Patent Publication Number: US-2016223472-A1

Title: Method and apparatus for calibration of a material characterization system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims priority from co-pending U.S. Provisional Patent Application Ser. No. 62/097,898 entitled “Method and Apparatus for Calibration of a Material Characterization System” filed with the U.S. Patent and Trademark Office on Dec. 30, 2014, by the inventors herein, the specification of which is incorporated herein by reference. 
    
    
     GOVERNMENT LICENSE RIGHTS 
     This invention was made with Government support under contract number SB1341-13-CN-0035, awarded by National Institute of Standards and Technology (NIST). The Government may have certain rights in the invention. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to systems and methods for evaluating a material through measurements of transmitted energy. More particularly, the present invention relates to systems and methods for calibration of a material characterization system that is based on measured electromagnetic waves. 
     BACKGROUND 
     Evaluation methods and apparatuses exist within various industries for characterizing electrical and physical properties of a material. Certain properties of a material may be determined by measuring the response of the material to electromagnetic waves impinging upon it, in terms of transmissivity, reflectivity, and absorptivity. In general, the characterization of a sample layer of material is based on a measurement of the electromagnetic scattering parameters of such layer as compared to the corresponding set of electromagnetic scattering parameters, using the same set up, of a layer of reference material used for calibration. Thus, two sets of measurements are performed requiring a set up as identical as possible to avoid characterization inaccuracies. 
     Accordingly, the performance and reliability of a material characterization system depends on the accuracy and repeatability of a set of measurements conducted to calibrate such system. In particular, the characterization of single-layer and multilayer materials by means of electromagnetic waves heavily relies on an accurate calibration of the scattering parameters of the system. 
     More specifically, a universal calibration method and apparatus to determine a characteristic of certain materials by means of radio frequency sensors have been addressed in the prior art, as described in U.S. Pat. No. 6,691,563 to Trabelsi et al. However, this method is primarily aimed to determine a universal calibration equation exclusively for estimating the level of moisture content of a material at a given time, based on experimental data. 
     Typically, instead of determining a status or a certain characteristic of a material at a given time, the goal of a material characterization system is to determine a set of properties of the material, such as those derived from a measurement of the transmissivity, reflectivity, and absorptivity of the material. This set of properties includes surface resistivity, ohmic conductivity, dissipation loss, complex magnetic permeability, and complex dielectric permittivity, in addition to thickness, density, homogeneity, and manufacturing defects, such as the presence of voids or undesired particles either during or after production of the material. 
     Currently, there is no well-established method of deterministically calibrating a material characterization system accurately by measuring and recording a single set of calibration data. Usually, because the accuracy of the material characterization system critically depends on having a set up as identical as possible for both calibration and characterization measurements, it is required that the sample under test and a reference material have the same thickness. In many cases, this might be difficult or impossible to achieve, particularly where the thickness of the sample under test is in the order of hundreds of microns. Also, preparing a reference layer identical to a sample layer might result in an inefficient and lengthy process. In addition, having a set of samples with a number of thicknesses to cover the range of possible samples to be characterized might be impractical or impose severe limitations to the material characterization system and its users. 
     As a result, users of a material characterization system typically experience inaccurate, lengthy, and inefficient calibration and characterization processes. On the one hand, different positioning or setups during the measurements of the reference material and the evaluation of the sample under test may largely compromise the accuracy of the characterization. Variations in position may be caused by a number of factors, including a lack of accurate control or not fine enough resolution of the positioning system, thickness variations of the measured materials, and fluttering and displacement of the material to be characterized. 
     On the other hand, the need to set up and measure a different reference material every time that a sample under test is changed or its thickness varies, involves a lengthier process and practical inconveniences that may severely impair the use of the material characterization system and build up to a highly inefficient characterization process. Each of these aspects is subject to uncertainties that make it difficult to create an accurate characterization of a material. 
     Previous efforts have been made to use electromagnetic waves in assisting with the calibration of a system to measure one or more properties of a material, as described in U.S. Pat. No. 6,754,543 to Wold and U.S. Pat. App. No. 20020075006 by Goldfine et al. However, these efforts have faced certain challenges and limitations. In particular, attempts made to characterize thin layers of material where thickness variations in the order of tens of microns may affect a measurement. Likewise, in a production environment, quality control of the material may be limited to measurements of a few samples because the time involved in evaluating the material may make prohibitive measuring the whole production. A major challenge is that in a production line, fluttering and displacement of a thin film of a material from a baseline position is typically unavoidable. Therefore, a characterization of a material may, as a result, be impractical and very challenging. 
