JPS58179947A - Optical head driver - Google Patents

Abstract

PURPOSE:To ensure the accurate focusing to the surface of a specimen different in thicknesses, by giving an electric conversion to the beam reflected from a surface to be insepected to obtain a signal and then shifting an optical head toward the optical axis in response to the thickness of the specimen and on the basis of the signal obtained from the above-mentioned electric conversion. CONSTITUTION:A specimen 42 is put on a turntable 40. The laser beam emitted from a laser device 32 irradiates a surface to be inspected via a polarized beam splitter 34, a 1/4 wavelength plate 36, a total reflection mirror 38 and an objective lens within an optical head driver 48. The reflected light goes backward to be reflected by the splitter 34 and then made incident to a detector 46. The detecting signal of the detector 46 is fed to a focus signal circuit 51 to be processed. Thus a focus signal is produced in response to the volume of the reflected laser beam. This focus signal is fed to a focus motor of the driver 48. With revolutions of the focus motor, an inner barrel containing an objective lens moves along the optical axis and stops at the focused position. Thus it is possible to ensure the accurate focusing to the surface 50 even with a specimen different in thicknesses.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical head driving device, and particularly to an optical head driving device for driving an optical head that irradiates a laser beam onto the surface of an object to be inspected such as a glass original plate for an optical video disk or an IC wafer.
It relates to a device for matching the focal point onto the surface.

The optical head is applied, for example, to an apparatus shown in FIG. 1 for inspecting defects occurring on an optical surface. This inspection device includes a laser device 4, a polarizing beam splitter 6, a wavelength plate 8, a total reflection mirror 10, a detector 12 for optical-to-electrical conversion, and an optical helad 14 in a head support 2 that is moved in the X direction. The objective lens 16 is composed of equal power. Stage 2 moved in the Y direction on the stage base 18
An object to be irradiated, such as a glass original plate 22 for a video disc, is placed on the substrate 0 . In such a force device, L
A laser beam is generated from the laser device 4, and this laser beam is polarized by a polarized beam.
The light passes through the total reflection mirror 10 and the objective lens 16, and is focused onto the inspection surface 24 of the glass original plate 22. and,
The reflected laser beam reflected by the inspection surface 24 is again guided to the detector 12 via the objective lens 16, the total reflection mirror 10, the 1/4 wavelength plate 8, and the polarizing beam smitter 6. Defects such as scratches and dust on the inspection surface z4 are inspected based on the intensity of the detected reflected laser beam. Therefore, in such an inspection apparatus, in order to properly introduce the reflected laser into the optical head 14, it is required that the focus of the objective lens 16 is accurately aligned on the inspection surface 24, and when an IC wafer, etc. Original glass plate 2 like
For those thinner than 2, the inspection surface has a minute depth of focus of the objective lens 16 (for example, if the spot diameter of the laser beam is 2 μm or less, the depth of focus is 1 to 2 μm).
There was a problem in which the test piece could not be inspected because it came off. In addition, in order to eliminate such a problem, it may be possible to perform focusing by moving the objective lens I6 along the optical path of the laser beam, but in this case, the objective lens I6 may be moved along the optical path of the laser beam. There was a risk that the optical axis of the laser beam would be tilted and the laser beam would not be irradiated along this optical axis.

The present invention was made in view of the above-mentioned circumstances, and provides a device that drives an optical head and accurately focuses the object on the surface of the object, even when the object has an optical plane with different thickness. It is on offer. Referring to the drawings below,
An embodiment of this invention will be described.

Figure WJ2 schematically shows a part of an apparatus for inspecting defects occurring on the surface of a glass original plate for an optical video 7'4 screen to which the apparatus for driving an optical head of the present invention is applied. This surface defect detection device gL is X”f”l K # @ −g
t'L6"y)"1"°00.1 Inside the head support 30, there are a laser device 32 such as an H.-Ne laser, a polarizing beam splitter 34, a wavelength plate 36, and a total reflection mirror 38. is placed, and
This head support 30 is provided with an optical head drive device 48 . Further, a turntable 40 is disposed below the lower pick head support 3o of the optical/RAD drive device 48, and an inspection surface 5o of a glass original plate for a video disk, an IC wafer, etc. is placed on this turntable 40.
A subject 42 having the following characteristics is placed. - Also connected to a turntable 40ii and a turntable 44, this motor 4
4, it is rotated in the R direction at a constant speed. A detector 46 is provided on the optical path of the reflected laser beam guided from the polarization beam smitter 34, and this detector 46 generates a detection signal based on the amount of reflected light. In addition, the detector 4
6 is connected to a circuit 51 that processes the detection signal and generates a focus signal for operating the optical head drive device 48. The detection signal is sent to the focus signal generation circuit 51 and a defect determination circuit (not shown).

