Device for multilayer optical recording and reproducing information

 

(57) Abstract:

The invention relates to optical recording and can be used for high-speed recording, playback and store large amounts of information. The device is implemented phase difference representation of the information in the interference lattice-Pete and high-speed scanning light beams. For this purpose, the output phase difference modulator connected to the electric input of the acousto-optic modulator and installed acousto-optical scanner. The scanner includes a baffle support and deflector "running of the lens. Electrical inputs deflectors are connected to the outputs of generators with linear frequency modulation (chirp). The start-up of generators produced by delay trigger pulses. For opto-electronic surveillance track data control circuit, the chirp generator support is connected to the output of the frequency shift and the start delay, the chirp generator running lenses" made manageable. The control input of this delay and the unit of frequency shift combined. Maintenance mode "running lens" allows high speed recording-playback, optical efficiency and uniformity of the raster. 3 Il. ANO for high-speed recording, play and store large amounts of information.

A device for multilayer optical recording and reading information [1], comprising a light source optically connected to a photodetector through sequentially arranged and optically coupled Electromechanical system for tracking the track (track) data, the rotating scanner and three-dimensional multilayer photosensitive recording medium.

Insufficient characteristics of such devices are insufficient speed recording/reproduction of information, limited by the speed of the mechanical scanner and Electromechanical tracking systems track, as well as insufficient resolution in the depth of the material (125 microns) that in a given thickness of environment reduces the memory capacity.

It is also known device that implements the method of the multilayer optical recording and reproduction of information [2]. The device contains a laser optically connected through serially arranged and optically coupled acousto-optic modulator and three-dimensional (homogeneous or multi-layer) of the photosensitive recording medium.

Acousto-optic modulator allows me localization of the interference patterns Pete.

Insufficient characteristic of such devices is not enough speed recording/reproduction of information, which is limited by the linear speed of the mechanical movement of the photosensitive medium.

The closest technical solution of the essential features is a device for multilayer optical recording and reading information [3] , which contains the light source, optically associated with the photodetector through the sequentially arranged and optically coupled acousto-optic modulator and the volumetric recording medium; a generator RF voltage is connected to the electrical input of the acousto-optic modulator, as well as through the block phase difference modulation from the light source; the unit of analysis read signal connected to the output of the photodetector.

The presence of unit phase difference modulation allows you to record in one Pete few (2-3) discharge binary data that allows you to zoom in as many times the speed and information density.

However, this device is fundamentally not significantly (an order of magnitude or more) to increase the speed of recording/reproduction of information.

The purpose of imali by introducing high-speed scan of the light beam and high-speed opto-electronic tracking track (track) data using acousto-optic deflector "running of the lens and deflector support.

This objective is achieved in that the device for a multilayer optical recording and reproducing information containing the light source, optically associated with the photodetector through the sequentially arranged and optically coupled acousto-optic modulator and the volumetric recording medium; a generator RF voltage is connected to the electrical input of the acousto-optic modulator, the analysis block read signal connected to the output of the photodetector; installed between the acousto-optic modulator and the recording medium optically coupled to the deflector support and deflector "running lens and deflectors arranged in series (one after another) and optically connected, respectively, with acousto-optic modulator and the recording medium, electrical inputs baffle support and deflector "running of the lens connected to the outputs, respectively, of the first and second voltage generators with linear frequency modulation; the generator output RF voltage is connected to the input of the frequency divider and through the block phase difference modulation - with electric entrance acousto-optic modulator; the output of the frequency divider is connected through a delay element and block shear ment delay - to the input of the start of the second generator voltage with linear frequency modulation, through the key - input control block phase difference modulation and then through the third delay element to the light source; a second delay element performed with controlled delay, and the control input of this delay and the unit of frequency shift combined.

New proposed signs: between the acousto-optic modulator and the recording medium set associated optical deflector support and deflector "running lens and deflectors arranged in series (one after another) and optically connected, respectively, with acousto-optic modulator and the recording medium. Electrical inputs baffle support and deflector "running of the lens connected to the outputs, respectively, of the first and second voltage generators with linear frequency modulation. The generator output RF voltage is connected to the input of the frequency divider and through the block phase difference modulation - with electric entrance acousto-optic modulator. The output of the frequency divider is connected through a delay element and a unit of frequency shift to the control input of the first generator voltage with linear frequency modulation, across the via the key - to the input of the control unit of phase difference modulation and then through the third delay element to the light source. The second delay element is made with a variable delay, and the control input of this delay and the unit of frequency shift combined.

