Liquid lenses quickly adjust focus to accommodate objects located at various working distances. Liquid
lenses are small, mechanically or electrically controlled cells containing optical-grade liquid. When a current
or voltage is applied to a liquid lens cell, the shape of the cell changes. This change occurs within
milliseconds and causes the optical power, and therefore focal length and working distance, to shift. Many
manufacturers have designed liquid lenses that operate via slightly diff erent processes: electrowetting,
current-driven polymer, or sound piezoelectric. Liquid lenses are an ideal solution for imaging applications
requiring rapid focusing, high throughput, and depth of fi eld and working distance accommodation.
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TECHNICAL NOTE
Liquid Lenses in Imaging
Applications of Liquid Lenses
Liquid Lenses Products
Electrostatic Pressure
Window
OFF
Water Oil Optical Axis
Window
Metal Metal
Insulation
Electrostatic Pressure
Window
ON
Oil Optical Axis
Window
Metal Metal
Insulation
Membrane
Actuator with Voice Coil
Container
Fluid
How Does a Liquid Lens Work?
Corning® Varioptic® Variable Focus Liquid Lenses focus using a process called electrowetting,
which is the application of electric fi elds to manipulate the wetting properties, and therefore shape and
curvature, of a liquid. The liquid lens cell contains two immiscible liquids: a non-conductive oil and a water
solution separated by an interface. Applying a voltage at the interface between the two liquids changes
the curvature, and therefore focal length, of the lens within tens of milliseconds. Applying more voltage
increases the overall curvature and optical power of the liquid lens. The Variable Focus liquid lenses’
capacitive characteristics allows for stable operation in high-temperature environments once a thermal
equilibrium is achieved. In addition, the two liquids within the lens have the same density, making the
system insensitive to vibration and shock.
Optotune Focus-Tunable Lenses consist of an optical fl uid-fi lled container sealed with a polymer
membrane. A current-driven actuator exerts pressure on the membrane, causing the curvature of the
lens (and therefore the optical power) to change. Due to their current dependency, electrically-focused
tunable lenses function with low operating voltages and focus within milliseconds. These lenses do not
alter polarization, have high laser damage threshold, and introduce minimal aberrations.
The adaptability, speed, and versatility of liquid lenses make them ideal for a variety of machine vision,
life science, and measuring and inspection applications. Due to their traditional mechanical layout,
standard machine vision lenses struggle to capture sharp and accurate images in high-speed or precise
applications that require quick refocusing.
Life Sciences: Liquid lenses improve and simplify the process of focus stacking (“z-stacking”) in microscopy
imaging applications. Focus stacking is often required when imaging with high magnifi cation
objectives due to their limited depths of fi eld. A liquid lens can quickly and precisely focus to various
object planes, therefore expediting the process of focus stacking. Liquid lenses can be easily integrated
into tube lenses or in infi nity space within a microscope.
Machine Vision: High-volume assembly lines require fast, accurate, and precise throughput. Integrating
a liquid lens into an inspection system is an optimal, compact, and economical solution when focusing at
multiple distances is required. Liquid lenses are an ideal solution for barcode inspection, package sorting,
quality control, and rapid automation.
Unmanned Aerial Vehicles: By adding a liquid lens to an unmanned aerial vehicle (UAV) imaging
system, image sharpness is quickly maintained across various heights. Liquid lenses are especially advantageous
in agricultural inspection and monitoring, geographic information systems, and in surveillance
applications.
Measurement and Dimensional Rendering: When paired with a distance sensor and camera, a
liquid lens can quickly image diff erent planes of a 3D object. The images are then stitched together in
software to create an accurate three-dimensional rendering.
As shown in the example of a typical inspection system, objects
of different heights are imaged as they pass by on a fast-moving
conveyor belt. A standard imaging lens requires mechanical
refocusing per every object, causing a delay that can limit highthroughput.
A liquid lens, free of mechanical translation, overcomes
these speed and depth of fi eld limitations by refocusing
to different heights in the matter of milliseconds.
Corning® Varioptic® Variable
Focus Liquid Lenses
Page 66
TECHSPEC® Liquid Lens
M12 Lenses
Page 339
TECHSPEC®
Liquid Lens Cx Lenses
Page 325
PixeLINK® USB 3,0 Autofocus
Liquid Lens Cameras
Page 394
Optotune
Focus-Tunable Lenses
Page 65
Pixelink® USB 3,0 Autofocus
Liquid Lens Board
Level Cameras
See website
TECHSPEC® MercuryTL
Liquid Lens Telecentrics
Page 349
IDS uEye LE USB 3,1 AF
Autofocus Liquid Lens Board
Level Cameras
Page 394