JPH05113369A - Spectral photometer - Google Patents

Abstract

PURPOSE:To achieve a wavelength original point confirmation operation while an arbitrary object is left in a sample chamber by providing a peak-detection circuit for monitoring fluctuation of a light source. CONSTITUTION:Light which impinges on an incidence slit 1 forms a spectrum image of the incidence light on the surface where an irradiation slit 3 is placed through a diffraction grating 2. Light which outgoes from the irradiation slit 3 to a sample chamber 6 is focused on a light-reception element 8 and is detected. A beam splitter 9 is inserted at the center of a flux of light which is directed toward the irradiation slit 3 from the diffraction grating 2 and impinges on a photodetector 10 where part of the flux of light which is emitted through the irradiation slit 3 to the sample chamber 6 is reflected, thus constituting a peak-detection circuit. A control circuit 11 counts the number of pulse motor drive pulses from a wavelength original point position of the diffraction grating 2 and converts it to a wavelength value of an irradiation slit irradiation light of a spectral meter for obtaining wavelength data on measurement. Also, the output of the light-reception element 9 which receives sample light is taken in through an amplification circuit 13 as spectral data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spectrophotometer having a function of monitoring a light source fluctuation. That is, the spectrophotometer is classified into a two-beam type and a single-beam type. There is a single light flux type in which a part of the light dispersed by the spectroscope is divided by a transparent crystal plate or the like to monitor the light source fluctuation. The present invention relates to such a type of spectrophotometer, and more particularly to means for detecting the wavelength origin of a spectroscope.

[0002]

2. Description of the Related Art In a spectrophotometer, the wavelength origin of the spectroscope, that is, the position of the wavelength value 0 which is the starting point of the wavelength scanning is detected, and the driving amount of the spectroscope is converted to the wavelength value from that position to display the wavelength display value. It is supposed to be. For the detection of the wavelength origin for this, when a diffraction grating is used as a light dispersion element of the spectroscope, the diffraction grating is rotated to perform the wavelength scanning of the spectroscope,
The position of the diffraction grating when the 0th-order diffracted light of the diffraction grating is emitted from the exit slit of the spectroscope and detected is used as the wavelength origin.

Prior to the subject of the present invention (0001)
In the single-beam type spectrophotometer as described in the section above, the above-mentioned operation of detecting and confirming the wavelength origin is performed by using the light which is emitted from the exit slit of the spectroscope to the sample chamber and enters the light receiving element through the sample chamber. I was going. In such a configuration in which the wavelength origin is detected by using the light irradiating the sample, there are the following problems.

When nothing is placed in the sample chamber, the light emitted from the exit slit of the spectroscope to the sample chamber is incident on the light receiving element, so that the wavelength origin can be detected without any trouble. However, usually some object is placed in the sample chamber depending on the intended use of the spectrophotometer. For example, when a flow cell is placed in the sample chamber for continuous analysis of a liquid sample, the light emitted from the exit slit of the spectroscope goes straight through the flow cell when the flow cell is empty or completely filled with liquid. There is no problem because it can be incident on the light receiving element, but when the sample liquid partially remains in the flow cell, the light is irregularly refracted and reflected by the sample in the flow cell and goes straight to the light receiving element. It is no longer possible, and the position of the detected wavelength origin will be slightly misaligned. When measuring the relative reflectance of the sample, a mirror that reflects the light toward the sample in the optical path that is emitted from the spectroscope exit slit and goes straight to the light receiving element in advance in the sample chamber, and the light reflected from the sample A mirror for reflecting the light toward the light receiving element is placed, but at this time, if it is a sample and the mirror of the reference sample is not placed at the sample position, the light emitted from the exit slit of the spectroscope enters the light receiving element. It is impossible to detect the wavelength origin itself.

The above problem is that the detection and confirmation of the wavelength origin may be performed without placing anything in the sample chamber in advance, but in practice, the confirmation of the wavelength origin should be performed once when the spectrophotometer is newly installed. It is not good, and it is necessary to check the spectrophotometer while using the spectrophotometer and adjust the spectroscope, so in such a case, a flow cell previously installed in the sample chamber for routine analysis. In other words, it is very troublesome to move the optical path changing mirror, and if possible, I would like to detect the wavelength origin while placing those objects in the sample chamber.

[0006]

DISCLOSURE OF THE INVENTION The present invention is a single-beam type spectrophotometer having a function of monitoring fluctuations in a light source, and is capable of confirming a wavelength origin even when an arbitrary object is placed in a sample chamber. It is intended to provide a photometer.

[0007]

A peak detection circuit is provided in a light detection circuit for monitoring fluctuations in a light source.

[0008]

Since the device for monitoring the fluctuation of the light source is designed to extract a part of the light dispersed by the spectroscope before entering the sample and make it enter the photodetector, the peak of the output of this photodetector If a circuit for detecting is also provided, the peak of the 0th-order light of the spectroscope can be detected by this circuit as well, and therefore the wavelength origin can be detected.

