# US 5,703,715 A · Device for stabilizing the focus of a microscope > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,703,715 A - Document ID: US5703715A - Status: Granted - Kind: A - Application number: 08/689,968 - Filed: 1996-08-16 - Granted: 1997-12-30 - Earliest claimed: 1995-08-16 - Assignees: Leica Mikroskopie und Systeme GmbH - Inventors: Norbert Gaul - Web page: https://patentgrep.com/patent/US5703715A ## CPC - G02B 21/241: {Devices for focusing (focusing in general G02B7/28)} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract A device for stabilizing the focus in a microscope (1) is described which has an objective (2) and a specimen stage (3), constructed in a movable fashion, for the purpose of setting the focus. The specimen stage (3) is constructed such that it can be moved via a toothed rack (4) and a drive gear (5) along the optical axis (22) of the objective (2). When the microscope (1) is heated by integrated electronic components (6) and/or an illuminating device (7), the body (13) of the microscope expands, and the microscope (1) is thereby defocused. Two rods (8 and 9) connected to one another, which have a different thermal expansion, are arranged between the toothed rack (4) and the specimen stage (3) for the purpose of compensating for the defocusing. ## Claims ### Claim 1 A device for stabilizing the focus in a microscope, the microscope having an objective and a specimen stage which, for the purpose of setting the focus, is constructed such that it can be adjusted in height along an objective axis by a drive gear and a toothed rack, and having a body of the microscope in which generate heat and cause a displacement, caused by heat, in distance of the specimen stage relative to the objective, and thus cause defocusing, said device comprising: at least two rods of different thermal expansion for compensating for the defocusing caused by heat, said rods being interposed between the toothed rack and the specimen stage, the second rod being connected with one of its ends to the toothed rack and with its other end to one end of the first rod, and the first rod bearing the specimen stage with its other end, said first rod counteracting the thermal elongation of the second rod and thus the displacement of the specimen stage through the thermal elongation of the first rod due to heat, wherein the specimen stage is tracked in distance as a function of temperature as a consequence of the different thermal expansions of the two rods. ### Claim 2 (depends on 1) The device for stabilizing the focus in a microscope as claimed in claim 1, wherein the first rod and the second rod are arranged next to one another and aligned in a parallel manner with the toothed rack. ### Claim 3 (depends on 1) The device for stabilizing the focus in a microscope as claimed in claim 1, wherein the second rod has a coefficient of thermal expansion which is greater than that of the first rod. ### Claim 4 (depends on 1) The device for stabilizing the focus in a microscope as claimed in claim 1, wherein the two rods are spaced from one another in order to reduce the friction of the two rods on one another. ### Claim 5 (depends on 1) The device for stabilizing the focus in a microscope as claimed in claim 1, wherein the second rod is comprised of aluminum and the first rod is comprised of iron. ### Claim 6 (depends on 1) The device for stabilizing the focus in a microscope as claimed in claim 1, wherein for the purpose of lateral guidance of the two rods on one another, one of the two rods bears a screw on its end opposite to the end where the two rods are connected to each other, and the other of the two rods has an elongate hole in which the screw engages. ### Claim 7 (depends on 1) The device for stabilizing the focus in a microscope as claimed in claim 1, wherein the lengths of the two rods are dimensioned differently. ### Claim 8 (depends on 2) The device for stabilizing the focus in a microscope as claimed in claim 2, wherein the second rod has a coefficient of thermal expansion which is greater than that of the first rod. ### Claim 9 (depends on 8) The device for stabilizing the focus in a microscope as claimed in claim 8, wherein the two rods are spaced from one another in order to reduce the friction of the two rods on one another. ### Claim 10 (depends on 9) The device for stabilizing the focus in a microscope as claimed in claim 9, wherein the second rod is comprised of aluminum and the first rod is comprised of iron. ### Claim 11 (depends on 10) The device for stabilizing the focus in a microscope as claimed in claim 10, wherein for the purpose of lateral guidance of the two rods on one another, one of the two rods bears a screw on its end opposite to the end where the two rods are connected to each other, and the other of the two rods has an elongate hole in which the screw engages. ### Claim 12 (depends on 11) The device for stabilizing the focus in a microscope as claimed in claim 11, wherein the lengths of the two rods are dimensioned differently. ### Claim 13 A device for stabilizing the focus of a microscope, comprising: a first rod bearing a specimen stage of the microscope; and a second rod connected at one end to the first rod and at its other end to a toothed rack of the microscope, wherein the first and second rods have different coefficients of thermal expansion. ### Claim 14 (depends on 13) The device for stabilizing the focus in a microscope as claimed in claim 13, wherein the first rod and the second rod are aligned parallel with the toothed rack. ### Claim 15 (depends on 13) The device for stabilizing the focus in a microscope as claimed in claim 13, wherein the second rod has a coefficient of thermal expansion which is greater than that of the first rod. ### Claim 16 (depends on 13) The device for stabilizing the focus in a microscope as claimed in claim 13, wherein the first and second rods are spaced from one another in order to reduce the friction of the first and second rods on one another. ### Claim 17 (depends on 13) The device for stabilizing the focus in a microscope as claimed in claim 13, wherein the second rod is comprised of aluminum and the first rod is comprised of iron. ### Claim 18 (depends on 13) The device for stabilizing the focus in a microscope as claimed in claim 13, wherein one of the first and second rods bears a screw on one end, and the other of the first and second rods has an elongate hole in which the screw engages. ### Claim 19 (depends on 13) The device for stabilizing the focus in a microscope as claimed in claim 13, wherein the first and second rods have different lengths. ### Claim 20 (depends on 13) The device for stabilizing the focus in a microscope as claimed in claim 13, wherein defocusing of the microscope is compensated for by the expansion of the first and second rods.