JPS63199310A - Method and apparatus for contactless automatic multi-point focus positioning - Google Patents

Abstract

PURPOSE:To attain focus positioning without moving an object in the horizontal direction by allowing a distance between each objective portion among plural ones set up on the surface of the object and an objective lens to coincide with the focal distance of the objective lens by a focus positioning mechanism. CONSTITUTION:Polarized He-Ne laser beams to be respective measuring light beams selectively radiated from laser mechanisms 1X-1Z are reflected to prescribed angle directions by respective 1st mirrors 2X-2Z so as to be projected to respective objective portions X-Z set up on the surface of the object 10. Respectively reflected measuring light beams are reflected by the 2nd mirror 3, refracted by an objective lens 4 so as to be projected to the object, reflected by the object, and refracted again by the objective lens 4 to form the images of respective measuring light beams 11 on respective optical axis 14X-14Z by an image forming lens 5. Respective measuring light beams 11 through the lens 5 are received by respective corresponding optical position detectors 8X-8Z and a distance L between each objective portion and the objective lens 4 is allowed to coincide with the focal distance F of the objective lens in each objective portion in accordance with each position signal generated at the time of receiving the beams by positions other than the centers 18X-18Z of the sensors 8X-8Z.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a non-contact multi-point automatic focus positioning method and apparatus using a polarized He--Ne laser beam as a measurement light beam.

<Prior Art> Optically and non-contact focusing on objects having various sizes, shapes, and physical properties is a technically difficult problem. However, since there are so many uses for this non-contact focusing technology, it is still a subject that many scholars are researching.

For example, the main applications of this non-contact focusing technology are as follows.

■ Move the objective lens to focus,
Moreover, if the objective lens is used as it is as an objective lens for optical instruments such as a microscope or a telescope, automatic focusing of these optical instruments can be performed.

■ If the objective lens is moved to focus, and the amount of movement of the objective lens is quantified using an encoder, etc., the distance from the object to the objective lens can be measured without contact. It can also be applied as a non-contact sensor for three-dimensional measuring instruments, and automatic displacement measurement of liquid surfaces.

- Since the position (distance) of objects can be adjusted, various parts (objects) can be positioned and installed at predetermined positions accurately and quickly.

■ If you perform the above position (distance) alignment at multiple points on one part (object) at the same time, you can accurately set the inclination (verticality) of that part.

■ A transparent body is interposed between the reflective object (object) and the objective lens, and the thickness of the transparent body is measured without contact based on the amount of movement of the objective lens at that time and the refractive index of the transparent body. can do.

As a result of many years of intensive research into technical issues related to the usefulness of fluorine, the present inventor has developed a non-contact automatic positioning device (Japanese Patent Application No. 60-214).
773)).

<Problem to be solved by the invention> □However, the above proposal is for focusing only on one location on the object, and the focus targets (target locations) at different distances from the objective lens are If there are multiple targets in one target, either the target or the device must be moved laterally depending on each location, and focus positioning must be performed on each individual target location. . In particular, when a non-contact automatic positioning device is combined with a microscope etc. to perform automatic focus positioning (autofocus), it is impossible to focus on multiple target areas one after another within a once fixed field of view. there were. For example, when visually inspecting multiple locations of a semiconductor product or plastic product that have predetermined unevenness using the microscope, each time the object or device is moved laterally (in the direction of viewing) depending on the inspection location. On the other hand, the microscope had to move laterally (that is, perpendicular to the approaching and separating directions) to position the inspection area (target area) in the center of the field of view of the microscope, otherwise it would not be in focus.

Therefore, the present inventor aimed to develop a non-contact multi-point automatic focus positioning device that can individually focus on multiple target parts of an object without moving the object or the device laterally. As a result of further research, the present invention (device) was discovered.

<Means for solving the problems> The configuration of the present invention to achieve the above object is shown in Figure 1 (A
) (B) (C) to FIG. 3 (A) (B) (C).

