Diffractive microlens arrays can completely collect the light at the focal
plane and concentrate it into a smaller spot size on the detector plane, th
e photodetector area can be substantially reduced. Increased gamma radiatio
n hardening and noise reduction result from the decrease in photodetector s
ensitive area. The diffractive microlens arrays have been designed by consi
dering the correlative optical and processing parameters for PtSi focal pla
ne array. They have been fabricated on the backside of PtSi focal plane arr
ay chip by successive photolithography and Ar+ ion-beam-etching technique.
The alignment of microlens array with PtSi focal plane array was completed
by a backside aligner with IR light source. The practical processes and fab
rication method are discussed. The performance parameters of PtSi FPA with
diffractive microlens array are presented.