The proposed solution is illustrated in the following graphic material.

Fig. 1 is a functional diagram of the device.

Fig. 2 - structure of the fragment of radially oriented lines.

Fig. 3, a, b, C, d, e, f - block diagram of the scanner.

Fig. 3, and the principle of operation of the scanner based on the running diffractive lens with maintenance.

Fig. 3, b - end position of the acoustic Zug in the aperture of the deflector "running of the lens when scanning raster 1st to 134-th position.

Fig. 3, in the initial position of the acoustic trains when the shift start raster (line) from the first to the seventeenth position.

Fig. 3, the end position of the acoustic Zug scanning raster with the 17th 150-th position.

Fig. 3, d - initial position of the acoustic trains when the shift start raster from the seventeenth to the first position (return to the state shown in Fig. 3, a).

Fig. 3, e - end position of Acura device.

The device includes an optical channel which is formed by sequentially (one after another) arranged and optically coupled to the light source 1, the optical communication element (lens) 2, acousto-optical modulator 3, the optical communication element (lens) 4, acousto-optical deflector support 5, the optical communication element (lens) 6, acousto-optic deflector "running of the lens 7, the optical communication element (lens) 8, a photosensitive recording medium (storage medium) 9 and the photodetector 10.

The output of phase difference modulation 11 is connected with an electric entrance acousto-optic modulator, the output voltage generators with linear frequency modulation 12, 13 are connected with electrical inputs, respectively, of the baffle support and deflector "running lens unit of analysis of the read signal 14 is connected to the photodetector. The generator output RF voltage 15 is connected to the input of the frequency divider 18, the output of which is connected through delay element 19 to the input of the start block of the frequency shift 16, through the element variable (controlled) by a delay of 17 - login-run generator 13 through the key 21 and the delay element 20 to the input of the start of the light source.

The control inputs of the shift h is="ptx2">

The unit of frequency shift 16 generates a sawtooth voltage to the frequency control voltage generator 12. The amplitude of this voltage constant, and the initial value is changed by the command "Track track". This block can be made on the basis of the pulse counter, the outputs of the bits which are connected with the inputs of the digital to analogue Converter. The number of pulses during the scan at the counting input of the counter is fixed, but the initial installation of its changes in accordance with the command code "Track track".

The device operates as follows.

The beam from the light source 1 is formed by the optical circuit 2 in the form of banners in the area of acousto-optical interaction of the modulator 3. The resulting diffraction light beams are combined in the addressed layer volumetric recording medium 9 is formed and recorded in the zone of intersection of the rays L1 and L2 (Fig. 2) the interference grating is Pete. To increase recording density of the size of the pit in the direction of the vector lattice is the lowest allowable equal to approximately two periods of the lattice; and the thickness of the recording medium is selected larger than the lattice-Pete depth. Etc) is of the recording medium (in our example, presented on Fig. 2, the disk radius). In Fig. 2 shows the structure of a fragment of one radially-oriented line. The figure explains the essence of the method of multilevel coding information by using the phase difference modulation [4]. Information parameter at the phase difference modulation is a phase difference of the spatial lattice of two adjacent pit. The phase shift occurs in the direction perpendicular to the scan, as shown in Fig. 2.

The information recording begins after closure of the key 21 and is produced by a pulsed illumination ultrasonic grating moving in the area of acousto-optical interaction of the modulator 3. With the arrival of the clock pulse at the input of the phase difference modulation 11 there is a change in phase of the voltage applied to the system acousto-optic modulator 3. At the output of the delay element 20 comes a series of detainees at the time of start-up pulses of the light source 1.

The delay is necessary to compensate for the time path of the sound from the piezo to the light aperture of the modulator 3. The delay is set such that the first light pulse coincided with the time of fill light aperture block photoresists modulation 11 is connected to the light source 1, and to the input of the modulator 3. This decision is important to ensure a high scanning speed, because it allows to eliminate the uneven arrangement of pits in the line to reduce intersymbol interference and to increase the total speed without reducing the density recording.

Diagram of the scanner shown in Fig. 3.

