JP4089314B2 - Spectrometer using 0th-order diffracted light of diffraction means - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spectrophotometer using zero-order diffracted light from a diffracting means that has been made unnecessary in conventional spectroscopic measurements.
[0002]
[Prior art]
As shown in FIG. 1, a reflection diffraction grating 110 is generally used as a spectroscopic element 110 that separates light to be measured from a light source 102 in a spectroscopic measuring instrument such as a spectrocolorimeter or a spectral luminance meter. When the light to be measured is incident on the reflection type diffraction grating 110, the 0th order diffracted light (regular reflection light) that is specularly reflected by the reflection surface of the diffraction grating 110 and the higher order diffracted light (for example, the first order) used for spectroscopic measurement. Light) is emitted. The high-order diffracted light diffracted by the diffraction grating 110 is collected by the condenser lens 112 and then received at a predetermined position of the line-type light receiving sensor 116 corresponding to each wavelength.
[0003]
By the way, since the 0th-order diffracted light (regularly reflected light) is light reflected directly from the reflection surface of the reflective diffraction grating 110, the 0th-order diffracted light (regularly reflected light) includes all the wavelength components of the light to be measured. ing. Since the 0th-order diffracted light including all wavelength components is bothersome and unnecessary for spectroscopic measurement, it was removed by an optical trap 120 provided in the spectroscopic instrument as shown in FIG.
[0004]
As described above, in the conventional spectrometer, the 0th-order diffracted light was considered unnecessary in the spectroscopic measurement. However, the inventors of the present application considered whether the 0th-order diffracted light could be effectively used for the spectroscopic measurement. As a result, the present invention has been conceived.
[0005]
[Problems to be solved by the invention]
Therefore, a technical problem to be solved by the present invention is to provide a spectroscopic measuring instrument that effectively utilizes zero-order diffracted light that has been considered unnecessary in spectroscopic measurement.
[0006]
[Means for solving the problems and actions / effects]
In order to solve the above technical problem, the present invention provides a diffractive means for spectroscopically measuring light to be measured, a first photoelectric conversion element for receiving zero-order diffracted light from the diffracting means, and a high-order diffracted light from the diffracting means. A second photoelectric conversion element that receives light, and a control unit that controls light reception by the second photoelectric conversion element based on a light reception output of zero-order diffracted light photoelectrically converted by the first photoelectric conversion element Is to provide.
[0007]
In general, when the light to be measured is incident on the diffraction means, the light to be measured is diffracted by the diffraction means. That is, when monochromatic light to be measured is incident on the diffractive means, the image of the 0th order diffracted light, the 1st order diffracted light, the 2nd order diffracted light,... Formed in position. Even when the light to be measured is not monochromatic light, the same is true for each wavelength, and a diffraction image corresponding to each wavelength is created at each position of the diffraction image.
[0008]
Therefore, according to the above configuration, a 0th-order diffraction image corresponding to the 0th-order diffracted light is formed on the first photoelectric conversion element, and diffracted light other than the 0th-order diffracted light, that is, the first-order diffracted light is formed on the second photoelectric conversion element. A high-order diffraction image corresponding to the folded light, the second-order diffracted light, or the like is formed.
[0009]
The 0th-order diffraction image formed on the first photoelectric conversion element is not a diffraction image diffracted corresponding to each wavelength but a regular reflection image including each wavelength. The light-receiving output of the 0th-order diffracted light has a certain correlation with the light-receiving output of diffracted light other than the 0th-order diffracted light, that is, the first-order diffracted light and the second-order diffracted light. Therefore, the integration condition in the second photoelectric conversion element can be estimated based on the light reception output of the 0th-order diffracted light in the first photoelectric conversion element, so that the control unit appropriately receives light in the second photoelectric conversion element. Can be controlled.
[0010]
In order to efficiently collect the 0th-order diffracted light on the first photoelectric conversion element, a condensing lens that collects the 0th-order diffracted light on the first photoelectric conversion element is provided between the diffracting means and the first photoelectric conversion element. It has been.
[0011]
In order to prevent the saturation phenomenon of the second photoelectric conversion element or to obtain an appropriate amount of received light, the control means controls the integration time of the second photoelectric conversion element.
[0012]
The control means controls the output gain of the second photoelectric conversion element because the integration amount integrated by the second photoelectric conversion element increases or decreases depending on the amount of the light to be measured.
[0013]
In addition, the spectrometric instrument according to the present invention can measure a change over time of the light to be measured based on the light reception output of the 0th-order diffracted light photoelectrically converted by the first photoelectric conversion element. That is, in addition to the original spectroscopic measurement function, the spectrophotometer also has a function of measuring a change with time of light to be measured in a short time.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a spectrometer according to the first embodiment of the present invention will be described with reference to FIGS.
