JP2010026344A - Confocal microscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a scanning confocal microscope using a Nipkow disk for accurately executing the three-dimensional shape measurement of a material to be measured at high speed. <P>SOLUTION: The confocal microscope includes: the Nipkow disk 10; a plurality of band path filters 11 through which light having a different wavelength band passes; a drive device 13 rotating the Nipkow disk 10; a rotary encoder 14 measuring the rotational displacement r of the Nipkow disk 10; a light source 15; an objective lens 18 whose focal length is changed according to the wavelength of the light and which includes axial chromatic aberration; a photodetector 20 detecting the light reflected on the material to be measured S; and a position determination section 22 determining the position of the material to be measured S, on the basis of the focusing state of the light on the material to be measured S, detected by the photodetector 20 and the rotational displacement r of the Nipkow disk 10 measured by the rotary encoder 14. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a scanning confocal microscope using a nipou disc.

2. Description of the Related Art Conventionally, a scanning confocal microscope using a nipou disc having pinholes formed in a spiral shape is known (see Patent Document 1). In the confocal microscope described in Patent Document 1, light from a light source is incident on pinholes of a Nipkow disk, and light that has passed through these pinholes is a plane conjugate with the pinhole (focusing plane) via the objective lens. ) A pinhole conjugate image is formed thereon. Then, the reflected light from the object to be measured passes through the objective lens and the pinhole of the Niipou disc again and enters the detector. When the object to be measured is on the in-focus surface, most of the reflected light from the object to be measured passes through the pinhole of the Niipou disc, but when the object to be measured is other than the in-focus surface, most of the reflected light is from the Niipou disc. Cannot pass through the pinhole. Therefore, the detector can obtain information on the in-focus surface of the object to be measured. By rotating the nippo disk, it is possible to scan the pinhole at high speed and acquire information on the in-focus surface over the entire surface of the object to be measured. Furthermore, it is possible to measure the three-dimensional shape of the object to be measured by executing the acquisition of information on the in-focus surface multiple times in the Z-axis direction (the direction perpendicular to the observation surface of the object to be measured). It is.
Japanese Patent No. 2836829

However, in order to perform the three-dimensional shape measurement of the object to be measured using the confocal microscope described in Patent Document 1, the information on the above-described focal plane is acquired in the Z-axis direction (observation surface of the object to be measured). Need to be executed multiple times. Thereby, the height position in the Z-axis direction of each measurement point of the object to be measured is determined. In order to perform multiple measurements in the Z-axis direction, the measuring device including the objective lens, nipou disk, etc., or the object to be measured must be moved in the Z-axis direction, which is affected by mechanical scanning accuracy. As a result, the accuracy of measurement may be reduced.
In addition, since the measurement is performed a plurality of times in the Z-axis direction, there is a problem that the time required for the process for obtaining the position of the measurement point of the object to be measured is greatly increased.

  The present invention has been made in view of the above problems, and provides a scanning confocal microscope using a nipou disk capable of measuring a three-dimensional shape of an object to be measured quickly and accurately. For the purpose.

  A confocal microscope according to an aspect of the present invention includes a nippo disk having a plurality of pinholes arranged in a predetermined manner and a plurality of nippo disks that are provided in a plurality of predetermined regions on the nippo disk and transmit light of different wavelength bands. A band-pass filter, a driving device for rotating the nipou disc to scan a plurality of points on the object to be measured, a rotary encoder for measuring the rotational displacement of the nipou disc, and the plurality of bandpass for illuminating the nipou disc A light source that emits light including the transmission band of the filter, and axial chromatic aberration that is provided so as to converge and guide the light that has passed through the pinhole onto the object to be measured, the focal length of which varies according to the wavelength of the light And an objective lens having a light source, and light reflected on the object to be measured are detected via the objective lens and the Nipkow disk. The position of the object to be measured is determined based on a light detector, a focused state of light on the object to be measured detected by the light detector, and a rotational displacement of the nipo disk measured by the rotary encoder. And a position determination unit for determining.

