JPH02163622A - Fourier-transformation infrared spectrophotometer - Google Patents

Abstract

PURPOSE:To improve the S/N of a spectrum, the stability and the reproducibility as a result of Fourier-transformation and a result of a final measurement by preventing an interferogram outputted from an analyzing part from being supplied to a data processing part, when an abnormality detecting circuit detects abnormality of the analyzing part. CONSTITUTION:The spectrophotometer is provided with an analyzing part A consisting of a light source 2, an interferometer 1, an interferometer driving circuit 3, a sample chamber 4, a detector 5, etc., and a data processing part consisting of an adding and averaging circuit 6 for adding and averaging an interferogram outputted from the analyzing part A, a Fourier-transformation circuit 7 for performing a Fourier- transformation processing to output data from the circuit 6, a spectrum arithmetic circuit 8 for calculating a spectrum related to an object to be measured, based on the output data from the circuit 7, etc. On this spectrophotometer, an abnormality detecting circuit X for detecting abnormality generated in the analyzing part A is provided. Also, the detecting circuit X is constituted so that when abnormality of the analyzing part A is detected, the interferogram outputted from the analyzing part A at that time is not supplied to the adding and averaging circuit 6 of the processing part B.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an analysis section comprising a light source, an interferometer, an interferometer drive circuit, a sample chamber, a detector, etc., and an interferogram output from the analysis section. data consisting of an averaging circuit that adds and averages the average of The present invention relates to a Fourier transform infrared spectrophotometric needle (generally referred to as FT-NR) equipped with a processing section, and particularly relates to a novel data sampling technique in the FT-IH.

[Conventional technology]

A conventional general Fourier transform infrared spectrophotometer has a light source 2 that emits infrared light for an interferometer 1, as shown in the overall schematic block circuit diagram of FIG. An interferometer drive circuit 3 consisting of a motor etc. for driving the interferometer 1. Measurement data output from the detector 5 in the analyzer A (generally an interface An averaging circuit 6 for averaging the data (referred to as a ferrogram), and a fast Fourier transform circuit for performing Fourier transform processing on the data output from the averaging circuit 6 (the averaged interferogram). 7 (commonly referred to as FFT) and its Fourier transform circuit 7
a data processing section B comprising a spectrum calculation circuit 8 and the like for obtaining a spectrum related to the measurement object based on processed data; and an interferometer drive circuit 3 in the analysis section A.
and an averaging circuit 6 and a Fourier transform circuit 7 in the data processing section B. It is comprised of a sequencer C that controls the spectrum calculation circuit 8 and the like in a predetermined sequence.

[Problem to be solved by the invention]

In the conventional Fourier transform infrared spectrometer needle as described above, all measurement data (interferogram) output from the detector 5 in the analyzer A is input to the averaging circuit 6 in the data processing section B. Since the system was configured to perform averaging processing, the following problems occurred.

In other words, for example, an object may come into direct contact with the device body during measurement and a shock is applied, or vibrations may be generated for some reason in the table or floor supporting the device body and the vibrations may be transmitted to the device body. When this occurs, the analysis unit A (particularly the interferometer 1) is affected by this, and the interferogram output from the detector 5 is temporarily disturbed, but the disturbed interferogram is also input to the averaging circuit 6. Since the Calorie calculation averaging process is performed, the Fourier transform results and spectra obtained thereafter are also disturbed, leading to deterioration of the S/N ratio, stability, and reproducibility of the measurement results.

Therefore, if it is found that vibrations as described in 1=acted during the measurement, it is necessary to restart the measurement from the beginning, but one measurement requires interferograms from several to hundreds of times. Since it is common practice to perform the arithmetic averaging of

Such problems occur not only when temporary vibrations as mentioned above act on the main body of the device, but also when an excessive current temporarily flows in the interferometer drive circuit 3 or when the detector 5 temporarily In other words, when pulse-like noise occurs,
This commonly occurs when a temporary abnormality occurs in the analysis section, and the possibility that such an inconvenient situation will occur is quite large.

The present invention has been made in view of the above-mentioned conventional situation, and its purpose is to prevent the abnormality from affecting the measurement results even if a temporary abnormality occurs in the analysis section. It is in.

