The functionality and performance of the micro lens array depend on its coating and fabrication. So here are the top four techniques that are used for its manufacturing:
Thermal Reflow Method: This method is suitable for small or mid-sized optical manufacturers where the low-precision lens is required.
- The substrate is coated with a photoresist layer that creates circular array patterns and allows the UV-light thrust through the mask.
- Once the photo-resist layer is developed, the cylindrical isolated structure is generated.
- This structure is heated at a certain temperature to turn it into a spherical microlens array.
- In this method, the need for optical separator is eliminated because the microlens array is fabricated by the common MEMS technique.
Microplasting Embossing Method: This is one of the low-cost and highly eﬃcient techniques. Its steps are:
- A silicon mold insert of circular openings is ﬁrst fabricated by a deep reactive ion etching process.
- Then, the polymer substrate is placed between the heating chambers and the silicon mold is inserted.
- Under an elevated heat temperature, the microlens is constructed by applying external pressure on the glass transition point.
- Finally, the pressure is released and the newly formed microlens is allowed to cool down under moderate temperature.
Microjetting Method: This is one of the most feasible and faster methods for fabricating microlens. The steps involved in this method are:
- The droplets of a UV-polymer liquid are ejected on the substrate.
- Once the liquid completely penetrates, the substrate is exposed to UV light and it is converted to a solid shape.
- The solid shape is allowed to cool down under the room temperature and finally, the microlens array is made.
- However, it’s important to note that, under this method, it’s difficult to control the consistency and feature size of the microlens.
Ultra-Precision Machining Method: It is the most eﬀective method to fabricate microstructures and nanostructures with good uniformity in a large area.
Let’s understand the steps involved in this method:
- A metal sheet is mounted on the side face of a cylindrical basement for a required period of time
- Now, the metal sheet is striped oﬀ and inserted in the injection mold.
- Finally, the microlens is produced by following the microinjection molding process.
All the above techniques come with pros and cons. Therefore, depending on the nature of the business, features of the microlens and the budget, any technique can be chosen.