  A confocal microscope according to another aspect of the present invention is provided in a plurality of regions on a Niipou disc having a plurality of pinholes arranged in a predetermined manner and a plurality of areas on the Niipou disc arranged in the rotation direction of the Niipou disc. A plurality of band-pass filters that transmit light in a wavelength band; a drive device that rotates the nippo disk; a light source that emits light including transmission bands of the plurality of band-pass filters that illuminate the nippo disk; An objective lens having on-axis chromatic aberration that converges light passing through the pinhole on the object to be measured, and light reflected on the object to be detected through the object lens and the Niipou disk And detected by the photodetector for each of a plurality of regions of the Nipkow disk. Serial characterized by comprising a processing unit for generating a three-dimensional shape data of the object to be measured by combining the image data by the reflected light from the object to be measured.

According to the confocal microscope according to the above configuration, the wavelength of the light passing through the pinhole of the nippo disk can be changed by rotating the nipou disk provided with the band-pass filter that transmits light of different wavelengths. Since the objective lens is provided with axial chromatic aberration, the in-focus position changes according to the wavelength. Thereby, a plurality of images at different focal positions can be acquired by rotation of the Nipo disk. Therefore, it is possible to measure the three-dimensional shape of the measurement object without moving the measurement apparatus including the objective lens, the nippo disk, or the like or the measurement object in the Z-axis direction.
ADVANTAGE OF THE INVENTION According to this invention, the scanning confocal microscope using the nipou disk which can perform the three-dimensional shape measurement of a to-be-measured object rapidly and correctly can be provided.

  Hereinafter, a confocal microscope according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[First Embodiment]
(Configuration of the confocal microscope according to the first embodiment)
FIG. 1 shows a basic configuration of a confocal microscope according to an embodiment of the present invention. As shown in FIG. 1, the confocal microscope includes a nipou disk 10, a band-pass filter 11 disposed on the nipou disk 10, a drive device 13 that rotationally drives the nipou disk 10, and a rotary encoder 14 that detects the rotation angle of the nipou disk 10. Prepare. The confocal microscope includes a light source 15 that irradiates light to the object S to be measured, an optical system such as a lens 16, a beam splitter 17, an objective lens 18, and a relay lens 19, a photodetector 20, and A / D conversion. And a signal processing system such as a position determination unit 22.

  As shown in FIG. 2, the Nipkow disk 10 is provided with a plurality of pinholes 12 spirally from the center of the disk-shaped disk to the outer periphery. In the spiral pinhole row, the pinholes 12 are arranged apart from each other by a predetermined interval, and the plurality of pinhole rows are arranged at predetermined intervals in the radial direction of the Niipou disc 10.

  The band-pass filter 11 is provided on the Nipkow disk 10 and transmits light having a specific wavelength, and reflects light having a shorter wavelength and light having a longer wavelength than the specific wavelength. In this embodiment, as shown in FIG. 2, the Niipou disc 10 is divided into six regions R1 to R6 in a fan shape, and each region R1 to R6 is provided with a bandpass filter 11 having different transmission band characteristics. Yes. FIG. 3 is a graph showing the transmission band characteristics of the bandpass filter 11 provided in the regions R1 to R6. As shown in FIG. 3, the bandpass filters 11 provided in the regions R1 to R6 respectively transmit light having different wavelengths λ1 to λ6.

  The drive device 13 is connected to a motor (not shown), and rotates the Nipou disc 10 provided with the pinhole 12. Since the Niipou disc 10 is provided with a plurality of pinholes 12 in a spiral shape, a plurality of measurement points on the object to be measured S can be scanned in a plane by being rotated. When the Niipou disc 10 in the present embodiment is rotated by one region R (60 °), an image of one screen of the object S to be measured can be formed. Therefore, by rotating the nipou disc 10 once by the drive device 13, it is possible to acquire images of the six objects to be measured S in the regions R1 to R6 of the nipou disc 10.

  The rotary encoder 14 measures the rotational displacement of the nipou disk 10 rotated by the driving device 13. The rotary encoder 14 is used to control exposure to the photodetector 20 (to be described later) and storage of the acquired image based on the measured rotational displacement of the nippo disk 10, and detects the absolute rotation angle of the nipou disk 10. You need to be able to do it. Therefore, for example, an absolute rotary encoder or an incremental rotary encoder having an origin can be used.