The non-contact multi-point automatic focus positioning method according to the first invention (the invention described in claim 1) includes laser mechanisms 1X to 1.
Each of the first mirrors 2
〜2Z in a predetermined angle direction, each measurement light beam reflected by each first mirror is reflected by the second mirror 3, and then refracted by the objective lens 4 and irradiated onto the target object. Each measurement light beam that has been reflected and refracted by the objective lens is imaged on each optical axis 14X to 14Z by the imaging lens 4, and each measurement light beam that has passed through the imaging lens is transmitted to each corresponding optical position detector. Light is received at 8X to 8Z, and each measurement light beam is centered at 18X to 1 at the sensor center of each optical position detector.
According to the position signal emitted when light is received at a position other than 8Z, at least either the target object or the objective lens is moved, and the distance between each target part and the objective lens is determined by the focal length F of the objective lens for each target part. In a state where the distance matches the focal length F, each measurement light beam 11C112c reflected by the second mirror,
13c and each measurement light beam 11f, 12f, 13f reflected by the object and refracted by the objective lens, each passing through three points: the focal point p1, the center point 19 of the objective lens, and the center of each sensor. It is parallel to the optical axes 14X to 14Z.

The non-contact multi-point automatic focus positioning method according to the second invention (the invention described in claim 2) includes measuring light beams 11 to 13.
laser mechanisms IX to IZ that selectively emit polarized He-Ne laser beams, and each measurement light beam emitted from the laser mechanisms to irradiate each target region X to Z set in plurality on the surface of the object 10. , first mirrors 2X to 2Z that reflect in each predetermined angular direction according to each target region, and a second mirror that reflects each measurement light beam reflected by the first mirror toward the object side.
a mirror 3; an objective lens 4 that refracts the measurement light beam reflected by the second mirror to irradiate the object; and an objective lens 4 that refracts the measurement light beam reflected by the object; an imaging lens 5 that refracts each measurement light beam and forms an image on each optical axis from 14X to 14Z; , each sensor center 18X~1
Optical position detectors 8X to 8Z that emit a position signal according to the light receiving position when light is received at a position other than 8Z; and a focus positioning mechanism that moves the distance between each target part and the objective lens to match the focal length F of the objective lens for each target part, and the distance matches the focal length F. In this state, the measurement light beams 11c, 12c, 13c reflected by the second mirror and the measurement light beams 11f, 12f, 1 reflected by the object and refracted by the objective lens.
Both of 3f are mutually focused at the focal point p1 and the center point 1 of the objective lens.
Each optical axis 14X passes through three points: 9 and the center of each sensor
It is parallel to 14Z.

<Example> O An example of the present invention (first invention and second invention) will be described below based on the apparatus shown in FIGS. 1(A), (B), and (C) to FIG. 4.

The non-contact multi-point automatic focus positioning device according to this embodiment is as follows:
3' laser mechanisms LX to IZ, first mirrors 2X to 2Z
, second mirror 3, objective lens 4, imaging lens 5, filled lens 6, magnifying lens 7. Three optical position detectors 8X~
8Z and a focus positioning mechanism 9. And 1
0 is an object, and its surface is provided with target parts x, y, and z at different distances from the objective lens 4.

The laser mechanisms IX-IZ each receive polarized He-Ne laser beams as measuring beams 11-13, i.e. polarized H
They emit e-N'e laser beams, and are provided corresponding to each target region x, y, z of the object 10, respectively. The laser mechanisms IX to IZ can emit any measurement light beams 11 to 13 by means of a switch (not shown).

The first noodle rollers 2X to 2Z each have a laser mechanism IX to
It is disposed on the exit side of the IZ and is capable of reflecting the measurement light beams 11 to 13 emitted from the respective laser mechanisms 1X to 1Z at a predetermined angle. Therefore, each first mirror 2X~2
Z has different inclination angles.

The second mirror 3 is a half mirror, and the first mirror 2X
The measurement light beams 11 to 13 reflected at ~2Z are each reflected toward the objective lens 4 on the object 10 side.

The objective lens 4 refracts the measurement light beams 11 to 13 reflected by the second mirror 3 and irradiates the measurement light beams 11 to 13 toward the object 10, and the measurement light beam 1 reflected from the surface of the object 10.
1 to 13 are refracted again. Further, the objective lens 4 is configured to be able to move toward and away from the object 10 by a focus positioning mechanism 9, which will be described later.

The imaging lens 5 refracts the measurement light beams 11 to 13 refracted by the objective lens 4, and aligns them with optical axes 14X to 14, which will be described later.
This is to form an image on the Z.

