JPH01182846A - Optical recording medium - Google Patents

Abstract

PURPOSE:To enable operation at ordinary temp. and to enable stable multi- valued recording by the single wavelength laser alone by forming the title medium of a compd., the absorptivity of the reactant of which changes as a digital quantity when the quantity of incident light is applied as the digital quantity thereto. CONSTITUTION:The absorption band of the reactant and the absorption band of the resulted product of reaction need be different in order to execute multi- valued recording. This recording medium is, thereupon, formed of the compd. the absorptivity of the reactant of which changes as a digital quantity when the quantity of the incident light is applied as the digital quantity thereto, for example, org. matter such as acetylene hydrocarbon and ethylene hydrocarbon, halogenated salts such as NaCl and KBr, inorg. glass, etc. The recording medium which has a large memory capacity, can operate at ordinary temp. and allows the stable multi-valued recording with single wavelength laser alone is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to optical recording, and more particularly to an optical recording medium capable of multilevel recording.

(Prior Art) With the rapid development of information processing technology in recent years, the need for large-capacity memory has been advocated, and optical disk memory is attracting attention as the core of this.

Hurler (D.) of IBM San Jose Research Center for further expanding the capacity of optical disk memory.

Haarer et al. have proposed a memory that utilizes the PHB (photochemical hole burning) phenomenon at ultra-low temperatures, and various research institutions are actively researching this. (For example, there is an invention described in Japanese Patent Publication No. 58-51355.) However, these only apply to the case where a substance that causes tautomerism due to proton transfer, such as polyfin or quinizarin, is used as a chemical substance that causes the PHB phenomenon. Although specific technical details have been disclosed, as an optical recording medium, it has the following major problems: ■ It can only operate at liquid helium temperatures, ■ It requires a variable frequency laser, and ■ The recorded information (holes) is unstable. There is.

On the other hand, it is a well-known fact that in photochemical reactions, there is a simple functional relationship between the amount of light absorbed and the amount of reaction products under certain conditions. Until now, the medium has not been known, and furthermore, there are no known examples of multi-level storage.

(Problem to be Solved by the Invention) The present invention has been made in view of the above-mentioned problems, and provides an optical recorder that has a large memory capacity, operates at room temperature, and can perform stable multilevel recording using only a single wavelength laser. The purpose is to provide a medium.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides an optical recording medium that utilizes a chemical change caused by a photochemical reaction, which comprises a compound in which the absorbance of one reactant changes as a digital amount when the amount of incident light is given as a digital amount. 6. The photoreactant used in the present invention is not particularly limited, but is an optical recording medium characterized by
In order to perform multivalue storage, the absorption bands of the reactants and the absorption bands of the reaction products must be different. Furthermore, a substance with a high reaction quantum yield and a reaction product with high absorbance is advantageous. Specific examples include organic substances such as acetylene hydrocarbons and ethylene hydrocarbons, halogenated salts such as NaCQ and KBr, and inorganic glasses.

(Function) The present invention will be explained in detail using FIG. Figure 1 shows the change in absorbance when a reactant is irradiated with a pulsed laser to cause a photochemical reaction. When a pulsed laser is irradiated at position A, a photoreaction occurs and absorption increases by ΔA due to the product. Since the magnitude of ΔA can be changed by changing the intensity of the pulsed laser, it can be selected to match the minimum resolution (threshold) of the detection system. Furthermore, at position B, turn on the pulse laser.
By increasing the irradiation rate, the absorption further increases by ΔA. Therefore, the number of pulse laser irradiations can be recorded, and this can be used as multivalue recording. .

(Example) Example 1 An example of the present invention will be described below. FIG. 2 shows an optical recording medium according to the present invention. This optical recording medium was produced as follows. Two quartz substrates were placed at an interval of 100 μs, the space was filled with acetylene, and the surroundings were sealed with silicone resin. The acetylene pressure was I Torr.

Excimer laser (193 nm, 100 nm) by ArF
mj/pulse) and 250 nm for each pulse.
The absorbance at was measured. The results are shown in Figure 3. This increase in absorbance is due to the polymer/molecule reaction of acetylene, which occurs because the generated polymer adheres to the quartz substrate. Furthermore, by changing the intensity of the excimer laser, it was also possible to change the increase in absorbance per pulse.

Example 2 Eximer laser (248 nm, 15G+++j/pulse) using KrF was used in the same manner as in Example 1.
), the same change in absorbance as in Example 1 was observed. However, in this case, it was necessary to sufficiently narrow down the laser spot.

〔Effect of the invention〕

According to the present invention, it is possible to provide an optical recording medium that has a large memory capacity, operates at room temperature, and is capable of stable multilevel recording using only a single wavelength laser.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing changes in absorbance for explaining the present invention in detail, FIG. 2 is a cross-sectional view of an optical recording medium, and FIG. 3 is a diagram showing changes in absorbance in Example 1. 21: Quartz substrate 22: Acetylene 23: Silicon resin agent Patent attorney Nori Chika Ken Yudo Mitsuyuki Matsuyama ABCDEFG)l Fig. 1 Fig. 2 θ 5 fD fs

Claims (3)

[Claims] (1) In an optical recording medium that utilizes chemical changes caused by photochemical reactions, when the amount of incident light is given as a digital amount,
An optical recording medium comprising a compound whose absorbance of a reactant changes as a digital quantity. (2) The optical recording medium according to claim 1, wherein the compound is an acetylene hydrocarbon or an ethylene hydrocarbon. (3) The optical recording medium according to claim 1, wherein the compound is an inorganic compound that generates a dye center upon irradiation with light.