JP2000352661A - Focusing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform focusing with a wide focusing detection range without increasing a sensor system nor adjusting it. SOLUTION: In this focusing device, autofocusing action by an auto-focusing controller 17 is performed when a space between a sample 1 and an observation optical system 5 is within the focusing detection range W, and the autofocusing action is switched to manual operation by a focusing operation part 21 when it is out of the range W, then autofocusing is performed by restoring control from the manual operation when it gets in the range W. In the automatic measurement of height, the respective coordinates of respective measuring points k1 to k6 including a Z-direction are taught. When the sample 1 is out of the range W, a focusing direction is estimated by an estimating action function 20 based on the taught coordinates, and a stage 2 is actuated in accordance with the estimated focusing direction so as to make the sample 1 within the range W. Then, the autofocusing action to the sample 1 is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focusing device which is applied to, for example, a measuring instrument for measuring height using a microscope or the like, and which focuses an observation optical system of the microscope on a sample.

[0002]

2. Description of the Related Art An autofocus unit used in a measuring instrument or a microscope irradiates a sample with a laser beam output from, for example, a laser diode through an observation optical system including an objective lens, and reflects light reflected from the sample by a light receiving element. Light is received, and a stage on which the sample is placed is moved up and down in the optical axis direction based on an electric signal corresponding to the received light amount to focus the observation optical system.

In this autofocus, focus detection is performed by an electric signal corresponding to the amount of light received by the light receiving element. Since the light receiving element does not detect the image formation state of the reflected light beam from the sample outside the focus detection range. , The auto focus operation cannot be performed.

As described above, when the observation optical system is out of the focus detection range, the stage on which the sample is placed is moved up and down in the optical axis direction, and a search operation is performed so that the observation optical system enters the focus detection range. Do. When the observation optical system enters the focus detection range by this search operation, the imaging state of the reflected light beam from the sample condensed on the light receiving element is detected, and the stage is moved based on the electric signal corresponding to the received light amount. The observation optical system is focused by moving up and down in the optical axis direction.

[0005] Therefore, in the above-mentioned auto focus, the focusing operation is immediately performed if the focus is within the focus detection range, but if the focus is out of the focus detection range, the search operation is performed to search the focus detection range. The focus operation cannot be performed.

In addition, even if the search operation is performed, if there is no contrast like a lens barrel sample, the focus detection range cannot be detected, and the focus operation cannot be performed.

As described in Japanese Patent Application Laid-Open No. 9-281384, a reflected light from an object to be measured is divided into two directions, and one of the reflected lights is received by a first light receiving device and a beam is received. The spot diameter is detected, the other reflected light is received by the second light receiver, and the overall intensity of the reflected light is detected. From the change in the beam spot diameter, coarse focus control is performed until near the best focus. The best focus position is determined by detection.

Japanese Patent Application Laid-Open No. 9-80301 discloses that the focus detection sensitivity and the focus detection range are variable.

[0009]

However, even if the technique described in Japanese Patent Application Laid-Open No. 9-281384 is adopted in the above-mentioned autofocus, if the sample has a region having a remarkably different height, the autofocus will not be performed. The focus operation cannot be performed because the focus detection range or search operation range is not entered.

In Japanese Patent Application Laid-Open No. 9-281384,
It is necessary to have two sensor systems like the first and second light receivers. In Japanese Patent Application Laid-Open No. 9-80301, it is necessary to adjust the variable of the focus detection sensitivity and the focus detection range for each sample. Must.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a focusing device capable of performing focusing with a wide focus detection range without increasing the number of sensor systems and without making adjustments.

[0012]

In the focusing apparatus of the present invention, light from a sample is received by a light receiving means through an optical system, and the optical system is focused on the sample based on an electric signal corresponding to the amount of received light. In the focusing device, the main control means for relatively moving and controlling the distance between the sample and the optical system in response to a manual operation, and the distance between the sample and the optical system based on an electric signal corresponding to the amount of light received from the sample. Is within the focus detection range, and
If the focus is within the focus detection range, the optical system performs a focusing operation on the sample. If the focus is out of the focus detection range, the main control unit issues a switching instruction to a manual operation, and outputs a focus detection range. And an auto-focus control means for performing a focusing operation by regaining control from the main control means when it is within the range.

