Interferometer, comprising - a light source (10; LQ), - a beam splitter (23; PBS), which splits a first beam emitted by the light source (10; LQ) into at least one measurement beam (M; M1, M2) and at least one reference beam, by means of which a first splitting plane is spanned, with the measurement beam (M; M1, M2) propagating in a measurement arm and the reference beam propagating in a reference arm up to reunification at a unification location in a first unification plane, wherein the first unification plane is oriented parallel to the first splitting plane, - a measurement reflector (30; 130; 230; MR), which is arranged in the measurement arm and connected to a measurement object (31; 131; 231) movable along a measurement direction (y), wherein the measurement beam (M; M1, M2) is incident at least twice on the measurement reflector (30; 130; 230; MR) in a perpendicular manner, - a reference retroreflector (RR2; RR), which is arranged in the reference arm, wherein the reference beam is incident at least once on the reference retroreflector (RR2; RR) - a detector arrangement (40; DET), by means of which at least a first distance signal in relation to the position of the measurement object (31; 131; 231) is registrable from the interfering measurement and reference beams (M; M1, M2; R) superposed at the unification location, - a first transparent plane plate (21; 121; 221; P1) and a second transparent plane plate (22; 122; 222; P2), which are arranged parallel to one another in the beam path between the light source (10; LQ) and the detector arrangement (40; DET), wherein the measurement reflector (30; 130; 230; MR) is movable along the measurement direction (y) in relation to both plane plates (21; 121; 221; P1; 22; 221; 222; P2) and - the reference retroreflector (RR2; RR) is embodied in the first plane plate (21; 121; 221; P1) and - the beam splitter (23; PBS) is arranged on the second plane plate (22; 122; 222; P2). - a light source (10; LQ), - a beam splitter (23; PBS), which splits a first beam emitted by the light source (10; LQ) into at least one measurement beam (M; M1, M2) and at least one reference beam, by means of which a first splitting plane is spanned, with the measurement beam (M; M1, M2) propagating in a measurement arm and the reference beam propagating in a reference arm up to reunification at a unification location in a first unification plane, wherein the first unification plane is oriented parallel to the first splitting plane, - a measurement reflector (30; 130; 230; MR), which is arranged in the measurement arm and connected to a measurement object (31; 131; 231) movable along a measurement direction (y), wherein the measurement beam (M; M1, M2) is incident at least twice on the measurement reflector (30; 130; 230; MR) in a perpendicular manner, - a reference retroreflector (RR2; RR), which is arranged in the reference arm, wherein the reference beam is incident at least once on the reference retroreflector (RR2; RR) - a detector arrangement (40; DET), by means of which at least a first distance signal in relation to the position of the measurement object (31; 131; 231) is registrable from the interfering measurement and reference beams (M; M1, M2; R) superposed at the unification location, - a first transparent plane plate (21; 121; 221; P1) and a second transparent plane plate (22; 122; 222; P2), which are arranged parallel to one another in the beam path between the light source (10; LQ) and the detector arrangement (40; DET), wherein the measurement reflector (30; 130; 230; MR) is movable along the measurement direction (y) in relation to both plane plates (21; 121; 221; P1; 22; 221; 222; P2) and - the reference retroreflector (RR2; RR) is embodied in the first plane plate (21; 121; 221; P1) and - the beam splitter (23; PBS) is arranged on the second plane plate (22; 122; 222; P2).