JPH022081B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention utilizes the specific absorption of infrared rays by plastics to continuously maintain the thickness of a film, especially an extremely thin film that is transparent or translucent even when running with fluctuations. The present invention relates to an infrared thickness meter suitable for thickness measurement.

[Prior Art] When a plastic film is irradiated with infrared rays, an infrared spectrum is obtained that is related to the specific absorption and thickness of the material. Infrared film thickness gauges are designed to measure film thickness by measuring the amount of transmitted light, since in principle the amount of absorption of a specific wavelength of infrared rays is proportional to the thickness of the film. , for example, JP-A-53-31155
Various devices using this principle are known, such as in Japanese Patent Publications. However, the measurement target with conventional equipment is a film with a film thickness of up to about 10 μm.
In contrast, films manufactured using currently developed film manufacturing technology have a film thickness of 0.5 to 5.0 μm.
There are extremely thin films, and there is a problem in that conventional devices cannot be directly applied to these extremely thin films, or even if they are applied, they cannot be accurately measured.

This is because when a parallel beam of infrared light is irradiated onto a film to be measured, mutual interference due to internal multiple reflections occurs on the top and bottom surfaces of the film, increasing measurement errors and eventually making it impossible to measure the film thickness. , and as the thickness of the film becomes extremely thin, the amount of specific absorption of the irradiated infrared rays also decreases significantly, resulting in a poor S/N ratio of the detection signal, making it impossible to obtain enough resolution to determine the thickness. It is from.

[Object of the Invention] The main object of the present invention is to eliminate optical interference, in other words, to prevent internal multiple reflections of the film from occurring, thereby improving the accuracy of measuring the thickness of the film.

Another object of the present invention is to enable a desired resolution to be obtained even with an extremely thin film, regardless of the sensitivity limit of a detection system for light transmitted through the film. Ultra-thin films include those that are left still, as well as films that run continuously.

Another object of the present invention is to take sufficient measures against fluctuations in a continuously running film.

Another object of the present invention is to enable simultaneous photometry at the same location to continuously and accurately measure the thickness of a film traveling at high speed.
Because there are error factors that depend on the optical system, electrical system, and sample system in thickness measurement, it is necessary to frequently check the calibration curve. Although photometry is employed, conventional two-wavelength time-division photometry using a rotary plate equipped with an interference filter inevitably includes measurement errors when the film is running at high speed.

Still another object of the present invention is to provide a calibration means, preferably an automatic calibration means, to prevent errors such as changes over time depending on the wavelength characteristics of the optical system including the light source and the photodetection system. It is.

[Summary of the Invention] A polarizer that intermittently generates infrared rays in a band including at least two wavelength components, a wavelength component exhibiting absorption characteristics unique to the film and a wavelength component exhibiting non-absorption characteristics, and polarizes the infrared rays into P-polarized light. and a light source unit that projects infrared light outputted from the light source unit from an oblique direction with respect to the film surface of the film at a predetermined angle, that is, a Brewster angle determined by the material of the film, and an optical scanning section that continuously varies the light angle within a predetermined angular range so that the infrared rays scan the film; a reflected light receiver that outputs a reflected light signal according to the intensity of the reflected light; A transmitted light spectrometer outputs a transmitted light signal, receives the reflected light signal and the transmitted light signal, removes background noise from the reflected light signal and the transmitted light signal, and processes the reflected light signal. a signal processing unit that identifies and validates the transmitted light signal at the minimum reflected light intensity, and calculates thickness data that is a basis for quantifying the thickness of the film based on the activated transmitted light signal of at least the two wavelength components; The basic feature is that when P-polarized light parallel to the incident plane is incident on the film at the Brieucster angle, there are no reflected light components on the top and bottom surfaces of the film, and optical interference can be eliminated. , all incident light becomes transmitted light, eliminating energy loss except for characteristic absorption in the film. Some films are left stationary at a predetermined location, but others run continuously,
Some films have fluctuations, so in order to activate the transmitted light signal only when the incident is at the Brieux-Star angle, we use the fact that there is reflected light from the film when the incident is at an angle other than the Brieux-Star angle. The optical scanning unit, the reflected light receiving unit, and a part of the signal processing unit that detects the reflected light and identifies whether the incident light is incident at the Brieucster angle, The thickness data of the film is calculated based on the transmitted light signal only when it is incident. And since it is simultaneous photometry (wavelength division photometry) at the same location, rather than time-division photometry that irradiates different locations as in the past,
The thickness of films running at high speed can be measured continuously and with high precision. Note that the above-mentioned wavelength division photometry is not limited to using only two wavelengths, and in some cases, wavelength division photometry of multiple wavelengths is effective.

A second invention includes all of the above-mentioned specific inventions in its main parts, and includes an optical path converting section that converts the optical path of transmitted light so that infrared rays projected onto a film pass through the film a plurality of times. It is characterized by increasing the absorption ability of the wavelength component of the infrared rays transmitted by the film, which exhibits absorption characteristics unique to the film.
In the case of incidence at the Brieucster angle, there is no multiple reflection light inside the film, so there is no energy loss that would become ineffective.Furthermore, unlike the conventional method, the incidence is not perpendicular to the film, but the multipath is obliquely incident on the film related to the Brieucster angle. Since a substantial optical path length is obtained with the optical system, the desired resolution can be obtained even with an extremely thin film, regardless of the sensitivity limit of the detection system for light transmitted through the film.

