JPH0457230A - Floating type optical head - Google Patents

Abstract

PURPOSE:To make a movable part light in weight and compact by separating a signal corresponding to the shifting amount of tracking into high frequency side and low frequency side signals and controlling a driving means and a tracking control means by the respective separated signals. CONSTITUTION:A tracing error signal 32 is separated into two frequency components of low frequency side and high frequency side signals by an LPF circuit 30 and an HPF circuit 31. The circuits 30 and 31 are respectively connected to phase compensating circuits 33 and 34 and respectively connected through drive control circuits 35 and 36 to a linear motor 7 and an actuator 37. Thus, since it is not necessary at all to provide any members for tracking control at the movable part, the movable part of a floating type optical head 1 can be made light in weight and compact, the rigidity of the movable part can be improved and access can be performed at high speed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical head used in an optical information recording/reproducing device, and in particular, an optical head consisting of a fixed part and a movable part. This invention relates to a floating optical head that maintains an objective lens incorporated in a floating optical head in a floating state due to a dynamic pressure air bearing effect.

[Conventional technology]

Conventionally, as this type of floating optical head, there is one shown in, for example, Japanese Utility Model Application Laid-Open No. 63-55211. This floating optical head has an objective lens 1, as shown in FIG.
Movable part 10 having a slider 101 incorporating 00
2, and a fixed part 105 having a light source 103 and a detection system 104.
and a slider 1 incorporating an objective lens 100.
01 from the surface of the optical disk 106 by the hydrodynamic air bearing effect, and the objective lens 100 and the optical disk 106
While keeping the distance approximately constant, the optical disc 10
A focusing lens 107 provided on a fixed part 105 corrects focus errors caused by changes in the flying height due to surface wobbling of the lens 6.
This method employs a focus control method that corrects the

In the above floating optical head, automatic focus control is performed by the focusing lens 107 provided in the fixed part, so there is no need to provide an objective lens actuator for automatic focus control in the movable part 102 of the optical head. Therefore,
This is a promising technology that can make the movable part 102 of the optical head significantly smaller and lighter than conventional optical heads, and can achieve faster access.

However, although the floating optical head proposed above has a unique configuration for automatic focus control as described above, it uses a conventional method for tracking control, which causes the following problems. have. That is, as shown in FIG.
A tracking actuator 108 is incorporated in the , and this tracking actuator 108 is composed of a tracking coil 109 provided on the side of the slider 101 incorporating the objective lens 100, and a permanent magnet 110 provided on the side of the movable part 102. . Then, a tracking actuator 108 provided in the movable part 102 corrects minute tracking errors of the floating optical head, and performs random access movement of the optical head to other targeted tracks. It is configured to be driven by a near motor 111 toward the inner and outer peripheries of the optical disc 106 .

Therefore, in the floating optical head, it is necessary to mount a tracking actuator 108 consisting of a permanent magnet 110 and a tracking coil 109 on the movable part 102 that moves by the access operation, and the movable part 102 is lighter than before. However, the weight increases due to the mounting of the tracking actuator 108, and there is a problem that sufficient acceleration to achieve high-speed access cannot be obtained.

Therefore, the present applicant solved the problems of the device according to the above proposal and made it possible to further reduce the weight and size of the movable part, thereby achieving high-speed access. In addition to this, a floating optical head has already been proposed in which tracking control is performed solely by a linear motor used for access operations (36th Japan Society of Applied Physics Academic Conference 2p-ZB-5°6 (1989)).

This floating optical head has a movable part 1 as shown in FIG.
20, slider 121, objective lens 122 and mirror 1
The movable part I20 is connected to a linear motor 124 used for access operation, while the fixed part 125 is comprised of a light source 126, a light detection system 127, a relay lens 128 for adjusting the focus, and the like. and,
Focusing control is performed by following the surface of the disk 129 with the slider 121 and driving the relay lens 128, and tracking and seek operations are performed only by a single linear motor 124 that drives the movable part 120.

In the case of the floating optical head according to this proposal, the movable part 12
Since there is no need to provide a tracking actuator at the movable part 120, the movable part 120 can be significantly reduced in weight and size, and high-speed access can be achieved.

[Problem to be solved by the invention]

However, the above conventional technology has the following problems. That is, in the case of the floating optical head proposed above, since both the tracking and seek operations are performed by only a single linear motor 124, the movable part 120 of the optical head follows one track. The linear motor 12 also controls fine tracking.
4 has no choice but to be carried out.

