JPH0572038A - Double-beam spectrophotometer - Google Patents

Abstract

PURPOSE:To make it possible to perform highly accurate measurement in a short time by alternately measuring sample light and reference light at the same time with two detectors. CONSTITUTION:The light from a light source 1 is split with a spectroscope 4 through a filter 2 and a slit 3. After chopping with a chopper 6, the light is split into two parallel luminous fluxes with a beam splitter 7 at the same time. The sample light which has passed through a sample to be measured S is condensed on a detector 8. The reference light which has passed through a reference sample K is condensed on a detector 9. A detector switching double-surface mirror 10, which is provided at the intersection of the light paths so that the mirror is freely moved back and forth. The light paths are switched. The sample light is received with the detector 9, and the reference light is received with the detector 8. A CPU 13 responds to the switching of the mirror 10, classifies the sample light and the reference light for every detector 8 or 9 and performs integration. The result is stored into a memory 14. The average value of the measured values of the detectors 8 and 9, which are computed based on the data, is displayed on a display part 15 as the true measured value. Thus, the measuring time is shortened, the adverse effects caused by different sensitivities between the detectors are eliminated and the accurate measurement can be performed.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a double beam spectrophotometer.

[0002]

2. Description of the Related Art The greatest advantage of double-beam spectroscopy is that it can cancel the changes over time in the light source, detector, and optical system.
However, depending on the device configuration, the offset may be incomplete,
There is a problem that the measurement time becomes long. For example, in the configuration using two detectors for sample light and reference light, the measurement time is short, but variations in sensitivity of the detectors and drift cannot be compensated, and therefore highly accurate measurement results can be obtained. In order to compensate for variations and drifts in the sensitivity of the detector, when one detector is used for measurement, it is the sum of the measurement times of both the reference light measurement and the sample light measurement. Therefore, the measurement time is twice as long as when two detectors are used. Also, in order to correct the change over time,
Since the reference light and the sample light must be alternately switched in a short time for measurement, a detector with a short replacement time is required, but the response time of the PbS detector used in the near infrared light region is With a long element, there is a problem that the measurement time must be long.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a double beam spectrophotometer capable of measuring with high accuracy in a short measuring time.

[0004]

In a double-beam spectrophotometer, a beam splitter that splits one light flux into two light fluxes, a reference light and a sample light, which are parallel in parallel, and two light receivers that separately receive the two light fluxes. Element, above 2 light flux and above 2
A means for changing the correspondence of the light receiving elements is provided.

[0005]

In the double beam spectrophotometer, the sample light and the reference light can be simultaneously measured by the two detectors in order to shorten the measuring time. Therefore, the problem is solved by separately arranging a method for canceling the disparity between the two detectors and the measurement circuit. Therefore, by switching the light beams incident on the detectors on the way and obtaining measurement data of the sample light and the reference light in both detectors, the adverse effect due to the difference in sensitivity between the detectors is eliminated. In this way, both the reference light and the sample light are measured in total within the fixed measurement time by the same amount as the above-mentioned fixed measurement time, and although the function is the same as that of the two-beam 1 detector, the measurement time is half. become.

[0006]

1 is a block diagram showing the construction of an embodiment of the present invention. Light from the light source 1 passes through the filter 2 and the slit 3, is dispersed by the spectroscope 4, passes through the slit 5, and
After being chopped by the chopper 6, it is split into two parallel light fluxes by the beam splitter 7, and one light passes through the measurement sample S and the other light passes through the reference sample K.
The sample light transmitted through the measurement sample S is focused on the detector 8 by the mirrors M5 and M6. The reference light transmitted through the reference sample K is focused on the detector 9 by the mirrors M7 and M8. The optical path is set so that the sample light and the reference light intersect at one point, and a detector switching double-sided mirror 10 is provided at the intersecting point so as to be movable back and forth. The light incident on 9 is switched, and the detector 9 receives the sample light and the detector 8 receives the reference light. The signals obtained by the detectors 8 and 9 are amplified by the amplifiers AMP1 and AMP2, and A / D
It is digitized by the converter 12, and by the CPU 13,
In response to the switching of the double-sided mirror 10, the sample light and the reference light are classified for each detector and accumulated and stored in the memory 14.
A measurement value is calculated for each detector from the data stored in the memory 14, and the average value is calculated as a true measurement value, and the display unit 15
To display. To switch the optical path, perform wavelength scanning an even number of times,
The measurement result may be added by switching every scan, or,
The measurement may be completed by one wavelength scanning, and the measurement may be performed in a time period during which the change of the sample light is sufficiently small during the scanning period.

In the above embodiment, the switching of the light beams incident on both detectors is performed by moving the switching mirror 10 in and out of the optical path, but it is also possible to switch the positions of both detectors. . The advantage of the method of alternating the positions of both detectors is that the influence of absorption by the switching mirror can be eliminated. .. Further, in the above embodiment, the measurement data is processed for each detector and then averaged. However, the data obtained by the two detectors are divided into sample light data and reference light data and integrated. Data processing may be performed by the integrated data. However, when using this method,
Care must be taken so that the photometric time of the sample light and the photometric time of the reference light measured by each detector are the same.

[0008]

According to the present invention, by simultaneously and alternately measuring the sample light and the reference light by the two detectors, the period in which neither light flux is measured is eliminated and the measurement time is shortened.
By replacing the detectors, it was possible to eliminate the adverse effect due to the difference in sensitivity between the detectors, shortening the measurement time and improving the measurement accuracy.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

[Explanation of symbols]

 1 light source 2 filter 3 slit 4 spectroscope 5 slit 6 chopper 7 beam splitter 8 detector 9 detector 10 optical path switching double-sided mirror 11 mirror driving unit 12 A / D converter 13 CPU 14 memory M1 to M8 mirror S measurement sample K reference sample

Claims (1)

[Claims] 1. A reference beam and a sample beam, which are parallel to each other in one light beam.
A double beam spectrophotometer having a beam splitter for splitting into two light beams, two light receiving elements for separately receiving the light beams of the two light beams, and means for alternating the correspondence relationship between the two light beams and the two light receiving elements. Total.