A third invention includes all of the above-mentioned specified inventions in its main part, and the subject film is continuously moved and responds to fluctuations caused by the movement of the film based on a reflected light signal output from a reflected light receiving section. Preferably, the light scanning section includes a vibrating mirror to adjust the setting projection angle in the light scanning control section. The light angle is corrected by servo control.

And, the fourth invention includes all of the above-mentioned specific inventions in the main part, and similarly to the third invention, the subject film runs continuously, and a signal for calculating thickness data that is the basis for quantifying the thickness of the film is provided. The present invention is characterized in that it further includes a data processing section that calculates the true thickness of the film based on the thickness data output from the processing section and a preset thickness conversion function.

Preferably, the light source section, the optical scanning section, the reflected light receiving section, and the transmitted light spectroscopic section are constructed integrally, and this integrated structure is arranged so as to be movable in the width direction of the film.
Then, a sample film of the same type is fixed on the same plane as the running surface of the film on the outside in the width direction of the running film, and the integrated structure is moved to the position of this sample film, and data of the sample film is collected. The data on the sample film is automatically calibrated using the data on the sample film, and the calibrated thickness data is output to the data processing section.

Hereinafter, the present invention will be specifically explained with reference to embodiments shown in the accompanying drawings together with other features.

[Example] FIG. 1 is a basic configuration diagram of the embodiment.

1 is an ultra-thin film (hereinafter referred to as the film) that travels at high speed in the direction of the arrow; 2 represents the wavelength component that exhibits absorption characteristics specific to film 1 (hereinafter referred to as the measurement wavelength and expressed as λ _S ) and the non-absorption characteristics. an infrared ray generating section 21 that intermittently generates infrared rays 20 including at least two wavelength components (hereinafter referred to as reference wavelengths and expressed as λ _R ); This is a light source unit that includes a polarizer 22 that polarizes the light into polarized light, that is, P-polarized light. 3 travels the P-polarized light 22 from the light source 2 on the film 1 from an oblique direction within a predetermined angular range ±Δθ centering on the Brewster angle θ _B determined by the material (especially refractive index) of the film 1. The vibrating mirror 30 and this vibrating mirror 30 are
and a drive section 31 that drives the. 4 is reflected light 40 of the P-polarized light 23 projected onto the film 1.
The reflected light receiving section receives the light and outputs an electrical signal, that is, a reflected light signal a, according to the intensity of the received light, and includes a condensing mirror 41, a cone mirror 42, and a reflected light detector 43. 5 is P-polarized light 2 projected onto film 1
3 converts the optical path of the transmitted light 50 so that it passes through the film 1 multiple times; 6 receives the transmitted light 51 that has transmitted through the film 1 multiple times; An electrical signal separated into two wavelength components λ _S and λ _R and corresponding to the intensity of each spectral light (hereinafter referred to as a transmitted light signal; the wavelength λ _S is the measurement wavelength signal b, and the wavelength λ _R is the reference wavelength signal. 60 is a flat reflecting mirror.

7 receives the reflected light signal a, the measurement wavelength signal b, and the reference wavelength signal c, and the light source section 2
The intermittent signal d outputted from the optical scanning section 3 and the periodic signal e outputted from the optical scanning section 3 are received, the received reflected light signal a is identified, and the Brewster angle of the light projected onto the film 1 is determined. The transmitted light signals b and c of the incident light 23 only when the incident light is incident at θ _B are activated, and the thickness data g is the basis for quantifying the thickness of the film based on the activated transmitted light signals b and c. A control circuit unit 70 is a signal processing unit that calculates the transmitted light signal and provides a control signal f to the vibrating mirror drive unit 31 in order to validate the transmitted light signal, and a signal that calculates thickness data and provides thickness data g to an external device (not shown). It consists of an arithmetic circuit section 71.

The intermittent light generated by the infrared ray generation unit 21 is angularly deflected by ±Δθ around the incident light set by the vibrating mirror 30, that is, the Brewster angle θ _B. The angularly polarized intermittent light enters the polarizer 22, and only the P-polarized light component is emitted. Polarizer 22
For example, a wire grid type is used.
When the P-polarized light 23 that has passed through the polarizer 22 is incident on the film 1 to be measured, a portion of the P-polarized light 23 is reflected as the reflected light 4.
The remaining light is transmitted as transmitted light 50 and reaches the reflecting mirror 52. At this time, film 1
If there is a Brewster angle incident on , the reflected light is 40
There is no light, and only the transmitted light 50 is present, and no optical interference occurs.

The light reflected by the reflection mirror 52 is incident on the film 1 again, and only the transmitted light 51 is guided to the transmitted light/spectroscopy section via the reflection mirror 60. The reflecting mirror 52 has one film per film.
A concave mirror is used so that when the incident angle of the first pass is the Brieucster angle θ _B , the other side is also always θ _B. Furthermore, although the example shown in FIG. 1 is a two-pass multi-pass system, as shown in FIG. A system can be constructed. In general, it is possible to easily configure an n-pass multipath system depending on the resolution of the transmitted light detection system.