The optical head drive device f1148 is constructed as shown in FIG. That is, an optical head 52 provided within the device 48
is attached to the head support member 3o via an optical head drive mechanism 54, and is placed on the optical path of the laser beam reflected from the total reflection mirror 38 by the optical head drive mechanism 54. . That is, the optical head drive mechanism 54 includes an outer cylinder 56, and the outer cylinder 56 is attached to one end of the head support 3o.

Further, an internal thread 58 is formed on the inner surface of the outer cylinder 56, and the internal thread 58 is made by a company such as lead 0.75. pitch 0
．． 75 single thread screw. A middle cylinder 60 is screwed inside the outer cylinder 56. That is, a male thread 62 that engages with the female thread 58 is formed on the outer surface of the middle cylinder 6o, so that the middle cylinder 6o is screwed and attached to the outer cylinder 56. Further, a female thread 64 is formed on the inner surface of the middle cylinder 6o, and this female thread 64 is, for example, a 14-thread thread with a lead 21 pitch of 1.5. An inner cylinder 66 is further screwed inside the middle cylinder 6o. That is, the optical head 52 is fitted and attached to the outer surface of the inner cylinder 66 so as to be engaged with the female thread 64, and the optical path of the laser beam passes through the inner cylinder 66. . An L drive section 70 is provided at 6 degrees of the middle cylinder. The drive unit 70 includes a worm wheel 72 attached to the outer surface of the middle cylinder 60, and the worm wheel 72 is rotatably connected to the middle cylinder 60. The worm wheel 72 meshes with the worm 14. The worm 74 is connected to the focus motor 16 and is rotationally driven by the focus motor 16. Inner cylinder 60
The stock nozzle 78 that prevents the rotation of the stock is fixed at its upper end to the outer cylinder 5C, and its lower end is fitted into a guide groove 80 formed on the inner surface of the inner cylinder 66 along the axial direction of the inner cylinder. There is.

Therefore, the optical head drive mechanism 54 having such a configuration
When the worm 74 is rotated by the focus motor 76 and the middle cylinder 60 is rotated via the worm wheel 12, since the rotation of the inner cylinder 66 is prevented by the stop horn arm 78, the inner cylinder 66 tb , the optical head 52 is moved along the optical path of the laser, ie, along the optical axis of the objective lens 82 while keeping it unchanged.

Further, the focus motor 76 is operated by a focus signal from the focus signal generation circuit 51, as will be described later. The optical head 52 is provided with an objective lens 82 for converging the radar beam onto the inspection surface 50 of the object to be irradiated. Further, a mechanism 83 for driving an objective lens is provided within the optical head 52. This objective lens drive mechanism 83 includes a spring 86, and the objective lens 82
are supported on the optical path of the Lede beam by springs 86. A voice coil 84 and a permanent magnet 87 are arranged above the objective lens 82;
is moved in the direction of its optical axis, that is, along the optical path of the radar. Further, the objective lens drive mechanism 83 is operated by a focus signal similarly to the focus motor 76.

Next, the operation of the apparatus for inspecting defects occurring on the optical surface described above will be explained.

Before the subject 42 is placed on the turntable 4o,
The focus motor 16 of the optical head drive mechanism 54 is rotationally driven, and the optical head 62 is moved to the highest position and maintained in a standby state. In this state, the object 42 is placed on the turntable 4° at the zeroth order, and the Rade device 3z is energized to generate a linearly polarized Rade beam. This laser beam is transmitted through a polarizing beam splitter 34.1
The light is guided to the objective lens 8z via the 74-wavelength plate 36 and the total reflection mirror 38, and is irradiated onto the inspection surface 5o of the subject 42 by the objective lens 82. Then, the laser beam irradiated on the inspection surface 50 is reflected, and the laser beam is reflected again by the objective lens 82, total reflection mirror 31, and 1
The light passes through the /4 wavelength plate 16f and is guided to the polarizing beam splitter J4. When the laser beam that has passed through the beam splitter 34 passes back and forth through the quarter-wave plate 36, the polarization direction of the laser beam is rotated by 90 degrees. The previously reflected laser beam is reflected by the polarizing beam splitter 34,
is guided to a detection device 46.