[0015]
As shown in FIG. 2, the spectrophotometer is emitted from the optical fiber 6, the objective lens 4 that condenses the light L to be measured from the light source 2 on the optical fiber 6, the optical fiber 6 that limits the measurement region at its side end face, and the optical fiber 6. The illumination lens 8 that converts the measured light L into parallel light, and the reflective diffraction that diffracts the measured light L and separates it into a 0th-order diffracted light L ₀ (regularly reflected light) and a first-order diffracted light L ₁ (high-order diffracted light). a grating 10, and each of the diffracted light _L 0, condenser lenses _12, 14 _{L 1} a respectively condensing, 0 a spot-type light receiving sensor 18 for receiving the order diffracted light _{L 0,} the line type for receiving the first order diffracted light _{L 1} A light receiving sensor 16.
[0016]
As shown in FIG. 4, the spectrometer is further amplified by amplifiers 22 and 23 that amplify analog electric signals photoelectrically converted by the line-type light receiving sensor 16 and the spot-type light receiving sensor 18, and the amplifiers 22 and 23, respectively. A / D converters 24 and 25 for converting the analog electric signals into digital signals, and the start / end control of the integration operation of the line-type light receiving sensor 16, the gain control of the amplifier 22, and the digital signal read control CPU30 which performs control.
[0017]
A spectroscopic measurement method using the spectrophotometer will be described with reference to FIGS.
[0018]
The light L to be measured emitted from the light source 2 is focused on the side end face of the optical fiber 6 by the objective lens 4, then passes through the optical fiber 6 and is collimated by the illumination lens 8. When light to be measured L of the parallel light is irradiated to the reflection type diffraction grating 10, light to be measured L is a predetermined angle, 0-order diffracted light L _0, 1 order diffracted light L _1, 2-order diffracted light, third-order diffracted light, etc. Is diffracted into
[0019]
The 0th-order diffracted light L ₀ as the regular reflection light is condensed on the spot type light receiving sensor 18 by the condenser lens 14. The light received by the spot type light receiving sensor 18 is photoelectrically converted, and then an analog electric signal is amplified by the amplifier 23. The analog electrical signal related to the 0th-order diffracted light L ₀ is converted into a digital signal by the A / D converter 25 and then read out by the CPU 30.
[0020]
On the other hand, the first-order diffracted light L ₁ as high-order diffracted light is also condensed on the line-type light receiving sensor 16 by the condenser lens 12. In the line-type light receiving sensor 16 in which a large number of photoelectric conversion elements are arranged in a straight line, each wavelength is positioned at a position corresponding to each wavelength (λ ₁ ,... Λ ₂ ,... Λ ₃ ) of the _first-order diffracted light L ₁ . A diffraction image is formed. The light received on the line type light receiving sensor 16 is photoelectrically converted, and then an analog electric signal is amplified by the amplifier 24. Each analog electric signal relating to each wavelength of the _first-order diffracted light L ₁ is converted into a digital signal by the A / D converter 24, and then the digital signal is sequentially read out by the CPU 30.
[0021]
Next, an integration operation control method in the spot type light receiving sensor 18 and the line type light receiving sensor 16 will be specifically described with reference to FIGS.
[0022]
Generally, 0 because the next intensity of diffracted light L ₀ is one-to-one correspondence with 1 intensity of diffracted light L _1, as shown in FIG. 5, the output level of 0 for order diffraction spot-type light receiving sensor 18 (A / The (D value) has a one-to-one correspondence with the output level (A / D value) of the line type light receiving sensor 16 for the first-order diffracted light.
[0023]
By the pre-measurement, an approximate measurement time, that is, an integration time (t _L1 , t _S1 ) is determined for the line type light receiving sensor 16 and the spot type light receiving sensor 18 (steps # 110 and # 210). Since the spot-type light receiving sensor 18 can read data in a short time, the integration time t _S1 of the first _zero-order diffracted light L ₀ is equal to or less than the integration time t _{L 1} of the first first-order diffracted light L _1. That is, t _L1 ≧ t _S1 may be satisfied. In line-type light receiving sensor 16 and the spot-type light receiving sensor 18, first 1 integration operation order diffracted light _{L 1} and the zero-order diffracted light _{L 0} relates the measured light L are started simultaneously (step # 120, # 220). 0 integral action of the order diffracted light _{L 0} is terminated after _{t S1} (Step # 230), 1 integration operation of the order diffracted light _{L 1} is ended after the lapse of _{t L1} (Step # 130).
[0024]
After completion of the integration operation, the measured values for the first-order diffracted light L ₁ and the zero-order diffracted light L ₀ is converted into a digital signal. Thereafter, 0 A / D value of the output level for order diffracted light _{L 0} (C1) is, after being read in CPU 30, is temporarily stored in a memory not shown (step # 240).