The light incident on the transmitted light/spectroscope unit 6 is split into a measurement wavelength component λ _S and a reference wavelength component λ _R , and the light intensity of each is detected simultaneously using each detector, and a measurement wavelength signal b and a reference wavelength component λ R are detected. The signal is inputted to the signal processing section 7 as the reference wavelength signal c. On the other hand, the reflected light 40 of the light 23 incident on the film 1 is reflected by the condensing mirror 4.
1 and guided to a reflected light detector 43. At this time, since the optical axis also changes due to the fluctuation of the object to be measured (wave fluctuation of the film), the cone mirror 42 is used to prevent detection errors due to optical axis deviation. The reflected light 40 guided to the reflected light detector 43 is converted into an electric signal, that is, a reflected light signal a, and is input to the signal processing section 7.

Next, the specific configuration of each of the above sections will be explained.

As shown in FIG. 3, the light source section 2 includes an infrared ray generation section 21 and a P-polarized light polarizer 22. The infrared ray generation section 21 includes a light source 2 such as a halogen lamp.
The light from 4 is condensed by a condensing mirror 25 and condensed by a slit 26. The light passing through the slit 26 is periodically blocked by the chopper 27 and becomes intermittent light. The intermittent light becomes parallel light by the collimating lens 28 and enters the broadband cut filter 29 . The broadband cut filter 29 passes infrared rays in a band including the measurement wavelength λ _S , the reference wavelength λ _R , and wavelength components used as reflected light, and cuts out other wavelength components. The emitted infrared rays 20 enter the polarizer 22. A wire grid type polarizer 22 polarizes this infrared ray 20 into P-polarized light. In addition, polarizer 2
2 can also be configured to be included in the infrared ray generation section 21.

A chopping detector 27D is provided in correlation with the chopper 27. The chopping detector 27D is composed of, for example, a photointerrupter, and outputs a chopping synchronization signal d as an intermittent signal synchronized with the intermittent light source light.

FIG. 4 shows a schematic configuration of the transmitted light/spectroscopy unit 6.
In the figure, transmitted light 51 that has passed through the film
is the measured wavelength λ _S by the bandpass film 61
Only the infrared rays near the reference wavelength λ _R are filtered and focused by the entrance slit 62 and then guided to the collimating lens 63 . Collimating mirror 63
The parallel light reflected by is guided to the diffraction grating 64 and separated into spectra. The spectral light is reflected again by the collimating mirror 63 to form a spectral band on the exit slit surface. At the same time as the spectral light 65 with the measurement wavelength λ _S is emitted through the slit 67 formed at the location corresponding to the measurement wavelength λ _S of the spectroscopic spectrum,
Slit 6 formed at a location corresponding to the reference wavelength λ _R
The reference wavelength λ _R is emitted from the spectroscopic unit 66 through the reference wavelength λ R .

The emitted light beams 65 and 66 are detected by respective photodetectors 65.
The light is received at D and 66D. Photodetector 65D, 66
D outputs a measurement wavelength signal b and a reference wavelength signal c according to the intensity of the spectral light. Note that the means for separating the spectrum into the measurement wavelength λ _S and the reference wavelength λ _R is a diffraction grating 6.
4 may be replaced with a prism.

Also, detectors 65D, 6 for measurement wavelength and reference wavelength are provided.
Regarding 6D, use one that has good sensitivity in the characteristic absorption wavelength region of the film to be measured. In an example in which a polyethylene terephthalate film (PET film) is used as the film 1, it is preferable to use a measurement wavelength of 2440 nm and a reference wavelength of 2400 nm. In this case, PbS, which has good sensitivity in the 1 to 2.5 μm band, is used. do. PbSe is used for objects having a characteristic absorption wavelength of 2.5 to 3.5 μm.

Furthermore, regarding the reflected light detector 43 (FIG. 1), since the reflected light 40 is generally weaker than the transmitted light 50, it has higher sensitivity than the detectors 65D and 66D, and has a wavelength (measurement wavelength) at which the influence of interference can be ignored. It is necessary to have a detection wavelength width (the shorter the wavelength, the better) and the detection wavelength width. Therefore, in the example, Si
A photodiode was used to utilize reflected light in the wavelength range of 700 to 1000 nm.

Next, the optical scanning section 3 is illustrated in FIG. Figures A and B show the scanning mechanism of the mirror 30, and Figure C shows the control mechanism for the scanning center.

A cylindrical shaft member 32 is located at the center of the lower end of the mirror 30.
is fixed and supported on a fixed shaft 33, and the mirror 3
0 is able to swing freely around the axis of a shaft 33. A mirror drive arm 34 for swinging the mirror 30 is connected to the shaft member 32, and a pin 36 is slidably inserted into a long hole 35 at the tip of the arm 34. It is eccentrically fixed to a rotating sector 37 which is a semicircular portion cut out in the circumferential direction. The rotation sector 37 is a synchronous motor 38
is rotated in the direction of the arrow in the figure. When the synchronous motor 38 rotates, the mirror drive arm 34 swings around the axis of the shaft 33, as shown by the dashed line in FIG. (Vibrate. rotating sector 3
In correlation with this, as shown in FIG.
7D outputs a vibrating mirror synchronization signal e which is switched by the edge of the rotating sector 37.

