An ultrashort throw ratio projection lens design based on a catadioptric structure

Hsiu Cheng Wang, Jui-Wen Pan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


In this paper, we present a rotational symmetry for an ultrashort throw (UST) lens with offset field. The UST lens has a throw ratio of 0.23 and a total track of 195 mm. The optical elements of the UST lens are comprised of two parts. First, a catadioptric projection lens where the catadioptric function permits reaching an ultrashort throw ratio, short total track, while at the same time requiring fewer lens elements. The second part is a collimating lens which takes advantage of the telecentric condition to generate uniform total internal reflection (TIR) in the TIR prism. With this design, an effective focal length of -1.96 mm and a f-number of 2.4 can be obtained. The root mean square spot size and lateral colour of all fields are smaller than one pixel in size. The maximum optical distortion of −0.97% and TV distortion of 0.2% are acceptable. In terms of image quality, the modulation transfer function (MTF) values for all fields are above 0.65 at 0.245 line pairs/mm. Even when the tolerance error is considered, the MTF values for all fields are still above 0.3. The suitability of the novel UST lens design for projection applications is discussed.

Original languageEnglish
Pages (from-to)1393-1403
Number of pages11
JournalJournal of Modern Optics
Issue number12
StatePublished - 12 Jul 2018
Event25th International Display Workshops, IDW 2018 - Nagoya, Japan
Duration: 12 Dec 201814 Dec 2018


  • Geometric optical design
  • Lens systems design
  • Projection system


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