JPH04130233A - Portable light chopper device and its driving device - Google Patents

Abstract

PURPOSE:To make it possible to set light paths for measuring light relatively freely by constituting the light paths in the two directions of a light transmitting parts and a reflecting parts on a portable chopper device whose setting is relatively free, and comparing the rotations of a plurality of the chopper devices in a phase comparator. CONSTITUTION:Light transmitting parts which are formed in cutout shapes for transmitting light and reflecting parts 1b on which a reflecting members are coated so as to reflect light are alternately provided along the circumference of a rotary plate 1. The rotary plate 1 is driven and rotted with a motor 3. When the rotary plate 1 is rotated, the beam-shaped light sent from a measuring light source to the rotary plate is transmitted through the light transmitting part for a certain time and reflected and quided to the other light path from the reflecting part 1b for the next time. When the rotary plate 1 is rotated, the part between a LED 6a and a phototransistor 6b of a phase detector 6 is crossed by the light transmitting part 1a or the reflecting part 1b of the rotary plate 1. Then, the intermittent light from the LED 6a is detected with the phototransistor 6b, and the rotating speed and the phase of the rotary plate 1 are detected. The output is sent into a driving device.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a portable optical chopper device that enables a plurality of portable optical chopper devices to be set at any desired position and driven, thereby expanding the range of use. It is related to.

[Prior Art] Optical chopper devices for separating and amplifying weak light from stray light by chopping light have been known for a long time. A portable optical chopper device is also known, which is convenient for performing various measurements by setting it in the position of .

FIGS. 6(a) and 6(b) show a conventional portable optical chopper device, in which transparent parts 61a that transmit light are provided at equal intervals along the circumference of a rotating plate 61. Board 6
1 is rotationally driven by a motor 64 fixed to the base material B3 via a shaft 62. In addition, an LED 8 is provided for determining the rotational phase of the rotating plate 61 based on the presence or absence of the transparent portion 61a.
5 and a phototransistor 66 are provided on the base material 63.

A portable optical chopper device having such a configuration is arranged as shown in FIG. 7 and used for various optical measurements. In the figure, the light emitted from the light source 71 is transmitted to the monochromator 72.
It becomes a monochromatic light beam 73, which is interrupted by the rotation of the rotary plate 61 and becomes an alternating current light beam 74, which is transmitted to the material to be measured 7.
5. The light passing through the material to be measured 75 is electrically converted by an optical sensor 76, and its output is sent to a lock-in amplifier 77 tuned to the intermittent frequency of the AC light beam 74.
After being amplified by , the measured value is displayed on an indicator (not shown).

The portable optical chopper device described above is limited to one optical path, and is therefore unsuitable for double-beam photometry for comparative measurement between a standard material and a material to be measured.

A spectrophotometer and the like are known as devices that enable this comparative measurement. In this device, as shown in FIG. 8, light is emitted from a light source 81, passed through a monochromator 82, and passed through an optical path 83. The light is directed in the circumferential direction of a first rotating plate 84b that is rotationally driven by a motor 84a of a chopper device 84. Light transmitting parts 84ba or reflecting parts 84 provided alternately along
The optical path is switched by bb, and the light on the optical path 83a that passes through the transparent part 84ba is
00%), the light on the optical path 83b reflected by the reflection section 84bb is sent to the material to be measured 87 via the mirror 86a. (The figure shows the state at the time when the light is reflected by the reflecting portion 84bb and passes through the optical path 83b shown by the solid line.

) The light that has passed through the object to be measured 87 through the optical path 83b indicated by the solid line is sent to the second rotary plate 84c. The light passing through the standard material 85 via the other optical path 83a indicated by the broken line is given a predetermined attenuation by the wedge filter 88, and then passes through the mirror 86.
b to the second rotary plate 84c.

The second rotating plate 84c is a pulley 84d, 84e,
84f' and belts 84g and 84h, it rotates synchronously with the first rotary plate 84b with a phase difference of 180 degrees, so that the light reflected from the first rotary plate 84b and passing through the material to be measured 87 is The light passes through the light transmitting portion 84ca of the second rotary plate 84c and enters the optical sensor 89. Furthermore, these rotating plates 84
b.