The mirror vibrating section shown in FIGS. 5A and 5B is fixed to a moving table 39 shown in FIG. 5C. The movable table 39 is slidably provided on a support base 391, and when a control signal f is input to a pulse motor 393 having a threaded rotating shaft 392, the movable table 39 is controlled to move left and right as shown by arrows in the figure. . When the movable table 39 moves, the entire mirror vibrating section is displaced with respect to the absolutely fixed axis 33, and the center of vibration of the vibrating mirror 30 is controlled. The moving table 39 is provided with a spring 394 on the non-driving side to prevent backlash. Further, the vibration and movement mechanism of the mirror 30 is not limited to the one shown in FIG. 5, but may be an electromechanical structure using a strain element such as a piezo element, or an acousto-optic structure using ultrasonic waves. In addition to control accuracy, it has the advantage of compactness.

FIG. 6 shows an external configuration diagram of the film thickness measuring device according to the embodiment. Figure A is a front view of the film 1 in the width direction, and Figure B is a sectional view taken along line B--B of A. The film 1 is guided by rollers or guide members (not shown) and runs continuously with some degree of vertical freedom, so that it undulates in the vertical direction.

101 is an upper frame 1 above the film 1;
02 and a lower frame 103 below the film 1 are integrally connected to each other. A guide stand 104 extending over the width of the film 1 is installed on the lower frame 103, and a movable stand 105 is connected via a rack and pinion 106 and rails and wheels 107 so as to be able to slide along this guide stand 104. .

The photometry section 108 is placed on the movable table 105, and includes a light projecting section 109 in which the light source section 2 and the light scanning section 3 described above are constructed, and a reflected light receiving section 4 and a transmitted light/spectroscopic section that are also described above. 6 and the light receiving section 11 constructed with
0, and the signal processing section 7 described above also has this measuring section 1.
Built in 08. On the other hand, the upper frame 10
A reflective mirror holding frame 111 is connected to the lower part of the film 1, and a reflective mirror (concave mirror) 52 having a length equal to or longer than the width of the film 1 is held.

The film thickness measuring device of this example is also equipped with an automatic calibration function, and a photo interrupter 112 attached to the lower part of the movement 105 is a detector that generates a timing signal for automatic calibration. The photo interrupter 112 generates a signal when light is interrupted by a light plate 113 protruding from the lower frame 103 on one side of the scanner frame 101. A standard sample holder 114 is installed above the thin light plate 113 so as to protrude from the scanner frame 101 toward one width edge of the film 1. Sample film is retained. A standard sample film (not shown) is fixed so as to be flush with the specified running surface of the film 1. Further, as can be seen from the figure, a gap 115 is formed between the standard sample holder 114 and the edge of the film 1 in the width direction. This void 1
15 is a measurement wavelength signal (V(λ _S )) as described later.
It is used when determining a signal correction coefficient from the reference wavelength signal (V(λ _R )).

The moving table 105 is a scanner frame 101
Its movement is controlled by a scanner control unit 116 attached to the scanner. Further, the measuring section 108 is connected to a data processing section 117 attached to the scanner frame 101 by a telescopic cable (not shown), and receives a signal from a signal processing section built in the photometry section 108 . An operation panel 118 is formed in the data processing section 117, and includes arithmetic control means such as a microcomputer or a microprocessor therein.

Note that the data processing section 117 may include the signal processing section described above. The signal processing section will be described in detail below.

Further, in the configuration shown in FIG. 6, the reflecting mirror 52 is a fixed concave mirror having a length equal to or greater than the width of the film 1, but if it is difficult to obtain a long concave mirror, it may be arranged to sandwich the film 1 and face the photometer 108. It may also be configured such that it is installed in the same position and moves in synchronization with the photometry section 108. In this case, a long concave mirror is unnecessary and a short one can suffice. Functionally, this example uses simultaneous photometry at the same location, so there is no problem even if there is a slight deviation in the optical path.

Next, FIG. 7 shows specific details of the signal processing section 7, which includes a vibrating mirror control circuit 70 and a thickness data calculation circuit 71.

The control circuit 70 for the vibrating mirror includes the reflected light detector 4
A differential amplifier 70 to which the reflected light signal a of No. 3 is input.
1. Timing generation circuit 702 to which the chopper synchronization signal d of the chopper synchronization detector 27D is input, sample and hold circuits 703 and 704, signal separation circuit 705 to which the vibration mirror synchronization signal e of the vibration mirror synchronization detector 37D is input, smoothing circuits 706 and 7
07, differential amplifier 708 and pulse motor 39
3 drive circuit 709, and controls the vibration center to follow so that the vibration center of the vibration mirror 30 always maintains the incident angle of the Brewster angle θ _B even if the angle of the film 1 to be measured changes. It is something.

The principle of follow-up control is illustrated in FIG. As shown in FIG. 1A, when the film 1 to be measured is running on a specified running surface, the light is incident at a Brewster angle θ _B. Incident light 23 is centered around θ _B ±Δθ
The intensity of the reflected light 40 is detected by scanning (deflecting) within the range of , the fluctuation angle ±α of the fluctuating film 1 is detected, and the vibration center of the vibrating mirror is controlled to move by α to cancel the fluctuation. be. Figure B shows the reflected light intensity when the film 1 is on the specified running surface (fluctuation angle 0), when it sways upward (+α), and when it sways downward (−α) at an angle of incidence θ. The graph shows the horizontal axis. A sine wave sampled around the Brewster angle θ _B is shown below this graph, and C1, C2, and C3 in the same figure show changes in the reflected light intensity at that time, respectively. If we separate this by the positive and negative rectangular waves of the vibrating mirror synchronization signal e and subtract the DC component of each half cycle from the +Δθ side from the −Δθ side, we can determine how much the object to be measured moves from the reference position. A method of canceling the fluctuation angle ±α by using the subtracted value (potential difference) after determining the fluctuation angle ±α of the dolphin (so as to control the ±α angle) vibrating mirror 30
move the center of vibration.

