JPH0453034A - Device for controlling optical axis of laser - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a laser optical axis control device.

2. Description of the Related Art Conventional laser beam axis control devices include, for example, Japanese Patent Laid-Open No. 62-283426 and Japanese Patent Laid-Open No. 62-2852.
There is one disclosed in Publication No. 33. These are 2
In an optical disc recording device that records information by irradiating a book beam onto the surface of an optical disc, a light receiving element detects two beams reflected by the optical disc, photographs these two beams, and records the photographic output. The spot interval between the two beams is determined by image processing and arithmetic processing, and the two beams are calculated based on the relative position error signal obtained.
The optical axis of one of the two beams is controlled.

By controlling the optical axis of one of the beams so that the error in the relative position of the two beams is minimized in this way, it is possible to maintain the relative positions of both beams with extremely high precision.

Problems to be Solved by the Invention In the conventional two-beam control device as described above, two
Since this method involves receiving the reflected return light of the beam, photographing the two beam spots, and determining the spot interval between the two beams based on the photographic output, the detection means is large-scale and expensive.

Furthermore, this also increases the time required to determine the spot spacing between two beams, making it unsuitable for controlling the spot spacing in real time.

Means for Solving the Problems Therefore, in order to solve such problems, the present invention provides a first beam for forming continuous grooves for guiding information tracks on an optical information recording medium, and a method for determining groove addresses and sector numbers. In an optical disk recording device that records information by irradiating a second beam forming a bit with information, the first beam and the second beam reflected by the optical information recording medium
It is equipped with a detection element that receives the beam, and the relative position f! in two directions is determined from the signal obtained by the first beam and the signal obtained by the second beam. ! Relative position error signal detection means for extracting an error signal is provided, and optical axis control means is provided for controlling the optical axis of one of the two beams based on the relative position error signal obtained by the relative position error signal detection means. Ta.

In addition, the relative position error signal detection means divides and samples the signal obtained by analog calculation of the signal from the four-divided detection element into one beam irradiation and two beam irradiation. The relative position error signal is detected by taking the difference between the signal obtained by doubling the signal and the signal obtained when two beams are irradiated.

Therefore, the two beams of reflected light from the optical information recording medium are received by the detection element, and the relative position error signal detecting means is used to find the difference between the signals obtained by the two beams to obtain relative position error signals in two directions. By taking out the two beams and controlling the optical axis of one of the beams using the optical axis control means, it becomes possible to maintain the spot interval between the two beams with a simple configuration and with high precision.

Example An embodiment of the present invention will be described based on the drawings.

FIG. 1 shows the configuration of a relative position error signal detection device l (see FIG. 2) as relative position error signal detection means. In addition, FIG. 2 shows the relative position error signal detection device 1.
1 shows the overall configuration of a laser control device 2 including:

The relative position error signal detection device 1 detects a first beam B reflected by an optical disc master 3 as an optical information recording medium.
A four-division light-receiving element 4 (having light-receiving surfaces a, b, c, and d) serves as a detection element that receives the first and second beams B2, and analog calculations are performed on the signals detected by the four-division light-receiving element 4. It consists of an analog arithmetic circuit 5 and a relative position error signal detection circuit 6 connected to the analog arithmetic circuit 5. The first beam B1 forms a continuous groove for guiding information tracks, and the second beam B2 forms bits having information such as groove addresses and sector numbers.

Also, based on the relative position error signal obtained by this relative position error signal detection device 1, two beams Bl and B2 are
Optical axis control means 7 for controlling one optical axis is provided within the laser control device 2.

In such a configuration, first, the overall configuration of the laser control device 2 will be briefly described based on FIG. 2. The laser light emitted from the laser light source 8 is split into a first beam B1 and a second beam B2 by a first polarizing beam splitter 9. The first beam B1 is incident on the first acousto-optic modulator 11 (AOMI) via the mirror 1.0, and the second beams B1 and B2 are incident on the second acousto-optic modulator 1 (AOMI).
2 (AOM2), and thereby the optical disc master 3
The information is pulse-modulated into two channels of information to be recorded. Thereafter, the first beam B pulse-modulated by the first acousto-optic modulator 11 is reflected by the second polarizing beam splitter 14 via the 1/2 wavelength plate 13, and is reflected by the third polarizing beam splitter 15. incident on . On the other hand, the second beam B2 pulse-modulated by the second acousto-optic modulator 12 enters the third polarizing beam splitter 15 via the acousto-optic deflector 16 (80D).

The first beam 1u1 and the second beam I32 combined by the third polarization beam splitter 15 in this way are 1/
The light is irradiated onto the optical disc master 3 via the four-wavelength plate 17,
As a result, information recording bits can be formed on the master disc.

Next, centering on the relative position error signal detection device 1 shown in FIG.
The method for adjusting the optical axes of the two beams will be briefly described.