  The light source 15 is a light source that emits light having a wavelength band wider than the maximum wavelength λ6 and the minimum wavelength λ1 of light transmitted through the plurality of bandpass filters 11, and a white light source such as a halogen lamp can be used, for example. . The light emitted from the light source 15 is converted into parallel light by the lens 16, and then illuminated on the Nipkow disk 10 through the beam splitter 17 and passes through the pinhole 12.

  The objective lens 18 is provided so that the light passing through the pinhole 12 is converged and guided onto the object S to be measured. The objective lens 18 is a lens in which the axial chromatic aberration is positively increased so that the focal length varies greatly depending on the wavelength of light passing therethrough. FIG. 4 is a diagram illustrating the function of the objective lens 18. As shown in FIG. 4, when the wavelengths of the light from the light source 15 that has passed through the Niipou disc 10 provided with the bandpass filter 11 are wavelengths λ1, λ2, and λ3 (λ1 <λ2 <λ3), the pinhole 12 The imaging positions of the images are h1, h2, and h3, respectively. Here, the image formation position h6 of the image of the pinhole 12 when the wavelength of the light transmitted through the bandpass filter 11 is the maximum wavelength λ6, and the image formation of the image of the pinhole 12 when the wavelength is the minimum wavelength λ1 The axial chromatic aberration of the objective lens 18 is determined so that the distance from the position h1 is equal to or greater than the measurement range of the object S to be measured.

  As shown in FIG. 1, the light reflected by the surface of the object S to be measured is incident again on the objective lens 18 and converged, and passes through the pinhole 12 of the Niipou disc 10. Then, it passes through the beam splitter 17, is converged by the relay lens 19, and enters the photodetector 20. The photodetector 20 has a CCD camera arranged at the focal position of the relay lens 19, and the incident light to the photodetector 20 when the image of the pinhole 12 is formed on the object S to be measured. Is set to maximize the amount of light. The photodetector 20 outputs the captured image to the A / D converter 21 as a detection signal Da.

  The detection signal Da from the photodetector 20 is converted into a digital signal Dd by the A / D converter 21 and input to the position determination unit 22. The position determination unit 22 determines the image formation state of the image of the pinhole 12 on the measurement object S based on the digital signal Dd. At the time when the image of the pinhole 12 is focused on the object S to be measured, the wavelength λ of the light transmitted through the bandpass filter 11 is obtained from the rotational displacement r of the Niipou disc 10 measured by the rotary encoder 14. The position determination unit 22 then measures the object when the image of the pinhole 12 is focused on the object S due to the wavelength λ of the light transmitted through the bandpass filter 11 and the axial chromatic aberration of the objective lens 18. The position of S is determined. Further, the arithmetic processing unit including the position determination unit 22 generates the three-dimensional shape data of the object S to be measured from the determination result.

(Operation of the confocal microscope according to the first embodiment)
Next, the operation of the confocal microscope shown in FIG. 1 will be described with reference to FIGS.

  The drive device 13 rotates the Nipkow disc 10 with the start of the measurement operation by the confocal microscope. The illumination light quantity of the light source 15 is adjusted so that the measured object S is reflected on the photodetector 20. The rotary encoder 14 provided on the Niipou disc 10 measures the rotational displacement r of the Niipou disc 10 during the measurement operation. The confocal microscope controls the electronic shutter of the photodetector 20 in accordance with the switching of the region R of the Niipou disc 10 based on the rotational displacement r of the Niipou disc 10. As a result, the photodetector 20 acquires one image exposed in one region R. When the amount of light incident on the photodetector 20 is weak, the image can be taken a plurality of times in the same region R, and this image can be added by the position determination unit 22 to increase the luminance.

