Bifocal and negative microlens arrays in hard optical materials

Using the methods of photoresist reflow and moulding, bifocal and negative microlens arrays, with diameters down to 10 /spl mu/m, have been fabricated in GaN-on-sapphire. The optical properties of these microlens arrays were characterised by a recently developed reflection/transmission confocal microscopy technique and agree well with calculated values.