The main control means includes a teaching function for teaching position data of a plurality of measurement points including a height direction on the sample, and a teaching function when receiving a switching instruction from the auto focus control means to a manual operation. The focusing direction based on the position data
Estimating means for relatively moving and controlling the distance between the sample and the optical system in accordance with the focusing direction.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an automatic height measuring device to which a focusing device using a confocal autofocus is applied.

The sample 1 is placed on a stage 2 which moves in the XYZ axis directions. Above the stage 2, an objective lens 3, a dichroic mirror 4, and an observation optical system 5 of a microscope are arranged on the same optical axis.

On the other hand, a collimator lens 7, a deflecting beam splitter 8, and a quarter-wave plate 9 are arranged on the illumination optical axis of the laser light output from the laser diode (LD) 6.

The dichroic mirror 4 has a characteristic of reflecting a wavelength region including the wavelength of the laser beam output from the laser diode 6 as a center wavelength.

A detection optical system 10 is arranged in the branching direction of the deflection beam splitter 8. The detection optical system 10 irradiates the sample 1 with the laser light output from the laser diode 6, receives the reflected light, and outputs an electric signal corresponding to the amount of the received light. A condenser lens 11 and a beam splitter 12 are arranged on the optical axis.

The light receiving element 14 is disposed on the transmitted light path of the beam splitter 12 via a pinhole plate 13, and the light receiving element 1 is disposed on the reflected light path via a pinhole plate 15.
6 are arranged. One pinhole plate 13 is disposed on the condenser lens 11 side (front side) by a distance S1 from the focal position P1 of the condenser lens 11, and the other pinhole plate 15
Is disposed on the light receiving element 16 side (rear side) by a distance S2 from the focal position P2 of the condenser lens 11. The focal positions P1 and P2 have an optically conjugate relationship with the image plane of the objective lens 3.

Here, the relationship between the distances S1 and S2 is: S1 = S2 (1), and the pinhole diameters d of the pinhole plates 13 and 15 are as follows.
1, d2 has a relationship of d1 = d2 (2).

The electric signals (hereinafter, referred to as sensor signals) I1 and I2 output from the light receiving elements 14 and 16 are sent to an auto focus (AF) controller 17.

This auto focus controller 17
Detects whether the focus position of the objective lens 3 is within the focus detection range based on the sensor signals I1 and I2 output from the light receiving elements 14 and 16, and when the focus position is within the focus detection range, It has an autofocus function of moving the stage 2 up and down at a fine pitch to execute focusing. When the stage 2 is out of the focus detection range, the main controller 18 issues a switching instruction Q to the manual operation to the main controller 1.
8 is prioritized. When the controller 17 detects that the objective lens 3 has been brought into the focus detection range by a manual operation, the controller 17 regains control from the main controller 18 and gives priority to the autofocus function of moving the stage 2 up and down at a fine pitch.

When the height is automatically measured, the autofocus controller 17 issues a focus direction estimation switching instruction F to the main controller 18 if the objective lens 3 is out of the focus detection range. I have.

More specifically, the auto focus controller 1
7 reads the sensor signals I1 and I2 of the signal levels shown in FIG.
From the sensor signals I1 and I2, an evaluation value ΔI ΔI = (I1−I2) / (I1 + I2) (3) as shown in FIG. 3 is calculated, and the position adjustment is performed so that the evaluation value ΔI becomes “0”. It has a function of generating the signal C and sending it to the stage 2. That is, the point where the evaluation value ΔI = 0 is the focus position.

The auto focus controller 1
7, a sum signal (I1 + I2) of the sensor signals I1 and I2 is obtained as shown in FIG. 4, and a range of the sum signal (I1 + I2) which is equal to or larger than the threshold Th1 is determined as the focus detection range W.
And

The auto focus controller 1
Reference numeral 7 has a function of driving the laser diode 6.

The main controller 18 comprises a personal computer and controls the operation of the entire measuring instrument. The main controller 18 has a function of communicating with the autofocus controller 17, a function of driving the stage 2 in the XYZ axis directions, and a height. It has a teaching function 19 at the time of automatic measurement and an estimation operation function 20.

