In this part, to improve fill factor of microlens array, we designed a new type of square-aperture planar microlens array
which is used for collecting and transferring optical information efficiently. By lithographic ion-exchange and a special
technology to remove the 1.0 micron layer of titanium on the glass substrate, square-aperture planar microlens array is
buried in the substrate and the fill factor of microlens array are larger than 98%. Each microlens unit of the array is
square and has an aperture size of 0.2mm with the excellent capabilities of external stress and temperature. At last, many
optical feature parameters of square-aperture planar microlens array are tested and analyzed, and the experimental results
show that good performance can be used farther in studies and tests later.