FIG. 9 shows an example of a specific waveform of the vibrating mirror control circuit 70, and its production will be explained. In addition, the alphanumeric characters a, a1 to a7, f1, f in parentheses in Figure 9
2 corresponds to the signal names in Fig. 7, and a1 to a7 in Fig. 9.
Similarly to a, the vertical axes of the graphs of f1 and f2 are voltage on the vertical axis and time on the horizontal axis.

In FIG. 7, a reflected light signal a inputted from a reflected light detector 43 is processed by a differential amplifier 701 and a sample hold circuit 703 to eliminate background noise due to dark current of the detector and the influence of ambient light. (BGN) is removed to obtain the signal a1 (9th
Figure a1). The hold timing of the sample hold circuit 703 is determined by using the signal d input from the chopper synchronization detector 27D as the timing generation circuit 702.
It depends on the timing signal that is output at an appropriate time during the light period.

From the output a1 of the differential amplifier 701, only the signal during the light projection period of the signal a1 is extracted by the sample and hold circuit 704, and a signal a2 is obtained (a2 in FIG. 9, and the same applies hereinafter). The hold timing of the sample hold circuit 704 is based on a timing signal output by the timing generation circuit 702 at an appropriate time during the light projection period.

The signal a2 is separated by the signal separation circuit 705 into a half period of the vibration period of the vibrating mirror, that is, a signal on the +Δθ side (signal a3) and a signal on the −Δθ side (signal a4). The timing of separation is the signal e from the vibrating mirror synchronization detector 37D. The separated signals a3 and a4 are sent to smoothing circuits 706 and 7, respectively.
07 and converted into flat DC signals as shown in FIG. 9 a5 and a6.

Signal a5 and signal a6 are + of differential amplifier 708,
- input, and a difference signal a7 between both signals is output from the differential amplifier 708 (a7 in FIG. 9). This difference signal a7 is calculated from the angle of incidence (the angle between the film to be measured and the measurement beam) and the target Brewstar angle θ _B
This signal is proportional to the deviation from the That is, a positive signal means that the vibration center of the vibrating mirror is located at an incident angle greater than θ _B , and a negative signal means that the vibration center of the vibrating mirror is at an incident angle smaller than θ _B. Note that when the vibration center is θ _B , the difference signal a7 does not become OV precisely, but it can be made to become OV by appropriately adjusting the comparison voltage of the direction discrimination circuit (sign detection circuit) in the pulse drive circuit 709. You can make corrections to

The pulse drive circuit 709 has an input signal a7 of OV.
(Precisely, the voltage when the center of vibration of the vibrating mirror is θ _B )
A drive signal f is outputted to the pulse motor 393 so that the drive signal f approaches . That is, if it is a positive signal, it outputs a signal f1 that moves it in the negative direction, and if it is a negative signal, it outputs a signal f2 that moves it in the positive direction. outputs a predetermined number of pulse signals proportional to the positive signal).
By performing the above operations continuously, even if the angle of the film 1 to be measured changes, the vibration center of the vibrating mirror 30 can always maintain the incident angle of the Brewster angle θ _B.

In this example, servo control is performed to maintain the center of vibration of the vibrating mirror 30 at an incident angle of the Brewster angle θ _B , but instead of this, the reflected light signal a obtained by scanning with a vibrating mirror etc. It is also possible to provide a minimum detection circuit for detecting the minimum value of , and to enable the transmitted light signals b and c at the timing of detecting this minimum value.

Next, the thickness data calculation circuit 71 will be explained.
The circuit 71 includes a background noise removal circuit 711 to which the measurement wavelength signal b of the measurement wavelength detector 65D is input, and a background noise removal circuit 7 to which the reference wavelength signal c of the reference wavelength detector 66D is input.
12 and their respective sample and hold circuits 71
3, 714, the background noise removal circuits 711, 712, and the sample hold circuit 71.
3,714 and a timing generation circuit 702 that provides a timing signal to the oscillating mirror synchronization detector 37D.
a timing generation circuit 715 to which the signal e of is input, and an automatic calibration start signal h output from the automatic calibration detector (photo interrupter) 112, and each sample hold circuit 7.
When the timing signal of the timing generation circuit 715 to which the outputs of 13 and 714 are input is input, the signal correction coefficient calculation circuit 716 calculates the ratio of both input signals when there is no film, and the sample and hold circuits 713 and 714 respectively. A log ratio circuit 717 receives the output of the signal correction coefficient calculation circuit 716, receives the other timing signal of the timing generation circuit 715, and calculates the logarithmic ratio of both signals when there is a film. , an external output circuit 71 which receives the status signal i generated by the timing generation circuit 715 and outputs the output of the log ratio circuit 717 to the external data processing section 117.
It consists of 8. Timing generation circuit 715
The status signal i is also input to the data processing unit 117 in order to distinguish between the film to be measured and the data of the standard sample. In addition, the measurement wavelength detector 6
5D and the reference wavelength detector 66D are connected to an electronic cooling control circuit 719 in order to obtain stable detection signals at all times.