[Failure to solve the problem]

In order to achieve the above object, the Fourier transform infrared spectrophotometer according to the present invention has the basic configuration as described at the beginning, and includes an abnormality detection function for detecting an abnormality occurring in the analysis section. In addition to providing a circuit, when the abnormality detection circuit detects an abnormality in the analysis section, the interferogram outputted from the analysis section at that time is configured not to be supplied to the averaging circuit in the data processing section. It has the following characteristics.

[Effect]

The effects achieved by employing such distinctive means are as follows.

That is, according to the Fourier transform infrared spectrophotometer according to the present invention, as will become clearer from the description of the examples described later, it is possible to prevent temporary abnormality from occurring in the analysis section due to vibration or other causes. When detected, the disturbed interferogram at that time is not supplied to the averaging circuit in the data processing section as in the conventional configuration, but is
It is ignored or rejected, and the averaging circuit averages only the undisturbed original data. Therefore, the Fourier transform result obtained based on it and the S/N ratio of the spectrum as the final measurement result. ,
Improved stability and reproducibility can be achieved.

In addition, even if a temporal abnormality occurs in the analyzer due to vibration or the like during measurement, the disturbed interferogram at that time will be automatically ignored or rejected, so if necessary, there will be a process to compensate for it. One series of measurements can be completed by simply adding vl (for example, 1 or 2 times) of interferograms to the averaging circuit, and there is no need to repeat measurements from the beginning as in the past, making it very easy to measure. can perform efficient measurements.

(Example) Below, an example of the present invention is illustrated in the drawings (Figures 1 to 5).
I will explain based on.

FIG. 1 shows an overall schematic circuit configuration diagram of a Fourier transform infrared spectrophotometer according to an embodiment of the present invention. In FIG. A light source that emits infrared light2. An interferometer drive circuit 3 consisting of a motor etc. for driving the interferometer 1. It is composed of a detector 5 and the like for detecting infrared light emitted from the interferometer 1 and passed through the sample chamber 4, and B is a data processing section that detects the infrared light emitted from the interferometer 1 and passed through the sample chamber 4. A buffer memory 9 that stores the measured data (interferogram) to be output one by one, and 0N10F as will be explained in detail later.
FIII? A gate switch 10 to be opened, an averaging circuit 6 for averaging interferograms input and supplied from the buffer memory 9 when the data switch 10 is turned on, and the averaging circuit 6 A fast Fourier transform circuit 7 (FFT) for performing Fourier transform processing on the data (averaged interferogram) output from It is composed of a spectrum calculation circuit 8 and the like.

Furthermore, the analysis section may be affected by abnormalities occurring inside it (for example, - temporal vibrations acting on the interferometer 1, excessive current flowing temporarily in the interferometer drive circuit 3, An abnormality detection circuit When an abnormality in part A is detected,
An interferometer drive circuit 3 in the analysis section A and a buffer memory 9 gate switch 10 in the data processing section B. Adding average circuit 6. Fourier transform circuit7. It is configured to send an abnormality signal to a sequencer C that controls the spectrum calculation circuit 8 and the like in a predetermined sequence.

When such an abnormal signal is input to the sequencer-C, the sequencer-C turns the gate switch 10 on.
By controlling to maintain the FF state, the disturbed interferogram outputted from the analysis section A at that time is configured not to be supplied to the averaging circuit 6 in the data processing section B.

In the Fourier transform infrared spectrophotometer configured as described above, as long as the analysis section A is operating normally (no abnormalities), the interferogram obtained from the detector 5 is temporarily stored in the bathophore memory 9. When the gate switch 10 is switched from the OFF state to the ON state, the current interface program stored in the buffer memory 9 is supplied to the averaging circuit 6 in the data processing section B, and then, The buffer memory 9
At the same time, the gate switch 10 is also reset and switched to the OFF state, which is repeated for a predetermined number of scans (for example, 1000 times). The abnormality detection circuit
If detected, the gate switch IO is forcibly maintained in the OFF state, so that the interferogram whose scan is disturbed is not supplied to the averaging circuit 6 in the data processing section B and is discarded. That will happen.

Note that if the interferogram is rejected due to a temporary abnormality as mentioned above, it is necessary to add (supplement) measurements for the number of scans that were rejected. When this occurs, supplementary scans may continue for a long time, so by setting an upper limit on the number of supplementary measurements in advance,
It is desirable to stop the measurement at a certain point.

2 to 5 show a specific example of the configuration of the abnormality detection circuit X.

