CN1121030C - Multi-layer optical head for 3D storage - Google Patents

Abstract

The invention relates to a multi-layer three-dimensional storage optical head. In the optical head, a laser, a frequency multiplier, a collimating mirror and two beam splitters form a main optical axis. The objective lens, the right beam splitter, the auxiliary collimating mirror, and the auxiliary laser are installed on the same optical axis, and the optical axis forms an angle of 90° with the main optical axis. The disk to be read and written is placed on the other side of the objective lens relative to the beam splitter, and another collimator and another laser are installed on the same optical axis as the left beam splitter. The optical axis is at an angle of 90° to the main optical axis, forming a Pay optical axis. The linkage focusing mechanism is connected with two collimating mirrors at the same time. The invention can read and write multilayer three-dimensional optical disks in parallel, and effectively improve the data reading and writing speed and storage capacity of the optical disks.

Description

Multilayer 3D storage optical head

Technical field The present invention relates to a multi-layer three-dimensional storage optical head, which belongs to the technical field of three-dimensional digital optical storage.

Background technology In the current various multi-layer three-dimensional storage, it is mainly based on the following modes. As shown in FIG. 1 , it is a schematic diagram of the principle of a current three-dimensional storage solution, and its storage body ( 2 ) is a storage body of a cube two-photon photochromic material. The cylindrical lens (4) gathers the light beam into a plane light for selecting the working surface. Another beam modulated by the data to be recorded passes through the memory bank through the objective lens (1). In this way, at the intersection of the two beams of light, the information is written into the storage body. When reading out, there is still plane light to select the working surface, and the incident light is evenly illuminated, and the information recorded on the working surface generates corresponding fluorescence, which is collimated by the readout objective lens (3) and then obtained by the CCD camera.

The relatively successful example in this regard is mainly the storage system jointly researched by the University of California and the American call-recall company. As shown in Figure 2, the recording body is a 1cm ³ two-photon absorbing material. The plane light is produced by the light path formed by the plane radiation mirror (135, 136, 148) and the achromatic sight (10), while the working illumination light path is composed of the lens (143, 144, 145, 146) and the sight (7), When read out, it is read out by a CCD (9) camera. This method requires a precise XYZ workbench to complete the selection of the working surface, and the recording volume cannot be very large, which restricts the application of this storage method. Although it provides high density and high data transfer rate, it is far from being practical due to its expensive and bulky three-dimensional workbench and parallel data reading method.

The purpose of the present invention is to design a multi-layer three-dimensional storage optical head, which overcomes the problem that the existing three-dimensional storage uses two intersecting beams of light, which cause the storage device to be huge, expensive and difficult to use. A multi-layer three-dimensional storage optical head suitable for application is designed with simple structure and convenient operation.

Summary of the invention The multi-layer three-dimensional storage optical head designed by the present invention includes a first laser, a second laser, a first frequency multiplier, a second frequency multiplier, a first collimator, a second collimator, and a second collimator. A beam splitter, a second beam splitter, an auxiliary collimator, an auxiliary laser, an objective lens, and a linkage focusing mechanism; the first laser, a frequency multiplier, the first collimator, the first beam splitter, and the second beam splitter Installed on the same optical axis from left to right to form the main optical axis; the objective lens, the second beam splitter, the auxiliary collimating mirror and the auxiliary laser are installed on the same optical axis, and the optical axis is at an angle of 90° to the main optical axis; the disk to be read and written Placed on the other side of the objective lens relative to the second beam splitter, the second laser, the second collimator and the first beam splitter are installed on the same optical axis, and the optical axis is at an angle of 90° to the main optical axis, forming a The auxiliary optical axis; the linkage focusing mechanism is connected with the first collimating mirror and the second at the same time; the auxiliary laser generates an auxiliary laser beam which is focused on the main reflective surface of the disc to be read and written through the auxiliary collimating mirror, the second beam splitter and the objective lens and the resulting signal completes focusing, tracking and tracking; the lasers on the main optical axis and the auxiliary optical axis generate lasers of two wavelengths required for wiping, and the two laser beams are incident through the objective lens after being synthesized by the beam splitter to the disk to be read and written to complete the erasing operation; one of the two wavelength lasers used by the frequency multiplier to generate the write operation, and to complete the write operation by cooperating with the laser generated by the laser; the two collimators in the main optical path The lens is zoomed and adjusted by a linkage focusing mechanism to realize the selection of the reading and writing layer.

