JPH041291B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a photometry method that accurately detects monitor light and accurately corrects sample light.

<Prior art> A method of measuring spectroscopic sample light using a solid-state image sensor is known (Japanese Patent Application Laid-Open No. 111878-1983).
For this photometry, it is also known to detect light that is directly guided from the light source (referred to as monitor light) without passing through the sample through an optical fiber or the like. (See US Pat. No. 4,266,878).

Furthermore, it is necessary to compensate for fluctuations in the light source intensity, etc., and a method of feedback controlling the light source intensity by detecting the monitor light intensity is also well known. (Refer to Utility Model Application Publication No. 52-13885, etc.).

<Problems to be Solved by the Invention> By the way, in the conventional technology for compensating for fluctuations in the light source intensity, etc., when detecting monitor light, the light source output is spatially divided using a half mirror or the like,
It is necessary to time-divide the optical path by intermittently switching the optical path using a rotating mirror, but in the former case, multiple photodetectors are required, and it is difficult to use elements whose temperature characteristics are exactly the same for each photodetector. It's difficult as of now. In the latter case, it is necessary to synchronize the gate of the detection circuit of the photodetector with the rotation of the rotating mirror, which complicates the mechanical drive mechanism and increases the size of the device.

Therefore, in order to solve the above-mentioned problem, the applicant of this case attempted to receive the monitor light using a part of the photoelectric conversion surface of the same solid-state image sensor that receives the sample light, and filed a patent application. (Special application 1982-
In this case, sample light detection and monitor light detection (hereinafter referred to as "monitoring") are performed in the same reading scan, so the charge accumulation time is the same. As a result, the photoelectric conversion surface of the solid-state image sensor (usually the photoelectric conversion surface used for monitoring) that receives one of the lights becomes saturated first, making it impossible to accurately correct the sample light. .

In order to solve this saturation problem, it may be possible to separate sample light detection and monitoring in time and perform separate scans, but since both detections are separated in time, the intensity and spectrum of the light source There is a problem in that the influence of time fluctuations in characteristics and the like becomes noticeable, resulting in detection errors in the sample light.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a photometry method that solves the above-mentioned technical problems, allows sample light detection and monitoring to be detected without separating them, and also solves the problem of element saturation.

<Means for Solving the Problem> The photometry method described in the claims for achieving the above object uses a photodetector for detecting monitor light in common with a solid-state image sensor for detecting sample light, and also uses a solid-state image sensor for detecting sample light. Divide the photoelectric conversion surface into a part that receives the monitor light and a part that receives the sample light, and when detecting the monitor light, set the charge accumulation time in the solid-state image sensor to the time T1 during which saturation by the monitor light does not occur. When detecting sample light, the charge accumulation time in the solid-state image sensor is set to a time T2 at which saturation by the sample light does not occur. In this method, a signal is extracted from a portion of the photoelectric conversion surface that receives the sample light, and detection of the monitor light and detection of the sample light are sequentially and alternately performed.

<Operation> According to the above configuration, when detecting monitor light, the charge accumulation time in the solid-state image sensor is set to a time T1 such that the element is not saturated with the monitor light,
When detecting sample light, the charge accumulation time in the solid-state image sensor is set to a time T2 such that the element is not saturated with sample light, so even if the same solid-state image sensor detects the monitor light and sample light, No element saturation problems occur.

Further, by continuously and alternately performing the detection of the monitor light and the detection of the sample light without any time interval, it is also possible to eliminate the adverse effects of intensity fluctuations of the monitor light.

<Examples> Examples will be described in detail below with reference to the accompanying drawings showing examples.

FIG. 1 shows an apparatus for carrying out this invention including a spectroscopic optical system, in which 1 is a light source, 2 is a sample, 3 is a slit, 4 is a plane mirror, and 5 is a diffraction grating which is the main part of the spectroscopic optical system. , 6 is a solid-state image sensor as a detector, and 7 is a computer that processes signals from the solid-state image sensor. Reference numeral 8 denotes an optical fiber connecting the light source 1 and the solid-state image sensor 6, which is connected to the solid-state image sensor 6 separately from the spectroscopic optical system.
It is connected to a part of the photoelectric conversion surface.

