JP2012058105A - Optical analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply and accurately test an optical system in a short time in an optical analyzer for analyzing a sample liquid by radiating light to the sample liquid in a measurement cell from a light source, detecting light transmitting the sample liquid by a measurement sensor, and analyzing the sample liquid.SOLUTION: The optical analyzer includes a power source 24 for adding a voltage to a light source 14 so that an amount of emitted light of the light source amounts to a prescribed set amount of light set in advance, a reference sensor 28 for detecting direct light from the light source, and a voltage control circuit 30 electrically connected to the power source and the reference sensor. Then, in testing the optical system, the voltage to be added from the light source to the power source is changed by control of the voltage control circuit so that the amount of the emitted light of the light source changes by a prescribed amount from the set amount of light, pure water is used as a sample liquid to detect the light transmitting the measurement cell by the measurement sensor, and a change amount of a light amount which has been subjected to a change by changing the voltage to be added from the light source to the power source is compared with a change amount of a light amount which is detected by the measurement sensor. When both of the change amounts are equal, the optical system is determined to be normal, and when both of the change amounts are not equal, the optical system is determined to be abnormal.

Description

  The present invention relates to an optical analyzer that analyzes sample liquid by irradiating light from a light source to a sample liquid in a measurement cell and detecting light transmitted through the sample liquid by a measurement sensor. The present invention relates to an optical analyzer that can easily and accurately perform the inspection in a short time.

  Conventionally, as shown in FIG. 2, a sample liquid 52 in a measurement cell 50 is irradiated with light (ultraviolet light having a wavelength of about 254 nm) 56 from a light source (mercury lamp) 54, and light 58 transmitted through the sample liquid 52 is measured by a measurement sensor. An optical analyzer that detects the concentration of the organic pollutant in the sample liquid 52 based on the signal from the measurement cell 50 in the calculation unit 62 that is detected by the (light receiving element) 60 and electrically connected to the measurement sensor 60. It has been proposed (see, for example, Patent Documents 1 and 2).

  In the optical analyzer described above, it is necessary to inspect an optical system including a light source, a measurement cell, and a measurement sensor periodically or as necessary. In this case, as an inspection method for the optical system, there is a method in which a standard solution is injected into a measurement cell and the standard solution is measured. In this case, a zero solution such as distilled water or a span solution such as a potassium hydrogen phthalate standard solution is used as the standard solution.

  In addition, as a simple inspection method for the optical system, when an optical filter having a specific absorbance is arranged in the optical path from the light source to the measurement sensor, and the measurement sensor signal when the optical filter is not arranged, and the optical filter are arranged There is a method of performing an inspection by comparing the signal of the measurement sensor.

JP 2009-85708 A JP 2009-85709 A

However, the method of inspecting an optical system using the optical filter described above has the following problems.
(1) In the inspection method using the optical filter, the transmittance when the optical filter is not disposed in the optical path is set to 100%, and when the optical filter is disposed in the optical path, the light amount of the light source is changed to appropriately adjust the transmittance. By changing to (for example, 50%), absorbance data is obtained. However, in the optical analyzer of FIG. 2, since the mercury lamp is lit by a constant voltage stabilizing power source, it is driven so that the voltage or current applied to the lamp is always constant. It is not necessarily proportional to the voltage or current. Furthermore, since the light quantity of the lamp is unstable when the mercury lamp is driven by the constant voltage stabilized power supply, it takes time for the light quantity to stabilize after the lamp is lit. It was difficult.
(2) In the inspection method using the optical filter, the absorbance of the optical filter changes over time due to deterioration of the optical glass, metal film, dielectric multilayer film, etc. of the optical filter due to ultraviolet light irradiation and humidity. Therefore, there was a possibility that the inspection could not be performed accurately.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide an optical analyzer capable of simply and accurately performing an inspection of an optical system in a short time.

  As a result of various studies to achieve the above object, the inventor detects direct light from the light source (light that does not pass through the measurement cell) with a reference sensor, sends the signal to the voltage control circuit, and In the voltage control circuit, when the power supply voltage value of the light source is compared with the signal value from the reference sensor and the power supply voltage value of the light source is controlled so that the amount of light emitted from the light source is always constant, It has been found that when the voltage applied to the light source is changed, the amount of light emitted from the light source can be changed immediately, so that the optical system can be inspected easily and accurately in a short time.

The present invention has been made based on the above findings,
In an optical analyzer that analyzes the sample liquid by irradiating the sample liquid in the measurement cell with light from the light source and detecting the light transmitted through the sample liquid with a measurement sensor.
A power source for applying a voltage to the light source so that the light amount of the light emitted from the light source is a predetermined light amount set in advance;
A reference sensor for detecting direct light from the light source;
A voltage control circuit that is electrically connected to the power source and the reference sensor, and controls a voltage applied from the power source to the light source so that the set light amount is equal to the light amount detected by the reference sensor. And
When inspecting the optical system including the light source, measurement cell, and measurement sensor, the voltage control circuit applies a voltage applied from the power source to the light source so that the amount of light emitted from the light source changes by a predetermined amount from the set light amount. The amount of change in the amount of light detected by the measurement sensor, the amount of change in the amount of light detected by the measurement sensor, and the amount of change in the amount of light detected by the measurement sensor The optical analyzer is characterized in that it is determined that the optical system is normal if the two variations are equal, and that the optical system is abnormal if the two variations are not equal.