The operation of the thickness data calculation circuit 71 is as follows: First, the transmitted light that has passed through the film 1 to be measured is set to the measuring wavelength λ _S
and the reference wavelength λ _R and the respective detectors 65D, 6
Signals b and c obtained by 6D are input to respective background noise removal circuits 711 and 712, and these circuits 711 and 712 output signals to detectors 65D and 65D.
Noise components such as 6D dark current and ambient light are removed. And each sample hold circuit 7
13, 714, only the signals transmitted through the film 1 during the light projection period are extracted. The outputs of both sample and hold circuits 713 and 714 are always signals generated by the timing generation circuit 702 and sampled at the same timing. In other words, the measurement wavelength signal V (λ _S ) and the measurement wavelength signal V (λ _R ) are always under the same conditions (at the same part of the film to be measured and on the same optical path).

The timing generation circuit 715 uses the vibration mirror synchronization signal e and the automatic calibration timing signal h from the automatic calibration timing detector 112 to generate control timing signals for the signal correction coefficient calculation circuit 716, the log ratio circuit 717, and the external output circuit 718. At the same time, a status signal i is output to the data processing unit 117. Based on the status signal i, the data processing section 117 identifies whether the thickness data signal g is data of the film to be measured or data of the standard sample. As shown in the timing chart of FIG. 10, the status signal maintains a high level when the measuring section 108 (see FIG. 6) is at the standard sample position, and when it moves from that position to the left in the figure, Falling from a high level. In response to the falling edge, the timing signal generation circuit 715 generates a signal of signal correction coefficient calculation timing, and activates the circuit 716. At this time, what is input to the circuit 716 is the part where the film to be measured does not exist in the measurement optical path (the gap 1 in FIG. 6).
15) measurement wavelength signal V ₀ λ _S and reference wavelength signal V ₀
(λ _R ). The signal correction coefficient calculation circuit 716 calculates the signal ratio K1 to (1) based on the timing signal.
Operates like an expression.

K1=V ₀ (λ _S )/V ₀ (λ _R )...(1) The value of this determined ratio is stored in the storage means in the circuit 716 and read out at an appropriate timing.
It is output to the log ratio circuit 717. Further, in another configuration, the data may be output to the data processing section 117.

The log ratio circuit 717 is a timing generation circuit 715
control timing signals from , that is, the measurement wavelength signal Vθ _B (λ _S ) and the reference wavelength signal when there is a film or standard sample to be measured in the measurement optical path and the incident angle of the measurement light is the Brewster angle θ _B Vθ _B (λ _S )
is received, the ratio of this signal is multiplied by the correction coefficient K1 read out from the circuit 716, and the result is subjected to a logarithmic operation to obtain thickness data A. Expressed as a formula, it becomes formula (2).

A=log {K1×Vθ _B (λ _R )/Vθ _B (λ _S )} (2) This circuit 717 linearizes the change in light intensity to the change in thickness. The analog thickness data obtained by the circuit 717 is converted into a digital signal by an external output circuit 718 in synchronization with the control timing of the timing generation circuit 715, and sent to the data processing unit 117 as digital thickness data g. Output. Particularly, the timing for the standard sample is shown in FIG. The log ratio calculation is timed in response to the fall of the vibrating mirror synchronization signal, and the external output timing is determined in accordance with the fall of this timing to output the standard sample thickness data signal. The data processing unit 117 identifies and stores the data as standard sample data based on the high-level status signal i indicating the standard sample period. The standard sample data is the photometry section 10.
8 (FIG. 6) at least twice.

The data processing unit 117 calculates the true thickness of the film to be measured. Before measurement, the standard thickness d ₀ of the film set in the standard sample holder 117 (FIG. 6A) is input to the data processing section 117 from the operation panel 118. The standard thickness d ₀ and the actual measurement data signal g from the photometry section 108 are connected at the timing when the status signal i indicates that the standard sample position is present (the value is set to A ₀ ), and as shown in equation (3). The ratio is determined and used as a thickness conversion coefficient for subsequent film thickness measurements.

K2=d ₀ /A ₀ (3) Using this coefficient K2, the thickness calculation is continuously performed in one or more repetitions thereafter. Assuming that the actual thickness data is A, the following equation (4) is calculated.

d=K2×A (4) The film thickness value d obtained by calculating the above equation (4) can be output to a desired output device, such as a chart recorder, printer, CRT, etc.
In addition, the output contents include displaying the profile of the object to be measured in the flow direction and width direction, and when the thickness deviates from the range of thickness do set from the operation panel (for example, if the thickness is 2 μm and it deviates from the range of ±0.5 μm). In such cases, it can be used to sound an alarm to warn you, or to use it as a control signal for the thickness of a film manufacturing device.

In addition, in the data processing unit 117 according to the above embodiment, the standard thickness d ₀ is input and the subsequent actual measurement thickness is calculated using the thickness conversion coefficient K2 using the actual measurement data A ₀ of the standard sample. The true thickness can be determined even without obtaining the actual measurement data A ₀ (by eliminating all equipment related to the standard sample). In other words, the number of passes to pass through the film is determined by the configuration of the multipass system.
Since the absorbance of the film is also known in advance, the true film thickness d ₀ uniquely corresponds to the measured and outputted thickness data A. Therefore, a function (a continuous quantity or a plotted quantity may be used) for quantifying the true thickness of the film by converting the thickness data A is set, and a storage means (ROM is preferable) in which this function is stored. The data processing unit 117
Be prepared for. If the type of film is different, for example, you can replace the ROM appropriately depending on the type of film. The device can be provided with versatility through simple means.