The teaching function 19 converts the position data of each of the measurement points k1 to k6 on the sample 1 into coordinates (X, Y, and Z) including the Z-axis data in the height direction, as shown in FIG.
Z).

When the measuring points k1 to k6 are taught as described above, the main controller 18 determines the measuring path from the coordinates (X, Y, Z) of the measuring points k1 to k6 during the automatic height measurement. Has a function. The measurement path is determined, for example, from the directions of the measurement points k1 to k6, or from the height order of the coordinates (X, Y, Z) of the measurement points k1 to k6.

When the main controller 18 receives an instruction Q for switching to a manual operation from the autofocus controller 17, the focusing operation section (manual operation section) 21
The function of driving the stage 2 in the Z-axis direction in response to the operation of the ascending button 21a or the descending button 21b is prioritized. In this case, the up button 21a or the down button 2
It is also possible to switch to the manual operation by the main controller 18 itself without pressing the 1b to drive and control the stage 2 in the Z-axis direction.

When the automatic operation controller 20 receives an instruction Q for switching to the manual operation from the auto focus controller 17 during the automatic height measurement, the estimating operation function 20 sets the coordinates (X, Y, Z) of each of the taught measurement points k1 to k6. ), The stage 2 is moved in accordance with the focusing direction.
It has the function of driving in the axial direction.

The auto-focus controller 17
Since the communication function between the main controller 18 and the main controller 18 takes time in normal communication, a method using a uniline message or the like may be used.

Next, the operation of the measuring instrument configured as described above will be described.

When a laser beam is output from the laser diode 6, the laser beam is converted into a parallel beam by a collimator lens 7, passes through a deflecting beam splitter 8 and a quarter-wave plate 9, and enters the dichroic mirror 4. Then, the light is reflected by the dichroic mirror 4, condensed by the objective lens 3, and irradiated on the sample 1.

The reflected light from the sample 1 returns on the optical path opposite to the laser beam irradiation on the sample 1, enters the dichroic mirror 4 through the objective lens 3, and is reflected by the dichroic mirror 4 to The light enters the 波長 wavelength plate 9.

As the laser light reciprocates through the quarter-wave plate 9, the polarization direction of the reflected light from the sample 1 is rotated by 90 °.

Thus, the reflected light transmitted through the quarter-wave plate 9 is reflected by the polarization beam splitter 8 and enters the detection optical system 10. The reflected light that has entered the detection optical system 10 passes through a condenser lens 11 and passes through a beam splitter 12
In one direction, and one of the reflected lights is transmitted to the pinhole plate 13.
And the other reflected light enters the light receiving element 16 through the pinhole plate 15.

The light-receiving elements 14 and 16 respectively output sensor signals I1 and I1 corresponding to the respective amounts of reflected light received.
2 is output. Then, these sensor signals I1, I2
Is sent to the auto focus controller 17.

This auto focus controller 17
Receives the sensor signals I1 and I2 output from the light receiving elements 14 and 16, obtains a sum signal (I1 + I2) as shown in FIG. 4 from the sensor signals I1 and I2, and calculates the sum signal (I1 + I2). A range equal to or larger than the threshold value Th1 is defined as the focus detection range W.

At the same time, the autofocus controller 17 detects whether the distance between the sample 1 and the observation optical system 5 including the objective lens 3 is within the focus detection range W based on the sensor signals I1 and I2. If it is within the focus detection range W, the above equation (3) is calculated from the sensor signals I1 and I2 to obtain an evaluation value ΔI, and a position adjustment signal C such that the evaluation value ΔI becomes “0” is generated. To stage 2.

Thus, the stage 2 is driven in the Z-axis direction, and the sample 1 is automatically focused on the objective lens 3.

On the other hand, if the distance between the sample 1 and the observation optical system 5 including the objective lens 3 is out of the focus detection range W, the autofocus controller 17 instructs the main controller 18 to switch to the manual operation Q Emits.

When the main controller 18 receives the instruction Q for switching to the manual operation, the main controller 18 has the initiative of the focusing operation. In this state, the up button 21a or the down button 21b of the focusing operation unit 21 is manually operated. Then, the stage 2 is driven in the Z-axis direction in response to the manual operation. This manual operation is performed by the main controller 1
8 itself.

