A transparent area on a A banknote (or ‘bill’ as it is often referred to in the US) is a type of negotiable promissory note, issued by a bank or other licensed authority, payable to the bearer on demand. More incorporating optical effects by applying different elements, such as inkless Producing a raised image by pressing the paper or substrate on the etched lines of the intaglio plate. The raised image can be detected on the opposite side of the paper. More, liquid crystals or an optically variable device. It is currently used both on A substrate used in the printing of banknotes, made of biaxially oriented polypropylene (BOPP) polymer. Polymer banknotes were first introduced in Australia and are widely used around the world. More and See Banknote paper. More banknotes.