The filled lens 6 further refracts the measurement light beams 11 to 13 refracted by the imaging lens 5, and each measurement light beam 11 to 1
3 is guided to the magnifying lens 7 in such a way that it does not deviate too far from the optical axis 14X-14Z.

The magnifying lens 7 further refracts the measurement light beams 11 to 13 refracted by the filled lens 6, and transmits them to the optical position detectors 8X to 8.
It leads to Z. Note that the distance 11 between the imaging lens 5 and the filled lens 6 and the distance between the filled lens 6 and the magnifying lens '7 are adjusted so that the measurement light beams 11 to 13 refracted by the filled lens 6 are always refracted by the magnifying lens 7. distance 1
The relationship between 2 is 1#! 1+1#! 2=1/f.

Here, f is the focal length of the filled lens 6.

The optical position detectors 8X to 8Z include upper photosensors 15X to 15Z and lower photosensors 16X to 16, respectively.
A photodiode (PD) composed of Z was adopted.

This photodiode (PD) can obtain a position signal containing position information of incident light without scanning the image.
Compared to solid-state imaging devices such as COD and MO8, it has higher resolution and can obtain a higher sampling grade. Note that a semiconductor device detector (PSD) can also be used instead of a photodiode (PD). The measurement light beams 11 to 13 after passing through the magnifying lens 7 are sent to the center of a dedicated sensor 1.
When light is received at 8X to 18Z, no position signal is emitted, but the light is shifted to either side from the sensor center 18X to 18Z and received by either the upper photosensor 15X to 15Z or the lower photosensor 16X to 16Z. When you do,
A position signal is sent to a focus positioning mechanism 9, which will be described later. In other words, the upper photo sensor 15X~15
Z transmits a signal that reduces the distance between the object 10 and the objective lens 4 to the focus positioning mechanism 9, and the lower photosensors 16X to 16Z transmit a position signal that increases the distance. .

As the focus positioning mechanism 9, a ``servo mechanism'' with an extremely fast operating speed, in which a motor is driven by a servo circuit, is employed. In this embodiment, although not shown, the focus positioning mechanism 9 is connected to the objective lens 4, and by moving the objective lens 4, according to the position signals from the optical position detectors 8X to 8Z, Object 1
The distance between 0 and the objective lens 4 can be adjusted, and the focal point p1 of the measurement light beams 11 to 13 can be adjusted to each target region XX on the surface of the object 10.
It is designed to match. In other words, each target region
The distance between Z and the objective lens 4 is made to match the focal length F of the objective lens 4 for each part Xz. Note that this focus positioning mechanism 9
The objective lens 4 and the object 10 can both be moved.

This non-contact multi-point automatic focus positioning device has the overall structure as described above, and when performing focus positioning of the target region X on the object 10, the laser mechanism IX, the first mirror 2X, the optical position Using detector 8X, other target area Y
When performing focus positioning of the laser mechanism IY, the first
When using the mirror 2Y and the optical position detector 8Y to perform focal positioning of another target region Z, the laser mechanism IZ
, a first mirror 2Z, and an optical position detector 8Z. Then, when performing focal position alignment of each target region X to Z, the measurement light flux 1 at each target region X to Z is
The focal points p1 of 1 to 13, the center point 19 of the objective lens 4,
Sensor center 18 of each corresponding optical position detector 8X to 8Z
Each of the optical axes 14X to 142 passing through three points X to 18Z is formed according to each target region X to Z.

Next, the effect will be explained.

First, each target region
~Z will be explained one by one. After that, an actual operation example in which the present device is used as an autofocus mechanism of a microscope will be explained as a concrete operation.

□ Basic action □ Goal. In the case of position
It shall be explained as m...-.

(a) State in focus FIG. 1(A) shows a state in focus. First, a case will be described in which the distance between the objective lens 4 and the target site X matches the focal length F of the objective lens 4. First, the measurement light beam 11a emitted by the laser mechanism IX in parallel to the optical axis 14X is reflected at right angles by the first mirror 2X,
The measurement light beam 11b is perpendicular to the optical axis 14X. This measurement light beam 11b is applied to the other first mirrors 2Y, 2 which are half mirrors.
It passes through Z and hits the second mirror 3, where it is reflected and becomes a measurement light beam 11c parallel to the optical axis 14X.

