Patent ID: 7236251

Claim:
An optical apparatus comprising: a light source; a light-branching member having a boundary surface for branching light from said light source into a reference light path and a signal light path; at least one objective placed in said signal light path; a scanning system for moving light collected by said objective and a sample relative to each other; a light-combining member having a boundary surface for combining together said reference light path and said signal light path; a light-detecting element for detecting light combined by said light-combining member; an optical path length control mechanism placed between said light-branching member and said light-combining member to vary an optical path length; and a scanning control mechanism; wherein said scanning system has, at least, a first scanning mechanism for moving said collected light and said sample relative to each other in a first direction parallel to an optical axis of said objective, and a second scanning mechanism for moving said collected light and said sample relative to each other in a second direction perpendicular to said first direction; and wherein said scanning control mechanism has a function of choosing between said first scanning mechanism and said optical path length control mechanism, and a function of determining a scanning speed of the chosen mechanism and a scanning speed of said second scanning mechanism.