JPS6241224Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a spectrophotometer suitable for analyzing light-scattering samples.

A two-beam spectrophotometer has good analysis accuracy because it can compensate for variations in the light source. If the sample is turbid, has an irregular shape that refracts light in various directions, or has a rough surface, the light transmitted through the sample will spread in various directions, so it is necessary to In order to effectively make the light incident on the photodetector and increase the detection sensitivity, it is preferable to use an end-on type photodetector with a wide light-receiving surface. However, even in this case, unless the sample is brought as close to the photodetector as possible, all the light emitted from the sample cannot be made to enter the photodetector.

A two-beam spectrophotometer constructed for the above-mentioned sample is shown in FIG. 1. In this system, end-on type photodetectors P1 and P2 are made to correspond to the measurement sample S and the reference sample R, and each sample is placed close to the light receiving surface of the corresponding detector. The light beams enter R and S, respectively. In this configuration, fluctuations in the light source and optical system are compensated for by the reference sample R, but the characteristics of the two photodetectors P1 and P2 do not exactly match, and the changes in sensitivity over time are not the same, so the two light The use of a detector causes a drift in the measurement output. This difficulty can be solved by proposing the configuration shown in FIG. 2, but the configuration shown in FIG. The reference sample R and measurement sample S are placed in the incident optical path of the photodetector. It cannot be said that all the light scattered by S is incident on the photodetector P. In order to bring the sample S as close to P as possible, the size of S needs to be small, and therefore samples of arbitrary shapes cannot be handled.

The present invention is an attempt to solve the problems of the two types of two-beam spectrophotometers mentioned above, and consists of a hemispherical concave reflecting shade facing the light-receiving surface of the end-on type photodetector, and A window is made near the apex of the shade so that the measurement sample S can be placed there, and a relatively small window is provided on one side of the shade to introduce the light beam that has passed through the reference sample into the reflecting shade. A two-beam spectrophotometer is provided. The present invention will be explained below with reference to Examples.

FIG. 3 shows the main parts of an apparatus according to an embodiment of the present invention.
In the figure, M is a spectroscope, and the spectrometer output light is divided into two directions alternately by a rotating mirror Sm in which transparent parts and reflection parts are arranged alternately in the circumferential direction, and the two divided beams are mirrored. By m1, m2, and m3, one of the light beams is made to enter the reference sample R, and the other light beam is made to enter the measurement sample S. P is an end-on type photodetector, and 2 at the right end is a light receiving surface. Reference numeral 1 denotes a hemispherical concave reflective shade whose inner surface is a mirror surface, and is placed close to the photodetector P with its surface facing the light receiving surface 2. A window W is bored near the top of the reflective shade 1, and a measurement sample S is placed in contact with this window. The measurement sample S may be placed in a sample cell, or it may be a solid lump arbitrarily cut from the subject, and its shape is not constant. One of the purposes of the present invention is to be able to handle samples with irregular shapes. A small window h is bored on the side of the reflective shade 1, and the light beam passing through the reference sample R is reflected by a mirror m and enters the reflective shade 1 through the small window h. Since the main purpose of the reference sample is to monitor changes over time in the light source, spectrometer beam splitter, etc., it does not need to be light scattering like the measurement sample.
It is sufficient to prepare an appropriate size of any specific material.

With the above configuration, the light incident on the measurement sample S is scattered considerably when it leaves the sample, but even the light scattered to the side enters the inner surface of the reflective shade 1 and is reflected, eventually reaching the light receiving surface 2. It will be incident. Therefore, even if the sample S is away from the light-receiving surface 2, it is essentially the same as being in contact with the light-receiving surface. The reference sample transmitted light incident through the small window h is also reflected by the inner surface of the reflective shade 1 and eventually enters the light receiving surface 2. The output of the photodetector P is switched into a light detection signal on the reference sample side and a light detection signal on the measurement sample side in synchronization with the division of the light flux by the rotating mirror Sm. These two signals are separated in synchronization with the beam splitting by the rotating mirror.

The two-beam spectrophotometer of the present invention has the above-mentioned configuration, and even if the measurement sample is far from the light-receiving surface of the photodetector, all the scattered light eventually enters the light-receiving surface of the photodetector due to the reflective shade, resulting in improved sensitivity. In general, the light beam passing through the reference sample is also incident on the reflector shade from a direction different from the light beam that illuminates the measurement sample due to the effect of the reflector shade, so the measurement sample and the reference sample can be placed arbitrarily far apart, preventing mutual interference. Since there is no such thing, it is possible to analyze samples of any size and shape. Therefore, even a large lens-shaped sample as shown in Fig. 4 can be placed in the window W, and since there are few restrictions on the size and shape of the measurement sample, a large number of measurements can be made as shown in Fig. 5. It is also possible to arrange samples so that they can slide and perform analysis one after another. Since FIGS. 4 and 5 show other examples of the use of the device shown in FIG. 3, the description of the beam splitting section will be omitted.

[Brief explanation of the drawing]

1 and 2 are schematic plan views of different conventional examples, FIG. 3 is a plan view of the main part of an embodiment of the device of the present invention, and FIGS. 4 and 5 are plan views of the main part showing the usage of the above embodiment. It is a diagram. P...photodetector, 1...reflection shade, 2...light receiving surface, S...
Measurement sample, R...Reference sample, W...Window, h...Small window.

Claims (1)

[Scope of utility model registration request] A hemispherical concave reflecting shade is provided with the concave surface facing the light-receiving surface of the end-on type photodetector, a window is bored near the apex of the reflecting shade so that the measurement sample can be placed in contact with the window, and a window is made on the side of the reflecting shade. A two-beam spectrophotometer in which a small window is bored to introduce the light beam that has passed through the reference sample into the reflective shade.