JPH0447892B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to optical recording in optical disk memories and the like, and by using biomaterials as optical recording media, it is possible to write and read information as gradation signals. This invention relates to a method for recording, reproducing, and erasing information that is easy and rewritable.

[Prior art]

Conventionally, as an optical recording medium, there has been one shown in FIG. In the figure, 1 is a metal vapor deposition film, 2 is a pore formed by irradiating the metal vapor deposition film 1 with a laser beam, 3 is a portion not irradiated with the laser beam, and 4 is a glass substrate. To record information on this conventional optical recording medium, the metal vapor deposited film 1 is irradiated with a laser beam. The part irradiated with the laser beam is
As the temperature rises, the metal part melts and desorbs, creating pores 2, which causes the part 3 not irradiated with the laser beam to become "0".
By setting the laser beam irradiation part to "1", the two can be distinguished, and a binary value as a digital memory can be obtained.

Conventional optical recording media are constructed as described above, and therefore, with the information recording, reproducing, and erasing methods using conventional optical recording media, once recorded signals cannot be erased, and therefore cannot be rewritten. Moreover, the signal could only take two values, "0" and "1", and therefore gradation recording, that is, analog recording was impossible.

[Summary of the invention]

This invention was made in order to eliminate the drawbacks of the above-mentioned conventional information recording and reproducing methods using optical recording media. A thin film of bacteriorhodopsin, which is
The purpose is to provide a completely new method for recording, reproducing, and erasing information.

[Embodiments of the invention]

First, the principle and operation of this invention will be explained with reference to the drawings.

Bacteriorhodopsin is a pigment protein present in the biomembrane of Halobacterium halobium, and is known to undergo photoreactions. Although the full details of this photoreaction have not yet been elucidated, several types of photoreaction intermediates have been discovered.

Therefore, the present inventors focused on the fact that if bacteriorhodopsin functions as a stable solid film and the progress of the photoreaction can be controlled, the bacteriorhodopsin film can be used as an optical recording medium. In particular, the photoreaction of the bacteriorhodopsin membrane is a cyclic reaction, some of the elementary reactions are reversible, and the progress of the reaction may be controlled by the intensity of the irradiated light. It has been discovered that a rewritable optical recording medium capable of recording gradations can be obtained using a bacteriorhodopsin membrane.

That is, as a result of intensive research based on the above considerations, the present inventor created an optical recording medium by depositing bacteriorhodopsin as a thin film on a substrate such as glass or silicon wafer, and created an optical recording medium by depositing bacteriorhodopsin on a substrate such as a glass or silicon wafer. This invention was created by focusing on the fact that a state in which optical properties have changed due to a reaction can be used as a signal for recording, reproducing, and erasing information.

FIGS. 3 and 4 show experimental results regarding the light absorption spectrum of bacteriorhodopsin membranes, which were conducted by the present inventor based on the above-mentioned points of interest.

FIG. 3 shows the light absorption spectrum of the bacteriorhodopsin membrane before photoreaction, and the absorption spectrum was measured at -60°C. Figure 4 shows the difference absorption spectrum, which is the difference between the absorbance of the bacteriorhodopsin membrane before and after the photoreaction.
500 nm).

From FIGS. 3 and 4, the bacteriorhodopsin membrane has a strong absorption band in the wavelength range of 500 to 600 nm before photoreaction, but the reaction intermediate of bacteriorhodopsin, which is stable at -60°C after photoreaction, 380～
It can be seen that it has a strong absorption band in the wavelength range of 450 nm, and the wavelength range of 500 to 600 nm, which is the main absorption band before the photoreaction, decreases significantly after the reaction. Also,
Experiments have shown that this reaction intermediate returns to its pre-reaction state when the ambient temperature of the optical recording medium is set around room temperature, and has the absorption spectrum shown in FIG. 3.

Furthermore, it has been found that by controlling the intensity or irradiation time during irradiation with green irradiation light, the differential absorbance of the differential absorption spectrum before and after the photoreaction shown in FIG. 4 can be made to have desired characteristics.

From the above experimental results, it was found that the following method can be used to record, reproduce, or rewrite information in gradations using a bacteriorhodopsin membrane.

1. To record information, green light or blue light is used as the recording irradiation light that causes a cyclic photoreaction in the bacteriorhodopsin membrane.

2. By maintaining the reaction intermediate in the written state after the photoreaction at a constant temperature in the range of -120°C to -40°C, the written state is stably maintained.

3. To reproduce the recorded information after optical writing,
An optical recording medium is irradiated with reproduction irradiation light having a wavelength range of 500 to 600 nm or 380 to 450 nm, and recorded information is reproduced from the reflectance or transmittance of the light.

4. To erase the information signal after optical writing,
It is sufficient to maintain the optical recording medium in a temperature range of -40°C to 50°C, and as a result, the cyclic photoreaction of the reaction intermediate proceeds and returns to the initial state before optical writing, and as a result, the written signal is erased. be done.

5. To perform gradation recording of information, the intensity or irradiation time of the optical writing irradiation light may be controlled.

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 schematically shows an optical recording medium on which information is recorded by a method according to an embodiment of the present invention. In the figure, 5 is a bacteriorhodopsin thin film formed on a glass substrate 10, and 6 is a laser beam. The beam-unirradiated portions 7, 8, and 9 are laser beam irradiated portions.