Then, the detection device 46 generates a detection signal having a level corresponding to the amount of light of the reflected laser beam. This detection signal is sent to a focus signal generation circuit 51 for processing, and the focus signal generation circuit 51 generates a focus signal corresponding to the amount of light of the reflected radar beam. This focus signal is sent to the focus motor 76 of optical head driver #154, and this focus motor 76 is driven. That is, the focus motor 76 is rotated by the focus signal, and the middle cylinder 60 is rotated via the worm 74 and the worm wheel 72. The rotation of the middle cylinder 60 causes the inner cylinder 66 to move upward and downward in the drawing along the optical path of the laser beam, and the distance between the objective lens 82 in the inner cylinder 66 and the inspection surface 50 is It is approximated to the focal length of the lens 82. The rotation of the focus motor 6 is stopped after the distance between the objective lens 82 and the inspection surface 50 approximates the focal length. After the focus motor 76 stops driving, the focus signal is sent to the objective lens drive mechanism 83, and the voice coil 84 and the magnetic circuit 87 move the objective lens 82 in the direction of its optical axis, ensuring that the focus of the objective lens 8z is accurate. is positioned on the inspection surface 50. The focusing of the objective lens 82 is performed as described above.
Optical head drive mechanism 54 and objective lens drive mechanism 83
The optical head driving mechanism 83 and the objective lens driving mechanism 83 are operated by a focus signal based on the amount of reflected laser beam. Note that after the objective lens/lens 82 is focused, the turntable 40 is rotated at a constant speed, and the head support member 30 is moved at a constant speed in the X direction, that is, in the radial direction of the turntable 42. The entire surface of the inspection surface 50 is scanned in a circular manner. The detection signal obtained from this scanning 9 is sent to a defect determining device, and this defect determining device inspects for defects such as scratches and dust on the inspection surface 50. If there is a defect such as a scratch or dirt on the pick or inspection surface 5o, the laser beam will be scattered by the scratch or dirt, and the intensity of the reflected laser beam will be reduced, which will cause the defect to be detected. Ru. Note that the shake of the inspection surface 50 due to the rotation of the turntable 42 during this scanning operation is corrected by the automatic focusing action of the objective lens driver @SS. Therefore, according to such an embodiment, even if the thickness of the object 42 is different, the distance between the objective lens 82 and the inspection surface 50 is approximated to the focal length of the objective lens 82 by the optical head driver $54, The objective lens sliding mechanism 83 allows the objective lens 82 to be accurately focused. As a result, the object 42 to be irradiated may be a glass original plate for a video disk or a glass plate having different thicknesses.
Even if the 1-lase original plate is a thin IC wafer or the like, the objective lens 82 can be easily focused on the inspection surface 5o of the irradiated object 42, making it possible to inspect the inspection surface 50 for defects. The optical head drive mechanism 54 does not directly move the optical head 52 along the optical path of the objective lens 82t and the laser beam, but moves the entire optical head 52 in the direction of the optical path. When the distance between the first objective lens 82 and the inspection T#SO is approximated to the focal length of the objective lens 82, it is possible to prevent the objective lens 82 from collapsing due to the movement, that is, from tilting the optical axis. , the focusing function of the objective lens 82 can be improved. Further, the optical head drive mechanism 54 has a middle cylinder 60.
Since the lead of the female screw 64 is set larger than the lead of the female screw 58 of the outer cylinder 56, the focus motor 7
Even if the amount of rotation is less than 6, the amount of movement of the optical head 52 can be increased. Furthermore, the optical head drive mechanism 54
Since the optical head 5z is screwed into the middle cylinder 60 via the inner cylinder 66, and the middle cylinder 60 is screwed into the outer cylinder 156 for support, it is possible to prevent the optical head 5z from becoming stiff. I can do it. Moreover, since the lead of the female screw 58 of the outer cylinder 56 is as small as 0.75, the weight of the optical head 52 will be explained with reference to FIGS. 4, 5, 6, and 47. . FIG. 94 is a block diagram of the apparatus shown in FIG. 2, and the same reference numerals in the figure indicate the same parts, and the explanation thereof will be omitted. In Figure 4,
Detection device 146 is described in U.S. Application No. 161,428. It is composed of a detection prism 88 and a photodetector 90 as described in the application date 208 June 1980. Regarding this detection device 46, U, S, P 4,079,247
It may also be combined with a cylindrical lens and a photodetector as described in . The photodetector 90 shown in FIG. 4 has two light-receiving areas. It is connected to the input terminal of the regulator 92.