However, in order to control this fine tracking,
It is necessary to control the drive of the linear motor 124 in a high frequency band, but due to the inertial mass of the movable part 120 of the floating optical head and the linear motor 124 itself, the drive control of the linear motor 124 in the high frequency band is difficult. As shown in the figure, it becomes unstable.

Therefore, in order to avoid unstable drive control of the linear motor 124 and operate the servo system that controls the tracking operation in a stable state, it is necessary to
In accordance with the frequency characteristics of 24, the frequency band of tracking servo control must be set low and narrow.

As a result, the response speed of the linear motor 124 becomes slow,
It becomes difficult to perform tracking that immediately controls minute tracking deviations, and a new problem arises in that sufficient tracking accuracy cannot be obtained.

[Means to solve the problem]

Therefore, the present invention was made to solve the above-mentioned problems of the prior art.The purpose of the invention is to significantly reduce the weight and size of the movable part of a floating optical head, and to provide access to the floating optical head. It is an object of the present invention to provide a flying optical head that is not only capable of achieving higher speeds but also capable of controlling tracking with high precision.

That is, the present invention includes an objective lens for converging a laser beam onto an optical disk, and a system in which the objective lens is made to float above the surface of the optical disk by a hydrodynamic air bearing effect.
a movable part that has a slider for keeping the distance between the objective lens and the optical disc substantially constant and is driven along the radial direction of the optical disc by a driving means; a light source for the laser beam; and a shift in focusing and tracking. In a floating optical head, the floating optical head includes a fixed part having a detection means for detecting the amount of light, and a focusing control means for controlling focusing based on a detection signal from the detection means. a tracking control means for performing tracking control optically; a signal separation circuit for separating a signal corresponding to the amount of tracking deviation outputted from the detection means into a high-frequency side signal and a low-frequency side signal; and the signal separation circuit. a first drive control circuit that controls driving of the drive means based on a low frequency signal separated by the circuit; and a tracking control circuit that controls the drive of the drive means based on a high frequency signal separated by the signal separation circuit. The second drive control circuit controls the drive of the drive control circuit.

The detection means for detecting the focusing shift amount includes, for example, a knife 22 that blocks one side of the laser beam LB focused by the condensing lens 21, and a laser beam LB taken out by the knife 22. Although a two-segment light receiving element 23 that receives light is used, the present invention is not limited to this, and a combination of a cylindrical lens and a four-segment light receiving element or the like may also be used.

Further, as a detection means for detecting the amount of tracking deviation, for example, the condenser lens 21 and the two-split light receiving element 23 are used.
The one consisting of is used.

Furthermore, the focusing control means includes, for example, a convex diffusing lens 15 that focuses the laser beam LB on a focal point F and diffuses it from the focal point F, and a diffusing convex lens 15 that converts the diffused laser beam LB into parallel light and directs it to the movable part 2. Although a convex focusing lens 16 is used, the present invention is not limited to this, and it is of course possible to use focusing control means consisting of a combination of other concave lenses and convex lenses.

In the embodiment described below, the convex diffusion lens 15 of the relay lens 17 is used as the tracking control means.
A case will be explained in which a device that moves the optical axis in a direction perpendicular to the optical axis is used, but the invention is not limited to this.
As shown in Figure (b), tracking control may be performed by moving the converging convex lens 16 of the relay lens 17 in a direction perpendicular to the optical axis. In this case, as shown in the figure, the convex diffusion lens 15 of the relay lens 17 is moved in the optical axis direction to control focusing.

Further, in the above embodiment, the convex diffusion lens 15 of the relay lens 17 is moved in a direction perpendicular to the optical axis to perform tracking control, and the convex convergence lens 16 of the relay lens 17 is moved in the direction of the optical axis. Although the case where focusing control is performed has been described, the present invention is not limited to this, and as shown in FIG. 9(a), one of the convex lenses 15 or 16 (in the illustrated example,
The convex lens 15)
Controlling both focusing and minute tracking with one actuator by using an actuator that can be driven in the axial direction and driving this actuator according to the higher frequency side of the focusing error signal and the tracking error signal. I can do it.

In this case, the actuator may be placed at any position of the relay lens F on the diffusion convex lens 15 side or the convergence convex lens 16 side.

