FOC-relginWhat is an example of micro imprinting?

One of the best examples of wafer level optics is the camera module on your mobile phone.

The basic idea is to fabricate layers of microlenses that are stacked up to make the complete optical element, which is then bonded directly onto the image sensor of the camera, at the wafer level.


wafer level optics EV GroupAt left is an image from EV Group, showing an exploded view of the  elements of a typical wafer level camera module.   (Image courtesy of EV Group –

These include the polymer lenses, spacers and aperture layers and the CMOS image sensor at the bottom.

Just seeing the photo might make you realize how accurately this device must be made and assembled to  work properly.  Current imprint technologies enable feature sizes as small as microns and positioning technologies allow position accuracies of sub-100 nm.  This is indispensable to the proper alignment of the multiple layers in such tiny modules.

Picture1Hundreds are imprinted at a time on a glass wafer substrate (like the one shown at right).  Each square on the wafer is a polymeric lens layer.  Each layer in the lens stack has its own stamp.  The most established wafer-level optics fabrication techniques allow double-sided molding of   microlenses onto the glass wafer.  The optical imprint resin is dispensed in a layer on the glass wafer.  The stamp is aligned, then lowered down onto the resin layer.  Controlled squeezing of the resin layer enables continuous filling of all lens cavities across the entire area of the stamp.  The resin is cured by exposure to UV light and the stamp is lifted away.

Highly accurate assembly and bond alignment of the multiple layers results in a very compact, highly accurate module that can be mounted directly onto a printed circuit board.  In the last 10 years this kind of moldule  has essentially replaced the conventional barrel-type cameras.

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Randall Elgin

About Randall Elgin

Randall Elgin, Business Development, Specialty Products, Technical Sales Randall started her career at Fiber Optic Center (FOC) in February 2010 as a technical specialist in encapsulation materials for optical applications. Since then she has worked with new materials, optical and otherwise, that enable high tech applications in the photonics industry. She regularly attends the photonics exhibitions in the US and Europe. Randall joined FOC from Nusil, where she spent 5 years working on the encapsulation issues for Solid State Lighting. Prior to that she spent 3 years at Lightspan in Wareham, MA, learning about and supporting emerging optical applications. Before Lightspan, she was an electrical engineer for 17 years at Sippican Ocean Systems in Marion, MA. Randall graduated from Boston University in 1984 with a Masters in Electrical Engineering. She and her husband reside outside New Bedford where they built a super energy efficient home, enjoy rural living and take in the New Bedford and Boston classical music scenes. Follow Randall through her twitter posts: @ImprintExptFOC @OKPExpert_FOC @PolymerExprtFOC