Method and apparatus for simultaneously recording multiple FT-IR signals

• US 4,511,986 A
• Filed: 08/30/1982
• Issued: 04/16/1985
• Est. Priority Date: 08/30/1982
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines SA (International Business Machines Corporation)
• Inventors: Bellar, Robert J., Golden, William G., Saperstein, David D., Vats, Ashok
• Primary Examiner(s): Chin, Gary
• Assistant Examiner(s): HERNDON, HEATHER R
• Application Number:
  US06/413,034
• Time in Patent Office: 960 Days
• Field of Search: 364/484, 364/485, 364/498, 364/576, 364/525, 250/338 R, 356/346, 346/33 A
• US Class Current: 702/77
• CPC Class Codes: G01J 3/453 by correlation of the amplitudes

Abstract

A method and apparatus for simultaneously recording multiple Fourier Transform Infrared (FT-IR) signals using an interferometer. The analog signals are coupled to switching means which is operable in response to a first control signal for synchronizing the operation of the interferometer and the control circuits and a second control signal for defining data acquisition intervals to direct the sampled data of the analog input signals over a circuit path including Sample and Hold and Analog to Digital Conversion circuits to a processor for storing the digital data corresponding to the analog input signals. The switching means is operated so that samples of the analog input signals are taken in sequence and stored in sequential storage locations in interleaved fashion. The processor is operable under program control to access the digital data so that all data samples for the same input signals are separated to produce an interferogram for each of the input signals. These interferograms can then be Fourier Transformed to produce spectra in the usual manner.

Claims

1. Apparatus for simultaneously recording, in a single beam Fourier Transform Infrared spectrometer, multiple signals defining at least two different interferograms comprising:

switching circuit means having at least two signal terminals, having a first and a second control circuit input terminal and having one output terminal;

means for coupling input signals to said at least two signal terminals;

sample-and-hold circuit means having an input terminal connected to the output terminal of said switching circuit means;

analog-to-digital circuit means having an input terminal connected to said sample-and-hold circuit means and having an output terminal for delivering digital data;

means for generating a first control signal for synchronizing said switching circuit means with an interferometer operation;

means for generating a second control signal defining data acquisition intervals;

means for coupling said first control signal to said first control circuit input terminal to reset said switching circuit means to a predetermined state;

means for coupling said second control signal to said second control circuit input terminal to switch the state of said switching circuit means for each of said signals defining data acquisition intervals so that data samples for each of said input signals are interleaved;

computing circuit means coupled to receive the digital data from the output terminal of said analog-to-digital circuit means, said computing circuit means being operable under program control to store said digital data, and for accessing said digital data so that all data samples for the same input signal are combined to produce an interferogram for each of the input signals.

2. The apparatus of claim 1 wherein said switching circuit means comprises a signle-pole-double-throw circuit arrangement.

3. The apparatus of claim 1 wherein said switching circuit means comprises digital circuit means.

4. The apparatus of claim 1 wherein said switching circuit means comprises a double-pole-double-throw circuit arrangement followed by a single-pole-double-throw circuit arrangement.

5. The apparatus of claim 4 wherein said digital data for each interferogram is stored in a first and a second data file and wherein the data in said first and said second data files is recombined under program control in accordance with an algorithm expressible as the sum of an Even 1st and an Odd 2nd divided by the sum of an Even 2nd and an Odd 1st or

6. A method for simultaneously recording, in a single beam Fourier Transform Infrared spectrometer, multiple signals defining at least two different interferograms, said spectrometer comprising

circuit means including at least two signal terminals, first and second control circuit input terminals, and switching circuit means;

sample-and-hold circuit means; and

analog-to-digital conversion circuit means having an output terminal for delivering digital data;

said method comprising the steps of;

coupling input signals to said at least two signal terminals;

generating a first control signal for synchronizing said circuit means with an interferometer operation;

generating a second control signal defining data acquisition intervals;

coupling said first control signal to said first control circuit input terminal to reset said switching circuit means to a predetermined state;

coupling said second control signal to said second control circuit input terminal to switch the state of said switching circuit means for each of said signal defining data acquisition intervals so that data samples for each of said input signals are interleaved;

storing the digital data from the output terminal of said analog-to-digital circuit means, and

accessing said digital data in an order so that all data samples for the same input signal are combined to produce an interferogram for each of the input signals.

7. The method of claim 6 wherein said storing step includes storing said digital data for each interferogram in a first and a second data file and wherein said accessing step includes recombining the digital data in said first and said second data files under program control in accordance with an algorithm expressible as the sum of an Even 1st and an Odd 2nd divided by the sum of an Even 2nd and the Odd 1st or