     Thus, there remains a need in the art for methods and apparatuses capable of providing the means to accurately and effectively calibrate a material characterization system, through measurements of electromagnetic waves, that avoid the problems of prior art methods and devices. 
     SUMMARY OF THE INVENTION 
     An improved method and apparatus to set up measurements for collecting data to calibrate a material characterization system are disclosed herein. One or more aspects of exemplary embodiments provide advantages while avoiding disadvantages of the prior art. The method and apparatus are operative to set up multiple configurations for measuring and recording a specific characteristic response of the system for each configuration, using electromagnetic waves. The apparatus is designed to enable the system to measure and record the position of a reference material and a set of calibration data for such reference material, while positioned at locations that correspond to a range of possible thicknesses or fluttering during measurements of a sample that the system is capable of characterizing. As a result, a sample under test having a specific thickness and measured at a particular position can be readily calibrated analytically or by using reference data previously recorded with the same set up. 
     The method of setting up multiple configurations for data collection to calibrate a material characterization system, using electromagnetic waves, includes the steps of attaching a supporting structure to a material characterization system to be calibrated and measuring and recording the S 11  and S 22  scattering parameters corresponding to a first reference material at different positions. The method further includes the steps of replacing the first reference material with a second reference material and measuring and recording the S 12  or S 21  scattering parameter, while maintaining the same mechanical set up at such different positions. The method also includes removing the supporting structure, as required, from the material characterization system. 
     The apparatus includes one or more structures configured and positioned to accurately set up a reference material at a plurality of positions to be measured by a material characterization system. By recording the measured characteristic response of such known reference material at these known plurality of positions, it is possible to calibrate and compare the corresponding response of a material to be characterized, having the same set up. 
     Accordingly, the collection of a set of calibration data for each possible position, corresponding to the different thicknesses or fluttering during measurements of a sample of a material to be characterized, allows a single calibration of the material characterization system. The minimum difference in distance among any two of these positions defines the distance resolution of the calibration. The apparatus may include technology to enable a distance resolution in the order of 10 microns. 
     As a result, the apparatus increases the accuracy of the positions at which the calibration data is collected. In addition, there is no need to measure a set of calibration data every time a material characterization measurement is performed, as is typically done using standard techniques. This is particularly important where evaluation of multiple samples of a material are required or in a production line where a material characterization system is used to monitor the quality of a material under production. 
     Thus, by enabling the collection of calibration data only once, at accurate positions, with a low distance resolution, the method and apparatus are capable of significantly improving both the calibration and the overall material characterization processes, as compared to standard techniques. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The numerous advantages of the present invention may be better understood by those skilled in the art by reference to the accompanying drawings in which: 
         FIG. 1  shows a schematic view of a method for calibration of a material characterization system, based on the transmission of electromagnetic waves. 
         FIG. 2  shows an exemplary set up for data collection to enable a calibration of a material characterization system using a two-stacked-tray supporting structure. 
         FIG. 3  shows a preferred set up for data collection to enable a calibration of a material characterization system using a two-stacked-tray supporting structure. 
         FIG. 4  shows an alternative set up for data collection to enable a calibration of a material characterization system. 
         FIGS. 5A and 5B  show various aspects of an apparatus using a two-stacked-tray structure in accordance with one embodiment. 
         FIG. 6  shows a perspective view of an apparatus using a two-stacked-tray structure in accordance with another embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is of a method and one or more particular embodiments of an apparatus, set out to enable one to practice an implementation of the invention, and is not intended to limit the preferred embodiment, but to serve as a particular example thereof. Those skilled in the art should appreciate that they may readily use the conception and specific embodiments disclosed as a basis for modifying or designing other methods and systems for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent assemblies do not depart from the spirit and scope of the invention in its broadest form. 
       FIG. 1  shows a schematic view of a method for calibration of an electromagnetic wave-based material characterization system. The method is operative to determine a set of values of the measured scattering parameters of one or more reference materials, representative of a range of possible thicknesses of a sample layer of a material to be characterized, using the same set up, according to the following:
         1. At step  110 , attaching a supporting structure to a measuring module tray of a material characterization system to be calibrated, such that the structure is substantially parallel to such measuring module tray.