As described above, when the stage 2 is driven by manual operation, the auto-focus controller 17 takes in the sensor signals I1 and I2 as needed to adjust the distance between the sample 1 and the observation optical system 5 including the objective lens 3. It is detected whether it is within the focus detection range W.

When the focus position of the objective lens 3 enters the focus detection range W by manual operation, the auto focus controller 17 issues a notice (stage control request R) to the main controller 18 to execute the focus control. Take back the initiative, and again from the sensor signals I1 and I2,
Is calculated to obtain an evaluation value ΔI, and this evaluation value ΔI is “0”.
A position adjustment signal C is generated and sent to the stage 2.

As a result, the stage 2 is driven in the Z-axis direction, and autofocus is performed so that the focal position of the objective lens 3 coincides with the measurement surface of the sample 1.

When the autofocus is performed on the sample 1 in this manner, the sample 1 is set on the basis of the focus position.
Height is required.

Next, the automatic height measurement will be described with reference to the automatic height measurement flowchart shown in FIG.

With the sample 1 fixed on the stage 2,
The teaching function 19 in the main controller 18 is started. The teaching function 19 stores, for example, position data of each of the measurement points k1 to k6 on the sample 1 as coordinates (X, Y, Z) including Z-axis data in the height direction as shown in FIG.

When the teaching is completed, the main controller 18 determines the measurement path from the coordinates (X, Y, Z) of the measurement points k1 to k6, for example, the measurement points k1 to k6.
Decide according to the directions.

When the automatic height measurement starts, the main controller 18 moves the stage 2 to XY so that the measurement point k1 on the sample 1 is positioned below the optical axis of the observation optical system 5 in step # 1 according to the measurement path. Move in the axial direction.

Next, when the measurement point k1 on the sample 1 is positioned below the optical axis of the observation optical system 5, the main controller 18 performs a focusing operation on the autofocus controller 17 in step # 2. Issue instructions.

In response to the instruction of the focusing operation, the autofocus controller 17 moves the stage 2 at a predetermined pitch in the Z-axis direction.
A sum signal (I1 + I2) is obtained from the sensor signals I1 and I2 output from the sensor signal 6, and a range in which the sum signal (I1 + I2) is equal to or larger than the threshold value Th1 is defined as a focus detection range W. Then, in step # 3, the autofocus controller 17 detects whether the measurement point k1 of the sample 1 and the focus position of the objective lens 3 are within the focus detection range W.

Here, the heights (Z-axis direction) of the measurement points k1 to k6 are in a positional relationship as shown in FIG. 7, and the focus detection range W of the autofocus at the start of the measurement is shown in FIG. , The auto focus controller 17
Detects that the measurement point k1 is within the focus detection range W, and proceeds to step # 7 to calculate the above equation from the sensor signals I1 and I2.
By calculating (3), an evaluation value ΔI is obtained, and a position adjustment signal C is generated and sent to the stage 2 so that the evaluation value ΔI becomes “0”.

As a result, the stage 2 is driven in the Z-axis direction, and the measurement point k1 of the sample 1 is automatically focused on the objective lens 3. When the autofocus is performed on the measurement point k1 of the sample 1, the height of the measurement point k1 on the sample 1 is obtained based on the focus position.

Next, the main controller 18 executes step #
In step 8, it is determined whether or not the height measurement at all the measurement points k1 to k6 has been completed. Since only the measurement at the measurement point k1 has been completed here, the process returns to step # 1 again to return to the next measurement point. The stage 2 is moved in the XY axis direction so that k2 is located below the optical axis of the observation optical system 5.

Next, when the measurement point k2 is positioned below the optical axis of the observation optical system 5, the main controller 18 determines in step # 2 that the autofocus controller 1
7 is instructed to perform a focusing operation.

This auto focus controller 17
Detects whether the distance between the measurement point k2 of the sample 1 and the observation optical system 5 including the objective lens 3 is within the focus detection range W in step # 3.

The measurement point k2 is, as shown in FIG.
Higher than 1, the auto focus controller 17
It is detected that it is out of the focus detection range W.

