JPS60184246A - Light recording medium - Google Patents

Abstract

PURPOSE:To enable a state of a thin film of a light recording medium changed in optical properties due to its cyclic photoreaction to be used as information of a record and a regenerated signal by forming bacteriorhodopsin on a substrate of a glass plate, silicon wafer or the like as the thin film of the light recording medium. CONSTITUTION:A thin bacteriorhodopsin film 5 is formed on a glass substrate 10 to form a light recording medium. Information can be recorded on this light recording medium by irradiating blue laser beams high in intensity on the parts 7-9 of the film 5 to be exposed at a constant temp. of -120--30 deg.C, greatly changing each light reflectance, transmittance, etc. of the parts 7-9 in this order, and realizing a gradational record from the changed states of the optical properties. The information can be regenerated by irradiating a light of 500- 600nm wavelength of 380-450nm wavelength to allow the light reflected with or transmitted through the exposed parts 7-9 to change in light intensity from that reflected or transmitted through the unexposed part 6 in accordance with a signal intensity. The recorded information can be erased by irradiating the laser beams on the part of the light recording medium to be erased and locally heating it.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an optical recording medium such as an optical disk memory, and uses a biological material as an optical recording medium to write and read information as a gradation signal. The present invention relates to an optical recording medium that is easy to write and can be rewritten.

[Prior art]

Conventionally, as an optical recording medium, there has been one shown in FIG. In the figure, 1 is a metal vapor deposited film, 2 is a pore formed by irradiating the metal stem deposited film 1 with a laser beam, 3 is an unirradiated part of the laser beam, and 4 is a glass substrate. In this conventional optical recording medium, the temperature of the part irradiated with the laser beam rises, and the metal part melts and desorbs, creating pores 2. This causes the part 3 not irradiated with the laser beam to become "0", and the laser beam The two can be distinguished by setting the beam irradiation part to "1", and 21 dL can be obtained as a digital memory.

Conventional optical recording media are configured as described above, so
Once a signal has been recorded, it cannot be rewritten, and the signal can only take on two values, "0'" and 1. Therefore, gradation recording, that is, analog recording, is impossible.

[Summary of the invention]

This invention was made to eliminate the above-mentioned drawbacks of conventional optical recording media, and it consists of a thin film of bacteriorhodopsin, a pigment protein present in the biological membranes of highly halophilic bacteria, on a substrate. The purpose of the present invention is to provide a completely new optical recording medium that is formed by forming a thin film, and that makes gradation recording possible and rewritable by utilizing changes in optical properties due to cyclic photoreactions of the thin film. It is said that

[Embodiments of the invention]

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

Bacteriorhodopsin is a highly halophilic bacterium (llalobac).
It is a pigment protein present in the biological membrane of Terium balobium, and is known to undergo photoreactions. Although the full details of the photoreaction have not yet been elucidated, several types of photoreaction intermediates have been discovered.

Therefore, the present inventors focused on the fact that bacteriorhodopsin can be used as an optical recording medium if bacteriorhodopsin is made to function as a stable solid film and the progress of the photoreaction can be controlled. In particular, the photoreaction of bacteriorhodopsin membranes is reversible, and the progress of the reaction may be controlled by the intensity of irradiated light, making it possible to record gradations using this bacteriorhotopsin membrane. It has also been found that a rewritable optical recording medium can be obtained. - 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 the cyclic This invention was created by focusing on the fact that a state in which optical properties have changed due to a photoreaction can be used as an information recording or reproduction signal.

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.

Figure 3 shows the light absorption spectrum of the hatateriotopsin film before photoreaction, and the absorption spectrum was measured at -60°C.
I did it. Furthermore, Figure 4 shows the difference absorption spectrum, which is the difference between the absorbance of the bacteriorhodopsin membrane before and after the photoreaction, and the photoreaction was performed by irradiating green light (wavelength 500 nm) at -60°C. This was done by doing this.

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, It can be seen that it has a strong absorption band in the wavelength range of 380 to 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.

In addition, experiments have shown that when the temperature of the optical recording medium is set to around room temperature by irradiating the optical recording medium with a laser beam and heating it, this reaction intermediate returns to its pre-reaction state and has the absorption spectrum shown in Figure 3. It turns out that it becomes.

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 experimental results described above, it has been found that the following method can be used to record, reproduce, or rewrite information in gradations using an optical recording medium having a batateriochromic film formed on a substrate.

