Apparatus for measurement of a fundus comprising a focusing system and a wavefront correction device

An ophthalmoscope for measuring a fundus of a subject comprising:

• a scanner for scanning light from a light source across the subject;
• a focusing unit which adjusts a defocus comprising:
• a first focusing mirror;
• and
• a second focusing mirror;
• wherein the first focusing mirror and the second focusing mirror are arranged so that an incident beam from the light source entering the focusing unit and an emitted beam exiting the focusing unit are substantially parallel to each other and are directed in substantially a same direction,
• wherein the focusing unit is positioned between the scanner and the subject;
• wherein adjustment of the defocus is accomplished by moving both the first focusing mirror and the second focusing mirror such that the incident beam and the emitted beam remain substantially parallel to each other, and
• wherein an optical path length between the scanner and the subject does not substantially change as the defocus is adjusted by moving both the first focusing mirror and the second focusing mirror;
• a wavefront sensor for detecting a shape of a wavefront;
• and
• a wavefront correction device;
• wherein the wavefront correction device adjusts a wavefront of the light from the light source based on the shape of the wavefront detected by the wavefront sensor, and is positioned between the focusing unit and the light source, and
• wherein an optical lens is not arranged on an optical path between the wavefront correction device and the subject.