JP3390106B2 - Optical microscope with automatic focusing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, when a sample is set in the focus of a microscope and moved horizontally for observation, automatically follows the unevenness of the sample so that it is always in focus. The present invention relates to an optical microscope equipped with a focusing device.

[0002]

2. Description of the Related Art FIG. 6 is a schematic structural layout diagram for explaining the prior art of an optical microscope equipped with an automatic focusing device.
In FIG. 6, 62 is a sample to be observed with an optical microscope, 61
Is a sample table on which the sample 62 is placed, 63 is an objective lens forming an optical microscope, 64 is an image forming lens forming the optical microscope, 65 is an image forming surface position of the image forming lens 64, 66
Is a drive mechanism unit for moving the sample table 61 up and down, 67
Is a half mirror provided in the optical path of the optical microscope, 68
Is a focusing lens for focusing the light reflected by the half mirror 67, 70 is a photoelectric conversion element provided at a position in front of the focusing surface of the focusing lens 68 for focusing, and 69 is a focusing lens. A half mirror provided in the optical path of the focusing imaging lens 68,
Reference numeral 71 denotes a photoelectric conversion element provided at a rear pin position from the image plane surface position of the focusing lens 68 for reflection, which is reflected by the half mirror 69.

A plurality of examples of an optical microscope equipped with an automatic focusing device according to the prior art will be described with reference to FIG. The optical microscope sets the sample 62 mounted on the sample table 61 at the focal position of the objective lens 63, forms a desired optical image of the sample 62 on the image forming surface position 65 by the image forming lens 64, and observes it. . In such an optical microscope, a photoelectric conversion device, for example, a television camera (not shown) is arranged at the image forming plane position 65 by the image forming lens 64, and the television camera
A video signal obtained by capturing a desired optical image of the sample 62 is output.
A video signal output from the television camera is input to, for example, a process device (not shown), a differential component is detected, and an output corresponding to the differential component moves the sample stage 61 up and down from the process device. It is output to the unit 66. The drive mechanism unit 66 adjusts the sample 6 according to the detected output so that the differential component detected by the process device has the maximum output.
There is an optical microscope equipped with an automatic focusing device having means for vertically driving a sample table 61 on which the sample No. 2 is mounted and controlling the relative distance between the sample 62 and the objective lens 63 to be in focus.

However, the optical microscope equipped with the above-described automatic focusing device detects the differential component of the video signal photoelectrically converted by the photoelectric conversion device arranged at the image plane 65 of the optical microscope. Therefore, focusing cannot be performed unless a differential component is detected from the image signal when focusing is performed, and the focusing has a step or a change in brightness on the sample 62.
It will be limited to the sample 62 having a clear contour. However, since the sample 62 has steps and changes in luminance and the contour is not always clear, the contour is used as a means (not shown) for compensating for the drawback of the optical microscope equipped with the automatic focusing device. An optical microscope equipped with an automatic focusing device having means for projecting a pattern having a change in luminance, always forming a pseudo contour, and detecting a differential component from a video signal including the pseudo contour on a sample 62 whose is there.

The optical microscope equipped with the automatic focusing device detects one differential component on the optical axis direction of the optical microscope at a time. The differential components at a plurality of points along the optical axis are the sample table 6
1 can be obtained by moving 1 in the optical axis direction by the drive unit 66.
This is an optical microscope equipped with an automatic focusing device having means for controlling the relative distance between the sample 62 having the maximum differential component and the objective lens 63 among the obtained plural differential components as the focusing position. Therefore, it takes a detection time and a driving time to examine the differential components of a plurality of points in the optical axis direction, and there is a problem that a quick focus detection cannot be performed.

Further, an optical microscope equipped with an automatic focusing device having means for detecting a focusing direction according to the prior art will be described with reference to FIG. A half mirror 67 is installed in the optical path of the optical microscope, specifically, in the optical path from the objective lens 63 to the imaging lens 64, and the reflected light from the half mirror 67 is imaged by the focusing lens 68. A photoelectric conversion element 70 is provided as a front pin sensor at a position in front of the image forming surface of the focusing lens 68 for focusing, and a half mirror 69 is installed in the optical path from the focusing lens 68 for focusing to the photoelectric conversion element 70. A photoelectric conversion element 71 is provided as a rear pin sensor at a rear pin position from the image plane position of the focusing lens 68 which is reflected by the half mirror 69.

Photoelectric conversion elements 70 and 71 are arranged in front of and behind the image plane surface of the focusing lens 68, respectively, to obtain a front pin signal and a rear pin signal as shown in FIG. There is an optical microscope equipped with an automatic focusing device that drives the driving mechanism unit 66 accordingly and moves the sample table 61 up and down to obtain the focusing position. It is a means to set the optical axis direction distance where the differential component output of the front focus signal and the rear focus signal are the same as the focal point position, and since the image formation at the front focus position and the rear focus position is both out of focus and blurred. , Is generally called the bokeh method.

