Optical recording method, optical recording medium, and optical recording system

Abstract

An optical recording method suited for recording a very small object or movement of a living organism such as a microorganism, which comprises irradiating an informative object set on or above a recording layer comprising a photosensitive material capable of undergoing a storable and detectable photochemical reaction, preferably a polymer material containing a photoreactive component capable of photoisomerization and having in the repeating unit thereof at least one group selected from a urethane group, a urea group, an amide group, a carboxyl group and a hydroxyl group, and recording a distribution of an optical near field generated from the informative object being irradiated on the photosensitive material as a photoreacting quantity of the photosensitive material.

What is claimed is:  
     
         1 . An optical recording method, comprising: 
 constituting a recording layer of a photosensitive material capable of undergoing a storable and detectable photochemical reaction;    setting an informative object on or above the recording layer at such a position that an optical near field generated from the informative object may reach the recording layer;    irradiating at least the area of the recording layer where the informative object is positioned with light to cause the informative object to generate the optical near field; and    recording the distribution of the optical near field on the photosensitive material as a photoreacting quantity of the photosensitive material.    
     
     
         2 . The optical recording method according to  claim 1 , wherein said informative object is made of a material which transmits light for irradiation.  
     
     
         3 . The optical recording method according to  claim 1 , wherein said informative object has a size of 100 nm or smaller.  
     
     
         4 . The optical recording method according to  claim 3 , wherein said informative object has a size of 25 nm or smaller.  
     
     
         5 . The optical recording method according to  claim 1 , wherein said light for irradiation is laser light.  
     
     
         6 . The optical recording method according to  claim 1 , wherein said photosensitive material is at least one of a material capable of forming unevenness in accordance with its photoreacting quantity to record the distribution of the optical near field, a material capable of changing its refractive index in accordance with its photoreacting quantity to record the distribution of the optical near field, a material capable of changing its light absorbance in accordance with its photoreacting quantity to record the distribution of the optical near field, a material capable of developing a potential difference in accordance with its photoreacting quantity to record the distribution of the optical near field, and a material containing a photoreactive component capable of changing its degree of orientation in accordance with its photoreacting quantity to record the distribution of the optical near field.  
     
     
         7 . The optical recording method according to  claim 6 , wherein said photosensitive material is a photoreacting polymer material capable of forming unevenness in accordance with its photoreacting quantity to record the distribution of the optical near field.  
     
     
         8 . The optical recording method according to  claim 6 , wherein said photosensitive material is a photorefractive material capable of changing its refractive index in accordance with its photoreacting quantity to record the distribution of the optical near field.  
     
     
         9 . The optical recording method according to  claim 6 , wherein said photosensitive material is a photoconductive material capable of developing a potential difference to record the distribution of the optical near field.  
     
     
         10 . The optical recording method according to  claim 1 , wherein said irradiating is conducted in a state that the informative object is set at a position within a 100 nanometers' distance from the recording layer.  
     
     
         11 . The optical recording method according to  claim 1 , wherein said irradiating is conducted in a state that the informative object is set in contact with the recording layer.  
     
     
         12 . The optical recording method according to  claim 1 , wherein said irradiating and recording are repeated two or more times in accordance with the movement of the informative object.  
     
     
         13 . An optical recording system comprising: 
 a recording layer on or above which an informative object is positioned and which is constituted by a photosensitive material capable of undergoing a storable and detectable photochemical reaction; and    a light source capable of irradiating at a time at least the area of the recording layer where the informative object is positioned.    
     
     
         14 . The optical recording method according to  claim 1 , which further comprises observing the recorded distribution of the optical near field by an observing means selected in conformity with the mode of recording.  
     
     
         15 . The optical recording method according to  claim 14 , wherein said photosensitive material is at least one of a material capable of forming unevenness in accordance with its photoreacting quantity to record a distribution of the optical near field, a material capable of changing its refractive index in accordance with its photoreacting quantity to record the distribution of the optical near field, a material capable of changing its light absorbance in accordance with its photoreacting quantity to record the distribution of the optical near field, a material capable of developing a potential difference in accordance with its photoreacting quantity to record the distribution of the optical near field, and a material containing a photoreactive component capable of changing its degree of orientation to record the distribution of the optical near field.  
     