This measurement light beam 11c is then refracted by the objective lens 4,
The measurement light flux Lid is irradiated onto the target region X of the object 10. At this time, the distance between the objective lens 4 and the target site X is the focal length F of the objective lens 4, so the focal point p1 of the measurement light beam lid matches the target site X.

The measurement light beam 11d is reflected at the target site X according to the principle of incident angle-reflection angle, becomes a measurement light beam lie, and is refracted by the objective lens 4. The measurement light beam 11f refracted by the objective lens 4 is guided again in a direction parallel to the optical axis 14X, passes through the second mirror 3 which is a half mirror, and is then refracted by the imaging lens 5. The measurement light flux 11g refracted by the imaging lens 5 forms an imaging point p2 on the optical axis 14X corresponding to the position of the center point 20 of the filled lens 6, and then becomes a measurement light flux 11h to the magnifying lens 7. I am guided.

At this time, the measurement light beam 11g is at the center point 2 of the filled lens 6.
0, it becomes a measurement light beam 11h and is guided to the magnifying lens 7 without changing its direction due to refraction. The measurement light beam 11i refracted by the magnifying lens 7 is received at the sensor center 18X of the optical position detector 8X. The state in which the measurement light beam 11i is received at the sensor center 1' 8X in this way is the focused state, and in this case, the focus positioning mechanism 9 connected to the optical position detector 8X is It does not operate and does not move the objective lens 4 at all.

(b) State where the objective lens is far away FIG. 1(B) shows a case where the distance between the target region X and the objective lens 4 is larger than the focal length F of the objective lens 4.

First, the process until the measurement light beam 11a emitted from the laser mechanism 1 is refracted by the objective lens 4 is the same as in the previous case (a), but the measurement light beam li refracted by the objective lens 4
d does not hit the target part X on the optical axis 14X,
It hits another reflection position 21 higher up and is reflected. Since this reflection position 21 is farther than the focal point p1 of the measurement light flux lid by the objective lens 4, the measurement light flux lie
is refracted closer to the outer periphery of the objective lens 4 than in the previous case (a), becomes a measurement light beam 11f that is not parallel to the optical axis 14X (tries to approach the optical axis 14X), and is guided to the imaging lens 5 and beyond. It will be destroyed. The light is finally received by the upper photosensor 15X of the optical position detector 8X, and the focus positioning mechanism 9 moves the objective lens 4 to the A side based on the position signal from the upper photosensor 15X. Then, when the focal point p1 of the measurement light flux lid by the objective lens 4 coincides with the target region X, that is, the measurement light flux 11i is detected by the optical position detector 8.
When light is received at the X sensor center 18X, the movement of the objective lens 4 toward the A side by the focus positioning mechanism 9 ends. The position of the objective lens 4 at this time is the same as in (a) above.

(C) State where the objective lens approaches the object (Figure 1)
shows a case where the distance between the target region X and the objective lens 10 is smaller than the focal length F of the objective lens 4. In this case, contrary to the previous case (c), the measurement light beam 11e is reflected at another reflection position 2Z below the optical axis 14X, and the measurement light beam 11e is reflected by the objective lens 4 more than in the previous case (a). The measurement light beam 11 is refracted inside (on the optical axis 14X side) and is not parallel to the optical axis 14X (trying to move away from the optical axis 14X).
f and is guided to the imaging lens 5 and beyond. The light is finally received by the lower photosensor 16X of the optical position detector 8X, and the focus positioning mechanism 9 moves the objective lens 4 toward the B side based on the position signal from the lower photosensor 16X. Then, the measurement light flux lid by the objective lens 4
The movement of the objective lens 4 ends when the focal point p1 matches the target region X, that is, when the objective lens 4 comes to the same position as in (a) above.

As described above, even if the position of the objective lens 4 deviates from the normal focal position, it can be automatically corrected and corrected.

In the case of elevation Y [Figs. 2(A) to 2(C), Fig. 4(a): In-focus state; Fig. 2(A) shows the in-focus state.