[0008]

In the optical microscope equipped with the automatic focusing device according to the prior art, the former prior art detects the differential component from the image signal of the portion of the sample desired to be observed so as to achieve the in-focus point. However, there is a problem that it takes time because it is controlled accurately. Further, in the conventional technique of projecting a pattern on a sample, there is a problem that the contour of the sample and the contour of the projected pattern interfere with each other and adversely affect the observation. The latter conventional technique has a problem that it is impossible to perform complete control on a sample having a complicated shape because the control is performed by the front pin and the rear pin, which is the control of two points on the optical axis. In order to solve the above-mentioned problems, the present invention is directed to a line sensor in which a laser spot light from a laser diode or the like is projected onto the surface of a sample, and the laser light reflected from the sample is inclined from the optical axis via a half mirror. It is an object of the present invention to provide an optical microscope equipped with an automatic focusing device capable of forming an image on a plate, detecting the amount of light, and adapting to a sample having irregularities.

[0009]

In order to achieve the above object, an optical microscope equipped with an automatic focusing device of the present invention comprises at least an objective lens provided so as to focus on a sample to be observed, An optical microscope including an imaging lens provided so as to connect an image of light from an objective lens to a predetermined imaging plane position, and at least the sample can be placed and moved in a horizontal direction and a vertical direction. In the optical microscope equipped with an automatic focusing device including a sample stage and a drive mechanism section that vertically moves the sample stage according to an input focus detection signal, the sample placed on the sample stage A means for projecting a laser beam on the optical axis, a half mirror provided in the optical path of the optical microscope for reflecting the laser beam reflected from the sample, and an image of the reflected light from the half mirror for forming an image on the objective lens. focus A focusing lens connected to a conjugate position, a line sensor including a plurality of photoelectric conversion elements provided at a required tilt with respect to an optical axis at an imaging point of the focusing lens, and the focusing lens. A reflecting mirror which is provided in the optical path of the imaging lens and rotates at a constant period, and detects a position on the line sensor where the incident light becomes maximum due to the turning of the reflecting mirror, and the position on the line sensor is detected. The difference between the optical path length to the position and the optical path length to the preset focus position is obtained as a focus detection signal, and the sample table is moved in the vertical direction by the focus detection signal.

Further, in the optical microscope equipped with the automatic focusing device of the present invention, the line sensor has means for changing the inclination with respect to the optical axis in accordance with the switching of the magnification of the objective lens,
The focus detection signal suitable for the magnification of the switched objective lens is obtained, and the sample stage is moved in the vertical direction. Also,
An optical microscope equipped with an automatic focusing device according to the present invention has a means for projecting a laser beam onto a sample, at least a laser emission source, and a beam expander for expanding the luminous flux of the laser beam emitted by the laser emission source. , And a half mirror provided in the optical path of the optical microscope so as to project the enlarged laser beam onto the sample.

[0011]

The optical microscope equipped with the automatic focusing device according to the present invention includes at least an objective lens provided so as to focus on a sample to be observed, and a light from the objective lens is imaged at a predetermined image plane position. Is an optical microscope including an imaging lens provided so as to be connected to, and at least a sample stage on which the sample is placed and movable in the horizontal direction and the vertical direction, and in accordance with an input focus detection signal. An optical microscope equipped with an automatic focusing device comprising a drive mechanism section for moving the sample table in a vertical direction, wherein a laser beam is projected by means for projecting a laser beam onto a sample placed on the sample table. , A laser beam reflected from the sample is reflected by a half mirror provided in the optical path of the optical microscope, and a plurality of photoelectric conversion elements are provided at a conjugate position with the focus of the objective lens and provided at a required inclination with respect to the optical axis. Na By forming an image of the reflected light from the half mirror on the line sensor with the focusing lens for focusing through a reflecting mirror that rotates in a constant cycle provided in the optical path of the focusing lens for focusing. , Detecting the position on the line sensor where the incident light is maximized by the rotation of the reflecting mirror, and obtaining the difference between the optical path length to the position on the line sensor and the optical path length to the preset focus position. The focus detection signal is used, and the sample stage is moved in the vertical direction by the focus detection signal.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic configuration layout diagram of an optical microscope including an automatic focusing device according to the present invention. In FIG.
Reference numeral 2 is a sample to be observed with an optical microscope, 1 is a sample table on which the sample 2 is placed and is movable in horizontal and vertical directions, 3 is an objective lens which constitutes the optical microscope, and 4 is a result which constitutes the optical microscope. The image lenses 5 are the image plane positions of the image forming lens 4, and 6
Is a drive mechanism section for moving the sample table 1 up and down according to the input focus detection signal, 7 is a half mirror provided in the optical path of the optical microscope, and 8 is a unit for connecting the light reflected by the half mirror 7. An imaging lens for focusing, 9 is a reflecting mirror provided in the optical path of the imaging lens for focusing 8, which rotates at a constant cycle, and 10 is an image plane position of the imaging lens for focusing 8. A line sensor composed of a plurality of photoelectric conversion elements, a laser diode 11 and a beam expander 12 that expands the luminous flux of the laser light emitted by the laser diode 11.
Reference numeral 13 denotes a half mirror that reflects the laser light that has been enlarged and projected by the beam expander 12.