             FIG. 2  shows an exemplary set up, wherein a supporting structure  20  comprises two stacked trays. A first bottom tray  24 , closer to a first probe  26  of the material characterization system, is disposed substantially parallel and in close proximity to a second top tray  28 , closer to a second probe  29  of the material characterization system. Bottom tray  24  has a propagation area  25  around the center to allow the propagation of electromagnetic waves, transmitted by first probe  26  to second probe  29  through bottom tray  24 .   Likewise, top tray  28  has a propagation area  27  around the center, wherein a reference material  23  is disposed on to perform calibration measurements. The dimensions of such area of top tray  28  should be similar to the dimensions of the propagation area of bottom tray  24 .   Both top tray  28  and bottom tray  24  are preferably aligned such that propagation area  25  of bottom tray  24  coincides with propagation area  27  of top tray  28 . More preferably, reference material  23  should be disposed as flat as possible, and in some instances, the top tray may comprise a thin layer of glass coated with the reference material to ensure flatness.   Alternatively, supporting structure  20  may comprise a single tray, performing as top tray  28  in  FIG. 2 , in which case the measuring module tray of a material characterization system to be calibrated performs as bottom tray  24  in  FIG. 2 .   
           2. Next, at step  120 , measuring and recording the amplitude and phase of the S 11  and S 22  parameters corresponding to a first reference material at different distances from the probes of the material characterization system.
             FIG. 3  shows a preferred set up, wherein a first reference material  30  is disposed on top tray  28 . Top tray  28  is moved in steps from or to bottom tray  24 , which remains fixed, to cover a range of movement that corresponds to the different thicknesses of the possible samples to be characterized by the material characterization system. Typically, the thickness of the sample to be characterized is within a range of between 50 microns and 40 mm at 10-micron steps.   Characterizing a sample under test requires calibration with a reference material positioned at the same location as the sample, such that the probes are at the same distance from the sample and from the reference material during each of the corresponding set of measurements. However, depending on the thickness or fluttering during measurements of the sample under test, the distance from the sample to at least one of the probes of the material characterization system may vary.   Therefore, a preferred set up includes one or more distance sensors  32   a  and  32   b  to measure the location of first reference material  30  with respect to bottom tray  24 , probe  26 , probe  29  or any other reference point at each calibration measurement position. This allows determining the location of first reference material  30 , at each measurement position, with respect to probes  26  and  29  of the material characterization system to be calibrated.   Ultimately, a matrix or table may be created containing the S 11  and S 22  calibration data and the position of the first reference material  30  with respect to probes  26  and  29  for each measurement of first reference material  30 .   Alternatively, step  120  may be performed by measuring and recording the amplitude and phase of the S 11  and S 22  parameters of one or more reference materials, one at a time, at least at two calibration reference planes located in between the probes.  FIG. 4  shows a set up wherein a first calibration reference plane  40   a  is established to position reference material  42   a  for measurements and data recording. Likewise, a second calibration reference plane  40   b  is established to position reference material  42   b  for measurements and data recording. Typically, a sample of a material under test would be disposed such that a range of positions of such sample is limited within a first variation reference plane  44   a  and a second variation reference plane  44   b . Calibration reference plane  42   a  is set up in between probe  26  and variation reference plane  44   a . Similarly calibration reference plane  42   b  is set up in between probe  29  and variation reference plane  44   b.      Thus, by determining the location of a sample under test at each measurement position by means of distance sensors  32   a  or  32   b , the distance between each calibration reference plane  40   a  and  40   b  and the sample can be calculated. As a result, the S 11  and S 22  parameters of reference materials  42   a  and  42   b  can be analytically calculated at the position of the sample, as well-known in the prior art. This calculation can be done for any position of the sample material to be characterized between calibration reference planes  40   a  and  40   b.      Preferably, reference materials  42   a  and  42   b  are identical. More preferably, reference materials  42   a  and  42   b  are actually the same piece of material used at different times. Most preferably, in addition, reference materials  42   a  and  42   b  comprise a material highly reflective of electromagnetic waves at the frequencies of interest, including a conductive material, such as a metal plate or a layer of a metal compound.   
           3. Next, at step  130 , replacing the first reference material with a third reference material to have a set up to perform calibration measurements of the S 12  or S 21  parameters, while maintaining the same mechanical set up used in step  120 . Preferably, the third reference material is air, such that replacing the first reference material basically reduces to removing the first reference material.   4. Next, at step  140 , repeating step  120  for the corresponding calibration measurements of the S 12  or S 21  parameter. After completing step  140 , the data required for calibration of material characterization system is complete.
