JPH075054U - Photometer - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a photometer that can reliably correct even when the light intensity of a light source changes suddenly and enables more stable and highly accurate measurement. A sample hold circuit 12 is provided between the switching element 8 and the reference-side photodetector 4 that detects the reference light obtained by extracting a part of the excitation light emitted from the light source 1. The output of the fluorescence side photodetector 7 for detecting the fluorescence emitted from the sample in the cell 5 is directly connected to the switching element.
The sample-hold circuit samples and holds the light intensity of the reference light received by the photodetector 4 when the switching element is in the conducting state with the photodetector 7, and then holds when the self conducts with the switching element. The calculated value is sent to the A / D converter 9 via the switching element. Therefore, the outputs of the respective detection elements are alternately fetched into the CPU 10, but the outputs of both photodetection elements processed by the CPU are detected at the same time, so that the correction is accurate.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a photometer, for example, a photometer used as a fluorescence detection device for a liquid chromatograph, in which a part of light (excitation light) with which a sample is irradiated is extracted and detected as a reference light. , And to the improvement of the mechanism for correcting the influence of the fluctuation of the intensity of the light emitted from the light source over time using the reference light.

[0002]

[Prior art]

 In a fluorometer, the light intensity of the light source fluctuates irregularly over time, so the intensity of the excitation light that illuminates the sample also fluctuates. This fluctuation affects the fluorescence intensity emitted from the sample and causes a measurement error. Therefore, for example, as disclosed in Japanese Utility Model Application Laid-Open No. 63-152552, a part of the excitation light is extracted as the reference light, and the fluorescence intensity emitted from the sample is divided by the reference light (the relative light intensity with respect to the excitation light is obtained). In some cases, the effect of measurement error on the fluctuation (fluctuation) of the light intensity of the light source is suppressed by performing the correction.

The structure will be briefly described. As shown in FIG. 7, after the light emitted from the light source 1 is separated into monochromatic light (excitation light) by the excitation-side spectroscope 2, it is then separated by the beam splitter 3. Part of the light is reflected and received by the reference light side photodetector 4, and the intensity of the reference light is detected.

In addition, the excitation light transmitted through the beam splitter 3 is irradiated onto the sample in the cell 5, the fluorescence emitted from the sample is dispersed by the fluorescence side spectroscope 6, and then the fluorescence side photodetector 7 receives the fluorescence. Then, the intensity of fluorescence is detected.

Then, the outputs of both the photodetection elements 4 and 7 are sent to the switching element 8 of 2 inputs and 1 output, and the both light intensity data (reference signal R, fluorescence signal S) are alternated in a time division manner. After being sent to the A / D converter 9 and converted into a digital signal there, the CPU 10 calculates the ratio (S / R) of signals sequentially input. Then, even if the intensity of the light emitted from the light source 1 changes, S and R also change according to the change, so that the ratio becomes almost constant and is corrected. If the ratio is obtained in this way, the ratio is converted to an analog signal and output via the D / A converter 11 (output as a fluorescent side measurement signal).

[0006]

[Problems to be solved by the device]

 However, the above-mentioned conventional device has the following problems. That is, since the reference signal R and the fluorescence signal S are alternately acquired by the switching element 8, S and R calculated by the CPU 10 are not the values measured (sampled) at the same time. Since the sampling time in this type of device is about several tens of ms ec, this time difference is ignored when the excitation light (reference light) and the fluorescence change slowly as shown in FIG. 8 (A). However, when the intensity (luminance) changes rapidly as shown in Fig. 2B, the effect of the time difference is apparent, as shown in Fig. 2B. It cannot be ignored and causes a measurement error. That is, the result (ratio) obtained by division based on the signals obtained between ab, cd, and ef varies greatly.

The present invention has been made in view of the above background, and an object of the present invention is to make sure that even when the light intensity of the light source changes abruptly, it is possible to surely correct the light intensity. It is to provide a photometer capable of highly accurate measurement.

