Small form-factor VGA camera with variable focus by liquid lens

Kari Oikarinen, Mika Aikio

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

Abstract

We present the design of a 24 mm long variable focus lens for 1/4" sensor. The chosen CMOS color sensor has VGA (640×480) resolution and 5.6 μm pixel size.
The lens utilizes one Varioptic Arctic 320 liquid lens that has a voltage-controllable focal length due to the electrowetting effect. There are no mechanical moving parts. The principle of operation of the liquid lens is explained briefly. We discuss designing optical systems with this type of lens.
This includes a modeling approach that allows entering a voltage value to modify the configuration of the liquid lens. The presented design consists only of spherical glass surfaces. The choice to use spherical surfaces was made in order to decrease the costs of manufacturing and provide more predictable performance by the better established method. Fabrication tolerances are compensated by the adjustability of the liquid lens, further increasing the feasibility of manufacturing.
The lens is manufactured and assembled into a demonstrator camera. It has an f-number of 2.5 and 40 degree full field of view. The effective focal length varies around 6 millimeters as the liquid lens is adjusted. In simulations we have achieved a focus distance controllable between 20 millimeters and infinity.
The design differs from previous approaches by having the aperture stop in the middle of the system instead of in front.
Original languageEnglish
Title of host publicationOptics, Photonics, and Digital Technologies for Multimedia Applications
PublisherInternational Society for Optics and Photonics SPIE
ISBN (Print)978-0-8194-8196-2
DOIs
Publication statusPublished - 2010
MoE publication typeA4 Article in a conference publication
EventSPIE Photonics Europe. Optics, Photonics, and Digital Technologies for Multimedia Applications - Brussels, Belgium
Duration: 12 Apr 201015 Apr 2010

Publication series

SeriesProceedings of SPIE
Volume7723
ISSN0277-786X

Conference

ConferenceSPIE Photonics Europe. Optics, Photonics, and Digital Technologies for Multimedia Applications
CountryBelgium
CityBrussels
Period12/04/1015/04/10

Keywords

  • adaptive optics
  • camera design
  • liquid lens
  • variable focus

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  • Cite this

    Oikarinen, K., & Aikio, M. (2010). Small form-factor VGA camera with variable focus by liquid lens. In Optics, Photonics, and Digital Technologies for Multimedia Applications [772316] International Society for Optics and Photonics SPIE. Proceedings of SPIE, Vol.. 7723 https://doi.org/10.1117/12.851142