When the optical head 52 is moved to the highest position Lmax sufficiently spaced from the surface 50 of the object to be inspected, the output signal from the comparator 92, that is, the focus signal is
It is maintained at essentially zero level. As the optical head 5z approaches the surface 50 of the object to be inspected, a focus signal as shown in FIG. 5 is generated from the comparator 92. In FIG. 5, the focal point of the objective lens 82, designated F, is located on the plane 50.

The focus signal generation circuit 51 sets the objective lens 82 to a point F.
, so that the optical head drive unit is positioned at
-I am making one. However, if the optical head shifter 48 is operated simply by the output signal from the comparator 92, there is a possibility that it will be determined that the objective lens 82 is located at the point F at the point Fima. This is because the output levels from the comparator 92 are equal at point F. and point F1ma. Therefore, the driver 94 shown in FIGS. 4 and 6 determines whether the objective lens 82 has passed the point Fima and approached the point F6, as described below.

After the optical head 52 has been moved to the top position ffilLmax by the focus motor 76, when a focus command is given to the device from a keyboard (not shown) at time to, the optical head 52 is moved by the focus motor 86.
begins to fall toward plane 50. That is, the flip-frog of driver 94 shown in @6 prisoner 96.98,100
When a high level signal V is applied to the input terminal of C 102 at time t as shown in Figure WJ7, C is applied to the set terminal of flip-flop 98 and the reset terminal of flip-flop 102 as shown in Figure 7 ( Given the set pulse shown in B), the flip flora f9
B is set, and the flip/7o gear 102 is reset. Therefore, from the output terminal Q of the flip-flora f91j, a high level signal is given to the FET J06 of the switching circuit 104 as shown in FIG.
The FET 106 conducts and the focus motor 76 becomes the motor servo amplifier f 10 II , FET 10
6 to a power supply 110 whose supply power can be variably adjusted. Therefore, the focus motor 86 is activated and the optical head 82 begins to descend. Also, from the output terminal Q of the flip-frog 98, the OR Kate 112
A high level signal is given to FET JJ4 through FET JJ4, and focus servo angle 116
1 to ground through voice coil 54Fi, which remains inactivated. The other FETs 117, 11 II, and J 20 of the switching circuit 104 are:
It is maintained in a non-retroactive state.

As the optical head 52 descends, the focus signal shown in FIG. 5 is converted into a comparator 92 and applied to the level shift circuit 121, where its level is shifted by the amount of focus vo. The level shifted focus signal is applied to the inverting input of the first comparator 122 and the non-inverting inputs of the second and third comparators 128 and 130. A voltage (V, -+-v.) is applied to the non-inverting input terminal of the first comparator 122, and voltages (v, +v0) and (V0) are applied to the second and third comparators 128 and 130, respectively. , +Vo) are applied. Therefore, the optical head 5z moves downward to a certain point L.
1t, the focus signal from the comparator 92 reaches the voltage vl, and the level shift circuit 121 transfers the focus signal to each controller 1M1, 11.
8. A signal with the voltage (■, +v0) level shifted is given at 130. Therefore, the first controller arm 12
At time t1, the output of 0-order optical head 52, which is changed from a low level to a high level as shown in FIG. When the focus signal C from the comparator 92 passes through, the level of the focus signal C from the comparator 92 becomes 1 lower than the voltage 1. Therefore, the output line of the comparator 122 of wJl, time 11Ls t, point t
3, the focus signal from the comparator 92 drops below that level or the tortoise pressure v1. Therefore,
The output from the third converter 130 is the 71st trunk)
The level is changed from high level to low level as shown in . Similarly, when the optical head 52 passes through the point 4, the output from the comparator 128 of 182 changes from a high level to a low level as shown in FIG. After passing @ and L@, the second
And the output from the third comparator 12B, 130 is
The level is changed from a low level to a high level as shown in FIG. 1st. The output signals from the second and third comparators 122, 128, 130 shown in FIG. 2nd and 3rd differential +) are supplied to the Mitzter circuit 124.132.134. This differential limiter circuit 124 is set as shown in FIG. 7 1 at the rising edge of a good signal as shown in FIG. 7 υ).
Generates a pulse. In other words, at time tl, the first clip-to-lag 960 input terminal is connected to the
) z + Lus is input and the first clip flon f
96 is set and a high level signal is generated from its output terminal q as shown in FIG.
70 is applied to the input terminal of 126. The second differential limiter circuit 132 generates a set pulse shown in FIG. 7 (IJ) at the falling edge of the signal shown in FIG. Flip
A set pulse is input to the flop 126, and a high level signal shown in FIG. The circuit 134 generates a set signal as shown in the 71st line at the rising edge of the signal shown in the 71st line. In other words, point L6 is input to the third flip-flop 136 at time t@, and the high level signal shown in FIG. 7 is generated from its output terminal Q.