84e rotation progresses, and the transparent portion 84b of the first rotating plate 84b
When the light starts to pass through the optical path 83a from a, the light passes through the standard material 85, the wedge filter 88, and the mirror 86b, is reflected by the reflection part 84cb of the second rotary plate 84c, and enters the optical sensor 89.

In this way, an AC output proportional to the difference in intensity of light passing through the standard material 85 and the material to be measured 87 at a frequency synchronized with the rotation of the chopper device 84 is sent to the output side of an amplifier (not shown) via the optical sensor 89. can get.

The servo motor 88a is driven by this output and information from a phase detection mechanism (not shown), and the amount of insertion of the wedge filter 88 linked to the servo motor 88a is feedback-controlled so that the output is minimized.
The transmittance of the material to be measured 87 can be determined by the amount of insertion.

[Problems to be Solved by the Invention] As described above, the portable chopper device of the type that intermittents light is not suitable for double-beam photometry, and cannot be used for double-beam photometry like a conventional spectrophotometer. The chopper device has a pair of rotary plates that are mechanically fixed, and there is a problem in that the optical path cannot be changed appropriately depending on the object to be measured.

An object of the present invention is to solve these problems and provide a portable chopper and its driving device that allow relatively free setting of the optical path for photometry.

[Means for Solving the Problems] The present invention provides a rotating plate provided with a means for chopping light along the circumferential direction, a means for rotating the rotating plate, and a means for detecting the rotational phase of the rotating plate. A portable optical chopper device that can be set at a desired position, characterized in that the rotary plate is provided alternately with transparent parts that pass light and reflective parts that reflect light along the circumferential direction. There is.

Further, the drive device of the present invention includes a rotary plate in which transparent parts for passing light and reflective parts for reflecting light are alternately provided along the circumferential direction, a means for rotating the rotary plate, and a rotary plate for rotating the rotary plate. a drive means for rotating one of the plurality of portable optical chopper devices at a rotation speed corresponding to a reference voltage; and a portable optical chopper driven by the drive means. a phase comparator that compares the rotational phases sent from the phase detection means of the two portable optical chopper devices including the device and outputs an output voltage corresponding to the phase difference; and a phase comparator that outputs an output voltage corresponding to the phase difference; A phase error detector that reduces a voltage corresponding to the phase difference, an integrator that integrates the output voltage of this phase error detector, and the other portable optical chopper device that rotates at a rotation speed that corresponds to the output voltage of this integrator. The present invention is characterized in that it includes a rotation drive means for rotating both portable optical chopper devices with a desired phase difference.

[A two-way optical path is formed by a transparent part and a reflective part in a portable chopper device whose effects can be set freely, and the rotations of multiple portable chopper devices are compared with a phase comparator to find the desired result. By driving with a drive device that can rotate with a phase difference, it becomes possible to construct a double-beam photometry system that has a wide range of use and can freely set the optical path intended by the experimenter.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1(a) and 1(b) are a front view and a side view of the rotating chopper device of this embodiment. In the figure, reference numeral 1 denotes a rotating plate, which includes a translucent part 1a formed in a cutout shape to transmit light along the circumference of the rotating plate 1, and a reflective member to reflect the light toward the paper side of this figure. Coated reflective part 1
b are provided alternately.

For the reflective part 1b, silver or aluminum is generally used as a reflective member for visible light, but it is sufficient to use a reflective member that is optimal for the wavelength range used by the chopper device.
S to increase the reflectance and protect the reflective surface.
It may also be coated with iO or other dielectric material.

The center of the rotary plate 1 is connected to a motor 3 via a shaft 2, and is driven and rotated by the motor 3. Further, the motor 3 is fixed to the base member 5 via a holding member 4a.

Furthermore, in order to detect the rotational speed and phase of the rotary plate 1 via the holding member 4b, the base member 5 is equipped with a phase detector 6 that sandwiches the rotary plate 1 and includes an LED 6a on one side and a phototransistor 6b on the other side. It is provided.

