Abstract:
The magnetic resonance signal analyzer allows to automatically generate a large variety of test signals including one or more frequencies. The test signals can be applied as electromagnetic fields or as currents to material under test. An electromagnetic or electrical response signal of the material under test be applied to the analyzer for processing to determine the response pattern of the material under test and then returned to the automatic controller of the frequency sources. The automatic controller determines the test signal with the most effective response for the particular matter under test.

Description:
This is a continuation-in-part application of my pending patent application 07/945,529, filed on Sept. 16, 1992, now U.S. Pat. No. 5,317,265, issued May 31, 1994. 
    
    
     BACKGROUND OF THE INVENTION 
     A magnetic resonance analyzer offers new advantages in the field of material analysis. It has been shown that the applicability of such an analyzer exceeds the range of tissue analysis and other medical applications. The magnetic resonance analyzer measures the degree and type of response of a matter under test, and, by comparison with reference matter, it assists in recognizing deviations from a desired response. This capability is enhanced by testing with resonance test patterns which relate to the significant characteristics for the particular matter under test as identified when determining the resonance frequencies. 
     The apparatus of the present invention relates to magnetic resonance test instrumentation. It exposes reference material to an electro-magnetic field and determines the resonance frequencies of the material exposed using a sequence of frequency patterns. The detected resonance frequencies are be used to establish test patterns to be used in subsequent operations for analyzing samples of the same type of material as and relative to the reference material. 
     SHORT DESCRIPTION OF THE INVENTION 
     The apparatus of the present invention includes the means for automatically selecting a sequence of test patterns and means for generating a selected test pattern sequence. Two methods of subjecting a matter to the pattern signals are provided. A first method uses an inductive coil for generating an electromagnetic field under control of test pattern signal and a sensor for electromagnetic fields for sensing the response. The second method uses probes for electrical signals, causing electrical currents between input probes. Test probes are used to sense currents at selected locations of the matter under test to evaluated the response of the matter under test to the applied test patterns. 
     The sensed analog response signals are processed in a first analog signal processing circuit and may generate a linear signal indicative for deviations from an expectant result. A second analog processing circuit performs a conversion from analog to digital representation of the response signal for evaluation in digital data processing means. Additional external equipment may be connected at suitable locations for evaluating a signal using commercially available equipment, such a spectrum analyzers etc. 
     The inductive coil for generating the electromagnetic fields and the sensor coil can be combined in various configuration for testing particular matter. While both coils can be concentric in many applications, it has been found that in some applications specially shaped coils such as conically formed coils are more suitable to subject the matter under test to the electromagnetic field. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic block diagram of the magnetic resonance analyzer and the automatic pattern control of the present invention 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The apparatus of the present invention can be used in various methods to test matter. In the following description of the preferred embodiment the test is performed in a chamber in which the matter under test is subjected to an electromagnetic field generated by a primary coil. A secondary coil is used to sense the sum of the test field and the response field. Primary and secondary coils may be concentric and the secondary coil may be located inside the primary coil. Both coils may be electromagnetically shielded to eliminate any influence from an external electromagnetic field. 
     The apparatus of the present invention has two signal frequency generators and a carrier frequency generator. The two frequency generators include the same type of major components: pattern select means 10 and 50, respectively, pattern generator 12 and 52, respectively, and digital to analog converters 14 and 54 respectively. The inputs of the digital-to-analog converters receive a sequence of binary coded values which are converted into analog signals. The resultant analog signals contain the frequencies which will cause a resonance response by the matter under test. The two analog signals are supplied to modulator 16. The carrier frequency generator 70 provides a selected frequency signal. The output signal of generator 70 is fed through a wave shaper 72 and drives the carrier input 74 of modulator 16. The output of modulator 16 provides the test pattern signal in which the carrier frequency pattern is modulated by the selected signal frequency pattern. The frequency spectrum of the test patterns reaches from 3 Hz to 14  KHz. In FIG. 1 there is provided a separate output EP OUT 18 which makes the test signal available to external probes. 
     Using test chamber 20 of the apparatus the test pattern signal is supplied to a primary excitation coil 22, which generates the electro-magnetic test field. The matter to be test 24 is placed inside coil 22. A secondary coil 26 senses the resultant electromagnetic field inside test chamber 20. The electrical output signal of secondary coil 26 includes a component from the test pattern field and a component representing the resonance signal of the matter under test responding to the test field. A low-pass filter 28 eliminates all frequency components above a certain frequency. The resultant filtered signal is compared with the electrical test pattern signal in comparator 30. The difference signal is amplified in amplifier 36 and supplied to an electronic switch 38. Switch 38 is provided to select either an external signal EP IN from an external device connected to line 34, or the filtered differential signal from amplifier 36. Switch 38 is controlled by a select signal on line 40. The selected signal is amplified in amplifier 42 and provided to two evaluation channels. The first evaluation channel converts the received signal into a digital signal in D/A converter 44. The resultant digital signal can be evaluated, processed, stored, modified or treated otherwise in an processing device 46, such as a special or common purpose computer. The second evaluation channel includes a demodulator 56, a voltage controlled oscillator 58 and an acoustic output device, such as a loudspeaker. 
     The magnetic resonance analyzer can generate a large variety of signal patterns. For testing a particular matter the optimum test pattern has to be determined which is significant to the particular matter its evaluation. When testing a sample at a later time, a so determined optimum test pattern is selected and imposed on the sample under test. The resultant resonance spectrum can be compared with the expected resultant test pattern and the user may draw a conclusions from the differences. Important features of the resultant signals are the resonance responses and the frequencies showing extraordinary peak emissions. 
     The resonance frequency analyzer of the present invention can be equipped with different types of primary and secondary coils depending upon the material and its shape to be tested. In a similar fashion the test signal can be supplied via output EP OUT 18 to input test probes which are inserted or attached to the material under test thereby causing an electrical current to flow between the input probes. Output sense probes can be inserted or attached at other locations of the material under test to identify the reaction of the material under test to the test signal. The output sense probes are to be connected to input EP IN 34. The detected signal is processed in the same manner as the signal from the secondary coil of the test chamber. 
     To determine the resonance frequencies of a particular matter under test the reference material is to be exposed to a plurality of test patterns and the resulting response is to be observed to determine which test pattern is to be used in testing against the reference matter. 
     In FIG. 1 an automatic controller 80 sequentially supplies input control signals to the frequency generators and thereby generates for each set of control signals a particular frequency pattern. For each of the successive frequency patterns the detected response is provided by processing means 46 and transferred via line 81 to controller 80, where it is recorded in a memory for further evaluation. The resulting response characteristics for the various frequency patterns are analyzed in controller 80 to determine which of the test patterns is to be used for testing material against their reference material. This analysis may select test patterns in accordance with the maximum amplitude of the difference signal received for each of the test patterns. It may select a test pattern in accordance with the strongest response signal sensed at he secondary coil, as represented by the largest difference signal over the frequency range of the applied test pattern. 
     Automatic controller S0 allows to scan a reference matter for most suitable frequency pattern, and to subject matter under test to a sequence of test pattern for comparison with expected responses or stored responses of corresponding reference matter. 
     Automatic controller S0 may include selection means which in response to an input of the matter to be tested selects one or more of the previously determined test patterns for that particular matter and generates a test pattern sequence for the matter under test.