JP2580987B2 - Optical writing and reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system using an objective lens.
The present invention relates to a biological writing and reading device . For more information,
The present invention relates to an optical writing / reading apparatus using a refractive index distribution type flat microlens array as the objective lens.

[0002]

2. Description of the Related Art FIG. 1 shows the most standard configuration of an optical head for an optical memory, which is used for a compact disc player for digital audio or an optical memory device for a still picture file. The main components are a semiconductor laser 1 as a light source, an optical system, a detector 2 as a light receiving element, and a driving system (actuator) 3 for focusing (focusing) and tracing (tracking) of pits.

In the example shown in the figure, light emitted from a semiconductor laser 1 is converted into a parallel beam by a collimating lens 4. This light passes through the polarizing prism 5 and reaches the quarter-wave plate 6. When the laser light (which is linearly polarized) passes through the quarter-wave plate twice, the polarization direction is rotated by 90 degrees. Therefore, 1 /
When the light reflected by the disk surface 8 through the four-wave plate 6 and the objective lens 7 reaches the prism 5 again through the quarter-wave plate 6, it is polarized by 90 degrees. The reflected light having been polarized by 90 degrees is reflected by the prism 5 and does not return to the laser 1. This prism is called a beam splitter. The reflected light is focused on the detector 2 via the condenser lens 9 and the cylinder lens 10. The detector 2 is a part that converts an optical signal into an electric signal using a photodiode.

The signals obtained from the detector include an RF signal as a main signal, a focus signal for performing focusing servo, and a tracking signal for tracing a track. The photodiode is usually divided into a plurality of parts, and a servo signal is obtained from the sum and difference of the outputs of the respective elements. The objective lens 7 is driven by a coil, and the relationship between the lens and the coil can correspond to the cone paper of the speaker and the voice coil. The lens is driven in a disk direction (focus) and a radial direction (radial) by an error signal detected by the detector 2. Methods for obtaining a focus signal include an astigmatism method, a knife edge method, and a critical angle method. Methods for obtaining a tracking signal include a three-beam method, a push-pull method, a synchronous detection method, and a heterodyne method. These details are given in the technical book.

[0005]

[SUMMARY OF THE INVENTION Now, the main signal and a focus signal as described above in such a conventional method, to obtain a laser beam of one of the tracking signal,
There have been problems with the stability of each signal and the complexity of the circuitry that separates these signals. The present invention eliminates these disadvantages and provides the optical head with a new function.

[0006]

SUMMARY OF THE INVENTION Optical writing of the present invention
Reader writes data to optical memory disk
A first light source for generating a first light beam;
Of reading data written by the light beam of
A second light source for generating a beam of light, and the first light source
The first light beam emitted from the optical memory disk.
A first objective lens converging on a laser, and the second light source
The second light beam emitted from the optical memory device
A second objective lens that converges on the optical memory;
Detecting the first light beam reflected from the disk;
First detecting means, and light reflected from the optical memory disk.
Second detection means for detecting the second light beam
Having the first objective lens and the second objective lens
Are formed on the same substrate.

[0007]

(Embodiment 1) FIG. 2 is an example showing the configuration of an optical head according to the present invention.
Two semiconductor lasers (laser diodes) 1 for the light source
Nos. 7 and 18 are used.
The collimating lens 19 having a lens array
I have. Polarizing beam splitter 5, quarter wave plate 6,
Each configuration of the tutor 3 is not different from the prior art. Feature of the present invention is in the objective lens, using a gradient index planar microlens array 11. The gradient index flat microlens array 11 can be formed by simultaneously arraying lenses having a diameter of about 0.5 mm in the same process.