In the chopper device configured in this manner, the motor 3 is driven by a drive device (not shown) to rotate the rotary plate 1. When the rotary plate 1 rotates, a beam of light sent from a measurement light source (not shown) to the rotary plate 1 passes through the light-transmitting part 1a to one optical path for a certain period of time, and for the next period of time. is reflected by the reflecting portion 1b and guided to the other optical path.

Usually, this chopper device is set obliquely with respect to the light source so that the reflected light from the reflecting portion 1b of the rotary plate 1 takes an optical path in a desired direction.

Also, when the rotating plate 1 rotates, the LED 8 of the phase detector 6
The light-transmitting part 1 of the rotary plate 1 is connected between the phototransistor a and the phototransistor 6b.
The phototransistor 6b detects the intermittent light of the LED 6a caused by the crossing of the LED 6a or the reflecting portion 1b, detects the rotational speed and phase of the rotary plate 1, and sends this output to the drive device.

The rotary chopper device of this embodiment can be used alone like the conventional rotary chopper device, but when multiple rotary chopper devices of this embodiment are used for double beam photometry, Its characteristics can be exhibited more effectively.

Figure 2 shows the drive for synchronizing each chopper device at the same rotational speed and rotating it with a desired phase difference when a double beam photometry system is assembled using multiple rotary chopper devices of this embodiment. FIG. 2 is a block circuit diagram of the device.

In the same figure, 21a is a rotation reference voltage for regulating the chopper device 22, 23 to a desired rotation speed, and this reference voltage 21a is passed through an error detector 24a consisting of a subtraction circuit and a power amplifier 25a to the first chopper unit. It is supplied to the motor 22a of the device 22.

An output proportional to the rotation of a phase detector 22c composed of an LED and a phototransistor that detects the rotation and phase of the rotating plate 22b of the first chopper device 22 is sent as a reference signal to an external lock-in amplifier (not shown). With,
It is sent to the V/F converter 26a and converted into a voltage value, and this voltage is negatively fed back to the error detector 24a so as to be subtracted from the reference voltage 21a, so that the rotation speed of the rotary plate 22b is defined by the reference voltage 21a. Feedback control is performed to maintain the rotation speed.

On the other hand, the second chopper device 28 is supplied with the output voltage of the integrator 27 via an error detector 24b consisting of a subtraction circuit and a power amplifier 25b.
A feedback loop consisting of a power amplifier 25b, a motor 23a, a rotary plate 23b, a phase detector 23c, and a V/F converter 26b is configured, and operates in the same way as the first chopper device 22, so that the integrator 27 This second chopper device 23 is driven to rotate at a rotation speed defined by the output voltage.

Phase detector 22C1 of both chopper devices 22.23
23c is connected to a phase comparator 28, which compares the rotational phases of the rotary plates 22b and 23b of both chopper devices 22, 23, and outputs the outputs of the phase comparator 28. An output corresponding to the phase difference can be obtained on the side. This output voltage is connected to one input of a phase error detector 29 consisting of a subtracting circuit, and the other input side is connected to the rotational phase difference between the first chopper device 22 and the second chopper device 23 to a desired level. A phase reference voltage 21b for making a phase difference is provided. In this phase error detector 29, the phase reference voltage 21b is subtracted from the output voltage of the phase comparator 28, and the subtracted voltage becomes the output of the phase error detector 29 and is sent as an input to the integrating circuit 27. ing.

When this photometry system is started, the first and second chopper devices 22 and 23 are not synchronized, but gradually become synchronously operating due to the PLL function of the phase comparator 28. When the synchronization state is reached and the output voltage of the phase comparator 28 and the phase reference voltage 21b are equal, that is, the rotating plates 22b of both chopper devices 22.28.

2H) becomes the desired phase difference and the output voltage of the phase comparator 28 becomes equal to the phase reference voltage 21b, the output of the phase error detector 29 becomes zero and the integrator 2
The output of 7 becomes a constant voltage extremely close to the rotational reference voltage 21a, and the second chopper device 23 is rotationally driven in a steady state in which the rotational phase difference with the first chopper device 22 is maintained at a desired phase difference. do.

