Gradient-index lens arrays are important elements for many optical systems. In some systems, the higher space factor is needed. That is to say, the area of receiving light should be enhanced and the loss of light information be decreased. However, this can be realized by changing the shape of lens.
In this work, thermal ion-exchanging technology was introduced as a method to generate gradient refractive-index distributions of hexagonal aperture microlens arrays. As important elements for many optical systems, this irregular microlens arrays can provide very high filling factor which is more than 95 percent and deduce the loss of optical information. We apply the ion-exchanged technique and photolithography to fabricate this irregular microlens arrays, for the first time to our knowledge. The aim of the research is to fabricate this irregular microlens arrays. Fabrication process includes three steps: first, mask with irregular figure is programmed and fabricated; then with photolithographic technology, the figure of mask is transferred to the glass substrate; At last, ion-exchanged process is needed. The experimental results show that good performance can be obtained through this new type lens and the high filling factor is satisfied. Moreover, the experimental index distribution of hexagonal aperture lens is gradient distribution. Therefore, the research on the irregular microlens arrays has an important meaning in application, and this new type microlens array is useful for some systems in which the loss of light information need to be reduced.