FOCUS DETECTION DEVICE, WAVEFRONT ABERRATION MEASUREMENT DEVICE AND LENS MANUFACTURING METHOD

PROBLEM TO BE SOLVED: To accurately detect a focus condition even with a simple configuration without requiring complicated operation.SOLUTION: A focus detection device 1 detects a focus condition in which a focal point of a condenser lens L (a point light source) coincides with a focal position of an object lens 11 and light that the object lens 11 emits by receiving the same from a focal point P of the condenser lens L becomes parallel luminous flux in an optical device 20 which has the object lens 11 which receives light from the condenser lens L. The focus detection device 1 comprises: an image detection device 12 which detects the light that the object lens 11 emits by receiving the same from the focal point P of the condenser lens L; an optical element 13 which is positioned on an optical path between the object lens 11 and the image detection device 12 and has an inspection mark; and a condition detection section 14 which detects the focus condition on the basis of an image of the inspection mark detected by the image detection device 12.