[0008]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, in the photometer according to the present invention, a light irradiation means for irradiating the light emitted from the light source to the sample and a part of the light before being irradiated to the sample are taken out for reference. First light detecting means for detecting as light, second light detecting means for detecting measuring light generated from the sample based on the irradiated light, and detection detected by the first and second light detecting means In a photometer having means for performing a correction process for a variation in the intensity of light emitted from the light source based on a signal, the means for performing the correction process is a detection signal output from at least the both light detection means. Of these, there is provided a switching means for sending one signal to the A / D conversion section at the next stage and an operation section to which the output of the A / D conversion section is connected, and the first photodetection means. Between the switching means or with the second light detecting means Setting a sample and hold circuit to at least one of between the serial switching means only, the two detection signals the arithmetic processing by the arithmetic unit, and to be made based on what is detected at the same time.

Further, in place of providing the sample hold circuit, a means for performing the correction process is provided with at least first and second A / D converters respectively connected to outputs of the both photodetector means, and both of them. It may be configured with a calculation unit to which the output of the A / D conversion unit is connected.

[0010]

[Action]

 When the sample-hold circuit is provided, the detection signals detected by the first and second photo-detecting means are alternately applied to the A / D conversion section and the arithmetic section in a time-divided manner. Thus, for example, the detection signal of one photodetector sent to the A / D converter via the switching unit and the detection signal of another photodetector detected at the same time are stored in the sample hold circuit. Then, when it becomes conductive with the switching section next time, the detection signal stored in the sample hold circuit is sent to the A / D conversion section. As a result, since the detection signal detected at the same time is given to the arithmetic unit that is digitized and given through the A / D conversion unit, even if the light intensity of the light source changes abruptly, it can be surely corrected. .

Further, when both the outputs of the first and second light detecting means are connected to the first and second A / D converters, there is no switching problem as described above, and the detection detected at the same time is performed. The signal can be sent to the calculation section at the same time via both A / D conversion sections, and is also corrected without being affected by the change in the light intensity of the light source.

[0012]

EXAMPLE A photometer according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows a first embodiment of the present invention, which is an example applied to a fluorometer. As shown in the figure, the basic structure of this embodiment is similar to the above-mentioned conventional apparatus (shown in FIG. 7), and therefore, the same reference numerals are given and the description thereof is omitted. In this example, a photo conversion element such as a photodiode or a photocell is used as the reference side photodetector 4, and a photoconversion element such as a photomultiplier tube is used as the fluorescence side photodetector 7. The element used in this way is replaced by a photodiode or the like because the light intensity of the reference light is high, but the light intensity of the fluorescence is weak, so it is possible to use light with a very small intensity such as a photomultiplier tube. This is to enable detection of received light. Therefore, of course, a photomultiplier tube or the like may be used as the reference side photodetector.

Here, in the present invention, a sample hold circuit 12 is provided between the reference side photodetector 4 and the switching element 8. The sample and hold circuit 12 samples the fluorescence signal S when the switching element 8 is in conduction with the fluorescence side photodetector 7 (state shown in the figure), that is, at the same time as the reference side. The light intensity of the reference light received by the photodetector 4 is adjusted so as to be sampled and held. Then, after that, when the switching element 8 is switched and becomes conductive with the reference side photodetector 4 (sample hold circuit 12), the held sampling value is sent to the A / D converter 9 via the switching element 8. Has become.

With such a configuration, as shown in FIG. 2, the A / D converter 9 and the CPU 10 alternately take in a time lag according to the switching timing of the switching element 8 (the fluorescence side signal is (Time a, c, e, the reference side signal is taken in at time b, d, f)), but each signal R, which is used for the division (S / R) of the reference signal R and the fluorescence signal S, which are arithmetically processed by the CPU 10. Since S is the light intensity data detected and sampled at the same time (time a, c, e), even if the light intensity emitted from the light source 1 changes rapidly, both signals are always Since the data obtained at the same time is guaranteed, the correction effect is surely exhibited.

Although the sample-hold circuit 12 is provided on the reference side in this embodiment, the present invention is not limited to this, and the sample-hold circuit 12 may be provided on the fluorescent side or may be provided on both sides.

FIG. 3 shows a second embodiment of the present invention. As shown in the figure, in the present example, unlike the above-described embodiment, the outputs of the reference side photodetector 4 and the fluorescence side photodetector 7 are set to the first and second sides, respectively, without providing a switching element. It is connected to the A / D converters 9a and 9b, and the outputs of both A / D converters 9a and 9b are connected to the CPU 10.