The measurement light beam 12a emitted from the laser mechanism IY is
The measurement light beam 12b is reflected by the mirror 2Y and is from a direction shifted by an angle q from the measurement light beam 11b for the target site X.
As a result, the second mirror 3 is hit.

Due to this difference in angle α, the measurement light beam 12c reflected by the second mirror 3 is guided in a direction parallel to the optical axis 14Y at this target site Y, and as in the case of the target site X, It passes through the objective lens 4, is reflected at the target site Y, and is refracted by the objective lens 4, becoming a measurement light beam 11f parallel to the optical axis 14Y. This measurement light beam 11f passes through the imaging lens 5 and passes through the optical axis 1 in the filled lens 6.
An image forming point p2 is formed on the optical position detector 8Y through the magnifying lens 7, and then the image forming point p2 is formed on the optical position detector 8Y at the sensor center 18Y.
The light is received at

In the case of this target region Y, since the measurement light beams 12c and 12r between the objective lens 4 and the imaging lens 5 are parallel to each other with respect to the optical axis 14Y as described above, the measurement light beam 12
In a state where the focal point p1 of d is in focus, as shown in FIG. Since the measurement light beam 11g is reflected at the focal point p1, it always forms an imaging point p2 at the same position, and the measurement light beam 12i that has passed through the magnifying lens 7 is at the sensor center 18Y of the optical position detector 8Y. The light is received.In other words, the optical axis 14
The distance 23 from X to the focal point p1 and the distance I from the optical axis 14X to the imaging point p2! , 4 remains unchanged. Therefore, the focal position can be adjusted for any target portion Y° having a different distance from the objective lens 4. On the other hand, this also shows that regardless of whether the object 10 approaches or moves away from the objective lens 4 as a whole, the focus can always be aligned on the target region Y. Therefore, even when performing focus positioning on another object having a different target region from this object 10, this device can be used as is, and it is possible to use the object 10 instead of the objective lens 4. There is no problem when moving the focus positioning mechanism 9. This point is the most distinctive feature of the present invention, and the same applies to the target region X described above or the target region Z described later.

(b) State where the objective lens is far away. Then, as shown in FIG. 2(B), if the distance between the target region Y and the objective lens 4 is larger than the focal length F of the objective lens 4, As in the case of , the measurement light beam 12i is received by the upper photosensor 15Y, so the objective lens 4 is moved to the A side, and the focal point p1 of the measurement light beam 12d by the objective lens 4 is made to coincide with the target region Y.

(C) A state in which the objective lens approaches the object, and
As shown in FIG. 2 (C), when the distance between the target region Y and the objective lens 4 is smaller than the focal length MF of the objective lens 4, the measurement light beam 12+ is directed downward, contrary to the previous (c). Since the light is received by the photosensor 16Y, the objective lens 4 is moved to the B side, and the focal point of the measurement light beam 12d by the objective lens 4 is
Match pl with the target site Y.

Field of target region Z [Figures 3 (8) to 3 (C)] The measurement light beam 13a emitted from the laser mechanism IZ is reflected by the first mirror 2Z and becomes the measurement light beam 13b to the destination target region Y It hits the second mirror 3 from a direction shifted by an angle β in the opposite direction to that in the case of .

Then, from the difference of this angle β 1t1 & , the measurement luminous flux 13
d is irradiated toward the target region 2.

In the case of this target region Z, when the focal point p1 of the measurement light beam 13d by the objective lens 4 matches the target region Z (see FIG. 3(A)), the measurement light beam 13i is detected by the sensor of the optical position detector 8Z. Light is received at the center 18Z. If the objective lens 4 is moving away from the object 10 (third (3)
B) Refer to the figure), the measurement light beam 13i is the upper photosensor 1.
57 and moves the objective lens 4 to the A side, and when the object 4 approaches the object 10 and shifts (see Fig. 3(C)), the measurement light beam 13i is directed toward the lower photo. When the light is received by the sensor 167, the objective lens 4 is moved to the B side, and the focal point p1 is aligned with the target region Z. Note that even in the case of this target region Z, the objective lens 4 and the imaging lens 5
Since the measurement light beams 13c and 13f between the two are parallel to the optical axis 142, even if the target region 2 is at a different position (with a different distance from the objective lens 4), The focus can be adjusted.