[Effects] As described in detail above, according to the infrared thickness gauge according to the present invention, optical interference caused by ultra-thin films can be reduced by making P-polarized light incident at the Brieucster angle. The film thickness can also be measured with high precision, and the multi-pass optical system can eliminate the lack of resolution in the detection section for the transmitted light of ultra-thin films, and it also eliminates measurement errors caused by fluctuations in the object to be measured. By detecting the light minimum, it can be controlled and effectively prevented. Furthermore, since the photometry was carried out simultaneously at the same location, both errors due to optical axis fluctuations during scanning of the measurement unit and errors due to differences in the photometry locations in conventional two-wavelength time-division photometry for objects traveling at high speed are generated. I never tighten it. When the automatic calibration means is also used, it is possible to effectively prevent errors due to changes over time that depend on the wavelength characteristics of the optical system including the light source and the detector.

By the way, the measurement target is a 4.0 μm PET film, the measurement wavelength is λ _S = 2440 nm, λ _R = 2400 nm, the reflected light detection wavelength range is 700 to 1000 nm, the mirror vibration frequency is 25 Hz, the mirror vibration angle is ±3°, and the measuring wavelength is λ S = 2440 nm, λ R = 2400 nm. In the above-mentioned infrared thickness meter with a frequency of 1 KHz and two passes of transmitted light, the vibration center setting angle was 58 degrees and the measurement target was ±0.1 μm.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of an embodiment according to the present invention, and FIG. 2 is an optical path diagram showing another example of a multipath optical system.
Figure 3 is a detailed view of the light source section, Figure 4 is a detailed view of the transmitted light/spectroscopic section, and Figure 5 is a detailed view of the optical scanning section.
Figure B is a plan view, Figure B is a side view, and Figure C is a perspective view of the movable table. FIG. 6 shows an external configuration diagram of the embodiment, and FIG. 6A is a front view, and FIG. 6B is a sectional view taken along line B--B of A. Fig. 7 is a block circuit diagram of the signal processing section, Fig. 8 A, B, C1, C2, and C3 are explanatory diagrams of the principle of servo control of the optical scanning section, and Fig. 9 a,
a1, a2, a3, a4, a5, a6, a7, f
1 and f2 are waveform diagrams showing examples of waveforms of various parts of the vibrating mirror control circuit, and FIG. 10 is a timing chart as an example of the thickness data calculation circuit. DESCRIPTION OF SYMBOLS 1... Film, 2... Light source section, 3... Light scanning section, 4... Reflected light receiving section, 5... Optical path conversion section, 6
...Transmitted light/spectroscopy section, 7...Signal processing section, 20...
...Infrared light, 22...Polarizer for P polarization, θ _B ...
Brieuster angle, 40...Reflected light, 51...Transmitted light.

[Claims]

1. In a device that measures the shape of an object in a non-contact manner by receiving the reflected light of the light irradiated on the surface of the object to be measured, a displacement meter that receives light and detects a distance to the object to be measured from a difference in the incident position of the reflected light on the light receiver; a three-dimensional drive mechanism that drives the displacement meter three-dimensionally; and the displacement meter. One angle changing mechanism that changes the mounting angle of the three-dimensional drive mechanism, the distance measurement value by the displacement meter, the drive amount of the three-dimensional drive mechanism, and the mounting angle of the displacement meter are input and necessary calculations are performed.
It is comprised of an arithmetic control mechanism that drives and controls the dimensional drive mechanism and the angle change mechanism, and is configured such that the rotation center axis of the angle change mechanism and the extension line of the optical axis of the irradiation light from the displacement meter intersect. A non-contact measurement device for measuring the shape of an object. 2. The object-shaped object according to claim 1, wherein the rotation center axis of the angle changing mechanism and the extension line of the optical axis of the irradiation light are configured to intersect within the range of the thickness of the irradiation light. Non-contact measuring device. 3. In a device that measures the shape of an object in a non-contact manner by receiving the reflected light of the light irradiated on the surface of the object to be measured, The measurement target is detected based on the difference in the incident position of the reflected light on the light receiver.

Claims (1)