Therefore, the auto focus controller 1
7 issues a switching instruction F to the main controller 18 for focusing direction estimation.

When the main controller 18 receives the focus direction estimation switching instruction F, the main controller 18 has the initiative in the focusing operation. Then, in step # 4, the estimation operation function 20 of the main controller 18 determines the height of the measurement point k2 based on the coordinates (X, Y, Z) of the measured measurement points k1, k2, for example. Since it is determined that the height is higher than the height k1, the focusing direction is estimated from the determination result, and in the next step # 5, the stage 2 is driven in the Z-axis direction according to the estimated focusing direction.

When the stage 2 is moved up and down in this way, the autofocus controller 17 fetches the sensor signals I1 and I2 as needed to detect whether the objective lens 3 is within the focus detection range W.

When the objective lens 3 enters the focus detection range W, the auto focus controller 17 proceeds to step # 7, informing the main controller 18 of the fact, and regains the initiative of the focus control. Again, the sensor signal I1,
The evaluation value ΔI is obtained by calculating the above equation (3) from I2, a position adjustment signal C is generated so that the evaluation value ΔI becomes “0”, and sent to the stage 2.

As a result, the stage 2 is driven in the Z-axis direction, and the measurement point k2 of the sample 1 is automatically focused on the objective lens 3.

When the autofocus is performed on the measurement point k2 of the sample 1, the height of the measurement point k2 of the sample 1 is obtained based on the focus position.

Thereafter, steps # 1 to # 8 are repeated in the same manner as described above, a focusing operation is performed on each of the measurement points k3 to k6, and the heights of these measurement points k3 to k6 are measured.

As described above, in the first embodiment, it is detected whether the focal position of the objective lens 3 is within the focus detection range W. If the focus position is within the focus detection range W, the automatic focus controller When the autofocusing operation is performed by the camera 17 and the focus is out of the focus detection range W, the operation is switched to the manual operation, the stage 2 is moved up and down, and the objective lens 3 is moved.
Is detected within the focus detection range W,
Since the autofocus is performed by regaining the control from the manual operation, even if the focus position of the objective lens 3 is out of the focus detection range W, the stage is manually operated without performing the time-consuming conventional search operation. 2 can be moved at high speed to bring the focal position of the objective lens 5 within the focus detection range W with respect to the inspection surface of the sample 1, and the autofocus operation for the sample 1 can be performed.

The teaching function 19 of the main controller 18 teaches each coordinate (X, Y, Z) of a plurality of measurement points k1 to k6 on the sample 1 including the Z-axis direction.
When the instruction F for estimating the focusing direction is received, the focusing direction is estimated based on the taught coordinates (X, Y, Z), and the stage 2 is operated in accordance with the focusing direction to focus the objective lens 3. Since the autofocus operation is performed on the sample 1 within the detection range W, even if the sample 1 has a step exceeding the focus detection range W of the autofocus, the conventional search operation is performed. It is possible to auto-focus on each of the measurement points k1 to k6 at high speed without measuring the height of the measurement points k1 to k6.

Therefore, the objective lens 3 is moved by the search operation.
Is not put in the focus detection range W, but the focusing direction is estimated from the coordinates (X, Y, Z) of the measurement points k1 to k6 at the time of teaching, so that the focus detection range W is widened. As described above, the autofocus operation can be performed, and the height can be measured at a plurality of measurement points k1 to k6 having steps at high speed.

(2) Next, a second embodiment of the present invention will be described with reference to the drawings.

FIG. 8 is a configuration diagram of an automatic height measuring device to which a focusing device using a passive type autofocus is applied.

The sample 1 is placed on a stage 2 operating in the XYZ axis directions. Above this stage 2, a laser light source 30 is arranged. A beam splitter 32 and an objective lens 33 of a scanning optical system 31 are arranged on the optical axis of the laser light output from the laser light source 30, and the laser light passes through the beam splitter 32 and the objective lens 33 to the sample 1. Irradiated.

On the reflected light path of the beam splitter 32,
A light receiving element 35 is arranged via a condenser lens 34. The light receiving element 35 irradiates the sample 1 with the laser light output from the laser light source 30, receives the reflected light, and outputs an electric signal (hereinafter, referred to as a sensor signal) corresponding to the amount of the received light. is there.

