JP2011017567A - Spectrophotometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide masks for optimizing the light quantities of spectrally separated light incident on a photodetector, thereby preventing a fall in S/N caused by a decrease in the light quantity of a light source, in a spectrophotometer using the photodetector having a plurality of light receiving elements.SOLUTION: The photodetector includes the plurality of light receiving elements for spectrally separating light emitted from the light source by an optical system, receiving the spectrally separated light, and simultaneously detecting other wavelengths. The masks are used in the detector for adjusting the light quantities varying with wavelengths. In each of light receivers of the receiving elements, the masks are placed each having a movable mechanism for adjusting the shape of an opening in each mask to a shape for providing light receiving sensitivity optimum for the detector.

Description

  The present invention optimizes the detection sensitivity of a photodetector of a spectrophotometer.

  The light source used in the spectrophotometer is a light source that decreases due to deterioration of the filament or electrode depending on the light emission time or the number of times of light emission. It is used until it decreases to about 50%. In a spectrophotometer using a light detector in which a plurality of light receiving elements are arranged, different light intensities are incident on the light detector depending on the characteristics of the light source, the spectroscope, etc. In a spectrophotometer that uses a photodetector in which light receiving elements are arranged, in order to average the light intensity that varies depending on the wavelength, a mask having a fixed-shaped opening that restricts the amount of light is placed in front of the light receiving portion of the light detector. Therefore, when the amount of light from the light source is reduced, the amount of light received by the photodetector is also reduced, leading to a decrease in S / N.

JP 63-94126 A

  The problem to be solved is to provide a mask for optimizing the amount of the split light incident on the photodetector in a spectrophotometer using a photodetector having a plurality of light receiving elements, and It is intended to suppress the S / N decrease due to the light amount decrease.

  The spectrophotometer according to the present invention is used in a detector comprising a plurality of light receiving elements that separates light emitted from a light source by an optical system, receives the dispersed light, and simultaneously detects other wavelengths. A mask having a movable mechanism that can adjust the shape of the opening of the mask for adjusting the amount of light depending on the wavelength to a shape that can obtain the optimum light receiving sensitivity for the detector is installed in the light receiving portion of the light receiving element.

  The spectrophotometer of the present invention makes the opening shape of the mask installed on the light receiving surface of the photodetector variable, and optimizes the amount of light received, so that the light amount is the initial value depending on the light emission time and the number of times of light emission. Even if the initial value is reduced to 70%, 60%, and 50%, the light amount per unit area of the light incident on the photodetector is reduced by adjusting the size of the opening of the mask. In addition, it is possible to provide a spectrophotometer that can improve the S / N ratio.

It is explanatory drawing which showed the implementation method of a spectrophotometer. It is explanatory drawing which showed the implementation method of the mask used for a spectrophotometer. It is explanatory drawing which showed the implementation method of the mask used for a spectrophotometer. It is explanatory drawing which showed the implementation method of the mask used for a spectrophotometer. It is explanatory drawing which showed the implementation method to the spectrophotometer. It is explanatory drawing which showed the implementation method of the mask used for a spectrophotometer. It is explanatory drawing which showed the implementation method of the mask used for a spectrophotometer. It is explanatory drawing which showed the implementation method to the spectrophotometer. It is one Example of the light quantity of a spectrophotometer. It is explanatory drawing which showed the implementation method of the mask used for a spectrophotometer.

  Embodiments of the present invention will be described below with reference to the drawings.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. The light emitted from the light source 1 is applied to the sample cell 2. The light that has passed through the sample cell 2 is irradiated onto the diffraction grating 3 and dispersed. The amount of light of the dispersed light is limited by the mask 4 with a light amount adjusting mechanism, and enters the light receiving portion of the photodiode array detector 5. The light incident on the light receiving portion of the photodiode array detector 5 is read as a signal by the signal reading portion 6. The signal read by the signal reading unit 6 is subjected to data conversion processing by the central processing unit 7 and displayed on the display monitor 8. The mask 4 with a light amount adjusting mechanism includes two light shielding plates 9 for shielding light, a light shielding plate base 10 for adhesively fixing the light shielding plate 9, a base 11 for holding the light shielding plate base 10, and an eccentric head for driving the light shielding plate. The number of the shafts 12 having four is four, the number of the motors 13 for driving the shaft 12 having the eccentric head is four, and the number of the elastic bodies 14 such as springs for attracting the light shielding plates 9 to each other is two. The motor 13 for driving the shaft 12 having the eccentric head is controlled by the central processing unit 7 via the motor control unit 16.

