Design of a panoramic annular lens with ultrawide angle and small blind area
Kun Zhang, Xing Zhong, Lei Zhang, Tianqing Zhang
Abstract
A panoramic annular lens (PAL) comprises a panoramic annular head unit (PAHU) and a relay lens group. Due to the properties of annular imaging, single-channel PAL systems contain a blind area in the central field of view (FOV), which is difficult to reduce in a traditional optical system structure. Therefore, we propose a novel reflective PAHU structure, using two mirrors to replace the traditional single-lens- or multilens-cemented PAHU, to achieve a smaller blind area and ultrawide-angle imaging. In this paper, we present the design of an ultrawide-angle PAL with a FOV of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mo stretchy="false">(</mml:mo> <mml:msup> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>22</mml:mn> </mml:mrow> <mml:mo>∘</mml:mo> </mml:msup> <mml:mo>∼</mml:mo> <mml:msup> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>120</mml:mn> </mml:mrow> <mml:mo>∘</mml:mo> </mml:msup> <mml:mo stretchy="false">)</mml:mo> <mml:mo>×</mml:mo> <mml:msup> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>360</mml:mn> </mml:mrow> <mml:mo>∘</mml:mo> </mml:msup> </mml:math> using our proposed method. The resulting optical system achieves a blind area ratio of less than 3.67%. Compared with the traditional PAL system with the lowest blind area ratio, the blind area ratio of our system is reduced by half, demonstrating the feasibility of the proposed method.