JPH07153083A - Method and apparatus for adjusting tilt of principal ray - Google Patents

Abstract

PURPOSE:To perfectly correct a tilt of a principal ray and improve an efficiency for reading signals by moving a light source in a first direction and rotating a reflecting element in a second direction. CONSTITUTION:A mirror face 10 of a mirror block 2 of a correct angle indicated by a solid line is inclined DELTAalpha to be a mirror face 10a indicated by a broken line because of an error in a forming angle of the mirror face itself, which would result in a tilt of a principal ray at an objective lens 1. As such, in order to prevent the principal ray from being tilted due to the inclination of the mirror face 10a, a laser diode 3 is moved and corrected DELTAY in a Y-axis direction. In consequence, a laser light 12a shown by a broken line is inclined 2DELTAalpha with respect to a laser light 12 before the laser diode 3 is moved, and the laser light 12a is reflected at the mirror face 10a shown by the broken line to reach an optical disc D through the objective lens 1. Since the laser diode 3 is corrected in position at this time, the principal ray of the laser light 12a at the objective lens 1 passes a predetermined position without being tilted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting the deflection of a chief ray of a lens in an optical system in which light from a light source such as a laser is reflected by a reflecting element and guided to the lens in, for example, an optical disk device. It relates to the adjusting device.

[0002]

2. Description of the Related Art Optical disc devices such as compact discs and magneto-optical discs are equipped with an optical pickup. This optical pickup is used to guide laser light to an optical disc and record / reproduce information on / from the optical disc or reproduce information on the optical disc.

[0003]

The above-mentioned conventional optical pickup has the following problems. That is, when the mounting accuracy of the laser light source and / or the mounting accuracy of the reflection mirror is poor when the laser light is reflected by the reflection mirror and guided to the optical disc through the objective lens, The light does not pass through a predetermined optical path, and the principal ray of the incident light falls on the optical axis of the objective lens, so-called principal ray deflection occurs.

That is, a conventional optical pickup (OP)
When the position (arrangement) of the optical system is deviated from the design center, aberration occurs and the signal reading accuracy of the optical pickup deteriorates. For this reason, it is necessary to align the optical system to eliminate the sag of the chief ray with respect to the objective lens.

Particularly in a thin optical pickup,
Since the optical path is bent by the reflection mirror (folding mirror) and the laser light is guided to the objective lens side as described above, the deviation of the chief ray occurs unless the angle of the reflection mirror is accurate.

Therefore, conventionally, the deviation of the principal ray with respect to the objective lens is corrected only by rotating the reflection mirror, but the deviation direction which can be corrected by the rotation of the reflection mirror is one-dimensional. However, it was not possible to deal with the error in the two-dimensional direction caused by the mounting error of the laser light source and the mounting error of the reflection mirror.

The present invention has been made in order to solve the above problems, and it is possible to completely correct the sag of the chief ray with respect to the lens, and thus to improve the signal reading performance. And its adjusting device.

[0008]

According to the present invention, the above object is to provide a method for adjusting the sag of a chief ray of a lens in an optical system for reflecting light from a light source by a reflecting element and guiding the light to the lens. That is, by moving the light source in the first direction and rotating the reflecting element with respect to the second direction, a sag of the chief ray is adjusted by a method of adjusting the sag of the chief ray.

In the present invention, preferably the light source is a laser and the reflecting element is a prism type mirror. Further, in the present invention, preferably, the first direction and the second direction are parallel to each other. Further, in the present invention, preferably, the optical system is provided in an optical pickup arranged corresponding to an optical disc of an optical disc device.

The above object of the present invention is, in the present invention, an adjusting device for adjusting the deflection of a chief ray with respect to the lens in an optical system for reflecting the light from the light source by a reflecting element and guiding it to the lens. Is first for the base member
This is achieved by means of an adjusting device for the chief ray deflection of the chief ray in which the reflecting element is set so as to be movable in the direction and the reflecting element is set to be rotatable in the second direction with respect to the base member.