[0025]
Next, a second measurement is performed. In the second integration operation, the integration result of the _0th-order diffracted light L0 is used for the integration operation of the _1st-order diffracted light L1, and the spot-type light receiving sensor 18 can read data in a short time. 0 integration time _{t S2-order} diffracted light _{L 0} is shorter than the first 0 integration time _{t S1} in order diffracted light _{L 0,} that is, set to _t S2 _{«t S1} (step # 242).
[0026]
In line-type light receiving sensor 16 and the spot-type light receiving sensor 18, the integration operation of the first order of the second diffracted light _{L 1} and the zero-order diffracted light _{L 0} is started at the same time (step # 150, # 250).
[0027]
0th integration operation of the diffracted light _{L 0} is terminated after _{t S2} (Step # 252), after being converted into a digital signal, 0 A / D value of the output level for order diffracted light _{L 0} (C2) is a CPU30 It is read (step # 254). At this time, the integration operation of the _first-order diffracted light L1 in the line type light receiving sensor 16 is continued.
[0028]
From second 0 A / D value of the output level for order diffracted light _{L 0} (C2), the estimated A / D value of the output level corresponding to the first integration time _{t S1} (C2 ') is calculated (step # 256). Thereafter, the integration time t _L2 at which the A / D value (C2) of the output level of the line type light receiving sensor 16 is appropriate is estimated (step # 258). 1 integration operation of the order diffracted light _{L 1} of the second are terminated after _{t L2} (Step # 160).
Obtainable.
[0029]
After completion of the integration operation, the analog electrical signal related to the second 1 each wavelength order diffracted light L ₁ was converted to a digital signal by the A / D converter 24 (Step # 170) after the digital signal she is sequentially read by CPU30 It is.
[0030]
The spectroscopic measuring instrument according to the present invention is also applicable to the case where light (that is, flicker light) whose measured light fluctuates periodically (that is, flicker light) is measured at a desired timing, such as a fluorescent lamp. Measurement of flicker light will be described with reference to FIGS.
[0031]
As shown in FIG. 8, the light of the fluorescent lamp repeatedly blinks at a predetermined cycle. When measuring the light of the fluorescent lamp as the light to be measured, the measurement timing of the _0th-order diffracted light L0 is set to be shorter than the blinking period of the fluorescent lamp.
[0032]
In the spot type light receiving sensor 18, the integration operation of the _zero-order diffracted light L0 of the light to be measured is started (step # 320). The integration operation of the _0th-order diffracted light L0 is completed in a short time (step # 330), and the measured value related to the _0th-order diffracted light L0 is converted into a digital signal, and then the A / D of the output level related to the _0th-order diffracted light L0. A value (C) is calculated (step # 340). After the A / D value (C) is read by the CPU 30, it is determined whether or not the A / D value (C) is equal to or greater than a predetermined threshold (step # 342). If the A / D value (C) is smaller than the predetermined threshold value, the integration operation of the _0th-order diffracted light L0 is performed again.
[0033]
If the A / D value (C) is equal to or greater than the predetermined threshold value, the integration operation of the _first-order diffracted light L1 of the light to be measured is started (step # 350). The integration operation of the _first-order diffracted light L1 ends after a predetermined time has elapsed (step # 360). Each analog electrical signal relating to each wavelength of the _first-order diffracted light L ₁ is converted into a digital signal by the A / D converter 24 (step # 370), and then the digital signal is sequentially read out by the CPU 30.
[0034]
By repeating such a series of measurements, it is possible to know the light emission state of the fluorescent lamp and its stability at a desired timing.
[0035]
In addition to the original spectroscopic measurement function, the spectroscopic measuring device having the above-described configuration also has a function of measuring a change over time in a short time of the light to be measured.
[0036]
For example, in a liquid crystal application product, light from a light source is transmitted or blocked by changing a twisted state of liquid crystal molecules. Liquid crystal devices are also used as high-speed optical shutters, and there is a desire to know the high-speed response of liquid crystal devices. Application of the spectrometer according to the present invention to liquid crystal device measurement will be described with reference to FIGS.
[0037]
When the liquid crystal device changes the light from the light source from the blocking state to the transmitting state, the intensity of the light to be measured changes as shown in the upper diagram of FIG. At this time, microscopically, the twisted state of the liquid crystal molecules changes. When the light emitted from the liquid crystal device is measured as the light to be measured, the measurement timing of the _0th-order diffracted light L0 is set to a shorter cycle than the switching cycle of the liquid crystal device, as shown in the middle diagram of FIG. Is done.
[0038]
As shown in FIG. 11, in the spot-type light receiving sensor 18, the integration operation of the _zero-order diffracted light L0 of the light to be measured is started (step # 420). The integration operation of the _0th-order diffracted light L0 is completed in a short time (step # 430), and the measured value related to the _0th-order diffracted light L0 is converted into a digital signal and then the A / D of the output level related to the _0th-order diffracted light L0. A value (C) is calculated (step # 440). One A / D value (C) is read by the CPU 30 and then plotted on the graph (step # 450).
