Short focus lens optical system and imaging device including the same

An imaging device comprising:

• an optical system;
• an image sensor for detecting an image of an object;
• and
• an image signal processor,
• wherein the optical system includes:
• a first lens having a positive refractive power and disposed along an optical axis and to face the object, the first lens further having a first convex face facing the object;
• a second lens having a positive refractive power and disposed along the optical axis adjacent to the first lens, the second lens further having a second convex face facing the object;
• a third lens having a negative refractive power and disposed along the optical axis adjacent to the second lens, the third lens further having a third concave face facing the image sensor;
• a fourth lens disposed along the optical axis adjacent to the third lens, the fourth lens being an aspherical lens;
• a fifth lens disposed along the optical axis adjacent to the fourth lens, the fifth lens being an aspherical lens and having a fourth face facing the object, the fourth face being convex where the fifth lens intersects the optical axis;
• and
• a sixth lens disposed along the optical axis adjacent to the fifth lens, the sixth lens being an aspherical lens,
• wherein the fourth face of the fifth lens and a fifth face of the sixth lens facing the object each has at least one inflection point, and characteristics of the optical system satisfy equation
• 0.4
• <
• f
• f
• ⁢
• ⁢
• 2
• <
• 1.6
• wherein “f” represents a focal distance of the optical system, and “f2” represents a focal distance of the second lens,
• wherein characteristics of the fourth lens satisfy equation
• -
• 0.15
• <
• f
• f
• ⁢
• ⁢
• 4
• <
• 0.15
• wherein “f4” represents a focal distance of the fourth lens, and
• wherein characteristics of the sixth lens satisfy equation
• 0
• <
• R
• ⁢
• ⁢
• 11
• -
• R
• ⁢
• ⁢
• 12
• R
• ⁢
• ⁢
• 11
• +
• R
• ⁢
• ⁢
• 12
• <
• 0.8
• wherein “R11” represents a curvature radius of the fifth face of the sixth lens facing the object, and “R12” represents a curvature radius of a face of the sixth lens facing the image sensor.