The microlens array has been introduced into the charge coupled device (CCD) image sensor to compensate for the low sensitivity level of the sensor. To realize a higher density image sensor, the authors have introduced additional degrees of freedom into the surface profile of the microlens. As a result, they have obtained a high-efficiency microlens which can realize a high-sensitivity level in the sensor. The new simulation program for microlens design is also described.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>