Optical circuit 4 generates a light beam in the form of banners in the area of acousto-optical interaction baffle support 5. Electric entrance baffle support is energized with a linear frequency modulation (chirp). The aperture time is the running time of an acoustic wave through the light aperture of the baffle selects a significantly lower duration of the sweep. Then, the chirp voltage causes a change of the angle of deviation of the diffracted beam. A matching lens 6 converts this angular displacement in translational motion of the beam. The velocity of the translational motion is chosen equal to the speed of sound in air vent "running of the lens 7. In the process of scanning the beam of light moves synchronously with the running of the lens" (accompanies it).

When running the lens reaches the end position (indicated in Fig. 3, dotted line), the frequency of the chirp voltage wadee position, where to this time had been formed following the chirp lens. The duration of the shift in the starting point of the sweep (the return stroke) is determined mainly by the value of the aperture time of the baffle support. The less time it takes, the higher the average speed of scanning. The duration of the reverse is possible to reduce up to 50 - 70 NS, then when the scan time 1 µs decline in the average scanning speed compared with the limit does not exceed 5-7%.

Maintenance mode "running lens" allows the scanner settings that are close to the maximum possible not only performance, but also on the optical efficiency and uniformity of the raster.

In addition to the sweep of the light beam, the scanner also performs the function of the actuator system tracking track. For this purpose, the duration of the chirp voltage "running lenses, you should choose less than the duration of one scan cycle. In our example, the scan time is approximately 1 μs, and the length of the chirp voltage selected is 0.64 μs.

The delay element 19 is set such that the recording of the first in the line of Pete coincided with the beginning of the chirp Zug ultrasonic is this wave should track the current position of the traveling lens. Changing the delay time of the launch of the "running of the lens and the corresponding value of the initial frequency of the voltage control vent maintenance is performed with the command "Track track".

In Fig. 3, b shows the relative deflector "running lenses" in the scan raster with 1 to 134-th position. In order to move the beginning of the sweep from the first position to the seventeenth, for example, it is necessary to reduce the interval between the chirp of the trains so that by the end of the next scan, already shifted, the chirp Zug ultrasound won the primary, the seventeenth position (see Fig. 3). In addition, the initial value of the frequency control signal deflector support you need to change so that after completion of the return stroke, the laser beam would have been in the 17th position and coincided with shifted in this position, the chirp train "traveling lens. Subsequent operation of the scanner is shifted from the initial position shown in Fig. 3,, the return Process in the source raster Nandinatha position is as conventionally shown in Fig. 3, d and Fig. 3, that is,

When reproducing information, the key 21 is opened, and the light source is switched to continuous radiation. The unit of phase difference modulation 11 off the optical scanner when the play does not differ from functioning in the recording mode. Under continuous illumination in a zone of intersection of the rays L1 and L2 (Fig. 2) there running interference grating, which interacts with the recorded gratings-potami and forms the input of the photodetector 10 is modulated by the intensity of the light beam. The photodetector converts it into a phase modulated RF voltage, which is then demodulated in the analysis block read signal 14. This signal is also a sign of the beginning of the track, which is used to generate the command "Track track".

LITERATURE

1. Pat. USA, N 4219704, G 11 B 21/04, 1980.

2. Inventor's certificate SU N1769233 G 11 7/00, 1992, bull. N 38.

3. I. B. Rudakov, I. W. Steinberg, Y. A. Sapelkin. Method of multi-layer optical information recording. Avtometrija, 1991, No. 3.

4. A. M. Driveways, Y. B. Okunev, L. M. Rajovic. Phase difference modulation. "Communication", M., 1967.

Device for multilayer optical recording and reproducing information containing the light source, optically associated with the photodetector through the sequentially arranged and optically coupled acousto-optic modulator and the volumetric recording medium, the generator RF voltage is connected to the electric input aku is the, between the acousto-optic modulator and the recording medium set associated optical deflector support and deflector "running lens and deflectors arranged in series (one after another) and optically connected respectively with the acousto-optic modulator and the recording medium, the electrical inputs of the baffle support and deflector "running of the lens connected to the outputs respectively of the first and second voltage generators with linear frequency modulation, the generator output RF voltage is connected to the input of the frequency divider and through the block phase difference modulation - with electric entrance acousto-optic modulator, the output of the frequency divider is connected: through the delay element and the block frequency shift to the control input of the first generator voltage with linear frequency modulation, via a second delay element to the input of the start of the second generator voltage with linear frequency modulation, through the key - input control block phase difference modulation and then through the third delay element to the light source, the second delay element is made with controlled delay, and the control input of this delay and the unit of frequency shift combined.

 

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