[Scope of Claims] 1. Polarized light that intermittently generates infrared rays in a band that includes at least two wavelength components, a wavelength component that exhibits absorption characteristics unique to the film and a wavelength component that exhibits non-absorption characteristics, and that polarizes this infrared rays into P-polarized light. a light source unit including a light source unit, and emits infrared rays output from the light source unit from an oblique direction at a predetermined angle with respect to the film surface of the film, and within a predetermined angular range around the projection angle; an optical scanning unit configured to continuously vary the infrared rays so that the infrared rays scan the film; and a reflected light that receives reflected infrared light projected onto the film and outputs a reflected light signal according to the received light intensity. a light receiving section; a transmitted light spectrometer that receives the transmitted infrared light projected onto the film, separates it into at least the two wavelength components, and outputs a transmitted light signal according to the received intensity of each of the spectral lights; , receiving the reflected light signal and the transmitted light signal;
The background noise of the reflected light signal and the transmitted light signal are respectively removed, the reflected light signal is identified, the transmitted light signal at the minimum reflected light intensity is enabled, and at least the two wavelength components of the enabled signal are transmitted. An infrared thickness meter characterized by comprising a signal processing section that calculates thickness data that is the basis for quantifying film thickness based on an optical signal. 2. Claim 1, wherein the polarizer is disposed in the optical path between the optical scanning section and the film surface.
Infrared thickness gauge described in section. 3. A light source unit that intermittently generates infrared rays in a band including at least two wavelength components, a wavelength component exhibiting absorption characteristics unique to the film and a wavelength component exhibiting non-absorption characteristics, and including a polarizer that polarizes the infrared rays into P-polarized light. , The infrared rays output from the light source section are projected obliquely at a predetermined angle to the film surface of the film, and are continuously varied within a predetermined angular range around the projection angle. a light scanning unit configured to scan the infrared rays on the film; a reflected light receiving unit configured to receive the reflected infrared light projected onto the film and output a reflected light signal according to the received light intensity; The optical path of the transmitted light is changed so that the infrared rays projected onto the film pass through the film multiple times, and the absorption ability of the wavelength component exhibiting absorption characteristics specific to the film among the infrared rays transmitted through the film is enhanced. a transmitted light spectrometer that receives the transmitted infrared light projected onto the film, separates it into at least the two wavelength components, and outputs a transmitted light signal corresponding to the received intensity of each of the spectral lights. receiving the reflected light signal and the transmitted light signal;
The background noise of the reflected light signal and the transmitted light signal are respectively removed, the reflected light signal is identified, the transmitted light signal at the minimum reflected light intensity is enabled, and at least the two wavelength components of the enabled signal are transmitted. An infrared thickness meter characterized by comprising a signal processing section that calculates thickness data that is the basis for quantifying film thickness based on an optical signal. 4. A light source unit that intermittently generates infrared rays in a band including at least two wavelength components, a wavelength component exhibiting absorption characteristics unique to the film and a wavelength component exhibiting non-absorption characteristics, and including a polarizer that polarizes the infrared rays into P-polarized light. , Projects the infrared rays output from the light source section obliquely at a predetermined angle to the film running surface of the traveling film, and continuously within a predetermined angular range around the projecting angle. an optical scanning unit configured to vary the infrared rays so that the film is scanned by the infrared rays; a reflected light receiving unit that receives reflected infrared light projected onto the film and outputs a reflected light signal according to the received light intensity; a light scanning control section that automatically corrects the set projection angle according to vibrations caused by the running of the film based on the reflected light signal; a transmitted light spectrometer that separates the light into two wavelength components and outputs a transmitted light signal according to the received intensity of each of the spectral lights, and receives the reflected light signal and the transmitted light signal;
The background noise of the reflected light signal and the transmitted light signal are respectively removed, the reflected light signal is identified, the transmitted light signal at the minimum reflected light intensity is enabled, and at least the two wavelength components of the enabled signal are transmitted. An infrared thickness meter characterized by comprising a signal processing section that calculates thickness data that is the basis for quantifying film thickness based on an optical signal. 5. The infrared thickness gauge according to claim 4, wherein the optical scanning section includes a vibrating mirror, and the adjustment of the set projection angle in the optical scanning control section is performed by servo control. 6. A light source unit that intermittently generates infrared rays in a band including at least two wavelength components, a wavelength component exhibiting absorption characteristics unique to the film and a wavelength component exhibiting non-absorption characteristics, and including a polarizer that polarizes the infrared rays into P-polarized light. , The infrared rays outputted from the light source section are projected obliquely at a predetermined angle to the film running surface of the traveling film, and continuously within a predetermined angular range around the projection angle. an optical scanning unit configured to vary the infrared rays so that the film is scanned by the infrared rays; a reflected light receiving unit that receives reflected infrared light projected onto the film and outputs a reflected light signal according to the received light intensity; a transmitted light spectrometer that receives the transmitted infrared light projected onto the film, separates it into at least the two wavelength components, and outputs a transmitted light signal according to the received intensity of each of the spectral lights; and the reflected light receive the signal and the transmitted optical signal,
The background noise of the reflected light signal and the transmitted light signal are respectively removed, the reflected light signal is identified and the transmitted light signal at the minimum reflected light intensity is enabled, and at least the above two wavelength components of the enabled signal are transmitted. A signal processing section that calculates thickness data that is the basis for quantifying the film thickness based on the optical signal; Thickness data output from the signal processing section; and a predetermined thickness conversion for quantifying the true thickness of the film. An infrared thickness gauge comprising: a data processing section that calculates the thickness of a film based on a function; 7. The light source section, the light scanning section, the reflected light receiving section, and the transmitted light spectroscopic section are integrally constructed, and this integral structure is movable in the width direction of the film. Infrared thickness gauge. 8 A patent in which a sample film of the same type as the film is fixed on the same plane as the film running surface on the outside in the width direction of the film to be set and run, and the integrated structure is movable to the fixed sample film position. The infrared thickness gauge according to claim 7. 9. The infrared thickness meter according to claim 8, wherein the thickness data is automatically calibrated based on a transmitted light signal from the fixed sample film. 10. Claim 6, wherein the data processing section is provided with a storage means that stores a thickness conversion function that can uniquely quantify the true thickness of the film using the thickness data output from the signal processing section as a variable. Infrared thickness gauge described in section.