  In the optical analyzer of the present invention, the amount of light is always stabilized so that measurement can be performed immediately after the light source is turned on. Therefore, for example, the light receiving sensitivity of the optical system can be inspected by appropriately reducing the set voltage value of the light source and appropriately attenuating the amount of light emitted from the light source. Such a function is obtained by using the direct light from the light source as reference light for feedback control, so that the light amount of the light source can be stabilized in a short time, and the set voltage value of the light source by the voltage control circuit. This is because the light quantity of the light source can be electrically attenuated so as to correspond to the insertion of the optical filter described above.

  The optical analyzer of the present invention can be configured, for example, as an organic pollution monitor, a multi-wavelength absorbance measurement type water quality analyzer, or the like. The optical analyzer of the present invention can also be configured as an optical analyzer that performs measurement by immersing a measurement cell in a solution.

  The optical analyzer of the present invention can easily and accurately perform an inspection of an optical system including a light source, a measurement cell, and a measurement sensor in a short time.

It is a conceptual diagram which shows one Embodiment of the optical analyzer which concerns on this invention. It is a conceptual diagram which shows an example of the conventional optical analyzer.

  Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 is a conceptual diagram showing an embodiment of an optical analyzer according to the present invention.

  The optical analyzer of this example irradiates the sample liquid 12 in the measurement cell 10 with light (ultraviolet light having a wavelength of about 254 nm) 16 from the light source (mercury lamp) 14 as in the optical analyzer shown in FIG. Then, the light 18 transmitted through the sample solution 12 is detected by the measurement sensor (light receiving element) 20, and the sample solution 12 is calculated based on the signal from the measurement cell 20 in the calculation unit 22 electrically connected to the measurement sensor 20. The concentration of organic pollutants is determined.

  Further, the optical analyzer of this example includes a power source 24 that applies a voltage to the light source 14 so that the light amount of the emitted light 16 of the light source 14 becomes a predetermined set light amount, and direct light (measurement cell) from the light source 14. A reference sensor 28 for detecting the light 26, and a voltage control circuit 30 electrically connected to the power supply 24 and the reference sensor 28. The voltage control circuit 30 controls the voltage applied from the power source 24 to the light source 14 so that the set light amount is equal to the light amount detected by the reference sensor 28, and includes a comparator 32. Further, a variable reference voltage source 34 is connected to the comparator 32. The variable reference voltage source 34 generates a voltage value set so as to obtain the set light amount, and can set an arbitrary voltage value. More specifically, the comparator 32 compares the signal value (light amount) from the reference sensor 28 with the set light amount (voltage value generated by the variable reference voltage source 34 corresponding to the set light amount), and the comparison result. The voltage value by the power source 24 is controlled based on the above.

  In the optical analyzer of this example, the optical system including the light source 14, the measurement cell 10, and the measurement sensor 20 is inspected as follows, for example. First, under the control of the voltage control circuit 30, the voltage applied from the power source 24 to the light source 14 is decreased so that the amount of light emitted from the light source 14 is attenuated by a predetermined amount from the set light amount. Then, pure water is used as the sample solution, the light 18 transmitted through the measurement cell 10 is detected by the measurement sensor 20, and the voltage applied to the light source 14 from the power source 24 (by lowering the set voltage value of the variable reference voltage source 34). The attenuation amount of the light amount to be attenuated by the decrease (corresponding to the attenuation amount due to the insertion of the conventional optical filter) is compared with the attenuation amount of the light amount detected by the measurement sensor 20, and if both the attenuation amounts are equal, the optical amount The system is determined to be normal, and if both attenuations are not equal, it is determined that there is an abnormality in the optical system. If it is determined that there is an abnormality, it may be determined where the abnormality is. Therefore, according to the optical analyzer of this example, the inspection of the optical system can be performed easily and accurately in a short time.

  The optical analyzer of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 Measurement cell 12 Sample liquid 14 Light source 16 Output light 18 Transmitted light 20 Measurement sensor 22 Operation part 24 Power supply 26 Direct light 28 Reference sensor 30 Voltage control circuit 32 Comparator 34 Variable reference voltage source

Claims (3)

In an optical analyzer that analyzes the sample liquid by irradiating the sample liquid in the measurement cell with light from the light source and detecting the light transmitted through the sample liquid with a measurement sensor.
A power source for applying a voltage to the light source so that the light amount of the light emitted from the light source is a predetermined light amount set in advance;
A reference sensor for detecting direct light from the light source;
A voltage control circuit that is electrically connected to the power source and the reference sensor, and controls a voltage applied from the power source to the light source so that the set light amount is equal to the light amount detected by the reference sensor. And
When inspecting the optical system including the light source, the measurement cell, and the measurement sensor, the voltage control circuit controls the light source so that the amount of light emitted from the light source changes by a predetermined amount from the set light amount. While changing the voltage, the light transmitted through the measurement cell is detected by the measurement sensor, and the amount of change in the amount of light that is to be changed by changing the voltage applied to the light source from the power source and the amount of light detected by the measurement sensor An optical analyzer characterized by comparing the amount of change and determining that the optical system is normal if the two amounts of change are equal, and determining that the optical system is abnormal if the amounts of change are not equal.   Under the control of the voltage control circuit, the voltage applied to the light source from the power source is reduced so that the light amount of the light emitted from the light source is attenuated by a predetermined amount from the set light amount, and the light transmitted through the measurement cell is detected by the measurement sensor, Compare the amount of attenuation of the light amount to be attenuated by decreasing the voltage applied to the light source from the amount of attenuation of the light amount detected by the measurement sensor, and if both attenuation amounts are equal, it is determined that the optical system is normal. The optical analyzer according to claim 1, wherein if the two attenuations are not equal, it is determined that the optical system is abnormal.   The optical analyzer according to claim 1 or 2, wherein a mercury lamp that emits ultraviolet light having a wavelength of about 254 nm is used as a light source, and an organic pollutant concentration in the sample liquid is measured.

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