Using the multi-layer three-dimensional storage optical head designed by the invention can read and write multi-layer three-dimensional optical discs in parallel, effectively improving the data read-write rate and storage capacity of the optical disc. Moreover, the structure is simple and easy to implement, so it is easy to be popularized in practical applications and made into a product, which has great use value.

Description of drawings

Fig. 1 is the working principle of various multi-layer three-dimensional storage at present.

Figure 2 is a schematic diagram of a storage system jointly researched by the University of California and the US call-recall company.

Fig. 3 is a schematic diagram of the structure of the multi-layer three-dimensional storage optical head of the present invention.

The following is a detailed description of each structural schematic diagram, as shown in Figures 1 to 3:

1 is the objective lens, 2 is the two-photon absorbing material, 3 is the objective lens, 4 is the cylindrical lens, 5 is the Nd-YAG laser, 6 is the mask, 7 is the aiming mirror, 8 is the recorder, 9 is the CCD camera, 10 is the disappearance Chromatic aberration sight, 11 is the He-Ne laser, 12 is the pulse delay table, 131~138 is the plane mirror, 141~147 is the lens, 15 is the first laser, 16 is the frequency doubler, 17 is the first collimator Mirror, 18 is the first beam splitter, 19 is the disk, 20 is the objective lens, 21 is the second beam splitter, 22 is the auxiliary laser, 23 is the auxiliary collimator, 24 is the second laser, 25 is the second collimator , 26 is a linkage focusing mechanism.

Detailed ways

As shown in Figure 3, the multilayer three-dimensional storage optical head of the present invention comprises two lasers 15 and 24, a frequency multiplier 16, two collimators 17 and 25, two beam splitters 18 and 21, an auxiliary collimator Straight mirror 23, an auxiliary laser 22, an objective lens 20 and a linkage focusing mechanism 26. The laser 15, the frequency doubler 16, the collimating mirror 17 and the left beam splitter 18 are installed on the same optical axis from left to right to form the main optical axis. The objective lens 20, the right beam splitter 21, the auxiliary collimating mirror 23, and the auxiliary laser 22 are coaxially installed, and the optical axis forms an angle of 90° with the main optical axis. The disc 19 to be read and written is placed on the other side of the objective lens 20 relative to the beam splitter 21, and the other collimating mirror 25 and another laser 24 are coaxially installed with the left side beam splitter 18, and the optical axis is parallel to the main beam splitter. The optical axes form an angle of 90° to form the auxiliary optical axis. The linkage focusing mechanism 26 is connected with the two collimating mirrors 17 and 25 at the same time. The auxiliary laser 22 generates an auxiliary laser beam which is focused on the main reflective surface of the disc 19 to be read and written through the auxiliary collimating mirror 23, the beam splitter 21 and the objective lens 20, and the resulting signal completes focusing, tracking and seeking. The lasers on the main optical axis and the auxiliary optical axis generate lasers with two wavelengths required for wiping. The two laser beams are synthesized by the beam splitter, pass through the objective lens, and are incident on the read-write disk to complete the wiping operation. The frequency doubler 16 is used to generate one of the two wavelength lasers for writing operation, and the writing operation is completed by cooperating with the laser light generated by the laser 24 . The two collimating lenses 17 and 25 in the main optical path are zoomed and focused by a linkage focusing mechanism to realize the selection of the read-write layer.

Fig. 3 is a working principle diagram of the present invention. An auxiliary optical path composed of an auxiliary laser (22) and an auxiliary collimating mirror (23) is used to focus on the bottom surface of the storage disk (19) to complete focusing and tracking. The lasers of two wavelengths required for work are produced by lasers (15 and 24), and the collimating mirrors (17 and 25) of the two laser beams are controlled by a linkage focusing mechanism (26) to select the layered read-write surface. The laser frequency multiplier (26) is used to convert the laser wavelength when writing and erasing. This method overcomes the equipment requirements of traditional three-dimensional storage, and the storage body can be formed into a disc-shaped structure similar to the current optical disc, which simplifies the storage mechanism, improves the storage time and expands the storage capacity.