□ Specific action □ As mentioned above, this device has the following effects at each target site χ~Z:
Since focus alignment (correction of focus deviation) can be performed separately for each, when objective lens 4 is also used as a microscope objective lens, multiple points (in this example, 3 points) can be adjusted in one fixed field of view. Automatic focus positioning (autofocus) is possible.

That is, the target parts X to Z to be focused on can be changed within a fixed field of view. Target area X below
An example of changing -2 is given below.

First, a case will be described in which the focus is changed from the focus on the target site X to the target site Y on the near side of the target site X (smaller distance from the objective lens 4).

First, the state where the focus is on the target part X (Fig. 1 (A)
) to observe and inspect target area X. And target area X
When the inspection/observation is completed, a switch (not shown) placed at the observer's hand is then turned over to emit the measurement light beam 12a from the laser mechanism IY. The measurement light beam 12a emitted from the laser mechanism IY hits the target region Y on the nearer side than the previous target region X, but the position of the objective lens 4 is
Since it remains at the position corresponding to , the measurement light beam 12i reflected from this target region Y is received by the lower photosensor 16Y. Therefore, the objective lens 4 operates the focus positioning mechanism 9 based on the position signal from the lower photosensor 16Y, moves the objective lens 4 to the B side, and positions the objective lens 4 just when the focus point p1 matches the target region Y. be done.

In this way, the optical focus of the microscope is also on this target site Y, so that the target site Y can be observed and inspected. Note that the above also applies to the case of changing to the target part on the near side, that is, the case of changing from the target part X to the target part Z or from the target part Y to the target part Z.

Next, in the opposite case, that is, from a state in which the focus is on the target region Y, the target region Y is further away (objective lens 4
A case of changing to target region X (which is located at a large distance from

In this case, a switch (not shown) is used to switch the measurement light beam 11a so that it is emitted from the laser mechanism IX. Then, since the target part X is farther from the objective lens 4 than the target part Y, the focal point p1 of the measurement light beam 11d does not match the target part light is received. Therefore, objective lens 4
moves toward the A side as if chasing the target part X, and stops at the focal point. This also applies when changing to a distant target site, that is, when changing from target site 2 to target site Y, or from target site Z to target site X. Like this 1
Within one fixed field of view, it is possible to focus on any of the three target areas X to Z by simply flipping a switch at hand.

Next, how to emit the measurement light beams 11 to 13 from the laser mechanism IX-IZ will be explained based on the embodiment shown in FIGS. 5(A) to 5(C).

Each laser mechanism 1X is installed on the exit side of each laser mechanism IX to IZ.
Opening/closing opening 23 corresponding to measurement light flux 11 to 3 from ~1Z
A shielding plate 24 that can freely form X to 23Z is provided. and,
The opening/closing ports 23X to 23Z are opened and closed by switches not shown. In addition, each opening/closing port 23X~2
Sensors (photocouplers) 25X to 25Z for sensing the measurement light beams 11 to 13 are provided at the portions corresponding to 3Z, respectively. In addition, these sensors 25X to 25Z are connected to each opening/closing port 2.
When opening 3X to 23Z, the measurement light beams 11 to 13 are not detected because they are removed from the positions corresponding to the measurement light beams 11 to 13. And three laser mechanisms IX~1z
From then on, measurement light beams 11 to 13 are all emitted. Therefore, by operating a switch (not shown) and opening the desired opening/closing ports 23X-23Z, the observer can emit only the necessary light beams from among the measurement light beams 23X-23Z. Furthermore, the sensor 26X-L25Z allows
It is possible to know which measurement light beams 11 to 13 are currently being emitted (which ones are blocked) by a display mechanism (not shown) near the switch, thereby improving the operability of the switch mechanism (not shown). be. Furthermore, this sensor 25X~
25Z to the computer and open/close each opening 23.
The opening order and opening time of X to 23z can also be automatically controlled by a computer.

Next, another example of how the measurement light beams 11 to 13 are emitted from the laser mechanisms 1X to 1Z will be described based on FIG. 6.

In this embodiment, one laser mechanism 1 is used to measure and travel light flux 11a.
This is an example in which 13a is emitted. That is, the measurement light beam 12a emitted from one laser mechanism 1 is branched by three half mirrors 26X to 26Z.