     
         16 . The optical recording method according to  claim 15 , wherein said photosensitive material is a photoreactive polymer material capable of forming unevenness in accordance with its photoreacting quantity to record the distribution of the optical near field.  
     
     
         17 . The optical recording method according to  claim 15 , wherein said photosensitive material is a photorefractive material capable of changing its refractive index in accordance with its photoreacting quantity to record the distribution of the optical near field.  
     
     
         18 . The optical recording method according to  claim 15 , wherein said photosensitive material is a photoconductive material capable of developing a potential difference to record the distribution of the optical near field.  
     
     
         19 . The optical recording method according to  claim 14 , wherein said irradiating is repeated at a given interval with pulse light to record a changing history of the informative object.  
     
     
         20 . The optical recording method according to  claim 14 , wherein said distribution of the optical near field is recorded as a change in refractive index or absorbance of the photosensitive material, and said observing is carried out with a scanning optical near field microscope.  
     
     
         21 . The optical recording method according to  claim 14 , wherein said distribution of the optical near field is recorded as generation of a potential difference on the photosensitive material, and said observing is carried out with a surface potential microscope.  
     
     
         22 . An optical recording medium comprising: 
 at least one recording layer for recording optical information with light for irradiation or a generated optical near field, wherein the recording layer comprises a polymer material containing a photoreactive component capable of photoisomerization and having in the repeating unit thereof at least one group selected from the group consisting of a urethane group, a urea group, an amide group, a carboxyl group and a hydroxyl group.    
     
     
         23 . The optical recording medium according to  claim 22 , which is a recording medium for calculators, an audio or visual recording medium or a recording medium for recording an optical near field intensity distribution.  
     
     
         24 . The optical recording medium according to  claim 22 , wherein said optical recording medium has a single recording layer which is provided on the surface or in the inside of said optical recording medium.  
     
     
         25 . The optical recording medium according to  claim 22 , wherein said optical recording medium has two or more recording layers, one of which is provided on the surface with the other recording layer or layers in the inside of said optical recording medium, or all of which are provided in the inside of said optical recording medium.  
     
     
         26 . The optical recording medium according to  claim 22 , wherein said optical recording medium has two or more recording layers with a buffer layer being interposed between two recording layers.  
     
     
         27 . The optical recording medium according to  claim 22 , wherein said photoreactive component is at least one selected from the group consisting of an azo group, a C═C group and a C═N group, all of which are capable of trans-cis photoisomerization.  
     
     
         28 . The optical recording medium according to  claim 22 , wherein said polymer has a structure represented by formula (I), (II), (III) or (IV):  
       
         
           
           
               
               
           
         
       
     
     
         29 . The optical recording medium according to  claim 22 , wherein said photoreactive component is contained by 30 to 70% by weight based on the polymer material.  
     
     
         30 . The optical recording medium according to  claim 22 , which is for holography.  
     
     
         31 . The optical recording medium according to  claim 22 , wherein said photoreactive component is capable of reversible photoisomerization, the molecular orientation of said photoreactive component is controllable by light, and said optical recording medium is capable of recording, reading out and erasing information.  
     
     
         32 . The optical recording medium according to  claim 31 , wherein said recording and reading out is carried out with linearly polarized light, and said erasing is carried out with circularly polarized light, random polarized light or linearly polarized light whose direction of polarization is different from that of the linearly polarized light used for recording.  
     
     
         33 . An optical recording medium having a recording layer comprising: 
 a photosensitive material capable of undergoing a storable and detectable photochemical reaction, said recording layer having recorded a distribution of an optical near field generated from an informative object being irradiated to furnish at least one of pieces of information (1) to (4): 
 (1) a record of an instantaneous form of a moving informative object;  
 (2) a record of movement of an informative object which is a fine particle movable by radiant pressure of light;  
 (3) a record of movement of an informative object which is an autonomically moving living organism; and  
 (4) a record of changing history of an informative object which undergoes change with time that can be recorded as optical information.  
   
     
     
         34 . The optical recording method according to  claim 1 , wherein said setting is conducted in a state that the informative object is set on the recording layer.  
     
     
         35 . The optical recording system according to  claim 13 , wherein the informative object is positioned on the recording layer.