  Here, a plurality of band-pass filters 11 are provided on the Niipou disc 10, and each band-pass filter 11 transmits light in the wavelength band shown in FIG. 3 as described above. Since the wavelength λ passing through the pinhole 12 is different in each of the regions R1 to R6 of the Nipkow disc 10, the detection signal Da detected by the photodetector 20 has a peak at any wavelength λ as shown in FIG. . That is, as shown in FIGS. 6A to 6C, when the object to be measured S is at an unknown position hf, when the wavelength λ of the light transmitted through the bandpass filter 11 changes due to the rotation of the Niipou disc 10, When transmitting a specific wavelength λf (for example, λ4), the image of the pinhole 12 is focused on the measurement object S, and the amount of light received by the photodetector 20 is maximized. When light of other wavelengths is transmitted, all are out of focus, and the amount of light received by the photodetector 20 is small.

  If the position of the measurement point of the object to be measured S is different from the position hf, the wavelength λ when the image of the pinhole 12 is focused on the object to be measured S is also different from the above λf. . The wavelength λ at which this in-focus is obtained and the position h of the object S to be measured are in a correspondence relationship based on the characteristics of the longitudinal chromatic aberration of the objective lens 18. Can be detected. Here, the wavelength λ can be obtained from the rotation angle r of the Niipou disc 10 measured by the rotary encoder 14. For example, when the rotation angle from the reference angle is in the range of r1 to r2, it is assumed that the light of wavelength λ1 is transmitted by the bandpass filter 11 provided in the region R1 of the Niipou disc 10. Then, for example, a table storing the correspondence relationship between the wavelength λ and the position h as shown in FIG. That is, the position in the Z-axis direction of the focal point on the measurement object S when the light of wavelength λi is transmitted is hi. As a result, the photodetector 20 detects six images at different focal positions by one rotation of the Niipou disc 10. In the above table, it is desirable that the intensity correction is performed in advance in consideration of the difference in intensity characteristics and sensitivity characteristics of the light source 15 and the photodetector 20 in each region (wavelength). Instead of providing a table, a program for calculating the position h of the object S to be measured by a function expressing the correspondence may be provided.

  Based on the height position h of each measurement point of the measured object S obtained in this way, three-dimensional shape data of the measured object S can be generated.

(Effect of the confocal microscope according to the first embodiment)
As described above, the confocal microscope according to the present embodiment rotates the nippo disk 10 provided with the band-pass filter 11 that transmits light in different wavelength bands, so that the light passing through the pinhole 12 of the nipou disk 10 is transmitted. The wavelength can be changed. The wavelength λ when the light passing through the pinhole 12 of the Niipou disc 10 is focused on the object S to be measured and the position h of the object to be measured have a correspondence relationship based on the characteristics of the longitudinal chromatic aberration of the objective lens 18. Therefore, the position h of the object to be measured can be detected from the wavelength λ of the light transmitted through the Niipou disk 10. In the confocal microscope according to the present embodiment, the three-dimensional shape measurement of the measuring object S can be performed without moving the measuring apparatus including the objective lens 18, the Niipou disk 10, or the like or the measuring object S in the Z-axis direction. it can. For this reason, there is no possibility that the measurement accuracy is lowered due to the influence of the mechanical scanning accuracy. Further, it is not necessary to perform the measurement a plurality of times in the Z-axis direction, and the time required for the process for obtaining the position of the measurement point of the object S to be measured can be shortened.

  According to the confocal microscope according to the present embodiment, the three-dimensional shape measurement of the object to be measured S can be executed at high speed and accurately.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to these, A various change, addition, a combination, etc. are possible within the range which does not deviate from the meaning of invention. For example, in the confocal microscope according to the embodiment of the present invention, the nipou disk 10 is divided into six regions and the band pass filters 11 that transmit light of different wavelengths are provided. It is not limited to six, and can be divided into more regions. The number of regions that can be divided is determined by the range of wavelengths included in the light emitted from the light source 15 and the range of wavelengths of light transmitted through the bandpass filter 11.

  In addition, the measurement range in the Z-axis direction of the object to be measured S that does not require mechanical movement of the confocal microscope is the maximum wavelength and the minimum wavelength of light transmitted through the plurality of bandpass filters 11 and the axis of the objective lens 18. It is determined by the magnitude of the upper chromatic aberration. When the range of the maximum wavelength and the minimum wavelength of light transmitted through the band-pass filter 11 is narrow, measurement in a wide range in the Z-axis direction is possible by combining with the movement in the Z-axis direction. When the range of the maximum wavelength and the minimum wavelength of the light transmitted through the bandpass filter 11 is widened, the shape measurement is roughly performed, but it is possible to overview a wide range in the Z-axis direction. In this case as well, a detailed shape measurement of the object S can be performed by combining with movement in the Z-axis direction.