By the way, minute tracking control as described above may be performed by any lens of the relay lens 17 on the side of the convex lens for diffusion 15 or the side of the convex convex lens for convergence 16, or by the lens of the relay lens I7 on the side of the convex diffusion lens 15 or Both focusing and minute tracking may be controlled by one lens of the converging convex lens 16, but an actuator that moves one lens in two axes has a higher frequency response than an actuator that moves one lens in one axis. Therefore, the control method shown in FIG. 9(b) and the embodiment in which one lens is moved only in one axis direction is superior to the control method shown in FIG. 9(a).

[Effect]

In this invention, as described above, a tracking control means for optically performing fine tracking control of the laser beam is provided in the fixed part, and a signal corresponding to the amount of tracking deviation outputted from the detection means is provided as a high frequency signal. a first drive control circuit that controls driving of the driving means based on the low frequency side signal separated by the signal separation circuit; A second drive control circuit is provided for controlling the drive of the tracking control means based on the high frequency side signal separated by the circuit.

Therefore, there is no need to provide any member for controlling tracking in the movable part, so the movable part of the floating optical disk can be significantly reduced in weight and size, and faster access can be achieved. .

Further, a signal corresponding to the amount of tracking deviation outputted from the detection means is separated into a high frequency side signal and a low frequency side signal by a signal separation circuit, and the low frequency side signal separated by the signal separation circuit. Since the driving of the driving means is controlled by the -th drive control circuit based on the above, the tracking deviation on the low frequency side can be controlled by the driving means having excellent frequency characteristics on the low frequency side.

- On the other hand, the driving of the tracking control means is controlled by a second drive control circuit based on the high frequency side signal separated by the signal separation circuit, and furthermore, this tracking control means Since tracking control is performed optically, it has excellent frequency characteristics on the high frequency side. Therefore, the tracking deviation on the high frequency side can be controlled by a tracking control means having excellent frequency characteristics on the high frequency side, and highly accurate tracking control becomes possible.

〔Example〕

The present invention will be explained below based on illustrated embodiments.

FIG. 2 shows an embodiment of a floating optical head according to the present invention.

In the figure, 1 indicates a floating optical head mounted on an optical information recording/reproducing apparatus, and this floating optical head 1 is roughly divided into a movable part 2 and a fixed part 3.

The movable part 2 includes an objective lens 5 for converging the laser beam LB on the optical disc 4, and a floating part of the objective lens 5 from the surface of the optical disc 4 using a hydrodynamic air bearing effect. The optical disc 4 has a slider 6 for keeping the distance substantially constant, and is driven along the radial direction of the optical disc 4 by a driving means 7.

The fixing unit 3 also includes a light source 8 of the laser beam LB, a detection means 9 for detecting the amount of deviation in focusing and tracking, and a focusing control means for controlling focusing based on the detection signal from the detection means 9. 10.

Further, to explain the structure of the floating optical head 1 in detail, as shown in FIG. A collimator lens 11 that converts the laser beam LB into parallel light, and this collimator lens 1
The laser beam LB converted into parallel light by 1 is
a beam shaping prism 12 that shapes the light into a circular cross-section;
A polarizing beam splitter 13 that separates the shaped laser beam LB into light irradiated onto the optical disk 4 and light reflected from the optical disk 4, and a quarter wavelength that mutually converts linearly polarized light and circularly polarized light. plate 14 and this 1/4 wavelength plate 1
In order to control the focusing of the laser beam LB that has passed through the laser beam LB, the laser beam LB is focused on a focal point F, and a diffusing convex lens 15 is used to diffuse the laser beam LB from the focal point F and convert the diffused laser beam LB into parallel light. A relay lens 17 as a focusing control means 10 consisting of a converging convex lens 16 that guides it to the movable part 2, and a beam splitter that further separates the reflected laser beam LB from the optical disk 4 separated by the deflection beam splitter 13 into two. 18, a condensing lens 19 that condenses one laser beam LB separated by this beam splitter 18, a two-split light receiving element 20 that receives the laser beam LB condensed by this condensing lens 19, and the above-mentioned A condensing lens 21 that condenses the other laser beam LB separated by the beam splitter 18, and a knife 22 that blocks one of the laser beams LB condensed by the condensing lens 21.
and a two-divided light receiving element 23 that receives the laser beam LB extracted by the knife 22.