[0008]

[0009] Polarizing beam splitter 5, quarter-wave plate 6
The light passing through is formed on the flat microlens array 11.
Two spots A and B by the two lens arrays
Becomes In the present invention, the spot A is used for writing only.
The spot B as its readout beam
Used. That is, spot A is
While focusing, it becomes an intensity modulated beam
Data is written on the Te optical disk. Spot B is
This is read immediately and the correctness of the recorded data is judged,
Instructs the troll system to rewrite data. In this method
According to this, it is possible to prevent errors due to defects on the recording media.
Disk memory that is currently 10 ^-6 -10 ^-7
Can be made closer to 10 ⁻¹² . De
The reflected light from the disk 8 is reflected by the beam splitter 5 when passing through the flat microlens array 11 and the quarter-wave plate 6 again, and is collected by the lenses 12, 13, and 14 arranged corresponding to the beams A and B. Be lighted. The detector 15 reads the main signal exclusively, and the detector 16 reads the focus error signal and the tracking error signal. Thus, in the present invention, the light source is
Each emitted beam can have a different function. As a result, the No. Each signal is stabilized, it is possible to avoid the complication of the circuit. Also shown in FIG.
When implementing with one light source as in the prior art, the light source
Error modulation complicates error detection.
If two light sources are used, the functions are completely separated and error detection is performed.
Can be easily performed. In this example,
The refractive index distribution type flat plate microlens
Is adopted.

Next, the refractive index distribution type flat microlens will be briefly described. The refractive index distribution type flat microlens diffuses heavy metal ions (Tl ⁺ , Cs ⁺ ) having high electron polarization in the molten salt through a mask provided on a glass substrate, and converts them into K ⁺ , Na ⁺ in the glass. It is formed by controlling the refractive index three-dimensionally. Therefore, a lens array as shown in FIG. 3 is obtained by batch processing. At present, the minimum diameter of the lens can be as small as about 0.5 mm, and the control of the lens constant is obtained by suppressing the ion exchange rate and the degree of diffusion. The process is Ti ( 1.5 μm ) on a glass plate.
After sputtering, the original shape of the lens array is formed by a photoetching method, ion exchange is performed in a molten salt, and the mask may be removed. Therefore, there is no spherical polishing step performed with a conventional lens, and an array of microlenses can be easily obtained.

[0011]

[0012]

[0013]

As described above, the optical writing of the present invention
The read / write device writes data to the optical memory disk.
A first light source for generating a first light beam to be incident;
Reading data written by the first light beam
A second light source for generating a second light beam;
The first light beam emitted from the light source is transmitted to an optical memory device.
A first objective lens that converges on a disk;
The second light beam emitted from the light source is stored in an optical memory device.
A second objective lens converging on the disk, and the optical memo
Detecting the first light beam reflected from the re-disc
A first detecting means for detecting the position of the optical memory disk;
Second detecting means for detecting the emitted second light beam
And the first objective lens and the second objective lens
By forming the optical head on the same substrate, it is possible to easily form a multi-beam optical head, to give different functions to each beam, to stabilize the signal and simplify the circuit. . In addition, the refractive index distribution type microlens is completely different from the conventional manufacturing of the lens, and the cost can be reduced. Furthermore, since plasticization of the microlens is possible in the future, a lightweight lens that can be easily servoed will be realized and will be suitable for the present invention.

As described above, the present invention provides a novel head configuration in the field of optical memory, and is widely applicable to digital audio, video disks, document still image disk files, and the like.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a conventional standard optical head.

FIG. 2 is a configuration diagram showing an example of an optical head according to the present invention.

FIG. 3 is a gradient index flat microlens used in the present invention.
Enlarged view of the Zuarei.

[Description of Signs ] 1, 17, 18 Laser Diode 2, 15, 16 Detector 4, 19 Collimating Lens 5 Polarizing Beam Splitter 6 Quarter Wave Plate 7 Objective Lens 8 Optical Memory Disk 9, 12, 13 Condensing Lens 10, 14 Cylinder lens 11 Flat microlens array

Claims (1)

(57) [Claims] 1. Writing data to an optical memory disk
A first light source for generating a first light beam, and reading data written by the first light beam.
A second light source that generates a second light beam to be emitted, and the first light beam that is emitted from the first light source.
A first objective lens that converges on a memory disk, and a second light beam emitted from the second light source.
A second objective lens for focusing on a memory disk; and the first beam reflected from the optical memory disk.
First detecting means for detecting light from the optical memory disk, and the second beam reflected from the optical memory disk.
And a second detecting means for detecting the system light, wherein the first objective lens and the second objective lens are the same.
Optical writing characterized by being formed on one substrate
Reader.