Reflective device (300; 710, 720; 810; 910, 920) for use in an optical measuring system (700; 906) and for arranging in a measuring object (800; 902, 904), comprising: an optical deflection device, which is configured to deflect a light beam arriving at the optical deflection device from an incident axis of the light beam, wherein the optical deflection device comprises a first mirror (322, 324) and a second mirror (324, 322) which are arranged in different mirror planes, and a retroreflector, which is configured to reflect the light beam parallel to its respective incoming direction for each of various incoming directions of a light beam onto the retroreflector, whereby the first mirror (322, 324) and the second mirror (324, 322) are aligned parallel to each other, and wherein the retroreflector and the optical deflection device are arranged in the reflective device (300; 710, 720; 810; 910, 920) in such a way and the reflective device can be arranged in the measuring object (800; 902, 904) in such a way that an incoming measuring beam of the optical measuring system (700; 906), which is pointed at the measuring object (800; 902, 904) and arrives in a first direction at the optical deflection device, is deflected by the first mirror (322, 324) of the optical deflection device 320) onto the retroreflector in a second direction different from the first direction so as to form a first deflected beam, and, following reflection at the retroreflector (210; 310; 410; 510; 610) so as to form a reflected beam, is deflected by the second mirror (324, 322) of the optical deflection device in a third direction that is reverse and parallel to the first direction so as to form a second deflected beam, wherein a first distance (d) is defined by a distance between the incoming measuring beam and the second deflected beam, and a second distance (b) is defined by a distance between the first deflected beam and the reflected beam, and wherein a distance between the first and second mirrors (322, 324) and/or the mirror planes is adjustable thereby enabling that the first distance (d) is varied independently from the second distance (b) and/or vice versa. an optical deflection device, which is configured to deflect a light beam arriving at the optical deflection device from an incident axis of the light beam, wherein the optical deflection device comprises a first mirror (322, 324) and a second mirror (324, 322) which are arranged in different mirror planes, and a retroreflector, which is configured to reflect the light beam parallel to its respective incoming direction for each of various incoming directions of a light beam onto the retroreflector, whereby the first mirror (322, 324) and the second mirror (324, 322) are aligned parallel to each other, and wherein the retroreflector and the optical deflection device are arranged in the reflective device (300; 710, 720; 810; 910, 920) in such a way and the reflective device can be arranged in the measuring object (800; 902, 904) in such a way that an incoming measuring beam of the optical measuring system (700; 906), which is pointed at the measuring object (800; 902, 904) and arrives in a first direction at the optical deflection device, is deflected by the first mirror (322, 324) of the optical deflection device 320) onto the retroreflector in a second direction different from the first direction so as to form a first deflected beam, and, following reflection at the retroreflector (210; 310; 410; 510; 610) so as to form a reflected beam, is deflected by the second mirror (324, 322) of the optical deflection device in a third direction that is reverse and parallel to the first direction so as to form a second deflected beam, wherein a first distance (d) is defined by a distance between the incoming measuring beam and the second deflected beam, and a second distance (b) is defined by a distance between the first deflected beam and the reflected beam, and wherein a distance between the first and second mirrors (322, 324) and/or the mirror planes is adjustable thereby enabling that the first distance (d) is varied independently from the second distance (b) and/or vice versa.