First, the measurement light beam 11a emitted from the laser mechanism 1 is
When the light hits the lowermost half mirror 26X, it is divided into those that are reflected and those that are transmitted. The transmitted light is directly transferred to the first mirror as the measurement light beam 11a for the target region X? Reflected at X. The light reflected by the half mirror X hits the half mirror 25Y directly above, where it is also divided into reflected light and transmitted light. The reflected light is used as the first measurement light beam 12a for the target area Y.
It is reflected by the mirror 2Y. And what passed through,
It is also reflected by the half mirror 25Z directly above it, and is reflected by the first mirror 2Z as the measurement light beam 13a for the target region Z. In this way, one parallel measurement light beam 11a
Three parallel measurement light beams 11 a % 12 a 51
3a, and the opening/closing openings 23X to 23Z with the respective sensors 25X to 25Z of the shielding plate 24 allow the measurement light fluxes 11a and 12a to be
, 13a, only the necessary ones can be selected and irradiated. The rest is the same as the previous embodiment.

In the above, an example has been shown in which the present device is used as an autofocus mechanism for a microscope, etc., but it can also be applied to other uses as mentioned at the beginning. In addition, although an example was shown in which one object 10 has three target parts X to Z, two
Alternatively, even for an object having three or more target regions, focus positioning can be performed for each target region.

<Effects> Since the non-contact multi-point automatic focus positioning method and device according to the present invention (first invention and second invention) have the contents as explained above, they can produce various effects as shown below. .

(a) Even if there are multiple target areas on the surface of a single object with different distances from the objective lens, each target area can be moved without moving the objective lens or the object laterally according to each target area. It is possible to perform focal position alignment. Therefore, when using this device for autofocusing of optical equipment, it is necessary to
Focus alignment of multiple target regions can be performed.

Furthermore, since the measurement light beams between the objective lens and the imaging lens are parallel to each other with respect to the optical axis, it is possible to perform focus positioning on any target site that is at a different distance from the objective lens. can.

(b) Since a polarized He-Ne laser beam was used as the measurement light beam, the light beam is thinner than other laser beams, and the focused spot is very small and does not spread, so the position on the optical position detector can be adjusted accordingly. Detection can be performed with high precision (high resolution). The diameter of the focused spot of this polarized He-Ne laser beam depends on the magnification of the objective lens, but is approximately 1 μm.
It is very small at ~100μ (that is, the focus positioning accuracy is high).

Further, according to the embodiment of the present invention, (C) Since the displacement of the measurement light beam is magnified by the magnifying lens, even small displacements are magnified accurately without missing them, and then the position is detected by the optical position detector, so that Accurate position detection can be achieved. Therefore, even in a situation where the distance between the objective lens and the object is large and the focus accuracy tends to decrease, highly accurate focus positioning can be achieved (that is, the focus positioning accuracy is high).

(d) Photodiode (PD) as an optical position detector
) only outputs the position of the center of gravity of the spot of the detected measurement light beam, so it is not affected by changes in the brightness distribution, and the focusing accuracy is not affected by the brightness distribution (contrast) on the surface of the object. (In other words, noise resistance and measurement reliability are high).

(e) Photodiode (PD) as optical position detector
In addition, since a servo mechanism was adopted as the focus positioning mechanism, the distance between the optical mechanism and the object can be adjusted with a quick operation of 10 ssec on average (in other words, the focus positioning speed is fast). .

[Brief explanation of the drawing]

