Method and device for determining the refractive index of a wedge-shaped test object

A method for determining a refractive index of an optical test object, wherein the test object is assumed to comprise at least one first surface and a second sur-face arranged at a wedge angle in relation to the first surface, the method comprises the following steps comprising:

• detecting a first reflection light beam, a second reflection light beam, and a third reflection light beam, wherein the first reflection light beam represents a light beam reflected on an outer side of the first surface and wherein the second reflection light beam represents a light beam reflected on an inner side of the sec-ond surface, and wherein the third reflection light beam represents a light beam reflected on a mirror surface of a mirror element, wherein the mirror element is interpreted as being arranged on a side of the test object opposite to a light source emitting the light beam;
• determining a first angle with the aid of the first reflection light beam and/or the second reflection light beam and determining a second angle with the aid of the third reflection light beam;
• calculating the refractive index using the first angle and the second angle;
• and
• actuating a rotation of the test object around a rotation axis arranged parallel to the light beam, wherein the step of rotating is performed simultaneously with the step of detecting.