The signal level of the sensor signal output from the light receiving element 35 varies depending on the relationship between the relative positions of the sample 1 and the objective lens 33 as shown in FIG. 9, and shows the maximum value at the in-focus position. This is because the amount of received light becomes maximum at the in-focus position.

The sensor signal output from the light receiving element 35 is sent to the auto focus controller 36.

This auto focus controller 36
Detects whether the focus position of the objective lens 33 is within the focus detection range W based on the signal level of the sensor signal output from the light receiving element 35. If the focus position is within the focus detection range W, the stage 2 When the focus is outside the focus detection range W, an instruction Q for switching to manual operation is issued to the main controller 37, and the stage 2 is quickly moved in the Z-axis direction by the manual operation. Objective lens 3
When the camera 3 is brought into the focus detection range W, it has a function of regaining control from the main controller 37 and performing a focusing operation.

At the time of automatic height measurement, if the objective lens 33 is out of the focus detection range W, the auto focus controller 36 issues a focus direction estimation switching instruction F to the main controller 37. ing.

More specifically, the auto focus controller 3
6 reads a sensor signal of the signal level shown in FIG. 9 output from the light receiving element 35 as needed, generates a position adjustment signal C such that the sensor signal indicates a peak value, and generates a position adjustment signal C.
Has the function of sending to

The auto focus controller 36
Is a threshold Th in the sensor signal as shown in FIG.
Two or more ranges are defined as the focus detection range W.

The auto focus controller 3
Reference numeral 6 has a function of driving the laser light source 30.

The main controller 37 comprises a personal computer and controls the operation of the entire measuring instrument. The main controller 37 has a function of communicating with the autofocus controller 36, a function of driving the stage 2 in the XYZ axis directions, and a height. It has a teaching function 19 at the time of automatic measurement and an estimation operation function 20. Among them, the teaching function 19 and the estimation operation function 20 have the same functions as the teaching function 19 and the estimation operation function 20 described in the first embodiment, and a description thereof will be omitted.

The main controller 37 issues a switching instruction Q from the autofocus controller 36 to a manual operation.
When the stage 2 is received, the stage 2 is raised or lowered in response to the operation of the up button 21a or the down button 21b of the focusing operation section (manual operation section) 21.

Next, the operation of the measuring instrument configured as described above will be described.

When laser light is output from the laser light source 30, the laser light passes through the beam splitter 32 of the scanning optical system 31, is condensed by the objective lens 33, and irradiates the sample 1.

The reflected light from the sample 1 returns on the optical path opposite to the laser beam irradiation on the sample 1, passes through the objective lens 33, enters the beam splitter 32, is reflected by the beam splitter 32, and is collected. The light is condensed by the optical lens 34 and enters the light receiving element 35.

The light receiving element 35 outputs a sensor signal according to the amount of received reflected light. Then, the sensor signal is sent to the auto focus controller 36.

This auto focus controller 36
Is a threshold Th in the sensor signal as shown in FIG.
Two or more ranges are defined as focus detection ranges W.

At the same time, the autofocus controller 36 detects whether or not the objective lens 33 is within the focus detection range W based on the signal level of the sensor signal output from the light receiving element 35. If so, a position adjustment signal C whose sensor signal indicates a peak value is generated and sent to the stage 2.

Thus, the stage 2 is driven in the Z-axis direction, and the sample 1 is automatically focused on the objective lens 33.

On the other hand, if the focus position of the objective lens 33 is outside the focus detection range W, the auto focus controller 3
6 issues an instruction Q for switching to the manual operation to the main controller 37.

When the main controller 37 receives the instruction Q for switching to the manual operation, the main controller 37 has the initiative of the focusing operation. In this state, the up button 21a or the down button 21b of the focusing operation unit 21 is operated manually. Then, the stage 2 is driven at a high speed in the Z-axis direction in response to the manual operation.

As described above, when the stage 2 is driven by manual operation, the auto focus controller 36 fetches a sensor signal at any time and
Is detected within the focus detection range W.