An optical microscope equipped with an automatic focusing device according to the present invention will be described with reference to FIG. The optical microscope sets the sample 2 mounted on the sample table 1 at the focal position of the objective lens 3, forms a desired optical image of the sample 2 on the image forming surface position 5 by the image forming lens 4, and forms an image. For example, a television camera (not shown) is arranged at the surface position 5 for observation. The laser light emitted from, for example, the laser diode 11, which is a light emission source of the laser light, is expanded in the luminous flux by the beam expander 12. The laser light whose luminous flux has been expanded is reflected by the half mirror 13.
The light is reflected by the laser beam, is condensed by the objective lens 3, and becomes a spot of laser light, which is projected on the surface of the sample 2.

The laser light projected on the surface of the sample 2 is reflected by the surface of the sample 2, passes through the objective lens 3 and the half mirror 13, and is reflected by the half mirror 7 to the focusing lens 8 for focusing. The laser light reflected by the half mirror 7 enters the focusing lens 8 for focusing, is reflected by the reflecting mirror 9 which rotates at a constant cycle, and is provided at the image plane position of the focusing lens 8 for focusing. Is projected onto the line sensor 10. In addition,
The center of the line sensor 10 is located at a position conjugate with the surface of the sample 2 with respect to the focusing lens 8 and the objective lens 3, and the line sensor 10 has a required inclination with respect to the optical axis of the optical microscope. It is arranged to have a value.

A further explanation will be given using the operation explanatory view of the reflecting mirror and the line sensor which rotate at a constant cycle shown in FIG. In FIG. 2, when the reflecting mirror 9 that rotates at a constant period is at the position shown by the solid line, the light incident from the focusing lens 8 is reflected by the reflecting mirror 9 and passes through the optical path P-Lo. Further, when the reflecting mirror 9 that rotates at a constant period is located at the position shown by the dotted line, the light incident from the focusing lens 8 is reflected by the reflecting mirror 9 and passes through the optical path P-Ln. Therefore, the light that has passed through the optical path P-Lo is not detected by the line sensor 10
The light that has entered the 0th element of the line sensor and has passed through the optical path P-Ln enters the nth element of the line sensor 10.

In this way, the reflecting mirror 9 rotates by the angle θ at a constant cycle, so that the difference in optical path length ΔZ = PLo-PLn (1) within ΔZ. , The focus position in the optical axis direction can be determined. In the present embodiment, when the incident light of the central element of the line sensor 10 has the maximum intensity as compared with the incident light of the other elements, it is set as the in-focus image forming position. The luminance distribution has the characteristics of J shown in FIG. When the distance between the objective lens 3 and the sample 2 becomes short, the characteristic of n in FIG. 3 and the characteristic of f in FIG. Therefore,
When the characteristic is n, the sample 2 is driven in a direction away from the objective lens 3, and when the characteristic is f, the sample 2 is driven in a direction closer to the objective lens 3, whereby the automatic focusing can be controlled. That is, ΔZ shown in the equation (1) is the range in which the focus can be detected, and ΔZ can be increased by increasing the inclination value of the line sensor 10. But,
When the inclination value of the line sensor 10 is increased, the amount of light received by the elements of the line sensor 10 decreases.

The objective lens 3 can be magnified by, for example, 5 times, 10 times, 20 times, 50 times, and 100 times by switching a plurality of objective lenses by an electric revolver of a rotary magnification changing mechanism. However, when switching is performed, automatic focusing at all magnifications with different depths of focus is required. For example, when the objective lens 3 has a magnification of 5, ΔZ shown in the equation (1) needs to be large and the amount of light needs to be small. When the objective lens 3 has a magnification of 100, ΔZ has to be small and the amount of light increases. Since it is necessary to increase the inclination value of the line sensor 10 when the magnification is 5 times (low magnification) and decrease the inclination value of the line sensor 10 when the magnification is 100 times (high magnification), automatic adjustment is performed at all magnifications. Focusing is possible.

