Semi-finished lens is the raw blank used to produce the most individualized RX lens according to thepatient's prescription. Different prescription powers request for different semi-finished lens types or base curves.
With the replacement of the lens Nowadays, the glass lens has gradually been replaced by the light and abrasion resistant optical resin lens. However, the technology is continuously improving. Now the PC lens with better quality has been developed and applied successfully to the optical industry. PC lens, also known as "space film", because of its excellent impact resistance, it also has a commonly known as bullet-proof glass.
1). The advantages of polycarbonate lenses:
----Used in industrial protective eyewear
----Can be surfaced to 1mm center thickness
----It is thermoplastic as it will be soften when heated
----It is flexible and impact resistance
----Higher index lenses reflects light more hence ARC is must
----Chromatic aberrations are more when polycarbonate look away from optic axis.
2). The suitable group of polycarbonate lenses:
----Primary and secondary students: polycarbonate lenses in Europe and the United States has become a requirement for primary and secondary students to wear safety lenses.
---Athletes: because athletes will have some fierce confrontation, and polycarbonate lenses have higher impact resistance and can athletes protect the eyes better.
---The people who want low diopters without frames: polycarbonate lenses can prevent the use of ordinary resin lens chipping, cracking holes at the phenomenon.