This high level signal is applied to the input terminal of the mono multivibrator 138, the flip-flop f91j, at the time t.
is applied to the reset holder R of and the input holder of the clip frog 100.

Therefore, the mono multivibrator 138 operates from time t6 as shown in the seventh me, and the clip flop 98
is reset, the clip flip 100 is set, and the output terminal of the flip flip 98 changes from high level to low level as shown in the 71st column, and the output terminal of the flip flip 100 changes from high level to low level as shown in the 7th column. The output terminal is
Becomes a high level. As a result, FET 10g becomes non-conductive, FET 116 conductive, motor amplifier 108 is connected to comparator g2, and a focus signal is applied to motor amplifier f101j. At this time t6, FETJ 14 is kept conductive by clip 70 tab 100 and focus amplifier 116 is grounded. The motor control unit 52 descends to the vicinity of the focal point @F, and as shown, the focus signal becomes negative.
As a result, the optical head 5z is raised toward the focal point F6. After a certain period of time r&IJ has elapsed since the optical head 52 rises and falls slightly from time t6, the optical head 52
The movement is stopped, and the objective lens 82 is at the focal position 'f'.
It is located at tF e.

1. When the optical head 52 is moved in one upward direction and has passed from the focal point; 1. When reaching , the mono multivibrator 1311
When the output from FET rises, FET 96, 126, 136 is set, FET 70 is reset, and Clip Frog 102 is set. 116
is made conductive by the high level signal shown in FIG. Therefore, the motor Boo is grounded via the FET 11g. Also, FET 114 is conductive and FET 120
The focus servo amplifier 116 is connected to the comparator 92 via the FET 120, and the focus signal is applied to the focus servo amplifier 116. The gain coil 84 is actuated by the focus signal amplified by the focus servo amplifier f116, and the focus of the cropping lens 82 is adjusted to be located on the plane 50, and even if the plane 50 changes slightly, the focus remains unchanged. It is located on the L1 plane 50.

Next, another embodiment of the present invention will be described with reference to FIG. In FIG. 8, the same parts as shown in FIG. 3 are designated by the same reference numerals, and the explanation thereof will be omitted.

In FIG. 8, it is attached to the outer@56f4 head support 30. An inner tube 66 is fitted inside the outer tube 56, and the inner tube 66 is supported so as to be movable along the optical path of the Lede beam within the outer tube 30. The optical head 5z is fitted into the cylinder 66, and the optical head 52 is placed on the optical path and supported by the inner cylinder. Finally, a rack 140 is provided on the outer surface of the inner cylinder 66, and this rack 140 is connected to a drive section 142. This driving section 142 is composed of a pinion 144 that meshes with the rack 140 and a focus motor 76.
By rotationally driving the inner cylinder 66, the optical head 52 is moved in the optical axis direction of the optical head, ie, in the optical path of the laser, via the pinion 144 and the rack 140. Further, the focus motor 76 is operated by a focus signal. In the past, according to such an example, compared to the embodiment shown in FIG.
Since this is done with a pinion 144 and a pinion 144, the structure can be simplified.

As a result, manufacturing becomes easier and the entire device can be made smaller.

Note that the present invention is not limited to the embodiments described above. For example, the optical head driving device according to the present invention is not necessarily applied only to a surface defect detection device, but is also applicable to video detection using a laser beam. The present invention can also be applied to optical video discs, etc., in which data is recorded on and read from discs.

