Shape measurement device and shape measurement method

A shape measurement method using a shape measurement device including a calculation unit and a measurement head, wherein

• the measurement head includes
• a probe that is locked to a tip of the measurement head,
• a rotation unit that rotates the locked probe, and
• an optical element that emits measurement light to the probe,
• the probe includes an optical path switching element that switches an optical path of the measurement light incident from the optical element,
• the optical path switching element has
• a first surface on which the measurement light incident from the optical element is incident,
• a second surface that reflects the measurement light incident from the first surface,
• a third surface that emits the measurement light reflected by the second surface to an object,
• a fourth surface that is in contact with the second surface, and
• a fifth surface that emits the measurement light having passed through the second surface to the object,
• the optical path switching element is capable of controlling a reflection ratio of the measurement light at the second surface and includes a first transmissive member having the first surface, the second surface, and the third surface, and a second transmissive member having the fourth surface and the fifth surface,
• an angle between a normal of the second surface and a rotation axis of the probe is greater than 45 degrees,
• an angle between a normal of the third surface and the rotation axis is less than 90 degrees, and
• a normal of the fifth surface is not parallel to the rotation axis, and
• the shape measurement method comprising:
• switching the optical path of the measurement light incident from the optical element to a direction of the fifth surface by the optical path switching element;
• performing scanning with the measurement light emitted from the fifth surface to the object at an angle not parallel to the rotation axis by the rotation unit while rotating the probe;
• and
• measuring the shape of the object that is present in the direction of the rotation axis based on reflected light from the object by the calculation unit.