JPH08233659A - Spectrophotometer - Google Patents

Abstract

PURPOSE: To provide a spectrophotometer by which a drift is reduced and temperature stability is enhanced even in a single beam system spectrophotometer using a photodiode array. CONSTITUTION: In a spectrophotometer to detect the light sent from light source chambers 3 and 4 by a photodiode array 16 of a polychromator chamber 17 after passing it through a flow cell 13 in a front optical part 18, one ends of heat pipes 19 and 20 are brought into close contact with the light source chambers 3 and 4, and the other ends of the heat pipes 19 and 20 are exposed outside of a shielding wall 21, and a cooling fun 22 is arranged to cool a heat pipe part appearing outside, and heat of the light source chambers is effectively removed by the heat pipes 19 and 20, and a photometric optical chamber 18 and the polychromator chamber 17 are prevented from being directly influenced by a cooling fan 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spectrophotometer using a photodiode array as a light receiving element.

[0002]

2. Description of the Related Art In some spectrophotometers, a photodiode array is used as a light receiving element of a detector. A spectrophotometer using a photodiode array as a detector can detect changes in the spectrum every moment, so it is used for various analyzes such as pharmaceuticals, foods, and the chemical industry.For example, not only a general-purpose spectrophotometer but also a liquid chromatograph The demand for the detector is rapidly increasing. In particular, when used as a detector for a liquid chromatograph, a detector having a highly sensitive analytical ability is required.

On the other hand, the spectrophotometer includes a single beam system and a double beam system. The single beam method is
The measurement optical path is set as one, and the measurement sample and the reference sample are sequentially mounted on the optical path, the measurements are separately performed, and the arithmetic processing is performed later to perform the measurement. In the double beam method, the measurement optical path is divided into two by a beam splitter or the like, a measurement sample is attached to one side, and a reference sample is attached to the other side so that the measurement is performed simultaneously. Since the double beam method can perform correction by the reference cell at the same time, drift is less likely to occur and stable measurement can be performed.

However, due to the fact that the photodiode array element itself is very effective, and the optical system becomes complicated when a double beam is used, a spectrophotometer using a photodiode array currently on the market has a single beam. Has been adopted.

[0005]

However, in the case of performing high-sensitivity analysis by the single beam method, unless the heat generated by the light source is effectively released to the outside, the optical system will be affected by the heat and the base will be affected. This will cause line instability. If you try to forcibly cool the light source or the light source chamber directly with a fan, the influence of the wind will appear around it, so the front optical part and the detection system installed adjacent to the light source chamber will change the environmental temperature due to the wind. It will be easier to receive.

Particularly, in recent years, in order to collect a spectrum in a wide wavelength range, a plurality of light sources may be turned on at the same time, and the lights may be mixed to be used.
The elimination of heat generated from the light source has been an important issue.

An object of the present invention is to solve the above problems and to provide a spectrophotometer which is stabilized by reducing the influence of the temperature of a single beam spectrophotometer using a photodiode array.

[0008]

The spectrophotometer of the present invention, which has been made to solve the above-mentioned problems, comprises a light source chamber containing a light source, a front optical section for allowing the measurement light from the light source to enter the sample to be measured, In a single-beam spectrophotometer in which a detection unit that detects the measurement light absorbed or reflected by the measurement sample with a photodiode array is installed in the shielding wall, one end of the heat pipe is closely attached to the light source chamber, It is characterized in that the other end is exposed to the outside of the shielding wall, and a cooling means for cooling the heat pipe portion exposed to the outside of the shielding wall is provided. Hereinafter, how this spectrophotometer works will be described.