  The principle of movement of the mask with a light amount adjusting mechanism is that the shaft 12 having an eccentric head rotates when the motor 13 is driven. Since the shaft portion of the shaft 12 having the eccentric head is located at the center of gravity of the eccentric head and the eccentric head of the shaft 12 having the eccentric head is in contact with the inner wall of the counterbore portion 17 of the shading plate base 10, the shaft head has an eccentric head. The shaft 12 rotates, pushes the inner wall of the counterbore portion 17 of the light shielding plate base 10, and the light shielding plate 9 operates vertically when the arrangement direction of the photodiode array is horizontal. For example, when all four eccentric heads of the shaft 12 are in the direction of FIG. 2, the opening area of the opening 15 is minimum, and when all four eccentric heads of the shaft 12 are in the direction of FIG. The area is maximized.

  FIG. 3 is a cross-sectional view of the light shielding plate base 10 and the pedestal 11 in a portion A of FIG. 2 to 4, the left side is the short wavelength side of the photodiode array detector, and the right side is the long wavelength side.

  Next, FIG. 5 shows an embodiment of light amount adjustment. In the following embodiment, two light sources, a tungsten lamp and a deuterium lamp, are used as the light source, and a silicon photodiode array detector is used as the photodiode array photodetector. First, the shaft 12 having the eccentric head of the mask 4 with the light amount adjusting mechanism has the light amount in the state of FIG. 2 and the initial light amount of the light source stored in the memory (not shown) in the central processing unit 7. Make a comparison decision. The determination ends without adjusting the light amount if the light amounts of all wavelengths are 90% or more of the initial value light amount. The initial value light amount is stored in the memory in the central processing unit 7 when the unused light source is initially turned on. If the light quantity is smaller than 90% of the initial light quantity, the four motors 13 are driven, and the direction of the eccentric head of the shaft 12 having the eccentric head is set to the state shown in FIG. If the direction of the eccentric head of the shaft 12 is in the state shown in FIG. 4 and the amount of light is not saturated, the adjustment is completed. If the direction of the eccentric head of the shaft 12 having the eccentric head is in the state shown in FIG. The motor 13 is driven so that the shaft 12 rotates by a certain angle so that the direction of the eccentric head of the shaft 12 with the head moves from the state of FIG. 4 to the state of FIG. Do work. The relationship of the motor 13 corresponding to the wavelength range causing saturation is shown in Table 1.

  In the first embodiment, for example, the mask 4 with the light amount adjusting mechanism is configured such that the shafts 18 having the eccentric shape portions are interlocked using the belt 19 as shown in FIG. It is possible to vary the opening area of the opening 15 of the mask 4 with a light amount adjusting mechanism. FIG. 7 is a cross-sectional view of the light shielding plate base 10 and the pedestal 11 in a portion A of FIG. Next, FIG. 8 shows an example of light amount adjustment. First, the light quantity when the mask 4 with light quantity adjustment mechanism is not moved and the initial light quantity of the light source stored in a memory (not shown) in the central processing unit 7 are compared and determined. The determination ends without adjusting the light amount if the light amount is 90% or more of the initial light amount. The initial value light amount is stored in the memory in the central processing unit 7 when the unused light source is initially turned on. If the light quantity is smaller than 90% of the initial light quantity, the four motors 13 are driven, and the direction of the eccentric head of the shaft 12 having the eccentric head is set to the state shown in FIG. If the direction of the eccentric head of the shaft 12 is in the state shown in FIG. 4 and the amount of light is not saturated, the adjustment is completed.

  If the direction of the eccentric head of the shaft 12 having the eccentric head is in the state shown in FIG. 4 and the amount of light is saturated, each motor 13 corresponding to the wavelength range causing the saturation is driven, and the eccentric head is driven. The motor 13 is driven so that the shaft 12 rotates by a certain angle so that the direction of the eccentric head of the shaft 12 with the head moves from the state of FIG. 4 to the state of FIG. 3, and the feedback operation is performed until no saturation occurs. .

  In the second embodiment, for example, the mask 4 with the light amount adjusting mechanism is configured such that the shafts 18 having the eccentric shape portion are interlocked with each other using a gear such as a gear, and the shaft 18 having the eccentric shape portion is driven by the single motor 13. The opening area of the opening 15 of the mask 4 with a light amount adjusting mechanism may be varied.

  In the first to third embodiments, for example, the shape of the light shielding plate is such that the light emitted from the light source 1 is dispersed by the diffraction grating 3 and incident on the light receiving portion of the photodiode array detector 5 and read as a signal by the signal reading portion 6. Then, the data may be converted by the central processing unit 7 and approximated to the light amount distribution displayed on the display monitor 8. For example, when a tungsten lamp and a deuterium lamp are used as the light source, a light quantity distribution as shown in FIG. 9 can be obtained. FIG. 10 shows a mask 4 with a light amount adjusting mechanism provided with a light shielding plate 20 that simplifies the approximate shape of the light amount distribution of FIG. The shape of the opening 15 of the mask 4 with the light amount adjusting mechanism is large in the wavelength range where the light amount of the short wavelength and the long wavelength is small, and it is possible to obtain a larger amount of light at the wavelength where the light amount is small.