[0009]

FIG. 1 shows an embodiment of the present invention. Reference numeral 1 is an entrance slit of the spectroscope, 2 is a diffraction grating of the spectroscopic element, 3 is an exit slit of the spectroscope, and each of these parts constitutes a spectroscope. 4 is a tungsten lamp as a light source for the spectroscope, and 4D
Is also a deuterium lamp, and one of the light sources is switched according to the measurement wavelength region such as visible light and visible ultraviolet light, and is made incident on the entrance slit 1 of the spectroscope. Reference numeral 5 is a light source switching mirror for that purpose. The light incident on the entrance slit is dispersed by the diffraction grating 2 to form a spectrum image of the incident light on the arrangement surface of the exit slit 3. The emission slit 3 extracts a portion of the light of a specific wavelength from this spectrum image and makes it emit to the sample chamber 6. The light emitted from the emission slit 3 to the sample chamber 6 is condensed on the light receiving element 8 by the condenser lens 7 and detected. The beam splitter 9 is arranged immediately before the emission slit in the spectroscope. This is a crystal parallel plane plate inserted at an angle of 45 ° with respect to the center ray of the light beam traveling from the diffraction grating 2 to the exit slit, and a part of the light beam emitted from the exit slit to the sample chamber is reflected and It is incident on the detector 10.

Reference numeral 11 denotes a control circuit, which sends a driving pulse to a pulse motor 12 for driving the diffraction grating to rotate the diffraction grating to perform wavelength scanning, and counts pulse motor driving pulses from the wavelength origin position of the diffraction grating. It is converted into the wavelength value of the light emitted from the exit slit of the spectroscope and used as the wavelength data for measurement. Further, the output of the light receiving element 8 which receives the sample light is taken in through the amplifier circuit 13 and used as spectrum data. Further, the output of the photodetector 10 is sampled to monitor the light source fluctuation. That is, the output of the photodetector 10 is sampled, the output of the light receiving element 8 is divided by the output, or the output of the photodetector 10 is inversely proportional to the gain of the amplifier circuit 13 to change the light source fluctuation. Compensate for impact.

The control device 11 can select two kinds of operation modes for detecting the wavelength origin of the spectroscope. The origin of the wavelength is detected by driving the diffraction grating of the spectroscope in the direction of wavelength 0 from an appropriate wavelength position while detecting the peak of the 0th-order diffracted light of the diffraction grating, and when the center of the peak is detected, This is an operation in which the count value of the counter that counts the pulses that drive the pulse motor 12 is set to 0 as the wavelength origin and the excitation phase of the pulse motor at that time is stored. After the wavelength origin is detected, the wavelength value is obtained from the count value of the counter that counts the pulses that drive the pulse motor. This operation for detecting the wavelength origin is performed every time the power is turned on as one of the initial setting operations of the spectroscope.

The first mode of the wavelength origin detection operation is a mode in which the wavelength origin is detected by the emitted light of the spectroscope emitted to the sample chamber 6. The other is a mode in which the wavelength is detected by the output of the photodetector 10. In either case, in principle, the position of the diffraction grating when the center of the output peak when the 0th-order light is incident on the light receiving element 8 or the photodetector 10 is detected is the origin of wavelength. In the mode in which the wavelength origin is detected by the device 10, the wavelength resolution in the monitor optical path including the diffraction grating 2, the beam splitter 9, and the photodetector 10 is the diffraction grating 2, the output slit 3, the condensing lens 7, and the light receiving element 8. It is lower than the optical path of the sample, and the position of the diffraction grating at which the 0th-order light of the diffraction grating is detected is slightly different due to a working error in the installation positions of the beam splitter 9 and the photodetector 10. This difference is an error specific to each spectrophotometer, and is fixed for each spectrophotometer.Therefore, this error is verified in the factory adjustment of the spectrophotometer, and the wavelength origin by the monitor light is verified. When the detection mode is selected, a program is given to the control device 11 so as to preset the count value corresponding to this error in the counter of the pulse motor drive pulse when the 0th-order light peak center is detected.

[0013]

According to the present invention, in the single-beam type spectrophotometer having the light source monitor function, two modes can be selected for timely confirmation of detection of the wavelength origin, so that the sample chamber of the spectrophotometer can be selected. The origin of wavelength can be detected without moving anything installed in the
The application range of this type of spectrophotometer is widened.

[Brief description of drawings]

FIG. 1 is a plan view of an apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 1 entrance slit 2 diffraction grating 3 exit slit 4 light source 5 light source switching mirror 6 sample chamber 7 condenser lens 8 light receiving element 9 beam splitter 10 photodetector 11 controller 12 pulse motor

Claims (1)

[Claims] 1. A single-beam spectrophotometer with a light source fluctuation monitoring function, wherein a part of light split by a spectroscopic element and made incident on a sample is split and made incident on a light detection element for light source fluctuation monitoring by a beam splitter. In, an operation mode of detecting the wavelength origin of the spectrophotometer using the output of the light receiving element that receives the sample light, and an operation mode of detecting the wavelength origin using the output of the light detection element for monitoring the light source fluctuation A spectrophotometer characterized by having both and being able to select both.