High-strength laminated sheet for optical applications

Abstract

A laminated sheet includes a surface layer having an optical surface that is of fire-polished quality and a core layer having a higher modulus than the surface layer to increase an overall stiffness or fracture toughness of the laminated sheet.

1 . An apparatus for forming a laminated sheet, comprising:
 an overflow means for forming opposed sheet-like flows, the overflow means having at least two independent compartments for receiving a viscous, flowable material;   a forming means positioned below the overflow means for converging and uniting the opposed sheet-like flows into a single drawn sheet flow;   means for pivotally adjusting the overflow means such that a surface of the overflow channel has a desired tilt angle with respect to the horizontal; and   means for delivering a viscous, flowable material into the compartments.   
     
     
         2 . An apparatus for forming a laminated sheet, comprising:
 an overflow channel for forming opposed sheet-like flows from a viscous, flowable material;   a slotted channel positioned below the overflow channel for forming a drawn sheet-like flow;   a forming body positioned below the overflow channel for converging and uniting the opposed sheet-like flows with outer surfaces of the drawn sheet-like flow to form a laminated flow;   means for pivotally adjusting the overflow channel such that a surface of the overflow channel has a desired tilt angle with respect to the horizontal; and   means for delivering a viscous, flowable material into the overflow channel.   
     
     
         3 . The apparatus of  claim 2 , wherein the slotted channel is fluidly connected to the overflow channel so as to receive viscous, flowable material from the overflow channel. 
     
     
         4 . The apparatus of  claim 2 , further comprising means for delivering a viscous, flowable material to the slotted channel. 
     
     
         5 . The apparatus of  claim 2 , wherein the slotted channel is formed in the forming body.