           A set of the measured S 11 , S 22 , and S 12  or S 21  scattering parameters have been recorded for each possible height position corresponding to the different thicknesses or fluttering during measurements of the sample to be characterized by the material characterization system, within a 10-micron distance resolution or as determined in step  120 .   Preferably, the measurements of the S 12  or S 21  parameter are performed using air as the third reference material. In such a case, only a measurement of the S 12  or S 21  parameter at each height position may be required.   
           5. Last, at step  150 , removing the supporting structure and movement or mechanical stability components, as required, from the measuring module tray of the calibrated material characterization system.       

     Once a sample layer of material under test is placed on the module tray of the calibrated material characterization system, the thickness and position of the sample can be measured using the measurement tool used during the calibration process. Therefore, the position of the sample will be within 10 microns, or as determined in step  120 , of two positions of the recorded calibration data. Therefore, the S 11 , S 22 , and S 12  or S 21  measured data corresponding to these two positions can be used to accurately characterize the sample layer of the material under test. 
     Those skilled in the art will recognize that the steps above indicated can be correspondingly adjusted for specific material characterization system configurations. In particular, the steps to complete the calibration measurements of the S 12  or S 21  parameter can be performed before the calibration measurements of the S 11  and S 22  parameters. Likewise, the use, position, and function of the bottom or top trays of the two-stacked-tray structure may be altered or switched depending on the particular material characterization system to be calibrated. Also, those skilled in the art will realize that other type of reference materials may be used to perform S 11 , S 22 , and S 12  or S 21  measurements using the same reference material, including one or a combination of more than one of a transparent conductive material, a nanowire or a copper mesh, metamaterials, and nanomaterials. 
     In accordance with certain aspects of an embodiment of the invention,  FIGS. 5A and 5B  show various aspects of an apparatus  50  that enables a calibration of a material characterization system. Apparatus  50  is configured to provide a plurality of measurement setups to collect a set of calibration data using one or more reference materials. Then these data may be used to calibrate a measurement for all the possible practical thicknesses or positions during measurements of a sample of a material to be characterized. In this configuration, each measurement setup is defined by a position controlled by four step motors  52   a ,  52   b ,  52   c , and  52   d , commercially available as well known to those skilled in the art. 
     In particular,  FIG. 5A  illustrates a side view of apparatus  50 , comprising a first bottom tray  54 , closer to a first probe  26  than to a second probe  29  of the material characterization system, and a second top tray  56 , closer to second probe  29  than to first probe  26  of the material characterization system. Bottom tray  54  is disposed substantially parallel and in close proximity to top tray  56 . Thus, bottom tray  54  and top tray  56  form a two-tray stacked structure. Preferably, bottom tray  54  and top tray  56  each has a rectangular shape with similar dimensions. In this embodiment bottom tray  54  and top tray  56  each has approximate dimensions of 300 mm in width and length and 5 mm in thickness. 
     Thus, in a preferred configuration, apparatus  50  comprises one or more distance sensors  32   a  and  32   b  to measure the location of a first reference material  51  with respect to bottom tray  54 , probe  26 , probe  29  or any other reference point at each calibration measurement position. Distance sensors  32   a  or  32   b  may include a laser sensor, an acoustic sensor, and a measurement tool either installed as part of or added-on to the material characterization system. 
     More specifically,  FIG. 5B  shows a top view of a configuration of apparatus  50 , in which step motors  52   a ,  52   b ,  52   c , and  52   d  are mechanically attached by means of screws to top tray  56 . In addition, top tray  56  comprises a first opening  57  of about 50 mm in width and 50 mm in length located at around the center of top tray  56 . Top tray  56  is positioned such that a second opening  53  of bottom tray  54 , having the same dimensions as first opening  57 , aligns with first opening  57  to allow the propagation of electromagnetic waves, between first probe  26  and second probe  29  through first and second openings  57  and  53 . Preferably, the dimensions of first opening  57  and second opening  53  are selected such that the spot size of first probe  26  and the spot size of second probe  29 , over the location of first opening  57  and second opening  53 , define an area smaller than the area of first opening  57  and second opening  53 . Most preferably, the spot size of first probe  26  and the spot size of second probe  29  each define an area no larger than 60% of the area defined by first opening  57  or second opening  53 . 
     In reference to  FIGS. 5A and 5B , four extension arms  58   a ,  58   b ,  58   c , and  58   d  are mechanically attached by means of screws to bottom tray  54 , such that extension arms  58   a ,  58   b ,  58   c , and  58   d  protrude toward top tray  56  substantially perpendicular to bottom tray  54 . Each extension arm  58   a ,  58   b ,  58   c , and  58   d  consists of a general purpose, circular cross-section steel rod of approximately 5 mm in diameter and about 50-mm long, positioned close to each corner of bottom tray  54 . 