On the other hand, the movable part 2 includes a mirror 24 that reflects the laser beam LB converted into parallel light by the relay lens 17 toward the optical disk 4, and a mirror 24 that focuses the laser beam LB reflected by the mirror 24 onto the optical disk 4. and a floating slider 6 for floating the objective lens 5 from the surface of the optical disk 4 so that the distance between the objective lens 5 and the optical disk 4 is approximately constant using a hydrodynamic air bearing effect. It is provided. This floating slider 6 is connected to the movable part main body 25 via a plate spring (not shown).

Furthermore, as shown in FIG. 1, the movable section 2 is movable along the radial direction of the optical disc 4 by a linear motor serving as a driving means.

In the floating optical head l, as shown in FIG. After that, the beam is shaped into a circular beam by the beam shaping prism 12. After that, this laser beam LB passes through a polarizing beam splitter 13 and a quarter-wave plate 14, is further converted into parallel light by a relay lens 17, is irradiated toward the movable part 2, and is focused by an objective lens 5. A track (not shown) of the optical disc 4 is irradiated with light.

The reflected light from the track of the optical disk 4 returns along the same path as above, is reflected by the deflection beam splitter 13, and is split into two directions by the beam splitter 18.

One of the laser beams LB is imaged by a condensing lens 19 onto a two-split light receiving element 20, and the image information recorded on the track is simultaneously read by this two-split light receiving element 20. As shown in FIG. 1, the two-split light receiving element 20 is connected to a summing amplifier 26, and a reproduced signal of image information is obtained as an output signal of the summing amplifier 26. Further, the two-split light receiving element 20 includes a differential amplifier 27.
It is also connected to the differential amplifier 27, so that a tracking error signal can be obtained as the output signal of the differential amplifier 27.

The other laser beam LB split by the beam splitter 18 passes through a condensing lens 21, and after one beam is blocked by a knife 22,
Only the other laser beam LB is imaged onto the two-split light receiving element 23. As shown in FIG. 1, the two-split light receiving element 23 is connected to a differential amplifier 28, and a focusing error signal is obtained as an output signal of the differential amplifier 28.

As is well known, the above-mentioned Naifezi method uses a laser beam LB that is imaged on one side of the light receiving element of the two-split light receiving element 23.
By blocking the light with the knife 22, a focusing error signal is obtained by utilizing the fact that the light receiving state of the two-split light receiving element 23 changes depending on the focusing state.

In the focused state, as shown in FIG. 3(a), since the light is focused only on the center of the two-split light receiving element 23,
When the output of the differential amplifier 28 becomes 0 and the focus is shifted, as shown in FIGS. 3(b) and 3(c), the light is focused only on one side of the light receiving element of the two-split light receiving element 23. A focusing error signal is obtained when the output of the differential amplifier 28 becomes + or -.

FIG. 1 shows the optical system and control system of the floating optical head.

The fixed part of this floating optical head is equipped with a tracking control means that performs fine tracking control optically, and a signal corresponding to the amount of tracking deviation output from the detection means, which is connected to a high-frequency side signal and a low-frequency side signal. a first drive control circuit that controls driving of a drive means that drives the movable part based on the low frequency side signal separated by the signal separation circuit; A second drive control circuit is provided that controls driving of a tracking control means that controls tracking based on the high-frequency side signal separated by the separation circuit.

More specifically, in the figure, 30.31 is the tracking error signal 32 output from the differential amplifier 27.
are a first filter circuit and a second filter circuit as a signal separation circuit into which are respectively inputted, and the tracking error signal 32 is passed through a first filter circuit 30 that passes only a signal on the low frequency side and a signal on the high frequency side only. The second filter circuit 31 that allows the signal to pass through separates the signal into two frequency components: a low frequency signal and a high frequency signal. The separation frequency by these first and second filter circuits 30.31 is set, for example, to a specific frequency within 2 to 3 KHz, and the separation frequency by these first and second filter circuits 30.31 is set to a specific frequency within 2 to 3 KHz, and the separation frequency is As such, the tracking error signal 3
2 is divided into two frequency components with a specific frequency f as the boundary.

The above-mentioned first and second filter circuits 30.31 are connected to phase compensation circuits 33.34, respectively, and these phase compensation circuits 33.34 pass through the first and second filter circuits 30.31. Among these signals, signals on the higher frequency side are subjected to signal processing such as greatly amplified to perform phase compensation. The phase compensation circuits 33 and 34 are
and a second drive control circuit 35.36, respectively, and these first and second drive control circuits 35.3
6 is connected to a linear motor 7 as a driving means and an actuator 37 as a tracking control means, respectively.