If the phase of the second chopper device 23 is delayed or advanced, the output of the phase error detector 29 is no longer zero, and the output of the integrator 27 is increased or decreased depending on the polarity of the output. Feedback control is performed so that both chopper devices 22 and 23 rotate synchronously with a desired phase difference.

In double beam photometry, the first chopper device 2
2 and the second chopper device 28 are often rotated with a phase difference of 180 degrees, but in order to set the phase difference to 180 degrees, a phase signal with a phase difference of 180 degrees is given to the phase comparator 28. The voltage generated at the output of the phase comparator 28 at this time may be given as the phase reference voltage 21b.

In the drive device of this embodiment, the V/F converter 26a
, 26b, the phase comparator 28, the integrator 27, etc., can be constructed from known ones.

As a specific usage example of the chopper device and drive device of this embodiment, a case where a spectrophotometer is assembled will be explained with reference to FIG. In the figure, light emitted from a measurement light source 80 passes through a monochromator 31, passes through an optical path 32, and is sent in the form of a beam to the rotary plate 22b of the first chopper device 22. Furthermore, the light on the optical path 3ga that has passed through the transparent portion 22ba of the rotary plate 22b passes through the reference cell 33° wedge filter 34. It passes through the mirror 35a and is sent to the rotating plate 23b of the second chopper device 23.

On the other hand, the light reflected by the reflection part 23bb of the rotating plate 23b of the first chopper device 22 and passing through the optical path 32b is reflected by the mirror 3
5b, the second chopper device 23 through the material cell 36
is sent to the rotary plate 23b.

First chopper device 22 and second chopper device 23
The rotary plates 22b and 23b of both chopper devices are rotated by the drive device 37 described in FIG. 2 at the same rotational speed with a phase difference of 180 degrees.

For example, when the reflecting portion 22bb of the rotating plate 22b of the first chopper device 22 is in a position to reflect the measurement light, the passing portion 23b of the rotating plate 23b of the second chopper device 23
a is rotated with a phase that allows the light on the optical path 32b to pass through.

The figure shows a state in which light passes through an optical path 32b indicated by a solid line.
ba and enters the optical sensor 38.

As the rotation of these chopper devices 22 and 23 progresses, the measurement light is transmitted to the transparent portion 2 of the rotary plate 22b of the first chopper device 22.
The light on the optical path 32a indicated by the broken line that passes through the reference cell 3
3, passes through the mirror 35a, is reflected by the reflection part 23bb of the rotary plate 23b of the second chopper device 23, and is reflected by the optical sensor 38.
incident on .

In this way, as the chopper device rotates, the optical path 32a
, Hb are formed alternately, and the light that passes through the reference cell 33 and data cell 36 is charged and converted by the optical sensor 38 to become an alternating current component with a frequency synchronized with the rotation, and is sent to the lock-in amplifier 39 tuned to this frequency. An output proportional to the difference in intensity between the two lights is obtained at the output side of the lock-in amplifier 39. The lock-in amplifier 39 has a drive device 3.
A reference signal indicating the rotational phase of the chopper device 22 is provided from 7. This reference signal causes the optical sensor 38 to
The polarity of the output is determined by detecting the alternating current sent from the

Depending on the output of the lock-in amplifier 39 and its polarity, the insertion amount of the wedge filter 34 is feedback-controlled via the servo motor 84a so that the output of the lock-in amplifier 39 is minimized.

The transmittance of the data cell 3B can be measured with the insertion amount of the wedge filter 34 when controlled to the minimum.

According to this application example, the measurement location and optical path 32a.

32b can be freely set according to the experimenter's will, making it possible to measure the object to be measured, which has been difficult with conventional spectrophotometers.

Another application example is shown in FIG. 4, and this application example is an example in which changes in the spectral characteristics of a material being evaporated in a vacuum apparatus are continuously measured.

