JPS6262281B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a chopper for a double-beam spectrophotometer, and more particularly to a chopper that can configure a necessary optical system without using variable optical elements in the optical system.

In double-beam spectrophotometers, methods such as those shown in FIG. 1 A and B are conventionally used to distinguish between reference light and sample light. That is, in FIG. 1A, two light beams are distinguished by using two detectors 1 and 1' and guiding the reference light 2 and sample light 3 to separate detectors 1 and 1', respectively. In addition, in FIG. 1B, a sector mirror 4 is used instead of a single detector, and this is rotated to alternately guide the reference beam 2 and the sample beam 3 to the detector 1. It distinguishes between two beams of light. However, when two detectors are used, measurement accuracy inevitably decreases due to differences in the sensitivity characteristics of each detector, while when only one detector is used, the sector mirror of the optical element is rotated. Therefore, there are problems in that the optical path slightly fluctuates and adjustment of the optical path becomes difficult.

The present invention aims to eliminate the drawbacks of the above conventional methods and construct an optical system that incorporates the advantages of both methods. The objective is to provide a chopper that allows the necessary optical system to be constructed without using mirrors. That is, the chopper according to the present invention can be used in a double beam spectrophotometer,
A mirror is placed at or near a mirror point that separates one light beam from a light source into two light beams, a reference light and a sample light, or a mirror point is placed at or near a mirror point to combine the two light beams into one light beam and guide it to the detector, and each It is characterized by having a blocking plate that crosses the plane formed by the central light beam, and moving on the plane to sequentially and periodically block at least two light beams, the reference light and the sample light.

Embodiments of the present invention will be described in more detail below with reference to the drawings. FIG. 2 is a perspective view showing an embodiment in which a chopper of the present invention is arranged at a mirror point that divides one light beam from a light source into two light beams, a reference light and a sample light; 5 indicates one light beam from a light source; 6 is a beam splitting mirror, and 2 and 3 are a reference beam and a sample beam as in the conventional method. The mirror 6 is composed of a plurality of elongated mirrors stacked one on top of the other with their directions alternately changed as shown in the figure, so the light flux 5 from the light source that enters the mirror 6 is as follows:
It is constantly divided into reference light 2 and sample light 3. The chopper 7 of the present invention is composed of an arm 8 and a blocking plate 9, and the blocking plate 9 extends in a direction transverse to the plane formed by each central light beam and rotates about 10. Therefore, as the chopper 7 rotates, the sample light 3, the light flux 5 from the light source, and the reference light 2 are sequentially and periodically blocked, and accordingly, the detector outputs a signal R corresponding to the reference light and noise without the incident light. A signal D and a signal S corresponding to the sample light are sequentially extracted. This relationship is shown in Figure 3 A and B. That is, in FIG. 3A, if the chopper 7 having the blocking plate 9 is rotated in the direction of the arrow from the position shown in the figure, the noise signal D will first be generated as shown in FIG. The signal R is taken out, and when it is further rotated by 60 degrees, the reference signal 2 is blocked and the sample signal S is taken out.When it is rotated further by 60 degrees, it is in the same state as the beginning, and the same process is repeated thereafter. Due to absorption by the sample, S is somewhat lower than R, and the gap between R and S corresponds to R+S.
Each signal extracted in this way is held in the order of reference signal R, sample signal S, and noise signal D, and the D component is subtracted from the R and S components as before, and the S/R
The light intensity of the sample can be found by dividing.

Unlike the above-mentioned embodiment, the same applies when a similar chopper 7 is arranged at a mirror point or a point close to the mirror point for combining the reference light and the sample light into one light beam and guiding it to the detector.

Further, the structure of the chopper 7 and its arrangement for each light beam are not limited to the above embodiment, and other embodiments as shown in FIGS. 4 and 5 are also possible. In the embodiment shown in FIG. 4A, a semi-transmissive mirror 11 is used to obtain the reference light 2 and the sample light 3, and the chopper 7 has three crotch-like shapes, and its cutoff plate 9 allows the sample light 3 to be , the light beam 5 from the light source, and the reference light 2 are sequentially blocked, and a signal as shown in (b) is obtained. Furthermore, in the embodiment shown in FIG.
is placed at an eccentric position, and in this case a signal as shown in (b) is obtained.

As described above, by using the chopper according to the present invention, the optical system of a double-beam spectrophotometer can be configured with only one detector and without using variable optical elements such as a rotating sector mirror, and can be used for measurement. This improves accuracy and also simplifies optical path adjustment.

[Brief explanation of the drawing]

Figures 1A and 1B are diagrams showing a conventional double beam optical system.
Fig. 2 is a perspective view showing an embodiment of the chopper according to the present invention, Fig. 3 A is a diagram showing the relationship between the chopper shown in Fig. 2 and each luminous flux, B is the same signal diagram, and Fig. 4 A is a different diagram. Fig. 5A is a diagram showing the relationship between the chopper and each luminous flux in the embodiment of Fig. 5, B is the same signal diagram, Figure 5 A is a diagram showing the relationship between the chopper in Fig. 2 with a different arrangement, and each luminous flux, B is the same signal diagram. . 1...Detector, 2...Reference light, 3...Sample light,
4... Sector mirror, 5... Luminous flux from the light source,
6...Light beam splitting mirror, 7...Chopper, 8...
...Arm, 9...Blocking plate, 10...Rotation center, 11...Semi-transparent mirror.

Claims (1)

[Claims] 1 In a double beam spectrophotometer, 1
A mirror is placed at or near a mirror point to separate one beam into two beams, a reference beam and a sample beam, or a mirror is placed at or near a mirror point to combine the two beams into one beam and guide it to the detector. 1. A stopper for a spectrophotometer, comprising a blocking plate that crosses a plane, moves on the plane, and sequentially and periodically blocks at least two beams of light, a reference beam and a sample beam.