When the focus position of the objective lens 33 enters the focus detection range W by manual operation, the auto focus controller 36 issues a stage control request R to the main controller 37 to regain control of the focus control. Then, a position adjustment signal C whose sensor signal indicates a peak value is generated again and sent to the stage 2.

Thus, the stage 2 is driven at a predetermined pitch in the Z-axis direction, and the sample 1 is automatically focused on the objective lens 33.

When the autofocus is performed on the sample 1 in this manner, the sample 1 is set based on the focus position.
Height is required.

Next, the automatic height measurement will be described.

With the sample 1 fixed on the stage 2,
The teaching function 19 in the main controller 37 is started. As in the first embodiment, the teaching function 19 is used for each measurement point k1 on the sample 1 as shown in FIG.
Ｋk6 are stored as coordinates (X, Y, Z) including the Z-axis data in the height direction.

When the teaching is completed, the main controller 37 determines the measurement path from the coordinates (X, Y, Z) of the measurement points k1 to k6, for example, the measurement points k1 to k6.
Decide according to the directions.

When the automatic height measurement starts, the main controller 37 moves the stage 2 so that the measurement point k1 on the sample 1 is positioned below the optical axis of the objective lens 33 according to the measurement path.
Is moved in the XY axis directions.

Next, when the measurement point k1 on the sample 1 is positioned below the optical axis of the objective lens 33, the main controller 37 issues a focusing operation instruction to the autofocus controller 36.

In response to the instruction of the focusing operation, the auto focus controller 36 moves the stage 2 at a predetermined pitch in the Z-axis direction, and the threshold value Th2 in the sensor signal output from the light receiving element 35 in the same manner as described above. The above range is defined as a focus detection range W.

Here, the heights (Z-axis direction) of the measurement points k1 to k6 are in a positional relationship as shown in FIG. 7, and the focus detection range W of the auto focus at the start of the measurement is shown in FIG. , The auto focus controller 17
Detects that the measurement point k1 is within the focus detection range W, detects whether the objective lens 33 is within the focus detection range W based on the signal level of the sensor signal, and If so, a position adjustment signal C whose sensor signal indicates a peak value is generated and sent to the stage 2.

Thus, the stage 2 is driven in the Z-axis direction, and the sample 1 is automatically focused on the objective lens 33.

When autofocus is performed on the measurement point k1 of the sample 1, the height of the measurement point k1 on the sample 1 is obtained based on the focus position.

Next, the main controller 37 determines that all the measurement points k
It is determined whether or not the height measurement at 1 to k6 has been completed. Here, since only the measurement at the measurement point k1 has been completed, the next measurement point h2 is positioned below the optical axis of the objective lens 33. Then, the stage 2 is moved in the XY axis directions.

Next, when the measurement point k2 is positioned below the optical axis of the objective lens 33, the main controller 37
An instruction for a focusing operation is issued to the autofocus controller 36.

This auto focus controller 36
Detects whether the objective lens 33 is within the focus detection range W with respect to the measurement point k2 of the sample 1 in the same manner as described above.

The measurement point k2 is, as shown in FIG.
Higher than 1, the auto focus controller 36
It is detected that it is out of the focus detection range W.

Therefore, the auto focus controller 3
6 issues to the main controller 37 an instruction F for switching the focus direction estimation.

When the main controller 37 receives the focus direction estimation switching instruction F, it has the initiative in the focusing operation. Then, the estimating operation function 20 of the main controller 37 outputs, for example, the measurement point k1,
Since it is determined that the height of the measurement point k2 is higher than the height of the previous measurement point k1 based on the coordinates (X, Y, Z) of k2, the focusing direction is estimated from this determination result, and the estimated The stage 2 is driven in the Z-axis direction according to the focus direction.

When the stage 2 is moved up and down in this way, the autofocus controller 36 fetches sensor signals as needed to detect whether the objective lens 33 is within the focus detection range W.

Then, when the objective lens 33 is in the focus detection range W
When the vehicle enters the range, the auto focus controller 36 issues a stage control request R to the main controller 37 to regain the initiative of the focus control, and again generates the position adjustment signal C such that the signal level of the sensor signal indicates the peak value. To stage 2.

As a result, the stage 2 is driven in the Z-axis direction, and the measurement point k2 of the sample 1 is automatically focused on the objective lens 33.