     Additionally, each extension arm  58   a ,  58   b ,  58   c , and  58   d  inserts into a corresponding circular through-hole  55   a ,  55   b ,  55   c , and  55   d  on top tray  56 . Preferably, the diameter of each circular through-hole  55   a ,  55   b ,  55   c , and  55   d  of top tray  56  is just large enough to allow top tray  56  to slide along extension arms  58   a ,  58   b ,  58   c , and  58   d , while maintaining mechanical stability during motion and during measurements at fixed positions. Those skilled in the art will recognize that other methods may be implemented for a stable mechanical guidance of top tray  56 . For instance, a different number of extension arms, preferably two or more, may be used. Alternatively, a semicircular dent in two or more sides of top tray  56  may be used to fit an extension arm as described above. 
     In a preferred configuration, and in reference to  FIGS. 5A and 5B , each step motor  52   a ,  52   b ,  52   c , and  52   d  includes an actuator arm  59   a ,  59   b ,  59   c , and  59   d  consisting of a fully threaded, circular cross-section steel rod of approximately 2 mm in diameter and about 100-mm long, positioned close to each corner of bottom tray  54 . More preferably, each actuator arm  59   a ,  59   b ,  59   c , and  59   d  is disposed substantially perpendicular to top tray  56  and extends to bottom tray  54  through a hole in top tray  56 . Most preferably, each step motor  52   a ,  52   b ,  52   c , and  52   d  is disposed on and mechanically attaches by means of two screws to top tray  56 , adjacent to extension arms  58   a ,  58   b ,  58   c , and  58   d , and close to each corner and the perimeter of top tray  56 . 
     Therefore, when step motors  52   a ,  52   b ,  52   c , and  52   d  actuate, corresponding actuation arms  59   a ,  59   b ,  59   c , and  59   d  may cause top tray  56  to move up or down, or equivalently away from or closer to bottom tray  54  at certain step increments. In other words, actuation arms  59   a ,  59   b ,  59   c , and  59   d  use bottom tray  54  as an anchor to push up top tray  56  away from the bottom tray  54  from a position in which top tray  56  and bottom tray  54  are at the closest distance. Preferably, step motors  52   a ,  52   b ,  52   c , and  52   d  move top tray  56  in increments as small as 10 microns. The step increment at which step motors  52   a ,  52   b ,  52   c , and  52   d  move top tray  56  determines a calibration distance resolution of the material characterization system. This configuration of apparatus  50  allows measurement setups to obtain calibration data of a sample of a material having a thickness of at least between 50 microns and 40 mm. 
     In general, apparatus  50  mechanically attaches to a measuring module tray of the material characterization system to be calibrated, such that bottom tray  54  and top tray  56  are disposed substantially parallel to such measuring module tray. Accordingly, apparatus  50  may have one or more sensors to level bottom tray  54  and top tray  56  with respect to the measuring module tray. Moreover, apparatus  50  may be integrated with the material characterization system in a fixed or temporary configuration. Thus, apparatus  50  may be portable and used to calibrate the material characterization system only once or as needed. Alternatively, apparatus  50  may be attached to and become an integral part of the material characterization system. 
     Preferably, in an alternative configuration, apparatus  50  further comprises hardware, software, and firmware to enable apparatus  50  to perform automated, electronic calibration of a material characterization system as a self-contained E-Cal Tray Kit. In a preferred configuration as an E-Cal Tray Kit, apparatus  50  comprises a motor controller to drive step motors  52   a ,  52   b ,  52   c , and  52   d  and is connected to a computer by means of a Universal Serial Bus (USB) connector. More preferably, an E-Cal Tray software installed in the computer may be used to perform automated measurements of the scattering parameters required for the calibration process. 
     The use of apparatus  50  as an E-Cal Tray Kit helps also to reduce inaccuracies of the characterization measurements by calibrating out any inconsistencies resulting from the manufacturing and assembly phases of the material characterization system. More specifically, an E-Cal Tray Kit may be programmed to automatically position top tray  56 , by means of a motorized unit, and measure the scattering parameters of a reference material at every 10 microns over a range of up to 40 mm or in accordance with the specifications of the material characterization system to be calibrated. Most preferably, such reference material comprises a material highly reflective of electromagnetic waves at the frequencies of interest, including a conductive material, such as a metal plate or a layer of a metal compound. 
