Fixed focal length optical lens architecture providing a customized depth of focus optical system

A fixed-focal length imaging system for a camera comprising:

• a set of four lenses having a common optical axis for forming a real image of an object;
• and
• an image sensor defining an imaging surface and having approximately 8 million pixels;
• wherein,
• the total track length (TTL) of the imaging system is less than approximately 5.4 millimeters;
• the ratio of the TTL to a real image circle diameter is less than approximately 0.95;
• the image sensor includes a pixel having a length of approximately 1.4 micro meters;
• the imaging system can exhibit an asymmetric modulation transfer function (MTF) that remains above 0.15 for a larger range of negative focal shifts than a range of positive focal shifts;
• and
• the camera is implemented inside a portable electronics device.

A method for a camera embedded in an electronic device comprising:

• receiving optical information regarding an object by using at least four lenses having a common optical axis;
• and
• forming a real image of the object by using an imaging surface;
• wherein
• a modulation transfer function (MTF) of the real image corresponding to an object distance of 350 millimeters is asymmetric having an extended near field depth for the real image;
• further wherein,
• the MTF can include values up to 0.35 and remains above the value of 0.15 for positive focal shifts of up to 25 micro meters and up to negative focal shifts associated with the object far field.