The detailed circuit shown in FIG. 6 has a configuration corresponding to the focus signal shown in FIG.
No. 079,247, which is not applicable to the detection device consisting of a combination of a cylindrical lens and a photodetector, but as mentioned above and explained above, the present invention makes it possible to The optical head drive mechanism that moves the optical head along the optical path of the Rade beam according to the thickness of the object to be irradiated based on the signal obtained by electrically converting the reflected laser light from the irradiation surface is installed in J! Even when the thickness of the irradiated object is different,
The optical head drive mechanism allows the objective lens in the optical head to be automatically focused. Further, since the optical head sliding mechanism does not directly move the objective lens but moves the entire optical head, it is possible to prevent the objective lens from collapsing and to achieve the above-mentioned focusing accurately.

[Brief explanation of the drawing]

FIG. 1 is a perspective view schematically showing a defect inspection device incorporating a conventional optical head, and FIG. 2 is a perspective view schematically showing a defect inspection device incorporating the optical head drive device of Jin's invention. Figure 3 is a WaI side view showing the optical head drive device shown in FIG. 2 in detail, Figure WJ4 is a block diagram showing the optical head drive device shown in FIG. 2, and FIG. FIG. 6 is a circuit diagram showing the blocks of tJA4 in detail, and FIG. 97 is a time chart showing the operation of each part of WJ6. 2... Head support body, 4... Laser device, 14.
...Optical head, 18.. Stage base, 22.. Glass original plate, 24.. Inspection direction, 30.. Head support.
32 Laser device, 34... Polarized beam sgelitter, 38... Total reflection mirror, 42... Subject, 46
... field detector 48 ... optical head drive device, 51.
... Focus signal generation circuit, 54. Optical head drive mechanism, 56.. Outer cylinder, 60.. Middle cylinder, 66.. Inner cylinder, 70.. Drive section, 76.. Focus motor,
78...stopper, 82...objective lens, 84...
Discoil, 86...Spring, 94...Driver, 104...Switching circuit, 108...Motor servo amplifier, 116...Focus servo amplifier, 121... Level shift circuit, 124
゜132.134... Differential limiter circuit, 138...
・Mono multi pie break. Applicant's representative Patent attorney Takehiko Suzue (Continued from Figure 3, page 1) Author: Kunio Yamamiya, 2-43-2 Hatagaya, Shibuya-ku, Tokyo, Japan Lymphus Optical Industry Co., Ltd. Author: Yoshi Kato, Tokyo 2-43-2 Hatagaya, Shibuya-ku, Miyako, 1, Lymphus Optical Industry Co., Ltd., Incident Display I! ! fill No. 57-62948 2, Name of the invention Optical head drive device 3, Person making the amendment Relationship to the case Patent applicant (037) Orinno 4S Optical Industry Co., Ltd. 4, Agent 5, Voluntary amendment 7 Contents of the amendment 111 The scope of claims is amended as shown in the attached sheet. (21 Specification, page 2, line 10 and l @ line 11, l2 [
This inspection device is... Laser device 4] [This inspection device is a radar device inside the head support 2]
I am corrected. (3) Lines 3 and 4 of No. 40 of the specification “In this case (
In 2, the above movement (:) is corrected to ``In this case (2, in 2, if the moving distance of the objective lens is large, the above movement 12''). (4) Specification No. 4α, line 17, ``X Direction CJ to “X”
(5) In the specification No. 5, line 13, “Reflected light lI =
The original detection signal is corrected to 1 according to the light intensity of the reflected light. (6) Specification W, 7α 7th α [The description 1 for the optical head 52 is corrected as [The housing 81 of the optical head 52 is]. (7) Specification No. 8jW line tt and 12th line l
2. The phrase "52 inside the optical head 52" is corrected to "1 inside the housing 8 of the optical head 52." 18) Lines 10 and 11 of page 10 of the specification (
2. The phrase ``focus signal corresponding to the optical mold of the reflected radar beam,'' is corrected to ``focus signal corresponding to the distance 52 between the focal plane of the objective lens 82 and the inspection surface 50.'' (9) On page 11, line 9 of the specification, "located." is corrected to "matched." Ql Specification page 11, line 14 and line 15 C:
The phrase "a focus signal based on the light weight 52 of the reflected radar beam" is corrected to "a focus signal based on the distance between the focal plane of the objective lens 82 and the inspection surface 50." 01) Change “X direction” on page 11 of the specification, line 18 of 8ft to “