A method of controlling the optical axis in the X-axis direction on a plane (X, Z-axis) perpendicular to the laser optical axis will be described. Figure 3 (a) to (d) are 4
This figure shows the state f when the divided light receiving element 4 is irradiated with two beams Bl and B2. In this case, one of the first beams B] is used for continuous irradiation, and the other second beam B2 is used for discontinuous irradiation. (A) shows the case where the same position is irradiated, and (B) to (D) show that the first beam B1 does not vary and the second beam B1 does not change.
The situation when beam B2 fluctuates is shown. The analog signal obtained by the analog calculation circuit 5 in these four cases is as follows: Vpx=a+d-(b+c)-(1). Figure 3 (a,
) to (d). In this case, the signal waveform Vpx is the fourth
As shown in the figure, ■ indicates when one beam is irradiated, and ■1 indicates when two beams are irradiated. Therefore, when two beams are irradiated, the amount of deviation of each of the two beams (the amount of deviation indicates the deviation from the center position of the four-split light receiving element 4) is added as a signal. This means that

The analog signal Vpx obtained by analog calculation in this way is sent to the relative position error signal detection circuit 6, where the relative position error signal Vex is obtained. That is, in this case, Sx,,Sx.

is the timing of sampling Vpx, Sx,
is when one beam is irradiated, and Sx is when two beams are irradiated. As a result, as described in FIG. 4, if Vpx is V when Sx, and V is Vpx when Sx, , then ■ represents the amount of deviation of the first beam Bl(7), ■,
represents the amount of deviation of the second beam B2.

Therefore, the relative error of these two beams is V'ex=V,
-(V, -V,) = 2V, -V, ...(2), and the value obtained by this equation (2) is the relative position error signal Vex
represents. FIG. 5 shows the relative positional relationship between the analog signal Vpx and the relative position error signal Vex when the relative positions of the two beams vary due to the optical axis adjustment method. Thereafter, a feedback loop is activated using the relative position error signal Vex obtained in this manner, and the signal is sent to the optical axis control means 7, thereby directing the second beam B2 in the X-axis direction, which is used as discontinuous irradiation for pit formation. It becomes possible to control the

Further, in this embodiment, only the method of adjusting the optical axis in the X-axis direction has been described, but in addition to this, when adjusting, for example, in the Z-axis force direction, the analog calculation circuit 5 converts equation (1) into a
, +h-(c+d), and the relative position error signal detection circuit 6
When Sz, Vpz is 1, Sz, 0), (7) Vpz is v, and Z is determined by calculating the relative position error signal Vez using formula 2)
The optical axis can be adjusted in the axial direction.

As mentioned above, two beams of reflected light from the optical disc master 3 are received by the four-split light receiving element 4, signals in two directions on the plane are extracted, analog calculations are performed, and the signals are used to detect the relative positions of the two beams. By performing signal sampling and calculation, it becomes possible to easily detect the positions of the two beams with high precision and with a simple configuration.

Effects of the Invention The present invention can record information by irradiating an optical information recording medium with a first beam that forms continuous grooves for guiding information tracks and a second beam that forms bits that have information such as groove addresses and sector numbers. A laser optical axis control device that performs recording includes a detection element that receives the first beam and the second beam reflected by the optical information recording medium, and detects a signal obtained by the first beam and a signal obtained by the second beam. a relative position error signal detecting means for extracting signals in two directions from the signal detected by the relative position error signal, and controlling one optical axis of the two beams based on the relative position error signal obtained by the relative position error signal detecting means. Since the axis control means is provided, the two beams of reflected light from the optical information recording medium are received by the detection element, and the relative position error signal detection means is used to calculate the difference between the signals obtained by the two beams and detect the difference in the two directions. By extracting the relative position error signal of the two beams and controlling the optical axis of one of the beams using the optical axis control means, it becomes possible to easily detect the spot interval between the two beams with high precision and with a simple configuration. be.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the configuration of the relative position error signal detection device of the present invention, FIG. 2 is a configuration diagram showing the laser beam axis control device, and FIGS. 3 and 4 are irradiated onto the detection element. FIG. 5 is a waveform diagram showing the relative positional relationship between the analog signal and the relative position error signal. DESCRIPTION OF SYMBOLS 1... Relative position error signal detection means, 4... Detection element, 7... Optical axis control means, B1... First beam, B2
...Second beam, Vex, Vez...Relative position error signal JZI diagram Applicant Ricoh Co., Ltd.

Claims (1)

[Claims] 1. Information is generated by irradiating an optical information recording medium with a first beam that forms continuous grooves for guiding information tracks and a second beam that forms bits that have information such as groove addresses and sector numbers. An optical disc recording device for recording, comprising a detection element that receives the first beam and the second beam reflected by the optical information recording medium, and a signal obtained by the first beam and a signal obtained by the second beam. and an optical axis for controlling one of the two beams based on the signal obtained by the relative position error signal detection means. A laser optical axis control device characterized by being provided with a control means. 2. The relative position error signal detection means samples the signals obtained by analog calculation of the signals from the four-divided detection elements, dividing them into 1-beam irradiation and 2-beam irradiation. A laser optical axis control device characterized in that a relative position error signal is detected by taking the difference between a signal obtained by doubling the signal and a signal obtained when two beams are irradiated.