The actuator 37 optically performs fine tracking control of the laser beam LB by moving the convex diffusion lens 15 of the relay lens 17 in a direction perpendicular to the optical axis.

Furthermore, 38 is a phase compensation circuit to which a focusing error signal 39 outputted from the differential amplifier 28 is input, and this phase compensation circuit 38 performs predetermined signal processing on the focusing error signal 39 to perform phase compensation. It is something. The phase compensation circuit 38 is connected to a third drive control circuit 40, and this third drive control circuit 40 is connected to an actuator 41.

This actuator 41 moves the converging convex lens 16 of the relay lens 17 in the optical axis direction.
Focusing control of the laser beam LB is performed optically.

In the above configuration, tracking control is performed in the floating optical head according to this embodiment as follows.

That is, as shown in FIG. 1, the floating optical head 1 converts the laser beam LB emitted from the semiconductor laser 8 provided on the fixed part 3 into a collimator lens 11, a beam shaping prism 12, and a deflection beam splitter 13. .1
The light is irradiated onto the optical disk 4 via the /4 wavelength plate 14, the relay lens 17, the mirror 24 provided on the movable part 2, and the objective lens 5. Then, the reflected light from the optical disk 4 is passed through the objective lens 5, the mirror 24, the relay lens 17, the 1/4 wavelength plate 14, the polarizing beam splitter 13, the beam splitter 12, and the condensing lens 19 onto the two-split light receiving element 23. Receive light.

Then, a tracking error signal 32 is obtained from a differential amplifier 27 connected to this two-split light receiving element 23.

The tracking error signal 32 outputted from the differential amplifier 27 is transmitted to the first and second filter circuits 30 and 31.
The first filter circuit 30 separates the low frequency components, and the second filter circuit 31 separates the high frequency components.

The output signal from the second filter circuit 31 is input to a phase compensation circuit 34, and is subjected to phase compensation such as amplification so that the higher frequency side becomes larger. The output signal from the phase compensation circuit 34 is input to the second drive control circuit 36, and the second drive control circuit 36 calculates the difference between the output signal from the phase compensation circuit 34 and a preset value. The actuator 37 is driven accordingly.

As shown in FIG. 1, this actuator 37 optically performs fine tracking control of the laser beam LB by moving the convex diffusion lens 15 of the relay lens 17 in a direction perpendicular to the optical axis. be. That is, as shown in FIG. 5(a), the actuator 37 is configured such that the high frequency component of the tracking error signal 32 matches a predetermined value, and the laser beam focused by the objective lens 5 is directed to a predetermined position on the optical disc 4. When the track is accurately followed, the convex diffusion lens 15 of the relay lens 17 is held at a predetermined position. On the other hand, as shown in FIG. 5(b), the actuator 37 causes the high frequency component of the tracking error signal 32 to deviate from the predetermined value, causing the laser beam LB focused by the objective lens 5 to reach a predetermined value on the optical disc 4. distance r from the truck
If the laser beam LB deviates by a distance r°, the diffusing convex lens 15 is moved by a distance r° in a direction perpendicular to the optical axis and opposite to the direction in which the laser beam LB deviates.
B is tracked onto a predetermined track of the optical disc 4. The above distance r゛ is r' = (Ft /
Fa) is given by r. Here, Fl indicates the focal length of the convex diffusion lens 15, and Fo indicates the focal length of the objective lens 5.

On the other hand, the output signal from the first filter circuit 30 is input to the phase compensation circuit 33.
The signal receives phase compensation such as amplification such that the higher frequency side becomes larger. The output signal from this phase compensation circuit 33 is input to the first drive control circuit 35,
The linear motor 7 is driven by the drive control circuit 35 in accordance with the difference signal between the output signal from the phase compensation circuit 33 and the target number of tracks.

As shown in FIG. 1, this linear motor 7 has a movable portion 2
The moving part 2 is moved along the radial direction of the optical disc 4, and the movable part 2 is made to follow a target track of the optical disc 4 in accordance with the low frequency side signal output from the first filter circuit 30.

In this way, by moving the convex diffusion lens 15 of the relay lens 17 in the direction perpendicular to the optical axis on the fixed part 3, minute tracking control of the laser beam LB held at a predetermined position is optically performed. Actuator 37 and differential amplifier 2 connected to two-split light receiving element 23
and a second filter circuit 30.31 that separates the tracking error signal 32 outputted from 7 into a high frequency side signal and a low frequency side signal, and a low frequency signal separated by this first filter circuit 30. Based on the side signal,
A first drive control circuit 35 that controls the drive of the linear motor; and a second drive control circuit 36 that controls the drive of the actuator 37 based on the high frequency side signal separated by the second filter circuit 31. It is configured to provide a.

