Date of Award
Master of Science in Electrical Engineering - (M.S.)
Electrical and Computer Engineering
N. M. Ravindra
Dentcho V. Ivanov
There is a growing trend in the study of Focal Plane Arrays(FPAs) of very small microlenses, used for a wide variety of imaging and sensing applications, to increase optical efficiency. Present day sensor technology might take a different direction altogether with the development of compact, high quality, high resolution imaging microlenses, which could make the fill factor >90%. A method to increase light sensitivity of Interline Transfer(IT) type image sensors is to position microlens FPAs on top of the image sensors. FPAs are structures of small lenses which focus the incoming light on the photo sensitive part of the image sensor. The objective of this thesis was to develop reliable and efficient microlens FPAs for a 320 X 244 element PtSi-IT infrared image sensor. The proposed FPAs overcome the difficulty most commonly faced with IT image sensors i.e. low light sensitivity, and in fact makes it superior in light sensitivity to Frame Transfer/Frame Interline Transfer types of image sensors. We have introduced additional degrees of freedom into surface profile of microlens. ZEMAX tool was deployed to model, analyze and assist in the design of the lenses. Standard IC processes were applied to fabricate the lenses with a strict control over process parameters. As a result, we have fabricated prototype microlenses which are expected to assist in obtaining the high sensitivity level of the sensor.
Pattnaik, Dhiren, "Design, fabrication and characterization of silicon microlenses for IR-CCD image sensors" (1998). Theses. 948.