[0039]
By repeating such a series of measurements, as shown in the lower diagram of FIG. 10, many A / D values (C) are plotted on the graph, and the time-series change of the twist of the liquid crystal molecules and the response speed of the liquid crystal device. Etc. can be known.
[0040]
Next, a spectrometer according to a second embodiment of the present invention will be described with reference to FIG.
[0041]
The spectrophotometer shown in FIG. 3 is different from that shown in FIG. 2 in the presence or absence of the condenser lens 14 and the arrangement of the spot-type light receiving sensor 18, but the other configurations are shown in FIG. Since it is the same as the above, the explanation will be made paying attention to the difference between the two.
[0042]
That is, the spot type light receiving sensor 18 is disposed in the vicinity of the line type light receiving sensor 16, and the condenser lens 12 used for the line type light receiving sensor 16 is replaced with the condenser lens 14 used for the spot type light receiving sensor 18. I also use it. That is, 0-order diffracted light L ₀ and 1-order diffracted light L ₁ diffracted by the diffraction grating 10 is in close positions. In order to realize this, the diffraction grating 10 having a smaller number of grooves than that shown in FIG. 2 is used. With the configuration described above, the number of parts can be reduced, and a reduction in size and space can be achieved.
[0043]
The spectrophotometer according to the present invention is applied to various spectrophotometers including the diffraction grating 10 in the measurement optical path, for example, a spectral luminance meter, a spectrocolorimeter, a spectrocolorimeter, and the like. Further, as an example of the diffraction grating 10, the reflection type diffraction grating using the reflected diffracted light by arranging the grating grooves on the flat or concave substrate has been described. However, the transmission type using the transmitted diffracted light that transmits the grating surface. A diffraction grating can also be used.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a spectrometer according to a conventional example.
FIG. 2 is an explanatory diagram showing a spectrometer according to the first embodiment of the present invention.
FIG. 3 is an explanatory diagram showing a spectrometer according to a second embodiment of the present invention.
FIG. 4 is a block diagram of a sensor control circuit used in the spectrometer of the present invention.
FIG. 5 is a diagram for explaining the relationship between the 0th-order diffracted light sensor output and the high-order diffracted light sensor output in the spectrometer of the present invention.
FIG. 6 is a timing chart of an integration operation in each light receiving sensor.
FIG. 7 is a flowchart of integration operation in each light receiving sensor with respect to FIG. 6;
FIG. 8 is a timing chart of integration operation in each light receiving sensor with respect to periodically fluctuating light.
FIG. 9 is a flowchart of integration operation in each light receiving sensor with respect to FIG. 8;
FIG. 10 is a diagram illustrating another usage pattern of the spectrometer of the present invention.
11 is a flowchart of the integration operation in the spot type light receiving sensor with respect to FIG.
[Explanation of symbols]
2 Light source 4 Objective lens 6 Optical fiber 8 Illumination lens 10 Diffraction gratings 12 and 14 Condensing lens 16 Line type light receiving sensor 18 Spot type light receiving sensor 22, 23 Amplifier 24, 25 A / D converter 30 CPU

Claims (3)

Diffractive means for splitting the light under measurement;
A spot-type first photoelectric conversion element that receives zero-order diffracted light from the diffraction means;
Disposed close to said first photoelectric conversion element, receives the high-order diffracted light from said diffraction means, a second photoelectric conversion elements of the line type separate from said first photoelectric conversion elements,
Control means for controlling the light reception by the second photoelectric conversion element based on the light reception output of the 0th-order diffracted light photoelectrically converted by the first photoelectric conversion element,
A spectrophotometer for collecting 0th-order diffracted light and higher-order diffracted light on a first photoelectric conversion element and a second photoelectric conversion element, respectively, through one condenser lens . The control means sets the integration time of the first photoelectric conversion element shorter than the integration time of the second photoelectric conversion element,
The first photoelectric conversion element and the second photoelectric conversion element start integration at the same time, and the integration time of the second photoelectric conversion element is determined based on the integration result of the first photoelectric conversion element that has been previously integrated. The spectroscopic measuring device according to claim 1, wherein the spectroscopic measuring device is controlled. The first photoelectric conversion element can read data in a shorter time than the second photoelectric conversion element,
When the first photoelectric conversion element repeats the integration operation at a predetermined cycle, the second photoelectric conversion element performs the integration operation when the light reception output of the first photoelectric conversion element exceeds a predetermined threshold value. The spectroscopic measurement device according to claim 1, wherein the spectroscopic measurement device is controlled to perform the following.

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