In: Mechanical Engineering
Explain with schematics the two-photon polymerization technique.What is its advantage over stereolithography.
Two-photon polymerization (2PP) is a technique based on the two photon absorbtion (TPA) method which deals with laser radiation in photosensitive polymers. The 2PP uses this method to do direct laser writing and is widely compared with stereolithography. In 2PP method the non linear interactions between materials and laser radiation through TPA is used for working. 2PP can be initiated by using near infrared laser pulses with small amount of UV sensitive material and tightly focusing femtosecond laser pulses. Here laser light mostly is used to focus onto the top of the sample material without interaction at bottom. Femtosecond lasers are used due to their very high peak intensities and moderate average laser power and they also favour TPA. The material is polymerized by moving the laser focus along the trace and by fabricating an polymeric 3D pattern.
The advantage of 2PP over sterolithography is the ability to scan wth high speed and also it benefits from the high resolution present.