Abstract:
This invention relates to a method for manufacturing a composite lens, comprising the steps of: forming a base-lens-forming material into a base lens; and forming a plastic material into a first plastic lens portion on a first lens surface of the base lens using a stamper by a hot embossing process, wherein a glass transition temperature of the plastic material is lower than that of the base-lens-forming material.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to a method for manufacturing an optical lens element, and more particularly, to a method for manufacturing a composite lens.  
       DESCRIPTION OF RELATED ART  
       [0002]     In an optical system, a great number of lens elements are generally employed for correcting chromatic aberrations, and monochromatic aberrations, such as spherical aberration, etc. Therefore, such optical system is generally unduly bulky.  
         [0003]     In order to reduce the size and weight of the optical system, a composite lens is employed. Generally, the composite lens consists of a plurality of lens units. The lens units are generally combined together with a glue. However, with the size of the composite lens becoming smaller and smaller, it is difficult to combine more multiple lens units together to form a composite lens. In addition, due to the difference of expansion coefficient between the glue and the lens units, the lens units are prone to be separated from each other, thereby the optical properties of the composite lens may be deteriorated.  
         [0004]     What is needed, therefore, is to provide an improved method for manufacturing a composite lens.  
       SUMMARY OF INVENTION  
       [0005]     A preferred embodiment provides a method for manufacturing a composite lens including the following steps of: forming a base-lens-forming material into a base lens; and forming a plastic material into a first plastic lens portion on a first lens surface of the base lens using a stamper by a hot embossing process, a glass transition temperature of the plastic material being lower than that of the base-lens-forming material.  
         [0006]     In another preferred embodiment, a method for manufacturing composite lenses including the following steps of: forming a base-lens-forming material into a base lens plate consisting essentially of a plurality of base lens units; forming a plastic material into a first lens layer on a first lens surface of the base lens plate using a stamper by a hot embossing process thereby obtaining a composite lens plate, the first lens layer consisting essentially of a plurality of first lens units, spatially corresponding to the plurality of base lens units, a glass transition temperature of the plastic material being lower than that of the base-lens-forming material; and cutting the composite lens plate into a plurality of separate composite lenses each having a base lens unit and a respective first lens unit thereon.  
         [0007]     Compared with the conventional methods for manufacturing a composite lens, a method for manufacturing a composite lens in accordance with a preferred embodiment can provides a composite lens have improved optical properties, which results from that the plastic lens portion is combined with the base lens together by the hot embossing process. In addition, a method for manufacturing composite lenses in accordance with another preferred embodiment can provide a plurality of composite lenses at one time, which can attain a high productivity.  
         [0008]     Other advantages and novel features will become more apparent from the following detailed description of embodiments when taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0009]     Many aspects of the present method can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, the emphasis instead being placed upon clearly illustrating the principles of the present method. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.  
         [0010]      FIG. 1  is a schematic, cross-sectional view of a composite lens formed by a method for manufacturing a composite lens in accordance with a preferred embodiment of the present invention;  
         [0011]      FIG. 2  is a schematic, cross-sectional view of a stage of the manufacturing method, showing a base-lens-forming material being stamped by two stampers each having a mirror-like surface portion;  
         [0012]      FIG. 3  is a schematic, cross-sectional view of a subsequent stage of the manufacturing method, showing a base lens formed in the stage of  FIG. 2 ;  
         [0013]      FIG. 4  is a schematic, cross-sectional view of a further subsequent stage of the manufacturing method, showing plastic materials being disposed between the base lens and two corresponding stampers;  
         [0014]      FIG. 5  is a schematic, cross-sectional view of a stage of a method for manufacturing composite lenses in accordance with another preferred embodiment of present invention, showing a base-lens-forming material being stamped by two stampers each having a plurality of mirror-like surface portions;  
         [0015]      FIG. 6  is a schematic, cross-sectional view of a subsequent stage of the manufacturing method, showing a base lens plate consisting essentially of a plurality of base lens units formed in the stage of  FIG. 5 ;  
         [0016]      FIG. 7  is a schematic, cross-sectional view of further subsequent stage of the manufacturing method, showing plastic materials being disposed between the base lens and two corresponding stampers; and  
         [0017]      FIG. 8  is a schematic, cross-sectional view of a composite lens plate consisting essentially of a plurality of composite lenses formed in the stage of  FIG. 7 . 
     
    
       [0018]     The exemplifications set out herein illustrate at least one preferred embodiment of the method in one form, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.  
       DETAILED DESCRIPTION  
       [0019]     Reference will now be made to the drawing figures to describe the present invention in detail.  
         [0020]     Referring to  FIG. 1 , a composite lens  40  formed by a method for making a composite lens in accordance with a preferred embodiment of the present invention is shown. The composite lens  40  includes a base lens  10  and two plastic lens portions  20 ,  30 . The base lens  10  has two opposite lens surfaces  12 ,  14 . The plastic lens portions  20 ,  30  are formed on the opposite lens surfaces  12 ,  14  by means of a hot embossing process, respectively.  