[0009]

In the spectrophotometer of the present invention, the heat generated by the light source is effectively transmitted from the light source chamber to the outside through the heat pipe, and the heat pipe is cooled by the cooling means provided outside the shielding wall. Is radiated to. Since the cooling means is provided outside the shielding wall and is shielded from the optical system of the spectrophotometer, these need not be directly affected by the cooling means, and the photodiodes that are particularly susceptible to temperature For the array as well, the change in the ambient temperature is small, and therefore the fluctuation of the baseline is small. Therefore, even with the single-beam measurement, the temperature drift is small and stable measurement can be performed.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a single beam type spectrophotometer showing an embodiment of the present invention. As shown in the figure, 1 and 2 are light sources having different emission spectrum wavelength regions, for example, a combination of a deuterium lamp 1 for the ultraviolet region and a halogen lamp 2 for the visible region is used. Reference numerals 3 and 4 denote light source chambers having a built-in light source, a part of which is provided with a window for extracting light, and transparent members 5, 6, 7, and 8 are attached thereto.

A front optical section 18 is provided adjacent to the light source chambers 3 and 4. The front optical section 18 has a light mixing element 9, which mixes the light from the light sources 1 and 2 and makes it enter the flow cell 13 via the mirror 10. The shutter 11 is driven by the motor 12 and is used to block the optical path when measuring the dark current of the photodiode array described later.
A polychromatic chamber 19 as a detection unit is provided adjacent to the front optical unit 18. A grating 15 and a photodiode array 16 are provided in the polychromatic chamber 19, the measurement light that has passed through the flow cell 13 is separated by the grating 15, and the photodiode array 16 detects the light output for each wavelength almost at the same time. The detection signal of the photodiode array 16 is sent to the signal processing circuit of the spectrophotometer so that arithmetic processing can be performed. Front optical part 1
8 is provided at a boundary portion between the polychromatic chamber 19 and the polychromatic chamber 19 so as to prevent influences other than the measurement light.

The computer control unit for controlling the entire spectrophotometer controls the lighting of the light source, the control of the drive part such as the shutter, the control of the device such as the drive control of the photodiode array, and the arithmetic processing of the measurement data. .

The above is the same structure as the conventional spectrophotometer. In the apparatus of the present invention, rod-shaped heat sinks 19 and 20 each having one end closely attached to the wall surfaces of the light source chambers 3 and 4 are attached. The heat sinks 19 and 20 are made of a good heat conductor, and the light source chamber 3 and
The heat of No. 4 is easily transmitted to the other ends of the heat sinks 19 and 20. Cooling fins 23 and 24 for improving heat dissipation are connected to the other ends of the heat sinks 19 and 20, and an air cooling fan 22 is attached to the cooling fins 23 and 24. In order to prevent the wind of the cooling fan 22 from directly hitting the light source chambers 3, 4, the photometric optical chamber 18, and the polychromatic chamber 19 near the center of the heat sinks 19 and 20, at least a portion contacting the heat sink is made of a heat insulating material. It is partitioned by a shield wall 21. That is, the heat sinks 23, 2
Reference numeral 4 is attached so as to penetrate the shield wall 21, and heat from the light source chambers 3 and 4 inside the shield wall 21 is transferred to the cooling fins 23 and 24 outside the shield wall 21. Of course, the entire shielding wall 21 may be used as a heat insulating member. The wind generated by the cooling fan 22 is an exhaust port 29 provided in a housing 28 that surrounds the entire device.
Is discharged from the outside.

Next, the operation of this apparatus will be described. At the time of measurement, two light sources, that is, the deuterium lamp 1 and the halogen lamp 2 are simultaneously turned on, and the measurement light mixed by the light mixing element 9 is incident on the sample of the flow cell 13 via the mirror 10. The measurement light absorbed by the sample in the flow cell 13 reaches the grating 15 through the slit 14, and the light of each wavelength dispersed by the measurement light is simultaneously detected by each element of the photodiode array 16 corresponding thereto, and a signal is obtained. Sent to the processing circuit. As a result, a spectrum over a wide wavelength range from the ultraviolet region to the visible region can be detected at the same time.

