1102  and a second optical element  1104 . In an illustrative embodiment, first optical element  1102  and second optical element  1104  are elliptical mirrors. 
     To use ATR  512 , a user may rotate ATR arm  222  away from ATR puck  702  and place a sample in either liquid or solid form on or in ATR puck  702 . For example, the user may use a pipette to place a drop of the sample on ATR puck  702 . The user may rotate ATR arm  222  toward ATR puck  702  after placement of the drop on ATR puck  702 . The user may then rotate ATR knob  224  to press the sample between ATR tip  800  and an upper surface of ATR puck  702  so that the crystal adequately contacts the sample as understood by a person of skill in the art. One or more of these operations may be automated. 
     After depression of button  106 , filtered light  548  is directed onto flipper mirror  700  positioned in the up position. An actuator is mounted to flipper mirror  700  to lower and raise flipper mirror  700  between a first down position as shown in  FIG. 9  and a second up position as shown in  FIG. 10 . In the first position, flipper mirror  700  does not receive filtered light  548 , which is instead received by optical element  514  which reflects filtered light  548  into accessory compartment  300  to form light  516 . In the second position, flipper mirror  700  is positioned to receive filtered light  548  and to reflect the received filtered light  548  toward optical element  802  and the crystal such that optical element  514  does not receive filtered light  548  or form light  516 . 
     Optical element  802  receives light reflected from flipper mirror  700  and reflects the received light toward first optical element  1102 . First optical element  1102  receives light reflected from optical element  802  and reflects the received light toward a lower surface  1200  (shown with reference to  FIG. 12 ) of ATR puck  702 . ATR puck  702  is formed of an optically dense crystal with a high refractive index at a certain angle. This internal reflectance creates an evanescent wave that extends beyond the surface of the crystal and into the sample held in contact with the crystal. This evanescent wave protrudes a few microns beyond the crystal surface and into the sample. In regions of the infrared spectrum where the sample absorbs energy, the evanescent wave is attenuated or altered. The attenuated energy from the evanescent wave exits the opposite end of the crystal and is received by second optical element  1104 , which reflects the received light toward ATR detector  1100 . ATR detector  1100  receives the reflected light from second optical element  1104 . ATR detector  1100  converts the received light into an electrical signal indicating an intensity of the evanescent wave. 
     In an illustrative embodiment, ATR detector  1100  includes a DLaTGS detector element, a window permitting the light to approach the DLaTGS detector element, and electronics to power the DLaTGS detector element, and to extract the signal information. The window both protects the DLaTGS detector element and is transparent over the desired spectral range. Typically, to perform multi-range IR two detectors are needed: one for the MIR (potassium bromide (KBr) window) and one for the FIR (polyethylene window). In an illustrative embodiment, the window of ATR detector  1100  is a diamond window, which allows a wide spectral range of data collection, from the FIR to the MIR, with one detector, and eliminates the need to swap detectors or insert an additional mirror. Further, the diamond window is not susceptible to moisture damage. 
     Various components of spectrometer  102  may be operably coupled to processor  118  to receive information from processor  118  and/or to send information to processor  118  under control of control application  114 . For example, processor  118  is operably coupled to the light source to control the switching on or off of the one or more light sources. Processor  118  also may be operably coupled to first detector  504 , second detector  506 , third detector  508 , Raman detector  524 , and ATR detector  1100  to receive the electrical signals generated by each detector. Processor  118  further may be operably coupled to the referenced actuators to control movement of the various described optical elements and to open and close purge shutters mounted in one or more walls of accessory compartment  300 . For example, purge shutters may be mounted to cover second light port  308  and third light port  404  so that an interior of spectrometer  102  can be purged as understood by a person of skill in the art. Processor  118  further may be operably coupled to interferometer  538 , validation wheel  546 , and/or aperture device  528  to control their operation. 
     With reference to  FIG. 13 , a top view of components of the bench compartment of spectrometer  102  is shown in accordance with a second illustrative embodiment. In the illustrative embodiment of  FIG. 13 , spectrometer  102  further includes a first moving mirror device  1300  positioned between optical element  542  and ATR  512  to optionally intercept filtered light  548 . First moving mirror device  1300  may include a first plate  1302  mounted to base plate  500 , a first optical element  1304  mounted to first plate  1302 , a second optical element  1306  mounted to first plate  1302 , a first track  1308  formed in first plate  1302 , and a first actuator  1310 . First optical element  1304  is mounted adjacent second optical element  1306  and at an approximately ninety degree angle with respect to a face of second optical element  1306 . Other arrangements may be used depending on the relative orientation of light ports to the exterior of spectrometer  102 . First actuator  1310  is mounted to move first optical element  1304  and second optical element  1306  between a first position, a second position, and a third position along first track  1308 . 