Therefore, there is no need to provide any member for controlling tracking in the movable part 2, so the movable part 2 of the floating optical head 1 can be significantly reduced in weight and size, and the rigidity of the movable part 2 can be reduced. It is possible to increase the speed of access and achieve faster access.

Further, the tracking error signal 32 output from the differential amplifier 27 connected to the two-split light receiving element 23 is separated into a high frequency side signal and a low frequency side signal by the first and second filter circuits 30 and 31. However, since the linear motor is controlled based on the low frequency side signal separated by the first filter circuit 30, the tracking deviation on the low frequency side is
As shown in FIG. 6, it has excellent frequency characteristics on the low frequency side, can be controlled by a near motor, and can perform tracking on the low frequency side with high accuracy. On the other hand, the drive of the actuator 37 is controlled by a second drive control circuit 36 based on the high frequency side signal separated by the second filter circuit 31,
Moreover, since this actuator 37 performs minute tracking control of the laser beam optically,
Excellent frequency characteristics on the high frequency side.

Therefore, the tracking deviation on the high frequency side can be controlled by the actuator 37 having excellent frequency characteristics on the high frequency side, as shown in FIG. 6, and highly accurate tracking control is possible. Moreover, since a large tracking deviation can be corrected by controlling the linear motor, the amount of tracking deviation to be corrected by the diffusion convex lens 15 of the relay lens 17 is only a small amount (several μm or less). Therefore, since the amount of movement of the convex diffusion lens 15 of the relay lens 17 is reduced, the deterioration of the imaging performance of the optical system due to the occurrence of aberrations due to the deviation of the convex diffusion lens 15 from the optical axis is also significantly reduced.

〔Effect of the invention〕

This invention has the above-described structure and operation, and it is possible to significantly reduce the weight and size of the movable part of a floating optical disk, and it is possible to achieve high-speed access as well as tracking. It is possible to provide a floating optical head that can be controlled with high precision.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of a floating optical head according to the present invention, Fig. 2 is a block diagram showing an optical system of the floating optical head, and Figs. 3 (a) to (c) are tracking diagrams. FIG. 4 is an explanatory diagram showing the error signal detection method, FIG. 4 is a graph showing the frequency characteristics of the first and second filter circuits, and FIGS. 5(a) and (b) are explanatory diagrams showing the tracking control state, respectively. , Fig. 6 shows the frequency characteristics of the beam near motor and actuator, Figs. 7 and 8 are configuration diagrams showing a conventional floating type optical head, and Figs. 9 (a) and (b) show the floating type optical head according to the present invention. FIG. 3 is an explanatory diagram of an optical system showing another embodiment of the molded optical head. [Explanation of symbols] l...Floating optical head 2...Movable part 3...Fixed part 4...Optical disk 5...Objective lens 6...Slider 7...Driving means 8...・Light source 9...Detection means 10-...Focusing control means 0.31...First and second filter circuits 2...Tracking error signal 5.36...First and second drive control Circuit 7... Actuator patent applicant: Fuji Xerox Co., Ltd. Representative: Patent attorney: Tomohiro Nakamura (1 other person) No. 4 Frequency diagram

Claims (1)

[Claims] (1) An objective lens for converging the laser beam onto the optical disk, and a slider for keeping the distance between the objective lens and the optical disk almost constant by raising the objective lens above the surface of the optical disk using a hydrodynamic air bearing effect. a movable part driven along the radial direction of the optical disk by a driving means; a light source of the laser beam; a detection means for detecting the amount of deviation in focusing and tracking; and a detection signal from the detection means. In the floating optical head, the floating optical head comprises a fixed part having a focusing control means for controlling focusing based on the fixed part, and a tracking control means for optically performing fine tracking control of the laser beam, and a focusing control means for controlling focusing based on the detection means. A signal separation circuit that separates a signal corresponding to the amount of tracking deviation to be output into a high-frequency side signal and a low-frequency side signal; A first drive control circuit for controlling the drive of the tracking control means, and a second drive control circuit for controlling the drive of the tracking control means based on the high frequency side signal separated by the signal separation circuit. A floating optical head featuring: