JPS5828652A - Continuous spectral measurement system - Google Patents

Abstract

PURPOSE:To measure with uniform sensitivity in the measurement of every each wavelength component, by constituting a spectral system so as to rotate many filters on a concentric circle at high speeds and marking the detector into one. CONSTITUTION:Light including the plural wavelength bands is introduced by a collimeter or an optical fiber, etc. and is radiated to a filter wheel 2 arranged plural optical filters 1 passing through each wavelength band on the circumference of a concentric circle in a spectral apparatus. Also, a sensor 4 detecting the position of the filter is provided on one place of the fringe of the wheel 2 and a pulse signal is taken out from the sensor 4 at every one revolution of the wheel 2 and is sent to a sampling gate control circuit 5. Hereby, measurement is performed with uniform sensitivity at the measurement of every each wavelength.

Description

[Detailed Description of the Invention] The present invention consists of a large number of wavelength components and the intensity (radiation) of each component.
This method involves continuous measurement of light that changes rapidly.

It has been desired to perform optical measurements of the above-mentioned nature in phenomena that we experience on a daily basis. For example, fire monitoring (temperature measurement), solar radiation measurement, and other online spectroscopic and colorimetric analyzes have been desired, but no conventional methods have been developed to satisfactorily achieve this. Ta.

Conventional photometric devices of this type can be categorized as either methods in which the spectroscopic system is driven at a constant speed and each wavelength component is output through one fixed detector, or vice versa, the spectroscopic system is fixed. There are three types of methods: a method in which the detector is scanned at the same time as the detector, and a method in which a multiple-tube spectroscopic system is provided for each wavelength to be measured, and correspondingly multiple detectors are combined to perform simultaneous measurements.
Regarding the first and second methods, with the current technology, it is almost impossible to scan the entire wavelength range within one second, and even if it were possible, it would be impractical considering the cost of the device. Simply put, it is impossible both in principle and in practice to extract light amount (radiation amount) data from each wavelength component simultaneously.

In the third method, a detector is required for each wavelength component, and it is necessary to match the sensitivity constants of these detectors, which inevitably leads to an increase in the size of electrical manufacturing.

Therefore, the present invention modified this third method, configured the spectroscopic system to rotate many filters concentrically at high speed, reduced the number of detectors to one, and realized simultaneous observation of each wavelength component. It is a device. It is also possible to adjust the zero point of each of a large number of surrounding circuits that perform the same function by using the blank part of the filter wheel in which the above-mentioned filters are arranged in concentric circles, providing stable results for long-term continuous measurements.

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

FIG. 1 is a block diagram of the entire apparatus according to an embodiment of the present invention, in which light containing a plurality of wavelength bands is guided through a collimator or an optical fiber, and a plurality of optical filters 1 passing through each wavelength band are arranged in concentric circles. The filter wheel 2 placed above is irradiated.

While rotating the wheel 2, a sensor 3 receives light that has passed through the optical filter 1 after the wheel 2. sensor 3
The output obtained through the l-V converter 8, which converts the current output from the
As shown in FIG. 2a, a pulse train with a different output is obtained for each wavelength component every 3.λ4 as shown in FIG. 2a. Each sampled pulse signal is processed by a plurality of sample and hold circuits SH1, SH2, and S provided corresponding to each wavelength band.
is applied to the sample and hold circuit array 6 consisting of H3 and sH4.
-) under the control of circuit 5.

Filter wheel 2. A sensor 4 for detecting the position of the filter is provided at one location on the periphery of the wheel 2. A pulse signal (FIG. 2b) is collected from the sensor 4 every rotation of the wheel 2, and the signal is sampled and sent to the control circuit 5. send. In this circuit, when each filter sequentially comes to the center of the incident light flux according to a program that corresponds to a predetermined filter position, P-)G of the sample holder circuit corresponding to each filter is sequentially closed and the sensor 3 is input the output signal. This manually powered sample holder circuit holds the input signal until the next sample and hold circuit sequence is generated. FIG. 2C shows the sample hold/arm output from the sample r-) control circuit 5, and each sample holder circuit SH1
, SH2...... Each gate G1, G2... of SH4
... is applied to any one of G4 according to the above program.