In the figure, the first chopper device 22 and the second chopper device 23 are rotationally driven by the drive device explained in FIG. 2 at the same rotational speed and with a phase difference of 180 degrees.

A light source 40 is emitted and the rotary plate 2 of the first chopper device 22
The light reflected or passed by 2b passes through the optical path indicated by the solid line or broken line, and the light reflected and passing through the solid line optical path passes through the vacuum chamber 41.
The material 42 is irradiated through the window 41a, and the light reflected from the material 42 passes through the mirror 48 and is sent to the second chopper device 2.
The monochromator 4 passes through the transparent part of the rotating plate 23b of No.
After reducing the stray light generated in the vacuum chamber 41 in step 4, the optical sensor 4
5 and enters the lock-in amplifier 46 where it is amplified.

Further, the light that has passed through the rotary plate 22b of the first chopper device 22 passes through the optical path indicated by the broken line, passes through the mirror 47, and then passes through the vacuum chamber 4.
The light is irradiated onto the reference piece 48 in 1 and reflected from the reference piece 48. The light is reflected by the rotary plate 21b of the second chopper device 23, passes from the monochromator 44 to the optical sensor 45, enters the lock-in amplifier 46, and is amplified. The measured light is compared with the light reflected from the material 42.

In the vacuum chamber 41, the vapor deposition substance is evaporated from the boat 41b,
The reference piece 48 is evaporated onto the material 42, but since the reference piece 48 is provided with a cover (not shown), there is no change in the characteristics during the vapor deposition.
Comparison measurements can be made with 2.

According to this application example, the portable chopper device of the present invention can also measure materials inside a vacuum deposition tank, which was difficult to do with conventional devices.

Another application example is shown in Fig. 5. This application example adjusts the thickness of the deposited film formed on the material being deposited in the vacuum chamber so that the wavelength at which the reflectance of the material is the lowest is the desired value. This is an example of an application where the thickness can be determined by whether the thickness has increased or not.

In other words, the data during vapor deposition is measured by taking advantage of the property that the wavelength at which the reflectance of light is lowest increases as the vapor deposition progresses.

In the figure, reference numerals 50 and 51 are interference filters that allow only light around a certain wavelength to pass through.
When the passing wavelength is λ1, which is shorter than the desired wavelength λ0, and the interference filter 51 is set to λ2, which is longer than the wavelength λ0, and the intensity of the light passing through both interference filters 50 and 51 is the same. , wavelengths λ1 and λ2 are selected such that the reflectance is the lowest at wavelength λ0.

Also in this application example, the first chopper device 22 and the second chopper device 23 are rotationally driven by the drive device explained in FIG. 2 at the same rotational speed and with a phase difference of 180 degrees.

Light emitted from the white light source 52 and reflected or passed by the rotary plate 22b of the first chopper device 22 passes through an optical path shown by a solid line or a broken line. The optical path is formed such that the light that is reflected and passes through the solid line optical path passes through the filter 50 via the mirror 53a, and the light that passes through the broken line optical path passes from the interference filter 51 to the mirror 53b.

Only the light having wavelengths around λ1 and λ2 that passes through these interference filters 50 and 51 is irradiated from the rotary plate 23b of the second chopper device 23 to the material 5B in the vacuum chamber 55 via the mirror 54a. The light reflected from document 5B is mirror 5
4b, the light is inputted from the optical sensor 58 to the lock-in amplifier 59 through a filter 57 that allows only light with wavelengths between λ1 and λ2 to pass through and blocks other stray light.

In the early stage of vapor deposition, the wavelength at which the reflectance of the material is the lowest is at a wavelength shorter than λ0, so the intensity of the light in the solid line optical path where the interference filter 50 is provided is higher than that where the interference filter 51 is provided. The intensity of light is weaker than that of the optical path indicated by the dashed line.

As the deposition progresses, the lowest reflection wavelength gradually moves toward longer wavelengths, so the intensity of light passing through the interference filter 50 increases.
On the contrary, the intensity of light passing through the interference filter 51 decreases.