Further, as shown in FIG. 4, when the spot of the laser light is projected on the contour portion 2a of the sample 2, the laser light is diffusely reflected and the maximum light amount = focus position as shown in FIG. However, there are cases where there are two or more peaks representing the brightness as shown in FIG. 5, but in such a case, if the maximum brightness point is set as the focus position, malfunction occurs. Therefore, in the optical microscope equipped with the automatic focusing device of the present invention, the sum S of the luminances V of all the elements of the line sensor 10 is obtained to prevent malfunction, and the luminance of the line sensor 10 is again set to k = 0,
By adding 1 and 2, all element positions X of the line sensor 10 that reach the (S / 2) value are obtained, and it is assumed that X = focal position. That is, the sum of the brightness V of all elements of the line sensor Seeking The position of X at which is assumed to be the focus position. According to the optical microscope provided with the automatic focusing device according to the present invention, it is possible to obtain a high-speed and high-precision focusing point.

[0019]

According to the present invention, a laser spot light from a laser diode or the like is projected onto the surface of a sample, and the laser light reflected from the sample is placed on a line sensor which is inclined from the optical axis through a half mirror. It is possible to provide an optical microscope equipped with an automatic focusing device capable of forming an image and detecting the amount of light to deal with a sample having irregularities.

[Brief description of drawings]

FIG. 1 is a schematic configuration layout diagram of an optical microscope including an automatic focusing device according to the present invention.

FIG. 2 is an operation explanatory view of a reflecting mirror and a line sensor which rotate in a constant cycle of an optical microscope including an automatic focusing device according to the present invention.

FIG. 3 is an output waveform diagram of a line sensor of an optical microscope equipped with an automatic focusing device according to the present invention.

FIG. 4 is a diagram illustrating a reflection state of laser light projected on a sample to be observed.

FIG. 5 is an output waveform diagram when the reflected light of the laser light shown in FIG. 4 is detected by a line sensor.

FIG. 6 is a schematic configuration layout diagram for explaining an optical microscope including a conventional automatic focusing device.

FIG. 7 is an output waveform diagram for explaining a conventional technique of an optical microscope including an automatic focusing device.

[Explanation of symbols]

1, 61 ... Sample stage, 2, 62 ... Sample, 3, 63 ... Objective lens, 4, 64 ... Imaging lens, 5, 65 ... Imaging plane position,
6, 66 ... Driving mechanism section, 7, 13, 67, 69 ... Half mirror, 8, 68 ... Focusing imaging lens, 9 ... Reflecting mirror,
10 ... Line sensor, 11 ... Laser diode, 12 ...
Beam expander, 70, 71 ... Photoelectric conversion element.

Continuation of front page (56) Reference JP-A-8-21961 (JP, A) JP-A-62-909 (JP, A) JP-A-7-104178 (JP, A) JP-A-6-294924 (JP , A) JP 64-55513 (JP, A) JP 7-72378 (JP, A) JP 53-50851 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) G02B 7/02-7/16 G02B 7/28-7/40 G02B 21/00 G02B 21/06-21/36

Claims (3)

(57) [Claims] 1. At least an objective lens provided so as to focus on a sample to be observed, and an imaging lens provided so as to connect an image of light from the objective lens to a predetermined image plane position. An optical microscope provided with at least a sample stage on which the sample is placed and movable in the horizontal and vertical directions, and a drive mechanism for moving the sample stage in the vertical direction according to an input focus detection signal. In an optical microscope equipped with an automatic focusing device consisting of a unit, means for projecting a laser beam onto a sample placed on the sample table, and an optical path of the optical microscope for reflecting a laser beam reflected from the sample. At a half mirror provided inside, an image forming lens for focusing that connects the image of reflected light from the half mirror to a conjugate position with the focus of the objective lens, and an image forming point of the image forming lens for focusing. On the optical axis And a line sensor composed of a plurality of photoelectric conversion elements provided with a required inclination, and a reflecting mirror that rotates in a constant cycle provided in the optical path of the focusing lens, and the rotation of the reflecting mirror Detects the position on the line sensor where the incident light is maximum, and obtains the difference between the optical path length up to the position on the line sensor and the optical path length up to the preset focus position as a focus detection signal, An optical microscope equipped with an automatic focusing device, characterized in that the sample stage is moved in a vertical direction by a focusing detection signal. 2. The line sensor according to claim 1, wherein the line sensor has means for changing a tilt with respect to the optical axis according to switching of the magnification of the objective lens, and focus detection suitable for the magnification of the switched objective lens. An optical microscope equipped with an automatic focusing device, characterized in that it obtains a signal and moves the sample stage in a vertical direction. 3. The device according to claim 1, wherein the means for projecting the laser light onto the sample is at least a laser emission source, and a beam expander for expanding the emission flux of the laser light emitted by the laser emission source. An optical microscope having an automatic focusing device, comprising: a half mirror provided in the optical path of the optical microscope so as to project the magnified laser beam onto a sample.