  The present invention can also be expressed as follows.

  A light source, a spectroscope that separates light emitted from the light source, a mask having an opening that restricts the amount of light split by the spectroscope for each wavelength, and light that is limited by the mask In a spectrophotometer including a photodetector having a light receiving portion in which a plurality of photodiode light receiving elements that perform conversion are arranged in combination, the mask is disposed between the spectroscope and the photodetector, and the opening Two light shielding plates for forming the portion are provided. When the arrangement direction of the photodiode light receiving elements of the light detector is horizontal, the mask has a light shielding plate placed on the vertical position of the light detector in the vertical direction. A gap between the light shielding plates, which is a portion where the emitted light is not shielded, becomes an opening. The mask has a drive mechanism unit that moves the two light shielding plates independently of each other, and drives the driving unit to move the light shielding plate to change the opening area of the opening of the mask. Thus, a spectrophotometer capable of obtaining the maximum amount within a range not saturated by the amount of light received by the light receiving element of the photodetector.

  A light source, a spectroscope that separates light emitted from the light source, a mask having an opening that restricts the amount of light split by the spectroscope for each wavelength, and light that is limited by the mask In a spectrophotometer including a photodetector having a light receiving portion in which a plurality of photodiode light receiving elements that perform conversion are arranged in combination, the mask is disposed between the spectroscope and the photodetector, and the opening It has one light shielding plate for forming the part. When the light receiving element arrangement direction of the light receiving unit of the light detector is horizontal, the light blocking plate is installed at an upper position or a lower position in the vertical direction of the light detector, and the light dispersed by the spectroscope is not blocked. The part becomes an opening. The mask has a driving mechanism unit that moves the light shielding plate, and the light shielding plate is moved by driving the driving unit, and the opening area of the opening of the mask is changed to change the opening of the light detector. A spectrophotometer that can obtain the maximum amount within a range that does not saturate depending on the amount of light received by the light receiving element.

  The mask is installed between the spectroscope and the photodetector, and has two light shielding plates for forming the opening. When the arrangement direction of the photodiode light receiving elements of the light detector is horizontal, the mask has a light shielding plate placed on the vertical position of the light detector in the vertical direction. A gap between the light shielding plates, which is a portion where the emitted light is not shielded, becomes an opening. The mask has a drive mechanism unit that moves the light shielding plates installed in the vertical position in conjunction with each other, and the light receiving element of the light detector receives light by moving a plurality of light shielding plates with one driving source. A spectrophotometer that can obtain the maximum amount without saturation depending on the amount of light.

DESCRIPTION OF SYMBOLS 1 Light source 2 Cell 3 Diffraction grating 4 Mask with light quantity adjustment mechanism 5 Photodiode array photodetector (photodiode array detector)
6 Signal reading unit 7 Central processing unit 8 Display monitor 9, 20 Shading plate 10 Shading plate base 11 Pedestal 12 Shaft with eccentric head 13 Motor 14 Elastic body 15 Opening portion 16 Motor control portion 17 Counterbore portion 18 Having an eccentric shape portion Shaft 19 belt

Claims (6)

A light source, a spectroscope that separates light emitted from the light source, a mask having an opening that restricts the amount of light split by the spectroscope for each wavelength, and light that is limited by the mask In a spectrophotometer equipped with a light detector having a light receiving portion arranged by combining a plurality of photodiode light receiving elements for conversion,
The spectrophotometer, wherein the mask includes a plurality of light shielding plates for forming the opening, and the opening area of the opening is variable by the movement of the light shielding plate independently. A light source, a spectroscope that separates light emitted from the light source, a mask having an opening that restricts the amount of light split by the spectroscope for each wavelength, and light that is limited by the mask In a spectrophotometer equipped with a light detector having a light receiving portion arranged by combining a plurality of photodiode light receiving elements for conversion,
The spectrophotometer, wherein the mask has a single light shielding plate for forming the opening, and the opening area of the opening is variable by the movement of the light shielding plate. In claim 1 or 2,
A drive unit for driving the light shielding plate;
The driving unit drives the light shielding unit to change the opening area of the mask opening so as to obtain the maximum amount within a range not saturated by the amount of light received by the light receiving element of the photodetector. Photometer. In claim 1,
A drive unit for driving the light shielding plate;
The drive unit drives each light shielding plate in conjunction with each other, and is a spectrophotometer. In claim 1,
The spectrophotometer characterized in that, when the arrangement direction of the photodiode light receiving elements of the photo detector is horizontal, the light shielding plate of the mask is installed facing the vertical position of the photo detector in the vertical direction. . In claim 1 or 2,
The spectrophotometer is characterized in that the shape of the opening of the mask is approximate to the intensity distribution of the wavelength-dependent light quantity obtained by the characteristics of the light source and the characteristics of the spectrometer.

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