Considering that the information in the current computer system is mainly stored and transmitted in the form of data strings. Therefore, data should be stored serially. In multi-layer manufacturing, because pre-grooves cannot be added to the middle layer, focusing, seeking and tracking become difficult. In addition, due to two-photon absorption, manipulation and confocality of beams of two wavelengths need to be addressed. In a readout device, interlayer interference needs to be dealt with. The present invention is characterized by

(1) Auxiliary beam realizes tracking and focusing In order to realize tracking and focusing, an auxiliary beam is introduced so that the auxiliary beam is always focused on the bottom surface to complete tracking, tracking and focusing. The main beam uses zoom technology to complete the selection of different surfaces. In the process of reading and writing on each layer, the reading and writing method similar to the current optical disc is still adopted, so that it can be easily transplanted and practicalized in the prior art.

(2) Dual-wavelength optical bifocal lens Because lasers of two wavelengths are still used in the process of writing and erasing, they all need to enter from the same main optical path. Since the main optical path needs to pass through all recording layers, to avoid interlayer interference, the beams of the two wavelengths should only intersect at the focal point. The two wavelengths are divided into two paths, inside and outside. For the lens, the inner and outer rings have the same focal length for the corresponding wavelength. In this way, the light energy of the two wavelengths can be effectively uniformly focused on one point, and the writing and erasing operation at the focal point can be realized without affecting the state of other recording points.

(3) Confocal technology for readout signal

In the read operation, a single-wavelength laser is used to read the signal, and this photon-absorbing material with fluorescent properties will fluoresce as long as it absorbs photons, regardless of the intensity of the light. Consequently, areas of the other layers that are illuminated will also fluoresce when read. This may cause crosstalk of the signal. To avoid this crosstalk, a confocal technique can be used. A baffle with a small cavity is introduced, its position is just confocal with the focus of the system, ie only light emitted at the focus of the system passes through the system to the detector. Because the quantum yield of other illuminated areas is not at the focus, and the blocking of the baffle, it will be much smaller than the useful signal. In this way, crosstalk of adjacent recording points can be avoided.

Embodiments of the present invention are described below.

Lasers with three different wavelengths are used in this system. Writing is to use a short-wavelength laser (355nm+590nm) to cause a photochemical reaction in the medium, and the molecules change from state "0" to state "1". A laser with a longer wavelength (590nm) is used for readout. Molecules in the state "1" will fluoresce under the irradiation of this wavelength laser, while molecules in the state "0" will not, so by detecting the readout light The fluorescent effect of the medium makes it possible to distinguish the written signal. For fluorescent materials, as long as the fluorescence quantum yield of molecules is increased, the state change of molecules under the irradiation of readout light can be avoided, so this is a non-destructive readout process. Since higher energy is required for erasing, two beams of light (1064nm+590nm) need to be irradiated at the same time.

Claims (1)

1. A multi-layer three-dimensional storage optical head, characterized in that the optical head includes a first laser, a second laser, a first frequency multiplier, a second frequency multiplier, a first collimator, and a second collimator , the first beam splitter, the second beam splitter, the auxiliary collimating mirror, the auxiliary laser, the objective lens and the linkage focusing mechanism; the first laser, the frequency doubler, the first collimating mirror, the first beam splitting mirror and the second The beam splitter is installed on the same optical axis from left to right to form the main optical axis; the objective lens, the second beam splitter, the auxiliary collimator and the auxiliary laser are installed on the same optical axis, and the optical axis is at an angle of 90° to the main optical axis; it is read and written The disk is placed on the other side of the objective lens relative to the second beam splitter, and the second laser, the second collimator and the first beam splitter are installed on the same optical axis, and the optical axis is at an angle of 90° to the main optical axis , constituting the auxiliary optical axis; the linkage focusing mechanism is connected with the first collimator mirror and the second collimator at the same time; the auxiliary laser generates an auxiliary laser beam that is focused on the main disc to be read and written through the auxiliary collimator mirror, the second beam splitter and the objective lens on the reflective surface, and the resulting signal completes focusing, tracking and tracking; the lasers on the main optical axis and the auxiliary optical axis generate lasers of two wavelengths required for wiping, and the two laser beams are combined by a beam splitter and then pass through The objective lens is incident on the disk to be read and written to complete the erasing operation; the frequency multiplier is used to generate one of the two wavelength lasers for the writing operation, and the writing operation is completed by cooperating with the laser generated by the laser; the two in the main optical path The collimating lens is zoomed and focused by a linkage focusing mechanism to realize the selection of the reading and writing layer.

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