Arrangement and Method for Robust Single-Shot Interferometry

An arrangement for robust two-beam interferometry, comprising the following:

• a source of short-coherent electromagnetic radiation (1, 103, 104) for illuminating an object (10, 107, 108, 109, 110),
• an interferometer with an object beam path (O), at least one reference beam path (R) and a measurement plane in the object beam path (O), in which the surface or volume elements of the object (10, 107, 108, 109, 110) to be optically measured are at least approximately located,
• at least one rasterized detector (20, 201, 202) for detecting electromagnetic radiation in the form of at least one spatial interferogram,
• wherein:
• at least one end reflector is arranged in the reference beam path (R) of the interferometer as a reference reflector, wherein the end reflector is formed as a triple reflection arrangement (113) with three reflecting surfaces,
• the three reflecting surfaces are each at least approximately perpendicular to a common reference plane (BE), and
• the three track lines of the planes, which are represented by the three reflecting surfaces, form a triangle ABC with an obtuse angle in the reference plane (BE), wherein the first reflecting surface (13, 131, 132) lies on a straight line on which the points C and B lie, the second reflecting surface (14, 141, 142) lies on a straight line (m) on which the points A and C lie, and the third reflecting surface (15, 151, 152) lies on a straight line (k) on which the points A and B lie,
• characterized in that
• the triple reflection arrangement is formed as a prism mirror group (111, 112, 114);
• the triple reflection arrangement is formed either with a W beam path (114) or with a crossed beam path (111, 112);
• the second reflecting surface (14, 141, 142) is used as the second of the three reflecting surfaces for reflection of a focused beam (FB) and the first reflecting surface (13, 131, 132) is used as the first or third of the three reflecting surfaces for reflection,
• the first reflecting surface (13, 131, 132) and the second reflecting surface (14, 141, 142) are disposed at an acute angle relative to each other, the first reflecting surface (13, 131, 132) and the third reflecting surface (15, 151, 152) are disposed at an obtuse angle relative to each other, and
• there is a normal N_m from point B, perpendicular to the second reflecting surface (14, 141, 142).

A method for robust two-beam interferometry for detecting distance, depth, profile, shape, waviness and/or roughness or the optical path length in or on technical or biological objects, and/or for optical coherence tomography (OCT) with formation of a spatial white light interferogram, comprising:

• providing an arrangement for robust two-beam interferometry, the arrangement comprising the following:
• a source of short-coherent electromagnetic radiation for illuminating the object,
• an interferometer with an object beam path (O), at least one reference beam path (R), and a measurement plane in the object beam path, in which the surface or volume elements of the object to be optically measured are at least approximately located, and
• at least one rasterized detector for detecting electromagnetic radiation in the form of at least one spatial interferogram, wherein
• in the reference beam path (R) of the interferometer, at least one end reflector having three reflecting surfaces is arranged as a reference reflector, and the three reflecting surfaces are each at least approximately perpendicular to a common reference plane,
• characterized in that
• in the reference beam path (R), a reduction of the aperture angle of the reference beam is performed with beam-limiting means (221, 222).

A method for robust two-beam interferometry for detecting distance, depth, profile, shape, waviness and/or roughness or the optical path length in or on technical or biological objects, and/or for optical coherence tomography (OCT) with formation of a white light spatial interferogram, comprising:

• providing an arrangement for robust two-beam interferometry, the arrangement comprising the following:
• a source of short-coherent electromagnetic radiation for illuminating the object,
• a first interferometer with an object beam path (O) and at least one reference beam path (R), and an the object beam path, in which the object is located, at least one rasterized detector for detecting electromagnetic radiation in the form of at least one spatial interferogram, wherein
• in the reference beam path (R) of the first interferometer, at least one end reflector having three reflecting surfaces is arranged as a reference reflector and the three reflecting surfaces are each at least approximately perpendicular to a common reference plane,
• characterized in that
• a second optical scanning of the end reflector (111, 112, 113, 114) is performed by a second separate interferometer with a laser light source in order to be able to measure a displacement in the z direction of the interferometer (61) belonging to the end reflector (114), which is rigidly connected to the end reflector (111, 112, 113, 114).