         [0021]     The base lens  10  is usually made of for example glass having a glass transition temperature in a range about from 500 to 700 degrees Celsius. The plastic lens portions  20 ,  30  are usually made of a plastic material, such as a thermoplastic material, an ultraviolet curable materials, etc. The thermoplastic material can be polycarbonate (PC), polystyrene (PS), polymethylmethacrylate (PMMA), etc. The ultraviolet curable material can be polydimethylsiloxane (PDMS), etc. A glass transition temperature of the plastic material is usually in a range from about 70 to about 130 degrees Celsius.  
         [0022]     FIGS.  2  to  4 , illustrate successive stages of the method for manufacturing the composite lens  40 .  
         [0023]     Referring to  FIG. 2 , a base-lens-forming material, such as a glass plate  10   a , and two stampers  50 ,  60  are provided for manufacturing a base lens  10 . The glass plate  10   a  has two opposite surfaces  12   a ,  14   a . The stamper  50  has a mirror-like surface portion  52  formed on a side thereof, and the mirror-like surface portion  52  may be convex, or non-convex, such as concave. The stamper  60  has a mirror-like surface portion  62  formed on a side thereof, and the mirror-like surface portion  62  may be convex, or non-convex, such as concave. In the illustrated embodiment, the mirror-like surface portions  52 ,  62  are convex. The mirror-like surface portions  52 ,  62  can be formed by an ultraviolet lithography electroforming micro-molding (hereinafter referred as UV-LIGA) process. A hot embossing process for manufacturing a base lens  10  may include the steps in no particular order of: disposing the stamper  50  in a manner such that the mirror-like surface portion  52  thereof faces the surface  12   a  of the glass plate  10   a , and disposing the stamper  60  in a manner such that the mirror-like surface portion  62  thereof faces the surface  14   a  of the glass plate  10   a ; heating the glass plate  10   a  to or above a glass transition temperature thereof, such as about 600 degrees Celsius; pressing the stampers  50 ,  60  toward the surfaces  12   a ,  14   a  of the glass plate  10   a  so as to form the base lens  10 ; cooling the glass plate  10   a  to room temperature, and removing the stampers  50 ,  60  thereby obtaining the base lens  10 .  
         [0024]     Referring to  FIG. 3 , the base lens  10  having two lens surfaces  12 ,  14  is shown. The surfaces  12   a ,  14   a  of the glass plate  10   a  are transformed into the lens surfaces  12 ,  14  of the base lens  10  respectively. The lens surfaces  12 ,  14  are consistent with the mirror-like surface portions  52  and  62  respectively. In the illustrated embodiment, the lens surfaces  12 ,  14  are concave. Alternatively, the base lens  10  could be formed by an injection molding process.  
         [0025]     Referring to  FIG. 4 , two stampers  70 ,  80 , and two plastic materials  20   a ,  30   a  are provided for forming two plastic lens portions  20 ,  30  on two opposite lens surfaces  12 ,  14  of the base lens  10 . The plastic materials  20   a ,  30   a  are thermoplastic materials, such as polycarbonate, and have the same glass transition temperature. The stamper  70  has a mirror-like surface portion  72 , and the mirror-like surface portion  72  may be convex, or non-convex, such as concave. The stamper  80  has a mirror-like surface portion  82 , and the mirror-like surface portion  82  may be convex, or non-convex, such as concave. In the illustrated embodiment, the mirror-like surface portions  72 ,  82  are concave. The mirror-like surface portions  72 ,  82  can be formed by an UV-LIGA process. Another hot embossing process for forming two plastic lens portions  20 ,  30  on two opposite lens surfaces  12 ,  14  of the base lens  10  may include the steps in no particular order of: disposing the plastic material  20   a  between the mirror-like surface portion  72  of the stamper  70  and the lens surface  12  of the base lens  10 ; disposing the plastic material  30   a  between the mirror-like surface portion  82  of the stamper  80  and the lens surface  14  of the base lens  10 ; heating the plastic materials  20   a ,  30   a  to or above a glass transition temperature thereof; pressing the plastic materials  20   a ,  30   a  toward the lens surfaces  12 ,  14  respectively by applying pressures onto the stampers  70 ,  80 . Then a composite lens  40  having two plastic lens portions  20 ,  30  is formed (as shown in  FIG. 1 ), after the plastic materials  20   a ,  30   a  are cooled down to room temperature, and the stampers  70 ,  80  are removed. If the plastic materials  20   a ,  30   a  are an ultraviolet curable material, such as PDMS, a curing step, i.e. applying an ultraviolet radiation to the plastic materials  20   a ,  30   a , prior to removing the stampers  70 ,  80  could be performed instead.  
