JPH01277330A - Optical head - Google Patents

Abstract

PURPOSE:To simplify the adjustment of vertical degree between a recording medium and an optical axis by fixing an optical path converting mirror on a fixing member to be optionally moved and adjusted on a base having a secondary curved face having a main point of an objective lens as its focus and fixing an objective lens positioning member on a mirror fitting member. CONSTITUTION:The upper face 10a of the base member 10 is worked as the secondary curved face having the main point 4a of the objective lens 4 as its focus and the fixing member 15 of the mirror 5 is set up on the upper face 10a of the base member 10 so as to be optionally moved and adjusted. The mirror fitting part 15a is fixed on the approximate center of the upper face of the member 15 and a fitting part 15b for fitting the objective lens positioning member 11A is fixed on the peripheral part of the member 15. Since the objective lens can be simply positioned and the optical axis made incident upon an optical recording medium can be made vertical by adjusting the mirror fixing member 15, the aberration of an optical spot on the recording medium can be reduced and reproducing characteristics can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical head used in a reproducing apparatus or recording/reproducing apparatus for optical recording media such as compact discs, optical discs, magneto-optical discs, and optical cards.

BACKGROUND OF THE INVENTION In recent years, with the spread of compact discs and the development of optical recording media such as optical discs, magneto-optical discs, and optical cards, optical heads for use in playback devices or recording/playback devices have been actively developed. Ta. Also,
Various improvements have been made to the positioning and adjustment methods of optical components, which are important in manufacturing optical heads.

A conventional optical head will be described below using drawings. FIG. 2 shows the configuration of a conventional optical head, in which a semiconductor laser 1. A collimating lens 2 for converting the diverging light emitted from the semiconductor laser 1 into a parallel beam, an optical recording medium 3. an objective lens 4 for focusing light on the optical recording medium 3; a mirror 5 for converting the optical path in the direction of the objective lens 4; a beam splitter 6 for separating reflected light from the optical recording medium 3; It consists of a photodetection optical system 7 and a photodetector 7a for detecting the light separated by the beam splitter 6. Also, Figure 3 shows the mirror 5
and a cross section of the attachment part of the objective lens 4, where 4a is the principal point of the objective lens 4, and 8 and 9 are the optical axis of incidence on the mirror 5 and the optical axis of reflection, respectively. The base member 10 has the principal point 4
The base member 10 is machined into a quadratic curved surface centered at point a, and the positioning member 11 is attached along the quadratic curved surface of the base member 10. The positioning member 11 is adjusted using an adjustment screw 12, and the adjustment screw 12 is fixed with an adjustment spring 13. Reference numeral 14 denotes an adjustment leaf spring provided diagonally to the adjustment screw 12.

An adjustment method for the above-mentioned conventional optical head will be described below. First, the relative positions of the semiconductor laser 1 and the collimating lens 2 are adjusted in the XYZ directions in FIG. 2, and the parallelism and emission direction of the light beam after passing through the collimating lens 2 are adjusted.

At this time, the beam splitter 6 and the mirror 5 align the zero-order objective lens 4 fixed to the base member IO with the optical axis 9, and adjust the angle α in the x and Z directions.

Aberrations on the optical recording medium 3 are suppressed by performing tilt adjustment in the γ direction using two adjusting screws 12.

After adjusting the light emission-condensing system as described above, the photodetection optical system 7 and the photodetector 7a are adjusted.

Complete the optical head adjustment.

Problems that the invention aims to solve However, in the conventional optical head described above.

Since the mirror 5 is fixed, the position of the light beam toward the principal point 4a of the objective lens 4 can be secured, but the inclination cannot be adjusted.
That is, there was a problem in that it was difficult to ensure the perpendicularity of the incident light onto the optical recording medium.

The present invention solves the above-mentioned problems with the conventional optical head.The present invention is an optical head that has better reproduction characteristics by reducing aberrations on the optical recording medium by ensuring perpendicularity between the optical recording medium and the optical axis. The purpose is to provide the head.

Means for Solving the Problems In order to solve the above-mentioned problems, the optical head of the present invention is capable of freely moving and adjusting a mirror for optical path conversion on a quadratic curved surface of a base member whose focal point is the principal point of the objective lens. It is attached to the installed mirror fixing member, and the positioning member of the objective lens is positioned and attached to the positioning attachment portion on the mirror fixing member.