When the autofocus is performed on the measurement point k2 of the sample 1, the height of the measurement point k2 of the sample 1 is obtained based on the focus position.

Thereafter, in the same manner as described above, a focusing operation is performed on each of the measurement points k3 to k6, and the heights of these measurement points k3 to k6 are measured.

As described above, according to the second embodiment, it is needless to say that the same effects as those of the first embodiment can be obtained, and further, the configuration can be made simpler than that of the first embodiment. .

Further, since the focus is determined based on the intensity of the reflected light from the sample 1, it can be applied to a scanning optical system such as a laser microscope.

The present invention is not limited to the first and second embodiments, but may be modified as follows.

For example, in the first and second embodiments, the case of using the confocal method and the passive type autofocus has been described. However, other methods of autofocus such as the phase difference method, the astigmatism, Method, optical lever method, pupil division method, image projection method, or the like may be used.

The auto-focus controller 17,
Although the main controller 36 and the main controllers 18 and 37 are configured separately, they can be realized by the same controller or by a combination of a focus detection unit and a control unit. In this case, the switching of the control is performed inside the control unit.

When automatically measuring the heights of a plurality of measurement points k1 to k6, the autofocus at these measurement points k1 to k6 is not limited to being performed based on the taught coordinates. The objective lens may be once raised to a predetermined height position for each of k1 to k6, and the objective lens may be lowered from this height position to focus on each of the measurement points k1 to k6.

Further, autofocusing at each of the measurement points k1 to k6 may be performed based on the design data of the sample 1.

[0124]

As described above in detail, according to the present invention, it is possible to provide a focusing device capable of performing focusing with a wide focusing detection range without increasing the number of sensor systems and without making adjustments.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an automatic height measuring device to which a first embodiment of a focusing device according to the present invention is applied.

FIG. 2 is a diagram showing signal levels of sensor signals output from light receiving elements used in a detection optical system of the measuring instrument.

FIG. 3 is a diagram showing a signal level of an evaluation value obtained by an autofocus controller of the measuring instrument.

FIG. 4 is a diagram showing a focus detection range in auto focus.

FIG. 5 is a diagram showing measurement points during teaching during automatic height measurement.

FIG. 6 is a flowchart of automatic height measurement in a measuring instrument.

FIG. 7 is a schematic diagram showing the height of each measurement point on a sample.

FIG. 8 is a configuration diagram of an automatic height measuring device to which a second embodiment of the focusing device according to the present invention is applied.

FIG. 9 is a diagram showing a focus detection range in auto focus.

[Explanation of symbols]

 1: sample, 2: stage, 3: objective lens, 4: dichroic mirror, 5: observation optical system, 6: laser diode (LD), 7: collimator lens, 8: deflection beam splitter, 9: 1/4 wavelength plate , 10: detection optical system, 11: condenser lens, 12: beam splitter, 13, 15: pinhole plate, 14, 16: light receiving element, 17: autofocus controller, 18: main controller, 19: teaching function, 20 : Estimation operation function 21: Focusing operation unit 30: Laser light source 31: Scanning optical system 32: Beam splitter 33: Objective lens 34: Condensing lens 35: Light receiving element 36: Autofocus controller 37: Main controller.

Claims (2)

[Claims] 1. A focusing device for receiving light from a sample by a light receiving means through an optical system and focusing the optical system on the sample based on an electric signal corresponding to the amount of received light. Main control means for relatively moving and controlling the distance between the sample and the optical system, and focusing the distance between the sample and the optical system based on the electric signal according to the amount of light received from the sample. It is detected whether it is within the detection range, and if it is within this focus detection range, the optical system performs a focusing operation on the sample. Command to switch to manual operation, and when it is within the focus detection range,
An autofocus control means for performing the focusing operation by regaining control from the main control means. 2. A teaching function for teaching position data of a plurality of measurement points including a height direction on the sample, and a main control means receiving a switching instruction from the auto focus control means to a manual operation. Estimating means for estimating a focusing direction based on the taught position data, and relatively controlling movement of an interval between the sample and the optical system according to the focusing direction. 2. The focusing device according to claim 1, wherein