Focusing properties of two-dimensional photonic quasicrystal flat lens at different object distances

We report the object-distance effect on the focusing properties of a two-dimensional (2-D), photonic quasicrystal (PQC) flat lens by numerical simulation. For the image power and image quality, the half-thickness of the flat lens is no longer the optimal object distance. The object-image distance is not always double the flat lens thickness, which is apparently different from a 2-D, periodic photonic crystal (PPC) flat lens and left-handed material (LHM) flat lens. With the point-light source located near half-thickness of the lens object distance, a 2-D PQC flat lens can achieve a perfect image in a certain range. With an appropriate object distance, a 2-D PQC flat lens is much better than a 2-D PPC flat lens in the aspect of imaging resolution. The results are beneficial to understand the focusing and imaging of a 2-D PQC flat lens. (C) 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.OE.51.7.074005]