As the solid-state image sensor 6, it is necessary to use one with a complex number of elements, and preferably the number of elements is 64.
Using a commercially available product of bit or larger, a part of the photoelectric conversion surface is connected to the light source 1 using optical fiber 8.
All you have to do is connect it to . In this example, the number of elements is 1
024bit, a photoelectric conversion surface with a total length of 28.67mm, and a focal plane of 25.00mm as a diffraction grating.
Since we used a holographic grating that forms an image, the 3.67 mm becomes a photoelectric conversion surface that is unnecessary for spectrum detection. An optical fiber 8 is connected to this unnecessary photoelectric conversion surface to monitor the light source output.

In addition to the holographic grating, a mechanically carved grating or the like may be used as the diffraction grating 5. In addition to those using a diffraction grating as the spectroscopic optical system, various known spectroscopic optical systems such as those using a prism spectrometer can be employed.

Using the photometer described above, the light incident on the sample 2 from the light source 1 can be measured on the sample with the solid-state image sensor 6 after passing through the optical system. The output of the light source 1 can also be monitored through the connected optical fiber 8.

In this invention, the accumulation time T2 during sample light detection and the accumulation time T1 during monitoring are each set according to the respective light intensities so that saturation does not occur in the solid-state image sensor 6 within one reading time. At the same time, we adopted a photometry method that performs both photometry almost continuously.

Specifically, as shown in Figure 2, monitoring is performed continuously without any gaps before and after sample measurement, so that the accumulation time in monitoring is T1 and the accumulation time in sample measurement is T2. Scan each as follows. A numerical value obtained by averaging the detection results of the monitor and the detection result of the monitor is used for sample light correction.

In addition, as shown in Figure 3, monitoring can be performed during the sample measurement, in which case the sample light detection value is the sum of the detection result of the detection and the detection result of the detection, and the sample measurement result is Correct based on monitoring results.

Note that the method of the present invention can be used not only for correcting the light source output, but also for monitoring the dark output (level output) by masking the photoelectric conversion surface on the optical fiber side, for example.

<Effects of the Invention> In this way, since monitoring is performed continuously without any pause before or during sample measurement, the sample measurement time becomes longer and the luminescence intensity of the light source output changes over time. As a result, even if the monitor light detection intensity fluctuates, changes in the measurement output over time can be kept to a minimum.

In either case, the accumulation time for sample detection and the accumulation time for monitoring are set separately, so that saturation of the solid-state image sensor on the light receiving side does not occur, and accurate sample light correction can be performed. can.

[Brief explanation of drawings]

FIG. 1 is a schematic system diagram of a spectroscopic apparatus used to carry out the present invention, and FIGS. 2 and 3 are graphs showing the temporal flow of photometry illustrating a specific implementation of the method of this invention. 1...Light source, 2...Sample, 3...Slit, 4
...Flat mirror, 5...Diffraction grating, 6...Solid-state image sensor, 7...Computer, 8...Optical fiber.

Claims (1)

[Scope of Claims] 1. Light incident on a sample from a light source is extracted, passes through an optical system, and enters a solid-state image sensor as sample light, and at the same time, the light from the light source is passed through an optical fiber to a photodetector as monitor light. incident,
In a photometric method for examining the optical properties of a sample by comparing the intensity of sample light and the intensity of monitor light, a photodetector for detecting the monitor light is shared with a solid-state imaging device for detecting sample light, and a solid-state imaging device for detecting sample light is used. The photoelectric conversion surface of the image sensor is divided into a part that receives the monitor light and a part that receives the sample light, and when detecting the monitor light, the charge accumulation time in the solid-state image sensor is determined by the time during which saturation by the monitor light does not occur. T1, the signal from the part of the photoelectric conversion surface that receives the monitor light is extracted, and when detecting sample light, the charge accumulation time in the solid-state image sensor is set to T2, which is the time during which saturation by the sample light does not occur. A photometry method characterized in that the signal is extracted from a portion of the photoelectric conversion surface that receives the sample light, and the detection of the monitor light and the detection of the sample light are successively and alternately performed.