[0011]

According to the above construction, the deflection of the chief ray with respect to the lens is adjusted in the optical system for reflecting the light from the light source by the reflecting element and guiding it to the lens. For this adjustment, the light source is moved in the first direction and the reflective element is rotated in the second direction. Thereby, the deflection of the chief ray in the lens can be adjusted two-dimensionally.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the examples described below are suitable specific examples of the present invention, and therefore, various technically preferable limitations are given, but the scope of the present invention particularly limits the present invention in the following description. Unless otherwise stated, the present invention is not limited to these modes.

FIG. 1 shows a preferred embodiment of an apparatus for adjusting the chief ray sag for carrying out the method for adjusting the chief ray sag of the present invention. For example, a compact disc (C
An optical pickup OP is arranged corresponding to the optical disc D such as D). This optical pickup OP is
It includes an objective lens 1, a prism type mirror block 2, a laser diode 3 and the like.

The optical pickup OP is an optical pickup for reading information recorded on the optical disc D, for example. The objective lens 1 is arranged between the optical disc D and the prism type mirror block 2. As shown in FIG. 2, the prism type mirror block 2 is
It is set to be rotatable with respect to the circular mounting hole 6 of the optical base 4 of the optical pickup OP.

As shown in FIG. 2, the laser diode 3
Are also set for the optical base 4. The laser diode 3 can move in the Y-axis direction, which is the first direction. The arrow Y-axis direction is a direction parallel to the optical axis direction of the objective lens 1.

On the other hand, as shown in FIG. 2, the mirror block 2 has an arrow R with respect to the rotation axis 8 which is the second direction.
It is set to be rotatable in the direction. In this embodiment, the Y-axis direction of the arrow and the rotation axis 8 are parallel.

Referring to FIG. 1, the mirror surface 10 of the mirror block 2 is formed at 45 ° with respect to the S surface.
This S surface is parallel to the optical base 4. If the mounting accuracy of the laser diode 3 and the mounting accuracy of the mirror block 2 are predetermined, the laser light 12 generated from the laser diode 3 is reflected by the mirror surface 10, passes through the objective lens 1, and passes through the objective lens 1. An image point IM is formed on the optical disc D by the lens 1.

However, if the mounting accuracy of the laser diode 3 and the mounting accuracy of the mirror block 2 are poor, the laser light 12 does not pass through a predetermined optical path in the objective lens 1,
The chief ray of the objective lens 1 is deflected.

Next, an example of a method of adjusting the sag of the chief ray with respect to the objective lens 1 will be described. FIG. 1A shows an example in which the angular error of the mirror surface 10 of the mirror block 2 is corrected or adjusted by moving the laser diode 3 side in the Y-axis direction.

In this example, since there is a molding angle error of the mirror surface 10 itself of the mirror block 2, for example, FIG.
As shown in (A), the mirror surface 10 at the correct angle shown by the solid line is inclined by Δα like the mirror surface 10a shown by the broken line. If this is left as it is, the chief ray deflection in the objective lens 1 occurs.

Therefore, the laser diode 3 is moved in the Y-axis direction by .DELTA.Y in order to correct the principal ray deflection due to the inclination of the mirror surface 10a. Thereby, the laser light 12a of the laser diode 3 shown by the broken line
Has an angle of 2Δα with respect to the laser beam 12 before the movement. This laser light 12a is reflected by the mirror surface 10a indicated by the broken line.
And then reaches the optical disk D through the objective lens 1.

At this time, since the position of the laser diode 3 is corrected, the laser beam 12a of the laser diode 3 is corrected.
The principal ray in the objective lens 1 due to does not fall as shown in FIG. 1, but passes through a predetermined position. Further, by moving the laser diode 3 in the Y-axis direction by ΔY in this manner, it is possible to correct an error in the Y-axis direction of the laser diode 3 itself and an attachment error of the mirror block 2.

Next, in FIG. 1B, on the contrary, when the laser diode 3 is mounted in the X-axis direction from the point O to O1 with a deviation of ΔX (the angle of the laser beam 12 is θ).
In addition, the deviation ΔX of the laser diode 3 in the X-axis direction
Shows an example of correcting or adjusting by rotating the mirror block 2 about the rotation axis 8. The mirror surface 10 in FIG. 1 (B) is a projection of the mirror block 2 in the S plane in FIG. 1 (A).

