Method for manufacturing lens

A method for manufacturing a lens, comprising the steps of:

• forming a first lens preform and a second lens perform, the first and second lens preform comprised of polymer, the first lens preform comprising a first surface and an opposite second surface, the first surface having a plurality of first lens structures formed thereon, the second lens preform comprising a third surface and an opposite fourth surface, the third surface having a plurality of second lens structures corresponding to the first lens structures;
• applying an oxygen plasma to the second surface to form a plurality of first groups for being irreversibly bonded to the fourth surface;
• applying an oxygen plasma to the fourth surface to form a plurality of second groups for being irreversibly bonded to the second surface;
• wherein an electrical pressure configured for generating the oxygen plasma is in a range from 1400 volts to 2000 volts, a time period for applying the oxygen plasma to the second surface and the fourth surface is in a range from 60 seconds to 70 seconds;
• bringing the second surface into contact with the fourth surface with an optical axis of each of the first lens structures aligned with the optical axis of a respective second lens structures,
• heating the first lens preform and the second lens perform to a temperature in a range from 90 to 120 Celsius degrees for a time in a range from 1.5 hours to 2 hours, and causing an irreversible bonding reaction between the first and second groups to chemically combine the second surface with the fourth surface, thereby obtaining a double sided lens perform, wherein a period from finishing applying the oxygen plasma to starting to bring the second surface and the fourth surface into contact with each other is less than 5 minutes;
• and
• dicing the double sided lens preform into a plurality of double side lenses, each of the double sided lens comprising one of the first lens structures and one of the second structure.