     Those skilled in the art will recognize other ways of integrating apparatus  50  with a material characterization system, including by means of a straight, L-shaped or U-shaped arm; a flange; fasteners; hooks; clamps; adhesive, and straps, depending on the temporary or permanent nature of the attachment. Preferably, the integration of apparatus  50  incorporates existing trays to compensate for manufacturing and material inconsistencies of the material characterization system. Accordingly, in an alternative configuration, apparatus  50  may not require two trays. However, replacement of a component of the material characterization to install apparatus  50  may be advisable in certain situations. 
     A preferred mechanism to attach apparatus  50  to a material characterization system includes a manner to have an adjustable set up, including by means of a gear mechanism, calibrated screws, and knobs. More preferably, the attachment mechanism is also reconfigurable to adapt to different settings of spacing and positioning of a material. Those skilled in the art will also realize that other operational modes of using apparatus  50  may be implemented, such as manual or semi-automated. In particular, the movement of apparatus  50  to set up a position may be controlled by a hand-operated dial system. 
     Those skilled in the art will also realize that in certain instances a sample of a material having an edge treatment, such as a radio frequency absorber material, may need to be measured. In these instances, the absorber material may be configured to easily integrate into the material characterization system. Alternatively, apparatus  50  may comprise an absorber material, configured as a mold and cast into top tray  56 , wherein a sample of a material to be measured fits. Thus, casting the absorber material allows to more easily obtain a desired shape, such as a wedge, as compared to casting the reference material. 
     In accordance with another embodiment,  FIG. 6  shows a perspective view of an apparatus  60 , comprising a two-stacked-tray structure consisting of bottom tray  62 , having a first propagation area (not shown), and top tray  64 , having a second propagation area  61 . Apparatus  60  further comprises three step motors  66   a ,  66   b , and  66   c , commercially available as well known to those skilled in the art. Each step motor  66   a ,  66   b , and  66   c  includes a linear actuator  68   a ,  68   b , and  68   c  and attaches to two mounting plates, a bottom mounting plate  69   a ,  69   c , and  69   e  and a top mounting plate  69   b ,  69   d , and  69   f . In addition, an external linear nut (ELN)  70   a ,  70   b , and  70   c  attaches to each mounting plate  69   a ,  69   b ,  69   c ,  69   d ,  69   e , and  69   f , such that linear actuators  68   a ,  68   b , and  68   c  are mechanically attached to ELN  70   a ,  70   b , and  70   c.    
     Preferably, each top mounting plate  69   b ,  69   d , and  69   f  attaches to top tray  64  by means of two thumb screws  65   a  and  65   b ,  65   c  and  65   d , and  65   e  and  65   f . Likewise, each bottom mounting plate  69   a ,  69   c , and  69   e  attaches to bottom tray  62  by means of two thumb screws (not shown). In this configuration, the thumb screws are preferred for easy mounting and dismounting of mounting plates  69   a ,  69   b ,  69   c ,  69   d ,  69   e , and  69   f  to and from bottom tray  62  and top tray  64 . However, those skilled in the art will recognize other means of attaching mounting plates  69   a ,  69   b ,  69   c ,  69   d ,  69   e , and  69   f  to bottom tray  62  and top tray  64 . 
     More preferably, mounting plates  69   a ,  69   b ,  69   c ,  69   d ,  69   e , and  69   f  are attached to bottom tray  62  and top tray  64 , such that step motors  66   a ,  66   b , and  66   c  are disposed equidistant one another around the perimeters of bottom tray  62  and top tray  64 , forming an equilateral triangle. Most preferably, step motors  66   a ,  66   b , and  66   c  are wired in series or daisy-chained together to a motor driver and controller connected to a computer via a USB cable, as well known in the prior art. Most preferably, an E-Cal Tray software is installed in the computer and may be used to perform automated measurements at different setups during the calibration process. 
     The method and various embodiments of the apparatus for setting up the data collection configurations to perform the calibration of a material characterization system have been described herein in an illustrative manner, and it is to be understood that the terminology used is intended to be in the nature of words of description rather than of limitation. Any embodiment herein disclosed may include one or more aspects of the other embodiments. The exemplary embodiments were described to explain some of the principles of the present invention so that others skilled in the art may practice the invention. Obviously, many modifications and variations of the invention are possible in light of the above teachings. The present invention may be practiced otherwise than as specifically described within the scope of the appended claims and their legal equivalents.