In this way, by rotating the mirror block 2 about the rotation axis 8 perpendicular to the S-plane by a predetermined angle θ, a deviation ΔX of the laser diode 3 in the X-axis direction.
Can be corrected or adjusted to prevent chief ray deflection.

In the illustrated embodiment, the laser diode 3
Can be independently and one-dimensionally moved and adjusted in the direction of the arrow Y, and the mirror block 2 can also be one-dimensionally moved around the rotation axis 8. In other words, the rotation of the mirror block 2 also referred to as a reflection mirror about one axis and the parallel movement of the laser diode 3 in one direction enable two-dimensional independent alignment of the principal ray deflection.

Therefore, by performing both of these movements, the sag of the chief ray can be completely corrected without using a complicated movable mechanism. That is, the optical path can be changed two-dimensionally and independently, and the deflection of the chief ray with respect to the objective lens can be completely corrected. Therefore, by using the optical pickup OP of the embodiment, the characteristics of the reproduction signal can be improved.

Further, since the movable mechanism is shared by the two elements (laser diode 3 and mirror block 2) themselves, each mechanism is simple. Furthermore, since all errors and mounting errors of each element (laser diode 3 and mirror block 2) can be corrected, accuracy of each element itself and mounting accuracy can be loosened.

After the error between the laser diode 3 and the mirror block 2 is adjusted as described above, the laser diode 3 is fixed to the optical base 4 with an adhesive, and the mirror block 2 is also fixed to the optical base 4. On the other hand, it is fixed by adhering with an adhesive. In the optical pickup OP, it is possible to set a good state in which the principal ray of the incident light and the optical axis of the objective lens 1 coincide with each other and the principal ray does not sag.

Adjustment of the positional deviation between the laser diode 3 and the mirror block 2 is appropriately performed while inspecting by, for example, the inspection device 20 shown in FIG. This can be done by moving and rotating the mirror block 2 in the direction of arrow R. Further, the adhesive can be injected by an instrument such as a dispenser after the adjustment of these optical elements to fix these elements.

The present invention is not limited to the above embodiment. For example, in the above-mentioned embodiment, the reproducing apparatus for the compact disc is described, but not limited to this,
It can also be applied to other types of optical disk devices, such as magneto-optical disk devices MO and MD.

[0031]

As described above, according to the present invention,
The deflection of the chief ray with respect to the lens can be completely corrected, and thus the signal reading performance can be improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an adjusting device for explaining a method for adjusting the deflection of a chief ray of the present invention.

FIG. 2 is a diagram showing a relationship between a laser diode, a mirror block, and an optical base.

[Explanation of symbols]

 1 Objective Lens 2 Mirror Block 3 Laser Diode (Light Source) 4 Optical Base 8 Rotation Axis (Second Direction) OP Optical Pickup Y First Direction

Claims (5)

[Claims] 1. A method of adjusting the sag of a chief ray with respect to the lens in an optical system for reflecting light from a light source by a reflecting element and guiding the lens to the lens, wherein the light source is moved in a first direction, and A method for adjusting chief ray sag, characterized in that the sag of the chief ray is adjusted by rotating the reflecting element in the second direction. 2. The method for adjusting chief ray deflection according to claim 1, wherein the light source is a laser and the reflecting element is a prism type mirror. 3. The method for adjusting chief ray deflection according to claim 1, wherein the first direction and the second direction are parallel to each other. 4. The method according to claim 1, wherein the optical system is provided in an optical pickup arranged corresponding to an optical disc of an optical disc device. 5. An adjusting device for adjusting the sag of a chief ray with respect to the lens in an optical system for reflecting the light from the light source by a reflecting element and guiding it to the lens, wherein the light source is in a first direction with respect to the base member. The adjusting device for the chief ray deflection, wherein the reflecting element is set so as to be movable in the second direction with respect to the base member.