When the deuterium lamp 1 and the halogen lamp 2 are simultaneously turned on for measurement, not only light but also heat is generated. The generated heat is shielded by the heat sinks 19 and 20 which are good heat conductors. Outside cooling fins 23, 24
And is forcibly cooled by the cooling fan 22. Therefore, the heat of the light source chambers 3 and 4 is effectively dissipated to the outside, and the inflow of heat to the front optical unit 18 and the polychromatic chamber 19 can be suppressed. Moreover, since the cooling fan 22 is located outside the shielding wall 21, the front optical section 18 and the polychromatic chamber 19 are not affected by the wind. Therefore, even in a device such as a single beam system that separately measures a measurement sample and a reference sample, the drift amount is small, and thus it is stable. In the present embodiment, two light sources are used at the same time, but the same effect can be obtained even if there is only one light source, although there is a degree of difference.

Further, as shown in FIG. 1, if the light source chambers 3 and 4 are connected to the front optical section 18 via the heat insulating members 25 and 26, the influence of heat can be further reduced. Drift is less likely to occur.

Further, a temperature sensor is provided near the cooling fins 23 and 24 which are forcibly cooled by the cooling fan 22,
If the rotation speed of the cooling fan 22 is controlled by feeding back the signal from the temperature sensor to the cooling fan 22, the influence of the change in the environmental temperature can be further reduced.

The embodiments of the present invention will be summarized below. (1) Shields a plurality of light source chambers with built-in light sources, a pre-optical part for making light from a light source incident on a sample to be measured, and a detector for detecting measuring light absorbed or reflected by the sample to be measured by a photodiode array In the single-beam spectrophotometer installed in the wall, one end of the heat pipe is brought into close contact with each light source chamber, the other end of the heat pipe is exposed to the outside of the shielding wall, and the heat pipe part that has gone out is cooled. A spectrophotometer comprising a cooling means. (2) Inside the shielding wall, a light source chamber containing a light source, a front optical part for making light from the light source incident on the sample to be measured, and a detector for detecting the measuring light absorbed or reflected by the sample to be measured by the photodiode array. In the single-beam type spectrophotometer installed in, the light source chamber is connected to the front optics part through a heat insulating member, one end of the heat pipe is brought into close contact with the light source chamber, and the other end of the heat pipe is exposed outside the shielding wall. The spectrophotometer is provided with a cooling means for cooling the heat pipe portion that has been exposed to the outside. (3) Shields a plurality of light source chambers containing built-in light sources, a pre-optical part for making light from the light source incident on the sample to be measured, and a detector for detecting the measuring light absorbed or reflected by the sample to be measured with a photodiode array In the single-beam spectrophotometer installed inside the wall, one end of the heat pipe is closely attached to the light source chamber, the other end of the heat pipe is exposed to the outside of the shielding wall, and the heat pipe part that has gone outside is cooled. A spectrophotometer, characterized in that the means and a temperature sensor are provided on the part to be cooled and the rotation speed of the cooling fan is controlled by feedback controlling the signal from the temperature sensor.

[0019]

As described above, according to the present invention,
The shielding wall prevents the influence of the cooling means from directly affecting the optical system and the detection system, and the heat from the light source chamber, which is the heat source, is taken out of the shielding wall using the heat sink, and then cooled. It is possible to perform proper cooling and reduce drift caused by temperature fluctuation.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a spectrophotometer that is an embodiment of the present invention.

[Explanation of reference symbols] 1: Deuterium lamp, 2: Halogen lamp 3, 4: Light source chamber 13: Flow cell 16: Photodiode 17: Polychrome chamber (detection section) 18: Front optical section 19, 20: Heat pipe 21: Shielding Wall 22: Cooling fan 25, 26: Insulation member

Claims (1)

[Claims] 1. A light source chamber having a built-in light source, a pre-optical part for making measurement light from a light source incident on a sample to be measured, and a detector for detecting the measurement light absorbed or reflected by the sample to be measured by a photodiode array. In a single-beam spectrophotometer installed inside the shielding wall, one end of the heat pipe is brought into close contact with the light source chamber, the other end of the heat pipe is exposed outside the shielding wall, and the heat pipe portion outside the shielding wall is exposed. A spectrophotometer provided with a cooling means for cooling.