Extended depth of field system for long distance iris acquisition

Yung Lin Chen*, Sheng Hsun Hsieh, Kuo En Hung, Shi Wen Yang, Yung Hui Li, Chung-Hao Tien

*Corresponding author for this work

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

1 Scopus citations


Using biometric signatures for identity recognition has been practiced for centuries. Recently, iris recognition system attracts much attention due to its high accuracy and high stability. The texture feature of iris provides a signature that is unique for each subject. Currently most commercial iris recognition systems acquire images in less than 50 cm, which is a serious constraint that needs to be broken if we want to use it for airport access or entrance that requires high turn-over rate . In order to capture the iris patterns from a distance, in this study, we developed a telephoto imaging system with image processing techniques. By using the cubic phase mask positioned front of the camera, the point spread function was kept constant over a wide range of defocus. With adequate decoding filter, the blurred image was restored, where the working distance between the subject and the camera can be achieved over 3m associated with 500mm focal length and aperture F/6.3. The simulation and experimental results validated the proposed scheme, where the depth of focus of iris camera was triply extended over the traditional optics, while keeping sufficient recognition accuracy.

Original languageEnglish
Title of host publicationNovel Optical Systems Design and Optimization XV
StatePublished - 2012
EventNovel Optical Systems Design and Optimization XV - San Diego, CA, United States
Duration: 15 Aug 201216 Aug 2012

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X


ConferenceNovel Optical Systems Design and Optimization XV
Country/TerritoryUnited States
CitySan Diego, CA


  • Cubic phase mask
  • Extended depth of field
  • Iris recognition


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