TECH FOCUS: OPTICS
Good vibrations
Greg Blackman reports on the latest lens technology presented during Vision Stuttgart, including optics designed to withstand shock
T
he benefits of liquid lenses and a lenses resistant to shock and vibration were
highlighted at the Vision trade fair in Stuttgart in November. Fujifilm’s Fujinon anti-shock
and vibration technology was shortlisted for the Vision Award, a prize recognising innovation in machine vision, while IDS and Baumer were among those displaying cameras able to control autofocus liquid lenses. Nick Sischka, senior vision
solutions engineer at Edmund Optics, told Imaging and Machine Vision Europe at the show, that the barrier to entry of liquid lenses has in the past been too high. Edmund Optics worked with IDS to build Corning Varioptic’s liquid lenses into IDS’s uEye LE board-level cameras, to make the lenses a reliable part of the camera module. Edmund Optics supplies liquid lenses from Varioptic, now owned by Corning. Liquid lenses are able to focus
on different object distances in milliseconds. Tey don’t contain mechanical moving parts, but form a lens from the film between
two immiscible fluids. Te liquid interface can be expanded or contracted by applying an electrical charge, a process called electrowetting. Te lenses excel in applications
where object distances can change rapidly requiring fast autofocus, such as when inspecting 2D codes on packages of different heights. Both IDS’s uEye LE camera
family and Baumer’s LX series 10 GigE cameras are able to control autofocus on Corning Varioptic’s liquid lenses. Te uEye LE cameras are equipped with S-mount or CS-/ C-mount, along with 6.4-megapixel IMX178 rolling shutter colour or mono sensor from Sony, or the 18.1-megapixel AR1820HS rolling shutter colour sensor from On Semiconductor (models with global shutter sensors are planned). Baumer’s LX series contains shading correction to correct lens and lighting artefacts.
Shockwaves Equipment installed in factories oſten has to be able to withstand tough working conditions, which includes being subjected to shock and vibration. Fujifilm investigated the impact of shock and vibration on industrial fixed focal length lenses, and found that the lens optical axis can shiſt, which is not acceptable for calibrated vision systems. Fujifilm first applied 10G
Fujifilm’s latest CF-ZA-1S lens series uses the anti-shock and vibration technology.
shocks to lenses from six different directions orthogonal to the optical axis. Tis was followed by exposure
30 Imaging and Machine Vision Europe • December 2018/January 2019
Machine vision applications oſten involve fast moving objects, different distances or different heights. Liquid lenses are small cells containing optical-grade liquid that change shape when a current or voltage is applied. By integrating this technology into imaging assemblies it has become possible to produce powerful lenses that combine precision and flexibility. Te new Liquid Lens M12 Lenses from Edmund Optics are the
latest in a range of new imaging lenses using this principle. With a high resolution f/2.4 design they provide high light throughput, while the liquid lens allows the focus to be changed within milliseconds. Te optical design has been optimized to account for the liquid lens allowing it to offer high image quality on sensor formats as large as 1/2” or even 1/1.8” depending on focal length. Tis innovative imaging product recently won second place in the
vision category of the 2019 Inspect Awards.
www.edmundoptics.eu/f/liquid-lens-12-imaging- lenses/39465/
to various sinusoidal vibrations according to IEC 60068-2-6, up to 500Hz and 100m/s². Te shock test was then repeated. Fujifilm’s investigations
showed that the position of the optical axis shiſted by up to 26μm on conventional lenses. Tat corresponds to a change of approximately seven pixels for second generation Sony Pregius sensors with a pixel size of 3.45μm. Te work led Fujifilm to develop
a new mechanical design for lenses, the Fujinon Anti-Shock and Vibration technology, which was
shortlisted for the Vision Award. Fujifilm used elastic fixation to secure the glass elements inside its anti-shock lenses, which minimises the adhesives that would otherwise fix glass elements within conventional camera lenses. Adhesives are unable to withstand shock and vibration over time, according to Fujifilm, causing the glass elements inside the lens to loosen and the resolution and mechanical stability to degrade. Te elastic fixation used in
anti-shock lenses gives a better performance over time; the shiſt in
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