Process for preparation of optical element, electrolytic solution used for the same and apparatus for preparation of optical element

Abstract

Disclosed herein are a process for easily preparing an optical element in a form of thin film which contains a functional material whose concentration changes gradationally in an in-plane direction and a thickness direction of a thin film, an electrolytic solution used for the process, and an apparatus for preparing an optical element. The process is designed to form an optical element on an optical element preparing substrate from an electrolytic solution containing a functional material by electrodeposition or photovoltaic electrodeposition. The process includes a step of changing concentration of the functional material in the electrolytic solution in the vicinity of the optical element preparing substrate, so that a resulting thin film changes gradationally in the concentration of the functional material in the in-plane direction and/or the thickness direction of the thin film.

What is claimed is:  
     
         1 . A process for preparation of an optical element comprising the steps of: 
 preparing a substrate having an insulating substrate and a conductive thin film formed thereon;    preparing an electrolytic solution containing a film forming polymer decreasing solubility or dispersibility in an aqueous liquid by a change in a pH value and a functional material in a certain concentration;    contacting the conductive thin film with the electrolytic solution in a presence of a counter electrode in the electrolytic solution and applying a voltage between the conductive thin film and the counter electrode for changing the pH value; and    varying the concentration of the functional material near the conductive thin film.    
     
     
         2 . The process for preparation of an optical element according to  claim 1 , wherein the functional material contained in the thin film has a concentration gradation in a thickness direction of the deposited film.  
     
     
         3 . The process for preparation of an optical element according to  claim 1 , wherein the functional material contained in the thin film has a concentration gradation in an in-plane direction of the thin film.  
     
     
         4 . The process for preparation of an optical element according to  claim 1 , wherein the concentration of the functional material in the electrolytic solution is varied by a flow of another electrolytic solution, which has a different concentration with that of the electrolytic solution, toward the substrate in the electrolytic solution.  
     
     
         5 . The process for preparation of an optical element according to  claim 4 , wherein the concentration of the functional material in the electrolytic solution flown toward the substrate in the electrolytic solution is varied with time.  
     
     
         6 . The process for preparation of an optical element according to  claim 1 , further comprising a step of transferring the deposited film formed on the substrate to another substrate.  
     
     
         7 . The process for preparation of an optical element according to  claim 1 , further comprising a step of performing heat treatment to the electrodeposited film.  
     
     
         8 . A process for preparation of an optical element comprising the steps of: 
 preparing a substrate having an insulating substrate, a conductive thin film and a photosemiconductive film formed thereon;    preparing an electrolytic solution containing a film forming polymer and a functional material in a certain concentration, the film forming polymer decreasing in solubility or dispersibility in an aqueous liquid by a change in a pH value;    contacting the photosemiconductive film with the electrolytic solution and applying a light to the photosemiconductive film for changing the pH value; and    varying the concentration of the functional material near the conductive thin film.    
     
     
         9 . The process for preparation of an optical element according to  claim 8 , wherein the functional material contained in the thin film has a concentration gradation in a thickness direction of the deposited film.  
     
     
         10 . The process for preparation of an optical element according to  claim 8 , wherein the functional material contained in the thin film has a concentration gradation in an in-plane direction of the thin film.  
     
     
         11 . The process for preparation of an optical element according to  claim 8 , wherein the concentration of the functional material in the electrolytic solution is varied by a flow of another electrolytic solution, which has a different concentration with that of the electrolytic solution, toward the substrate in the electrolytic solution.  
     
     
         12 . The process for preparation of an optical element according to  claim 11 , wherein the concentration of the functional material in the electrolytic solution flown toward the substrate in the electrolytic solution is varied with time.  
     
     
         13 . The process for preparation of an optical element according to  claim 8 , further comprising a step of forming a thin film over an entire surface of the substrate by application of a voltage exceeding a Schottky barrier of the photosemiconductive film on the optical element preparing substrate without irradiation with light.  
     
     
         14 . The process for preparation of an optical element according to  claim 8 , further comprising a step of transferring all the thin films formed on the substrate to another substrate.  
     
     
         15 . The process for preparation of an optical element according to  claim 8 , further comprising a step of performing heat treatment to the deposited film.  
     
     
         16 . An electrolytic solution as used to the method of  claim 1 , comprising a film-forming polymer, which decreases in solubility or dispersibility in an aqueous solution as a pH value changes, and a functional material, the film-forming polymer having both hydrophobic groups and hydrophilic groups with a number of hydrophobic groups accounting for 30% to 80% of a total number of hydrophobic groups and hydrophilic groups.  
     
     
         17 . An apparatus for preparing an optical element on a substrate having conductive thin film comprising: 
 an electrodeposition vessel holding an aqueous electrolytic solution, which contains a film-forming polymer and a functional material, the film-forming polymer decreasing in solubility or dispersibility in an aqueous liquid as the pH value changes;    a counter electrode which is placed in the electrodeposition vessel and is electrically connected to the conductive thin film;    a unit that irradiates with light the photosemiconductor thin film on the optical element preparing substrate, and    a mechanism to cause a flow of an aqueous electrolytic solution, which contains a film-forming polymer and a functional material, the film-forming polymer decreasing in solubility or dispersibility in an aqueous liquid as a pH value changes.    
     
     
         18 . The apparatus for preparing an optical element according to  claim 17 , further comprising a voltage applying unit that applies voltage across the conductive thin film and the counter electrode.  
     
     
         19 . An apparatus for preparing an optical element on a substrate having an electroconductive thin film comprising: 
 an electrodeposition vessel holding an aqueous electrolytic solution, which contains a film-forming polymer and a functional material, the film-forming polymer decreasing in solubility or dispersibility in an aqueous liquid as a pH value changes;    a counter electrode which is placed in the electrodeposition vessel and is electrically connected to the conductive thin film;    a voltage application unit that applies a voltage across the conductive thin film and the counter electrode, and    a mechanism to cause a flow of an aqueous electrolytic solution, which contains a film-forming polymer and a functional material, the film-forming polymer decreasing in solubility or dispersibility in an aqueous liquid as a pH value changes.