With such a configuration, as shown in FIG. 4, the reference signal and the fluorescence signal sampled at the same time (time a, b, c) are simultaneously given to the A / D converters 9a, 9b, respectively. After being converted into a digital signal, it can be input to the CPU 10 at the same time. As a result, it is not necessary to alternately take in data as in the first embodiment described above, and higher speed processing is possible. The rest of the configuration and effects are similar to those of the first embodiment described above, and therefore their explanations are omitted.

In order to demonstrate the effect of the present invention, the Raman scattering data of water was measured using the conventional apparatus shown in FIG. 7 and the apparatus of the first embodiment shown in FIG. At this time, the excitation wavelength was 350 nm and the fluorescence wavelength was 397 nm. Both devices used the same conditions except for the presence or absence of the sample and hold circuit (components used, sensitivity during measurement, etc.). The results are shown in FIG. 5 (present invention) and FIG. 6 (comparative example), respectively. As is clear from the figure, it can be confirmed that the noise is reduced in the present invention, and the fluctuations of the light source are corrected.

In the above-described embodiment, the correction is made by dividing the reference signal R and the fluorescence signal S, but the specific correcting means is not limited to this. The photometer to be applied is not limited to the fluorescence photometer, but can be applied to an optical measuring device that uses a part of light from a light source such as an absorptiometer as a reference signal.

[0020]

[Effect of device]

 As described above, in the photometer according to the present invention, the detection signal for measurement of fluorescence or the like and the reference detection signal for performing the predetermined calculation processing and correction in the calculation unit are sampled at the same time. Therefore, even if the light intensity of the light source fluctuates abruptly, it can be surely corrected, and more stable and highly accurate measurement is possible.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an operation.

FIG. 3 is a view showing a second embodiment of the present invention.

FIG. 4 is a diagram illustrating an operation.

FIG. 5 is a graph showing an experimental result for demonstrating the effect of the present invention.

FIG. 6 is a graph showing experimental results for demonstrating the effect of the present invention.

FIG. 7 is a diagram showing a conventional example.

FIG. 8 is a diagram for explaining a conventional problem.

[Explanation of symbols]

 1 light source 2 excitation side spectroscope 3 beam splitter 4 reference light side photodetector 5 cell 6 fluorescence side spectroscope 7 fluorescence side photodetector 8 switching element 9 A / D converter 9a first A / D converter 9b second A / D converter 10 CPU 11 D / A converter

Claims (3)

[Scope of utility model registration request] 1. A light irradiating means for irradiating a sample with light emitted from a light source, a first light detecting means for extracting a part of the light before irradiating the sample and detecting it as reference light, and the irradiation. Second light detecting means for detecting the measurement light generated from the sample based on the emitted light, and the intensity of the light emitted from the light source based on the detection signals detected by the first and second light detecting means. In a photometer provided with a means for performing a correction process for fluctuations, the means for performing the correction process uses at least one of the detection signals output from the both light detecting means as an A / D converter in the next stage. And a calculation unit to which the output of the A / D conversion unit is connected, and between the first light detection unit and the switching unit, or between the second light detection unit and the second light detection unit. At least one side of the switching means The hold circuit is provided, a photometer the two detection signals the arithmetic processing by the arithmetic unit, and to be made based on what is detected at the same time. 2. A light irradiating means for irradiating the sample with light emitted from a light source, a first light detecting means for extracting a part of the light before irradiating the sample and detecting it as reference light, and the irradiation. Second light detecting means for detecting the measurement light generated from the sample based on the emitted light, and the intensity of the light emitted from the light source based on the detection signals detected by the first and second light detecting means. In a photometer provided with means for performing a correction process for fluctuations, the means for performing the correction process includes at least first and second A / D conversion units respectively connected to the outputs of the both light detection units, and A photometer comprising: an arithmetic unit to which outputs of both A / D converters are connected. 3. The sample is a fluorescent sample, the second sample
The measurement light detected by the light detection means is fluorescence.
Or the photometer described in 2.