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

(2) While keeping an optical recording medium using a bacteriorhodopsin film at a constant temperature in the range of -120°C to -30°C, the thin film is irradiated with the recording irradiation light to cause a writing light reaction. The state after the photoreaction is the writing state,
Furthermore, the optical medium in the writing state is heated to -120°C to -3°C.
By holding the temperature at a constant temperature in the range of 0° C., the writing state can be maintained stably for one period t7.

(3) After optical writing, in order to reproduce the recorded information, 50
An optical recording medium is irradiated with nailing irradiation light having a wavelength range of 0 to 600 nm or 380 to 450 nm, and the recorded information is reproduced from the reflection or transmittance of the light.

(4) To erase the information signal after optical writing, it is sufficient to irradiate the area to be erased with a laser beam and heat the area, thereby causing a cyclic photoreaction to proceed locally. The reaction intermediate returns to the initial state before optical writing,
As a result, the write signal is partially erased.

(5) To perform gradation recording of information, it is sufficient to control the intensity or irradiation time of the illumination light for optical writing.

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

FIG. 2 schematically shows an optical recording medium according to an embodiment of the present invention. In the figure, 5 is a bacteriorhodopsin thin film formed on a glass substrate 10, 6 is an area not irradiated with a laser beam, and ? , 8. 9 is a laser beam irradiation section.

To record information on the optical recording medium, -120°C to -
At a constant temperature of 30"C, the portions of the bacteriorhodopsin thin film 5 that are to become the irradiated parts 7, 8, and 9 are irradiated with blue laser light of high intensity in this order. This causes the irradiated parts 7, 8, and 9 to Therefore, the optical properties, such as the reflectance and transmittance of light, change greatly in the order of the irradiation parts 7, 8.9, and the state in which the optical properties have changed is used as the information recording state to realize gradation recording of information. be done.

Then, in order to reproduce information from the optical recording medium, the optical recording medium is
A reproduction irradiation light having a wavelength range of m is irradiated. Then, the reflectance or transmittance of the reproduction irradiation light in the laser beam irradiation parts 7, 8.9 differs from the reflectance or transmittance in the unirradiated part 6 depending on the signal strength, and therefore, Information can be played back.

Furthermore, in order to erase the recorded information on the optical recording medium, it is sufficient to irradiate the portion of the optical recording medium where the information is to be erased with a laser beam and heat it locally. The rate or transmittance returns to the value before the information was recorded, and the recorded information can be erased. Then, if the information is recorded again using the above-mentioned recording method, rewriting of the information can be realized.

V.41b, The bacteriorhodopsin thin film is not limited to a pure one, 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 present invention, an optical recording medium is constructed by forming an N film of bacteriorhodopsin, which is a pigment protein of highly halophilic bacteria, on a substrate. This has the effect of providing an optical recording medium that is capable of recording and reproducing information in gradations and rewriting information by skillfully utilizing changes in properties.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a conventional optical recording medium, FIG. 2 is a perspective view of an optical recording medium according to an embodiment of the present invention, and FIG. 3 is a characteristic diagram showing the absorption spectrum of a bacteriorhodopsin film before photoreaction. FIG. 4 is a characteristic diagram showing the difference absorption spectrum of light before and after photoreaction. 5... Bacteriorhodopsin thin film, 10... Glass substrate. Agent Masuo Oiwa Figure 1 Figure 2 Figure 6 Figure 3 U! Length (nm) - Figure 4 1゜2゜: 3゜4゜Indication of the case of the Director-General of the Japan License Agency.Relationship with the case of Patent Application No. Sho 59-40808 and the name of the optical recording medium oil stopper case 1 , 1'' Permission 19 [i Person Address 9 I) East 1112, Chiyo 111-ku, Tokyo; 3 C) Name (
6) E, Ryodenki Co., Ltd. Representative Kata 111 Jin 8 Department Attorney 5 Column 6 of the detailed explanation of the invention of the specification subject to amendment, Contents of Supplement iE (1) Mei 8IIIfi-Page 3 No. 13 Correct "It is reversible" in the line to "It is a cyclic reaction." (2) In the first line of page 5, "absorbance decreased significantly after reaction" was corrected to "absorbance decreased significantly after reaction." Below

Claims (1)

[Claims] +11 An optical recording medium comprising a thin film of bacteriorhodopsin whose optical properties change upon photoreaction on a substrate.