In other words, when it is programmed to sample only the blue wavelength component λ1, the sampling pulse is applied only to the gate holder circuit s+1 for λ1. If the incidence of the wavelength component λ1 changes from moment to moment and increases slightly with, for example, the 20th rotation of the wheel, the output of the sample-and-hold circuit SH1 changes stepwise and becomes K as shown in FIG. 2C.

For convenience, the output of the sample-and-hold circuit SH1 is smoothed by passing it through a low/f filter LPF1 in the next stage to obtain a smoothed continuous waveform with a stepped portion as shown in FIG. 2d. Similar to the sample and hold circuit array 6, a plurality of low-pass filters 7 are prepared corresponding to the number of each wavelength component.

With this configuration, other wavelength components λ2...
...For each of λ4, the ever-changing incidence can be extracted as an analog value in the same way as for λ1 by controlling the sampling gate control circuit, and these outputs are expressed as 21' in Fig. 1. ...shown as 24'. These outputs are obtained in the form of continuous waves as shown in FIG. 2d, which is a major feature of the present invention.

Next, automatic zero point correction, which is another feature of the present invention, will be described. The automatic correction circuit has a capacitor 9 inserted in series between the 1-2 controller 8 and the sample-hold circuit 6, and its output side is grounded through an analog switch 1O. The timing for grounding this switch 10 is based on sampling r-) when the specific position signal of the filter wheel taken in by the control circuit 5, that is, the output of the sensor 3 when the incident light can pass through the filter wheel, should naturally become KO. The signal drives analog switch 10 closed. There are two possible ways to extract this specific position signal.

First, one of the optical filters is left blank so that no light passes through it, and the position signal extracted by this configuration is shown in FIG. The second method is to obtain a KA pulse when the sensor 4 passes through a light-opaque portion between optical filters, and the position signal extracted by this configuration is shown in FIG. 2fK.

When there is no input light passing through the optical filter 01-v:F7
Is the offset voltage of Part 8 Konode? 9, but if you turn on the analog switch 10 with the A4 pulse train O signal from either of the above two, the output terminal of the capacitor 90 will be grounded and the voltage will be corrected correctly, making it truly compatible with the light passing through the optical filter. It becomes possible to obtain an output of 40%.

As described above, in the spectroscopic measurement method of the present invention, the magnification is
In the above embodiment, the offset voltage of the 1-V converter is corrected at a rate of tk, so that measurement with uniform sensitivity is possible in the measurement of each wavelength component. Although four bands are shown, this number is not limited. position sensor 4
may be a reflective type or a magnetic sensor instead of a light transmitting type, or may be provided for each optical filter.

[Brief explanation of the drawing]

Figure 1 is a four-dimensional diagram showing an embodiment of the present invention, and Figure 2 is a diagram showing the embodiment of the present invention.
FIG. 3 is a pulse waveform diagram illustrating the circuit shown in FIG. 1... Optical filter, 2... Filter wheel, 3
...Sensor, 4...Optical filter position sensor, 5.
... Sampler gate control circuit, 6... Sample holder circuit row, 9... Capacitor, 10... Analog switch

Claims (1)

[Claims] A rotating filter wheel is constructed by concentrically arranging a large number of optical filters with multiple cylinders that separate light whose intensity changes continuously into wavelength components. A position sensor is provided that detects the position of the optical sensor and outputs an output, and the output for each wavelength component obtained from the optical sensor is synchronized with the position sensor output signal and input to a sample holder provided corresponding to each wavelength component. , a continuous spectroscopic measurement method in which the outputs of these sample holders are passed through a row/yass filter and extracted as a continuous DC output from K.