"X direction" 52 Correct. az In the 3rd and 4th lines of page 13 of the specification, “
"Laser light" is corrected as "Lede beam" (=correct. a3 In the specification, 14i, 18th line, 151' (
2nd line, 15α, 6th line, 15th page, 13th line, 15fi, 17th line, 17th page, 13th line, 1811
5th line, 18th member, 19th line, 15α, 6th line, and 23rd @ 4th line (2) Correct "con-f-factor 921" to "differential amplifier 921. α Brown Details 16fi, line 5 of the specification and page 17 of the specification, line 2 ≦ 2 ``Focus motor 86'' is corrected to ``Focus motor ye Jr.''. Head 82"
Correct "optical head 52" C2. (To) Specification WL page 17, line 12 g = Between “optical head 52” and “1 F” 6; [Inspection surface 5 (j
Add 4 towards l-. αη Specification page 17, line 24, line 15 and line 1
In the sixth line, the line ``is applied to the system shift circuit 121, and its level is shifted by the force v0.The focus signal whose level has been shifted is'' is deleted. (To) Specification @ page 17, line 2o [Voltage (v, +v.)] is changed to [1! Pressure (Vl) Jg2 Correct. 09 Specification page 18, 2nd and 3rd lines “Voltage (
v, +v. ) and (■, +v0)” as [voltage cl and (
V l ) Correct to J. ■ Page 18 of the specification, line 6, line 7, line 8, line 9, and line 1O, i2 "And then...
Given. Therefore, the phrase ``output of the first converter 122'' is corrected to ``when the level reaches the voltage V, the output of the first converter 122''. Ql) "FET116" on page 21, line 9 of the specification is rF
ET J J yJ r2 Correct. (2) Specification wJ page 22, lines 6 and 7, g = "The objective lens 82 is located at the focal position F0." [The 1° focal position F of the objective lens 82 is inspected] It is located on the plane 50. ] Correct. (C) Specification No. 22 [1st line O] [Correct setting time Tf5J to "setting time T0". 04) Page 22, lines 14 and 15 of the specification
2. The phrase "Flip flop f100 has been reset" has been changed to "Flip flop 98°100 has been reset."
I am corrected. (c) Page 18, line 6 of the specification and! 17th line feeling = “F
ET116 is conductive, FBTJJ8 is ``[F
ET 118 and FBT 120]. (b) In line 23αg of the specification, ``continuity'' is corrected to ``interruption.'' C Jun Specification No. 26fi$, line 16, ``converter'' is corrected to ``differential amplifier.'' Seiji On page 26, lines 19 and 20 of the specification, the phrase “time chart” was replaced with “time Φ chart,”
and FIG. 8 are partial sectional views of an optical head driving device according to a second modified embodiment of the present invention. ” he corrected. (Among the drawings in Figure 21, Figures 1, 2, 3, 4, and 6 are corrected to the attached drawings.) 2. an optical head comprising an objective lens for directing a laser beam reflected from a surface to be inspected and a beam splitter for directing a laser beam reflected from a surface to be inspected; a mechanism for moving the optical head along its optical axis; a mechanism for moving along two axes, and a reflective laser beam directed from the beam splitter.
means for detecting the beam and generating a focus signal at a level having a correlation with the distance between the objective lens and the object plane; and means for supplying the focus signal to the optical head until the focus signal reaches a certain level 52; an optical head drive circuit that operates the mechanism; and an objective lens drive circuit that operates the objective lens moving mechanism in response to a supplied focus signal after the optical head is positioned at a predetermined position. An optical head drive device comprising:

Claims (1)

[Claims] An optical head is provided with an objective lens that directs the introduced laser beam toward the surface to be inspected, a beam splitter that directs the laser beam reflected from the surface to be inspected in a certain direction, and the optical head is moved along its optical axis. a mechanism for moving an objective lens along its optical axis; and a mechanism for detecting a reflected radar beam directed from the beam sgeritter and determining an inter-hole relationship at a distance between the objective lens and the object plane. means for generating a focus signal of a certain level; an optical head drive circuit that is supplied with this focus signal and operates the optical head mechanism until the focus signal reaches a certain level; and an objective lens drive circuit that operates the objective lens moving mechanism in accordance with a supplied focus signal after the optical head is positioned at a QIF position.