To record information on the above optical recording medium, -120℃
At a constant temperature of -40 DEG C., the parts of the bacteriorhodopsin thin film 5 that are to become the irradiation parts 7, 8, and 9 are irradiated with high-intensity blue laser light in this order. As a result, the optical properties of the irradiating parts 7, 8, and 9, such as light reflectance and transmittance, change greatly in the order of the irradiating parts 7, 8, and 9, and the state in which the optical properties have changed is Gradation recording of information is realized as the information recording state.

To reproduce information from the optical recording medium,
The optical recording medium is irradiated with reproduction irradiation light having a wavelength range of 500 to 600 nm or 380 to 450 nm. Then, the reflectance or transmittance of the reproduction irradiation light in the laser beam irradiation parts 7, 8, and 9 differs from the reflectance or transmittance in the unirradiated part 6 depending on the signal strength, and therefore, these Information can be reproduced from

In addition, in order to erase the recorded information on the optical recording medium, the ambient temperature of the optical recording medium must be set at -40°C to 50°C.
As a result, the cyclic photoreaction of the thin film progresses, and the light reflectance and transmittance of the thin film return to the values before the information was recorded, thereby erasing the recorded information. Then, by recording the information again using the above recording method, rewriting of the information can be realized.

In addition, in the above embodiment, the case where information is recorded and retained is explained with the ambient temperature of the optical recording medium being set at -120°C to -40°C, but the above information is recorded at room temperature ±10°C and the recorded information is retained. In order to
The temperature may be set at a constant temperature of 40° C., and the same effect as in the above embodiment can be obtained even in this case.

Further, as other embodiments of the present invention, there are the following methods. When recording information and maintaining the recorded state, keep the ambient temperature of the optical recording medium at -120℃~
The temperature can be maintained at a constant temperature of -30°C, which maintains the recording state stably.Also, to erase recorded information, the area of the thin film where the information should be erased may be heated locally by irradiating the area with a laser beam. As a result, the optical properties of the thin film return to the state before recording, and the recorded information is erased.

In yet another embodiment of the present invention, the atmospheric temperature of the optical recording medium is kept at a constant temperature of -120°C or lower for recording and retention of information, and red laser light (wavelength > 700 nm) is used for erasing recorded information. may also be irradiated, and even in this case, the same effect as in the above embodiment can be achieved.

Furthermore, the bacteriorhodopsin thin film is not limited to a pure bacteriorhodopsin film, and may be a bacteriorhodopsin thin film containing, for example, a lipid or a synthetic polymeric substance such as polystyrene.

〔Effect of the invention〕

As described above, according to the method for recording, reproducing, and erasing information according to the present invention, optical properties of an optical recording medium formed by forming a film of bacteriorhodopsin, which is a pigment protein of highly halophilic bacteria, are achieved by a reversible photoreaction. Since the changes in the information are skillfully utilized, information can be recorded and reproduced, and the information can be rewritten.

[Brief explanation of the drawing]

FIG. 1 shows an example of a conventional optical recording pattern, FIG. 2 shows an optical recording pattern according to an embodiment of the present invention, and FIG. 3 shows an absorption spectrum of a bacteriorhodopsin film before photoreaction. Characteristic diagram,
FIG. 4 is a characteristic diagram showing the differential absorption spectra of light before and after photoreaction of the bacteriorhodopsin membrane. 5...Bacteriorhodopsin thin film, 10...Glass substrate.

Claims (1)

[Claims] 1. An optical recording medium comprising a thin film of bacteriorhodopsin formed on a substrate is irradiated with recording light according to information, and the optical properties of the thin film are changed by the irradiation of the light. The state is set to the above-mentioned information recording state, and the thin film in the recording state is irradiated with a predetermined reproduction irradiation light, and the information is reproduced from the reflectance or transmittance of the light at that time. A method for recording, reproducing, and erasing information, characterized in that the information is erased by irradiating erasing irradiation light or by holding the thin film at a predetermined temperature to return the optical properties of the thin film to the state before the information was recorded. . 2. The method for recording, reproducing, and erasing information according to claim 1, wherein the recording irradiation light for recording information on the thin film is green or blue laser light. 3. Claim 1, wherein the reproduction irradiation light for reproducing the recorded information is a laser beam in the wavelength range of 500 to 600 nm or 380 to 450 nm.
How to record, reproduce, and erase information described in Section 1. 4. Recording of information as set forth in claim 1, characterized in that the ambient temperature of the optical recording medium at the time of recording the information and in the recording state is a constant temperature in the range of -120°C to -40°C. How to play/delete. 5. A patent characterized in that the ambient temperature of the optical recording medium is set to room temperature ±10°C when the information is recorded, and is brought to a constant temperature in the range of -120°C to -40°C within 1 minute after recording the information. A method for recording, reproducing, and erasing information as set forth in claim 1. 6. Information recording and recording according to claim 4 or 5, characterized in that the ambient temperature of the optical recording medium at the time of erasing the recorded information is in the range of -40°C to 50°C. How to play/delete. 7. Claim 1, characterized in that the ambient temperature of the optical recording medium during and in the recording state is a constant temperature of -120°C to -30°C.
How to record, reproduce, and erase information described in Section 1. 8. The erasing of the recorded information is carried out by irradiating a portion of the thin film where information is to be erased with a laser beam to locally heat it. How to record, reproduce, and erase information. 9. The method for recording, reproducing, and erasing information according to claim 1, characterized in that the ambient temperature of the optical recording medium during information recording and in the recording state is kept at a constant temperature of -120° C. or lower. 10. The method for recording, reproducing, and erasing information according to claim 9, wherein the erasing irradiation light for erasing the recorded information is a red laser beam having a wavelength of 700 nm or more.