     With reference to  FIG. 14 , a top view of components of the bench compartment of spectrometer  102  is shown in accordance with the second illustrative embodiment. At the first position, as shown in  FIG. 14 , first optical element  1304  is configured to intercept filtered light  548  from optical element  542  and to reflect light  1400  toward fourth light port  406  to direct light  1400  exterior of spectrometer  102  as defined by base plate  500 . At the second position, second optical element  1304  is configured to intercept filtered light  548  from optical element  542  and to reflect light  1402  toward first light port  218  to direct light  1402  exterior of spectrometer  102  as defined by base plate  500 . In the second position, a face of second optical element  1304  aligns with a line  1404  as indicated in  FIG. 14 . At the third position (not shown), neither first optical element  1304  nor second optical element  1306  intercepts filtered light  548  from optical element  542  to allow filtered light  548  to continue toward optical element  514 . As further shown in  FIG. 14 , optical element  530  is positioned to receive light  1404  through fifth light port  408  or to reflect light  1404  through fifth light port  408 . 
     With reference to  FIG. 15 , a top view of components of the bench compartment of spectrometer  102  is shown in accordance with a third illustrative embodiment. In the illustrative embodiment of  FIG. 15 , spectrometer  102  further includes a second moving mirror device  1500  and a third moving mirror device  1512 . Second moving mirror device  1500  is positioned between optical element  542  and ATR  512  to optionally intercept filtered light  548 . Third moving mirror device  1512  is positioned to replace optical element  534  between aperture device  528  and interferometer  538 . 
     Second moving mirror device  1500  may include a second plate  1502  mounted to base plate  500 , a fourth optical element  1506  mounted to first plate  1502 , a second track  1508  formed in second plate  1502 , and a second actuator  1510 . A third optical element  1504  is mounted to base plate  500 . Third optical element  1504  is mounted at an approximately ninety degree angle with respect to a face of fourth optical element  1506  though again other arrangements are possible depending on the orientation of light ports exterior to spectrometer  102 . Second actuator  1510  is mounted to move fourth optical element  1506  between a first position and a second position along second track  1508 . Third moving mirror device  1512  may include a third plate  1514  mounted to base plate  500 , a fifth optical element  1516  mounted to third plate  114 , a third track  1518  formed in third plate  1514 , and a third actuator  1520 . 
     With reference to  FIG. 17 , a top view of components of the bench compartment of spectrometer  102  is shown in accordance with the third illustrative embodiment. Third optical element  1504  is fixed to base plate  500  and is positioned to receive light  1600  from interferometer  538  and to reflect light  1602  toward fourth light port  406  to direct light  1602  exterior of spectrometer  102  as defined by base plate  500 . At the first position, fourth optical element  1506  is configured to intercept filtered light  548  from optical element  542  and to reflect light  1604  toward first light port  218  to direct light  1604  exterior of spectrometer  102  as defined by base plate  500 . At the second position, fourth optical element  1506  does not intercept filtered light  548  from optical element  542  to allow filtered light  548  to continue toward optical element  514 . 
     Third actuator  1520  is mounted to move fifth optical element  1516  between a first position and a second position along third track  1518 . At the first position, fifth optical element  1516  is configured to receive light  532  from aperture device  528  and to reflect light  536  toward interferometer  538  as described previously with reference to optical element  534 . At the second position, fifth optical element  1516  does not intercept light  536  from aperture device  528  and is positioned to unblock third optical element  1504  from receiving light  1600  from interferometer  538 . 
     The word “illustrative” is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as “illustrative” is not necessarily to be construed as preferred or advantageous over other aspects or designs. Further, for the purposes of this disclosure and unless otherwise specified, “a” or “an” means “one or more”. Still further, the use of “and” or “or” is intended to include “and/or” unless specifically indicated otherwise. 
     The foregoing description of illustrative embodiments of the invention has been presented for purposes of illustration and of description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and as practical applications of the invention to enable one skilled in the art to utilize the invention in various embodiments and with various modifications as suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.