FIG. 1(A) is a schematic explanatory diagram of the present device according to an embodiment of the present invention (first invention and second invention) showing a state in which the focus is on the target region X, and FIG. 1(B) Figure 1 shows a state in which the objective lens is moving away from the target region X (
A) A schematic explanatory diagram equivalent to Fig. 1(C) is a schematic explanatory diagram equivalent to Fig. 1(A) showing a state in which the objective lens is too close to the target region , a schematic explanatory diagram of the present device according to an embodiment of the present invention (first invention and second invention) showing a state where the focus is on the target region Y, and FIG. Figure 2 shows the lens moving away from the camera (
A) is a schematic explanatory diagram equivalent to Fig. 2(C) is a schematic explanatory diagram equivalent to Fig. 2(A) showing a state in which the objective lens is too close to the target region Y; , a schematic explanatory diagram of the present device according to an embodiment of the present invention (first invention and second invention) showing a state where the focus is on the target region Z, and FIG. Figure 3 shows a state in which the lens is moving away (
A) A schematic explanatory diagram equivalent to FIG. 3(C) is a schematic explanatory diagram equivalent to FIG. A schematic explanatory diagram showing the case where the objective lens moves to follow the target region Y in FIG. FIG. 6 is a schematic explanatory diagram showing still another example of how to emit a measurement light beam. IX, IY, IZ - Laser mechanism 2X, 2Y, 2Z - First mirror 3 - Second mirror 4 - Objective lens 5 ... - Imaging lens 6 - Filled lens 7 - Magnifying lens 8X, 8Y, 8Z, - 1. Imaging lens 9--Focus positioning mechanism 10--Object lL12.13--Measurement light flux 14X, 14Y, 14Z, ---1 Optical axis 15X, 1
5Y, 15z・-Upper photosensor 16X, 16Y, 1
6Z-・Lower photosensor 18X, 18Y, 18
z-(! - Center 19 - Center point 20 of the objective lens - Center point X, Y, Z of the filled lens - Target area α - Angle β of the measurement light beam 12b - Angle L of the measurement light beam 13b - Objective Distance between lens and object F - focal length of objective lens

Claims (2)

[Claims] (1) Polarized He-Ne laser beams as measurement light beams 11 to 13 selectively emitted from laser mechanisms 1X to 1Z,
In order to irradiate a plurality of target parts X to Z set on the surface of the object 10, each of the first mirrors 2X to 2Z reflects in a predetermined angle direction, and each measurement light beam reflected by each of the first mirrors is After being reflected by two mirrors 3, it is refracted by an objective lens 4 and irradiated onto the target object.The measurement light beams reflected by the target object and refracted by the objective lens are directed to each optical axis 14X by the imaging lens 4. 14Z, each measurement light flux that has passed through the imaging lens is received by each corresponding optical position detector 8X to 8Z, and each measurement light flux is focused on the sensor center 18X to 1 of each optical position detector.
According to the position signal emitted when light is received at a position other than 8Z, at least either the target object or the objective lens is moved, and the distance L between each target part and the objective lens is determined by the focal length F of the objective lens for each target part. In a state where the distance L matches the focal length F, each measurement light beam 11c, 12c reflected by the second mirror,
13c and each measurement light beam 11f, 12f, 13f reflected by the object and refracted by the objective lens, each passing through three points: the focal point p1, the center point 19 of the objective lens, and the center of each sensor. A non-contact multi-point automatic focus positioning method characterized by being parallel to optical axes 14X to 14Z. (2) Laser mechanisms 1X to 1Z that selectively emit polarized He-Ne laser beams as measurement light beams 11 to 13, and each measurement light beam emitted from the laser mechanisms to the object 10.
First mirrors 2X to 2Z that reflect in respective predetermined angular directions according to each target area in order to irradiate each target area X to Z set on the surface; and each measurement light beam reflected by the first mirror. a second mirror 3 that reflects the light toward the object, and an objective lens that refracts the measurement light beam reflected by the second mirror to irradiate the object and refracts the measurement light beam reflected by the object. 4, an imaging lens 5 that refracts each measurement light beam refracted by the objective lens and forms an image on each optical axis from 14X to 14Z; Each measurement light beam passing through the imaging lens is placed at the center of each sensor from 18X to 1
Optical position detectors 8X to 8Z that emit a position signal according to the light receiving position when light is received at a position other than 8Z; and a focus positioning mechanism that moves the distance L between each target part and the objective lens to match the focal length F of the objective lens for each target part, and the distance L matches the focal length F. In this state, the measurement light beams 11c, 12c, 13c reflected by the second mirror and the measurement light beams 11f, 12f, 1 reflected by the object and refracted by the objective lens.
Both of 3f are mutually focused at the focal point p1 and the center point 1 of the objective lens.
Each optical axis 14X passes through three points: 9 and the center of each sensor
A non-contact multi-point automatic focus positioning device characterized by being parallel to 14Z.