Effect In the above configuration, the objective lens can be easily positioned, and the optical axis incident on the optical recording medium can be made perpendicular by adjusting the mirror fixing member. It is possible to reduce aberrations and improve reproduction characteristics.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of essential parts of an optical head in one embodiment of the present invention. Note that the optical head of this embodiment, like the conventional optical head shown in FIG. 2 above, includes a semiconductor laser 1, a collimating lens 2, an objective lens 4, a mirror 5,
It is equipped with a beam splitter 6 and a photodetection optical system 7, and the explanation thereof will be omitted, and the same members are given the same reference numerals. In FIG. 1, the upper surface 10a of the base member 10 is processed into a quadratic curved surface whose focal point is the principal point 4a of the objective lens 4 installed above. It is movably installed on the upper surface 10a of the. On the upper surface of this mirror fixing member 15, a mirror attachment part 15a is provided near the center, and a positioning attachment part 15b for positioning and attaching the objective lens positioning member 11A is provided at the periphery.
1 positioning member 11 is attached.

An adjustment method for the optical head of the above embodiment will be explained. First, the semiconductor laser 1 and the collimating lens 2 are adjusted in the same manner as before, and then the positioning member 11A to which the objective lens 4 is attached is attached to the positioning attachment part 15b of the mirror fixing member 15 so that the optical axis 9 is always aligned with the objective lens 4. Position and install so that it passes through the principal point 4a. The mirror fixing member 15 is adjusted using the adjustment screw 12 so that the optical recording medium 3 and the optical axis 9 are perpendicular. At this time, the mirror fixing member 15 is attached to the principal point 4 of the objective lens 4 provided on the base member 10
By moving on a quadratic curved surface with focal point a, the optical axis 9 always passes through the principal point 4a of the objective lens 4, and
After adjusting the light emitting and condensing system so that the optical axis 9 is perpendicular to the optical recording medium 3, which can be easily adjusted to 0 or more, light detection is performed in the same way as in the conventional optical head. The optical system 7 and the photodetector 7a are adjusted, and the adjustment of the optical head is completed.

As described above, in the optical head of this embodiment, by adjusting the adjustment screw 12 from the base member 10 side,
The perpendicularity between the optical recording medium 3 and the optical axis 9 can be easily adjusted, and the best reproduced signal characteristics can be obtained.

Effects of the Invention In the optical head of the present invention, a mirror for optical path conversion is attached to a mirror fixing member movably installed on a base member formed into a quadratic curved surface with the principal point of the objective lens as the focal point,
and attaching the positioning member for the objective lens by positioning it to the positioning mounting part on the mirror mounting member, determining the position of the objective lens so that the optical axis always passes through the principal point of the objective lens, and fixing the mirror fixing member. This is an excellent optical head that can easily adjust the perpendicularity between the optical recording medium and the optical axis by moving on a quadratic curved surface, and can obtain the best reproduction signal characteristics.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of essential parts of an optical head in an embodiment of the present invention, FIG. 2 is a configuration diagram of a conventional optical head, and FIG.
The figure is a schematic cross-sectional view of the main parts of a conventional optical head. 1... Semiconductor laser, 2... Collimator lens, 3
... Optical recording medium, 4... Objective lens, 4a... Principal point, 5... Mirror, 6... Beam splitter, 7...
...Photodetection optical system, 7a...Photodetector, 10...Base member, IIA...Positioning member, 15...Mirror fixing member, 15a...Mirror mounting part, 15b...
・Positioning mounting part. Agent Yoshihiro Morimoto 1st figure 3-1 handbook 4-period entry" 4-1 end Ri...mirror tσ Be one mantle p material 〃^-AL-1i (Mebe winter λ ls・-Oler Ensobe Oni/i, Mira-1 Poor 6th Part l Left b4d Kankaku 4th Plate 2nd figure!-・+F4 this Rede 2...Ko Maetren person ゛6--Bee person group 9 Ivy 7-1. Optical axis light Figure 8

Claims (1)

[Claims] 1. A semiconductor laser, an objective lens for condensing light emitted from the semiconductor laser onto an optical recording medium, a beam splitter provided between the semiconductor laser and the objective lens, and a beam splitter for condensing light emitted from the semiconductor laser onto an optical recording medium. a photodetection optical system installed in a direction in which the reflected light is separated by the beam splitter; a mirror for converting the optical path of the light emitted from the semiconductor laser toward the objective lens; and a mirror for mounting and fixing the mirror. 2, comprising a mirror fixing member and a positioning member for positioning the objective lens, the mirror fixing member being focused at the principal point of the objective lens;
1. An optical head, characterized in that the optical head is movably installed on a base member formed into a curved surface, and the positioning member is attached to a positioning attachment portion on the mirror fixing member.