Tech Briefs Magazine - May 2022 - PIT-22

senting Standard Broadband Anti-Reflection,
has very low reflectivity when
only a small percentage of the lens clear
aperture (CA) is used, but reflectivity
sharply increases closer to the edges of
the lens. Because of this, a coating that
may initially not seem like it would provide
higher transmission, like MgF2
be a better option.
, may
There is no one-size-fits-all approach
for selecting the best coatings or optical
components. Coating and lens manufacturers
can manipulate many different
parameters to balance the different
specifications of your lenses. Speak to
your optical manufacturer for guidance
on what lens geometries and coating
types can get you both the resolution
and coating performance needed for
your application.
This article was written by Cory Boone,
Lead Technical Marketing Engineer; Chris
Cook, Technical Fellow, Thin Film Development;
and Amy Frantz, Design Engineer; Edmund
Optics®
(Barrington, NJ). For more information,
visit http://info.hotims.com/
82321-223.
Manufacturing Wafer-Level Optics Using UV Adhesives and Polymers
M
icro-optics and nanostructures
are key technologies
for the latest optoelectronic
components in smartphones,
smart glasses and vehicles. Some
examples used in consumer
electronics include microlenses
in time-of-flight or ambient
light sensors, diffractive optical
elements (DOE) for structured
light generation, as well as surface
relief gratings with nanometer
precision in diffractive
waveguides that enable new applications
like 3D sensing and
augmented reality glasses.
This technology is also used in
vehicles in microlens-based ultra-compact
projection systems
for headlamps or decorative and
functional lighting applications
that can be integrated anywhere
in a car. With that said, there is a
need for robust and economic
manufacturing solutions in consumer
electronics and automotive applications
where several hundred thousand to a
million pieces are produced each year.
ments; however, it is difficult to
handle, leading to more complex
and expensive manufacturing
and assembly processes.
That explains why, for miniaturized
optical applications, fast
UV-curing materials are used
almost exclusively. These materials,
with their defined transmission
properties, are essentially
optical-grade
adhesives.
Figure
1. Wafer-level manufactured nanostructures (left) and microlenses
(right) enable small-form-factor and high-resolution optical sensors
for applications such as 3D sensing. (Image: DELO)
Nano-Imprint Lithography
Injection molding is an established
and efficient manufacturing process that
could theoretically be used as a solution.
However, it is not able to fulfill the precise
alignment needed for such miniaturized
optoelectronics. It also requires
thermoplastic materials, like PC or
PMMA. These materials are not able to
meet the optical and mechanical requirements
needed, especially at elevated
temperatures. Glass seems like a good
choice because it meets all the requireUV
Since
they are able to take on
many other tasks besides bonding,
with the most prominent
being optical functions, these
unique adhesives are often
called UV-curable polymers.
With these materials, lenses
and nanostructures are produced
using nano-imprint lithography
(NIL). NIL is an assembly
process that has become
indispensable within the semiconductor
industry. It is defined
as a high throughput, high-resolution
parallel patterning method where a surface
pattern of a stamp is replicated
into a material by mechanical contact
and 3D material displacement. The
achievable structural resolution can be
as low as 10 nm. Lateral alignment accuracies
below 5 µm can be achieved with
standard industrial equipment.
Stamp
12 34 5
Dispensing
Glass or foil
Imprinting
UV curing
Figure 2. Typical process flow for nano-imprint lithography (Image: DELO)
22
DemoldingFinished lens
Photonics & Imaging Technology, May 2022
PIT Application Briefs 0522_1.indd 22
Cov
ToC
4/18/22 2:11 PM
http://info.hotims.com/82321-223 http://info.hotims.com/82321-809
Tech Briefs Magazine - May 2022

Table of Contents for the Digital Edition of Tech Briefs Magazine - May 2022