The difference in intensity between the two lights is monitored by a lock-in amplifier 59,
When the intensity of both lights becomes equal and the output becomes zero, it can be determined that the deposited film has been formed to a predetermined thickness.

With conventional equipment, it is difficult to assemble the measurement system for this application example described above.

Note that the present invention is not limited to the above-mentioned embodiments, and can be implemented with various modifications without changing the gist.

For example, the reflective portion of the rotary plate of the portable optical chopper device may be formed to be inclined at a predetermined angle with respect to the rotation axis.

In addition, although the driving device in the embodiment has been described as driving two portable optical chopper devices, if a phase comparator, integrator, etc. are prepared as necessary, it can drive any plurality of portable optical chopper devices. Can drive chopper equipment.

Further, the drive device of the present invention can also be used as a drive device for a conventional intermittent type portable optical chopper device.

[Effects of invention According to this invention, an optical bench and a vacuum chamber.

In other arbitrary environments, an optical system for double-beam photometry can be constructed in places where it is difficult to assemble a measurement system using conventional double-beam photometry devices.

Furthermore, by using the drive device of the present invention, an efficient and flexible double beam photometry measurement system can be constructed using a plurality of portable optical chopper devices.

[Brief explanation of drawings]

1(a) and 1(b) are front and side views of a portable optical chopper device according to an embodiment of the present invention, and FIG. 2 shows two portable optical chopper devices shown in FIG. 1 synchronously driven. FIG. 3 is a block diagram of an embodiment of the drive device of the present invention; FIG. 3 is a block diagram of an application of these embodiments to a spectrophotometer for double beam photometry; FIG. 4 is a diagram showing the spectral characteristics of a material in a vacuum deposition tank. Fig. 5 is a block diagram when applied to a system that continuously measures changes in , and Fig. 5 is a block diagram when applied to a system that monitors the formation of a deposited film on a material in a vacuum evaporation tank. Fig. 6 (a)
(b) is a front view and a side view of a conventional optical intermittent type portable chopper device, FIG. 7 is a block diagram illustrating how to use the conventional portable optical chopper device shown in FIG. 6, and FIG. The figure is a configuration diagram for explaining the configuration of a conventional spectrophotometer. 1...Rotating plate 1a...Transparent part 1b...Reflecting part 3...
- Motor 5... Base member 6... Phase detector 6a... LED 8b... Phototransistor 22, 23... First and second chopper devices 22a, 23a -... Motor 22b ,
23b - Rotating plates 22c, 23c... Phase detectors 24a, 24b... Error detectors 25a, 25b... Power amplifiers 26a, 26b - V/F converter 27... Integrator 28...・Phase comparator 29...Phase error detector Applicant's agent Patent attorney Takehiko Suzue 2nd figure ilb ward WIl & 5 figure 6th ward 7th ward

Claims (2)

[Claims] (1) A rotary plate provided with a means for chopping light along the circumferential direction, a means for rotating this rotary plate, and a means for detecting the rotational phase of the rotary plate, and can be set at a desired position. A portable optical chopper device, characterized in that the rotary plate is provided alternately with transparent parts that pass light and reflective parts that reflect light along the circumferential direction. (2) A rotary plate in which transparent parts that pass light along the circumference and reflective parts that reflect light are provided alternately, means for rotating this rotary plate, and phase detection of the rotational phase of the rotary plate. a driving means for rotating one of the plurality of portable optical chopper apparatuses at a rotational speed corresponding to a reference voltage; a phase comparator that compares the rotational phases sent from the phase detection means of the portable optical chopper device and outputs an output voltage corresponding to the phase difference; and a voltage corresponding to the desired phase difference from the output voltage of this phase comparator. A phase error detector that reduces the output voltage of the phase error detector, an integrator that integrates the output voltage of this phase error detector, and a portable optical chopper device that rotates the other portable optical chopper device at a rotation speed corresponding to the output voltage of this integrator. 1. A drive device for a portable optical chopper device, comprising: rotational drive means for rotating the chopper device with a desired phase difference.