  When the band-pass filter 11 having a narrow transmission wavelength region is used, the measurement accuracy at the height position of the object S to be measured is improved, but the amount of light obtained by the photodetector 20 is reduced. Further, the intensity according to the wavelength of the light source 15 is not always constant. Therefore, the position determination unit 22 can adjust a signal obtained by performing processing such as multiplying the count according to the region R of the nippo disk 10 or changing the number of additions.

It is a figure which shows the structure of the confocal microscope which concerns on embodiment of this invention. It is a figure which shows the Niipou disc of the confocal microscope which concerns on embodiment of this invention. It is a graph which shows the wavelength of the light which the band pass filter of the confocal microscope which concerns on embodiment of this invention permeate | transmits. It is a figure explaining the function of the objective lens of the confocal microscope which concerns on embodiment of this invention. It is a figure explaining operation | movement of the confocal microscope which concerns on embodiment of this invention. It is a figure explaining operation | movement of the confocal microscope which concerns on embodiment of this invention. It is a figure explaining operation | movement of the confocal microscope which concerns on embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Nipou disc, 11 ... Band pass filter, 12 ... Pinhole, 13 ... Drive device, 14 ... Rotary encoder, 15 ... Light source, 16 ... Lens, 17 ... Beam splitter, 18 ... objective lens, 19 ... relay lens, 20 ... photodetector, 21 ... A / D converter, 22 ... position determination unit, S ... measured object.

Claims (5)

A nipou disc having a plurality of pinholes arranged in a predetermined manner;
A plurality of band-pass filters that are provided in a plurality of predetermined regions on the Nipou disc and transmit light of different wavelength bands;
A driving device for rotating the Niipou disc to scan a plurality of points on the object to be measured;
A rotary encoder for measuring the rotational displacement of the Niipou disk;
A light source that emits light including transmission bands of the plurality of band-pass filters that illuminate the Niipou disc;
An objective lens having an axial chromatic aberration that is provided so as to converge and guide the light that has passed through the pinhole onto the object to be measured, the focal length of which varies according to the wavelength of the light;
A photodetector for detecting the light reflected on the object to be measured through the objective lens and the nipou disc;
A position determination unit that determines the position of the object to be measured based on the focused state of light on the object to be measured detected by the photodetector and the rotational displacement of the Niipou disc measured by the rotary encoder. A confocal microscope comprising: and. The position determination unit is configured to determine the optical axis of the in-focus position of the object to be measured from the in-focus position of the light on the object to be measured and the transmission wavelength of the band-pass filter specified by the rotational displacement of the Nipkow disk. The confocal microscope according to claim 1, wherein a position in a direction is determined. 2. The confocal microscope according to claim 1, wherein the photodetector captures an image for each predetermined region of the Niipou disc based on a rotational displacement of the Niipou disc measured by the rotary encoder. The confocal microscope according to claim 1, wherein the plurality of band-pass filters are provided in each of a plurality of fan-shaped regions divided in a rotation direction on the nipou disc. A nipou disc having a plurality of pinholes arranged in a predetermined manner;
A plurality of band-pass filters that are provided in a plurality of regions on the nipou disk arranged in the rotation direction of the nipou disk and transmit light of different wavelength bands;
A driving device for rotating the nipou disk;
A light source that emits light including transmission bands of the plurality of band-pass filters that illuminate the Niipou disc;
An objective lens having on-axis chromatic aberration for converging on the object to be measured, the light irradiated from the light source to the Niipou disk and passing through the pinhole;
A photodetector for detecting the light reflected on the object to be measured through the objective lens and the nipou disc;
An arithmetic processing unit that synthesizes image data of reflected light from the measurement object detected by the photodetector for each of a plurality of areas of the Nipkow disk and generates three-dimensional shape data of the measurement object. A confocal microscope characterized by this.

Images