There always exist some new challenges for lens designers to keep their old-line technology update. To minimize lens
volume is one of the most notified examples. In this paper we designed a single thick lens, constructed by using one
oblique (reflective) surface, apart from two conventional refractive surfaces, to bend the optical path of the optical
system to achieve this goal. Detail design procedure, including system layout and lens performance diagrams, will be
Following the first order layout, we applied aspherical form to the two refractive surfaces in order to correct the spherical
aberration up to an acceptable condition. Then, the reduced aberrations such as coma, astigmatism, field curvature and
distortion can easily be corrected with some calculations related to spherical aberration as shown in the publication of H.
H. Hopkins (1950). Plastic material is used in the design, because the aspherical surfaces can then be manufactured in a
more cost effective way. The final specification of the design is: EFL is 4.6 mm, the F number is 2.8, the over all
thickness of lens is 3.6 mm, its MTF is 0.3 at 227 lp/mm in center field and chief ray angle is less than 15 degrees. Lens
data as well as optical performance curves are also presented in the paper. In conclusion we have successfully finished a
mega-pixel resolution lens design and its overall thickness is compatible with the state of the art.