         [0026]     FIGS.  5  to  7 , illustrate successive stages of a method for manufacturing a plurality of composite lenses  40  in accordance with another embodiment of the present invention.  
         [0027]     Referring to  FIG. 5 , a base-lens-forming material, such as a glass plate  10   b , and two stampers  500 ,  600  are provided for manufacturing a base lens plate  100  (see  FIG. 6 ). The base lens plate  100  consists essentially of a plurality of base lens units arranged in a pattern, for example an array. In the illustrated embodiment, the base lens plate  100  consists essentially of two base lens units. The glass plate  10   b  has two opposite surface  12   b ,  14   b . The stamper  500  has a plurality of mirror-like surface portions  52  arranged corresponding to the pattern of the base lens units, and the mirror-like surface portions  52  may be convex, or non-convex, such as concave. The stamper  600  has a plurality of mirror-like surface portions  62  arranged corresponding to the pattern of the base lens units, and the mirror-like surface portions  62  may be convex, or non-convex, such as concave. In the illustrated embodiment, the mirror-like surface portions  52 ,  62  are convex, and can be formed by an UV-LIGA process. A hot embossing process for manufacturing a base lens plate  100  may include the steps in no particular order of: disposing the stamper  500  in a manner such that the mirror-like surface portions  52  thereof faces the surface  12   b  of the glass plate  10   b ; and disposing the stamper  600  in a manner such that the mirror-like surface portions  62  thereof faces the surface  14   b  of the glass plate  10   b ; heating the glass plate  10   b  to or above a glass transition temperature thereof, such as about 600 degrees Celsius; pressing the stampers  500 ,  600  toward the surfaces  12   b ,  14   b  of the glass plate  10   b  so as to form the base lens plate  100 ; cooling the glass plate  10   b  to room temperature, and removing the stampers  500 ,  600  thereby obtaining the base lens plate  100 .  
         [0028]     Referring to  FIG. 6 , a base lens plate  100  consisting of two base lens units is shown. Each of the base lens units has opposite lens surfaces  12 ,  14  which are transformed from the surfaces  12   b ,  14   b  of the glass plate  10   b . The lens surfaces  12 ,  14  are consistent with the mirror-like surface portions  52  and  62  respectively. Alternatively, the base lens plate  100  could be formed by an injection molding process.  
         [0029]     Referring to  FIG. 7 , two stampers  700 ,  800 , and two plastic materials  20   b ,  30   b  are provided for forming two opposite plastic lens layers  200 ,  300  (see  FIG. 8 ) each consisting of two plastic lens portions on the base lens plate  100 . The plastic lens portions are spatially corresponding to the base lens units of the base lens plate  100 . The two plastic materials  20   b ,  30   b  are thermoplastic materials, such as polycarbonate, and have the same glass transition temperature. The stamper  700  has a plurality of mirror-like surface portions  72  arranged corresponding to the pattern of the base lens units, and the mirror-like surface portions  72  may be convex, or non-convex, such as concave. The stamper  800  has a plurality of mirror-like surface portions  82  arranged corresponding to the pattern of the base lens units, and the mirror-like surface portions  82  may be convex, or non-convex, such as concave. In the illustrated embodiment, the mirror-like surface portions  72 ,  82  are concave, and can be formed by an UV-LIGA process. A hot embossing process for forming two opposite plastic lens layers  200 ,  300  each consisting of two plastic lens portions on the base lens plate  100  may include the steps in no particular order of: disposing the plastic material  20   b  between the mirror-like surface portions  72  of the stamper  700  and the lens surfaces  12  of the base lens units, and disposing the plastic material  30   b  between the mirror-like surface portions  82  of the stamper  800  and the lens surfaces  14  of the base lens units; heating the plastic materials  20   b ,  30   b  to or above a glass transition temperature thereof; pressing the plastic materials  20   b ,  30   b  toward the lens surfaces  12 ,  14  respectively by applying pressures onto the stampers  700 ,  800 . Then, a composite lens plate  400  consisting of two composite lens units is obtained (as shown in  FIG. 8 ), after the plastic materials  20   b ,  30   b  are cooled down to room temperature, and the stampers  700 ,  800  are removed. If the plastic materials  20   b ,  30   b  are ultraviolet curable materials, such as polydimethylsiloxane, a curing step, i.e. applying an ultraviolet radiation thereto prior to removing the stampers  700 ,  800  could be performed instead.  
         [0030]     Referring to  FIG. 8 , a composite lens plate  400  consisting of two composite lenses are shown. After cutting the composite lens plate  400  into two pieces along a dash line (as shown in  FIG. 8 ), two separate composite lenses each consisting of a base lens unit and two plastic lens portions formed thereon are obtained at one time. It could be understood by those skilled in the art, mirror-like surface portions of a stamper, such as stamper  500 ,  600 ,  700  or  800 , may have different shapes.  
         [0031]     It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.