That is, FIG. 2 shows an excessive vibration detection circuit a configured to issue an abnormal signal when the vibration acting on the device (particularly the interferometer 1) exceeds a set value. A vibration sensor 11 such as a piezo-type accelerometer attached to the interferometer 1 (see FIG. 1), a preamplifier I2 corresponding to the vibration sensor 11, a smoothing circuit 13 for averaging the output from the preamplifier 12, and the smoothing circuit 13. Output voltage from ■
and a comparator 14 that compares the voltage and the set voltage VCC and issues an abnormal signal when V>Vcc.

Further, FIG. 3 shows an overcurrent detection circuit configured to issue an abnormal signal when an excessive current flows through the interferometer drive circuit 3. This is a normal interferometer drive circuit 3
In order to cut off the control current of the drive motor 15 when it becomes excessive, the motor drive circuit 1 is installed.
6 and an overcurrent prevention relay 17 controlled thereby, the control signal from the motor drive circuit 16 for the overcurrent prevention relay 17 is taken out as it is as an abnormal signal. It is composed of

Figure 4 shows an excessive output detection circuit C configured to issue an abnormal signal when an excessive voltage such as pulse noise is output from the detector 5. a preamplifier 18 provided for the preamplifier 18; a gain adjustment amplifier 19 for adjusting the output from the preamplifier 18;
A peak value storage circuit 20 that stores the average value of the maximum peak values of the output voltage from the gain adjustment amplifier 19 during normal times.
and a comparator 21 that issues an abnormal signal when the output voltage from the gain adjustment amplifier 19 becomes larger than the output voltage from the peak value storage circuit 20.

As shown in FIG. 5, the abnormality detection circuit If any one of them generates an abnormal signal, the abnormal signal is transmitted to sequencer-C.

〔Effect of the invention〕

As is clear from the detailed description above, according to the Fourier transform infrared spectrophotometer according to the present invention, an abnormality detection circuit is provided for detecting an abnormality occurring in the analysis section, and
When the abnormality detection circuit detects an abnormality in the analysis section, the interferogram outputted from the analysis section at that time is not supplied to the averaging circuit in the data processing section. Even if a temporary abnormality occurs in the analysis section due to the cause, the disturbed interferogram at that time is ignored or discarded without being supplied to the averaging circuit in the data processing section as in the conventional configuration. In the averaging circuit, only the undisturbed original data is averaged. Therefore, the Fourier transform result obtained based on this and the S/N of the spectrum as the final measurement result are
In addition to being able to improve the ratio 5 specific stability and reproducibility, it has also demonstrated the remarkable effect of being able to perform very efficient measurements without having to start over from the beginning as in the past. .

[Brief explanation of the drawing]

FIG. 1 shows an overall schematic block circuit diagram of the Fourier transform infrared spectrophotometer according to the present invention, and FIGS. 2, 3, 4, and 5 are schematic circuit diagrams of the main parts thereof, respectively. be. FIG. 6 shows the technical background of the present invention and the conventional technique 4.
This is for explaining the problems of 4j, and shows an overall schematic block circuit configuration diagram of a Fourier transform infrared spectrophotometer having a conventional configuration. 4 A...Analysis section, 1...Interferometer, 2...Light source, 3...Interference needle drive circuit, 4...... Sample chamber, 5...Detector, B...Data processing section, 6...Additional averaging circuit, 7...Fourier transform circuit, 8... ...Spectrum calculation circuit, X...Abnormality detection circuit.

Claims (1)

[Scope of Claims] An analysis section consisting of a light source, an interferometer, an interferometer drive circuit, a sample chamber, a detector, etc., an averaging circuit that adds and averages interferograms output from the analysis section, and the averaging circuit. A Fourier transform infrared device comprising a Fourier transform circuit that performs Fourier transform processing on the output data from the Fourier transform circuit, and a data processing section that includes a spectrum calculation circuit that calculates a spectrum related to the measurement target based on the output data from the Fourier transform circuit. In the spectrophotometer, an abnormality detection circuit is provided to detect an abnormality occurring in the analysis section, and when the abnormality detection circuit detects an abnormality in the analysis section, an interface output from the analysis section at that time is provided. A Fourier transform infrared spectrophotometer characterized in that the ferrogram is configured not to be supplied to the averaging circuit in the data processing section.