Abstract: The invention relates to a microscope (1), in particular an ophthalmic surgical microscope having a vitreoretinal viewing system (6), an optics carrier (14) and a support (2). The invention also relates to a method and a motion controller controlling the movement of the vitreoretinal viewing system (6). The optics carrier (14) is attached movably to the support (2). The vitreoretinal viewing system (6) in turn is attached movably to the optics carrier (14). The vitreoretinal viewing system (6) comprises a front piece (30), such as a optics carrier (14). To avoid contact of the front piece (30) with an eye (16) while the optics carrier (14) is moved for focusing a microscope lens (18), the position of the front piece (30) is automatically maintained stationary with respect to the support (2). This is obtained by controlling the vitreoretinal viewing system (6) to perform a counter movement to the movement of the optics carrier (14).

Abstract: The invention relates to a microscope (1), in particular an ophthalmic surgical microscope having a vitreoretinal viewing system (6), an optics carrier (14) and a support (2). The invention also relates to a method and a motion controller controlling the movement of the vitreoretinal viewing system (6). The optics carrier (14) is attached movably to the support (2). The vitreoretinal viewing system (6) in turn is attached movably to the optics carrier (14). The vitreoretinal viewing system (6) comprises a front piece (30), such as a optics carrier (14). To avoid contact of the front piece (30) with an eye (16) while the optics carrier (14) is moved for focusing a microscope lens (18), the position of the front piece (30) is automatically maintained stationary with respect to the support (2). This is obtained by controlling the vitreoretinal viewing system (6) to perform a counter movement to the movement of the optics carrier (14).

Abstract: A case hardening steel high in impact strength, consists essentially of carbon in an amount of from 0.1 to 0.3% by weight, silicon in an amount of from more than 0.3 to 1.0% by weight, manganese in an amount of from 0.3 to 1.7% by weight, phosphorus in an amount of not more than 0.03% by weight, sulfur in an amount of not more than 0.03% by weight, molybdenum in an amount of not more than 1.0% by weight, aluminum in an amount of not more than 0.04% by weight, nitrogen in an amount of not more than 0.03% by weight, and balance being iron and inevitable impurities. The case hardening steel meets an equation of [C %]+5([P %]+[S %])≦([Mn %]+[Mo %]+1.8)/8.