Confocal displacement sensor

A confocal displacement sensor capable of measuring a thickness of a measurement object having first and second surfaces on opposite sides, the confocal displacement sensor comprising:

• a light projecting unit which emits light having a plurality of wavelengths;
• a first head unit which includes a first confocal optical system having a first diffraction lens, generating chromatic aberration along an optical axis direction in the light emitted by the light projecting unit, and converging the light on the first surface of the measurement object;
• a second head unit which includes a second confocal optical system having a second diffraction lens, generating chromatic aberration along an optical axis direction in the light emitted by the light projecting unit, and converging the light on the second surface of the measurement object;
• a first spectroscope which divides a first light by each wavelength, the first light having been reflected by the first surface and having passed through the first confocal optical system;
• a first light receiving unit which receives the divided first light for each wavelength and acquires an intensity of the light for each wavelength;
• and
• a control device which is configured to be able to adjust an optical axis of the first head unit using a reference member having the first and second surfaces parallel to each other instead of the measurement object,
• wherein the first head unit is configured such that a first primary light having one wavelength, which is emitted to the first surface through the first head unit, is reflected by the first surface and passes the first confocal optical system through a path of a first multi-order light having the one wavelength when the optical axis of the first head unit is orthogonal to the first surface,
• wherein the second head unit is configured such that a second primary light having one wavelength, which is emitted to the second surface through the second head unit, is reflected by the second surface and passes the second confocal optical system through a path of a second multi-order light having the one wavelength when the optical axis of the second head unit is orthogonal to the second surface, and
• wherein the control device includes an intensity information display control unit causing a display unit to display, when adjusting the optical axis, as first intensity information, information on an intensity of a first determination light acquired from the first primary light having been reflected by the first surface and having passed the first confocal optical system through the path of the first multi-order light from among the intensities of the lights that the first light receiving unit receives, in a state where the reference member is disposed between the first head unit and the second head unit.

A confocal displacement sensor capable of measuring a thickness of a measurement object having first and second surfaces on opposite sides, the confocal displacement sensor comprising:

• a light projecting unit which emits a plurality of light having a plurality of wavelengths;
• first and second head units;
• a first optical member provided in the first head unit, having a diffraction lens for generating chromatic aberration along an optical axis direction in the plurality of light emitted by the light projecting unit, and converging the plurality of light having chromatic aberration to emit each of the plurality of light to the first surface of the measurement object;
• a first pinhole member provided in the first head unit and having a plurality of first pinholes through which a plurality of light, which have been focused and reflected by the first surface, passes as a plurality of first lights from among the plurality of light emitted to the first surface by the first optical member;
• a second optical member provided in the second head unit, having a diffraction lens for generating chromatic aberration along the optical axis direction in the plurality of light emitted by the light projecting unit, and converging the plurality of light having chromatic aberration to emit each of the plurality of light to the second surface of the measurement object;
• a second pinhole member provided in the second head unit and having a plurality of second pinholes through which a plurality of light, which have been focused and reflected by the second surface, passes as a plurality of second light from among the plurality of light emitted the second surface by the second optical member;
• an acquisition unit which acquires intensities of the plurality of first light having passed through the plurality of first pinholes for each wavelength and acquires intensities of the plurality of second light having passed through the plurality of second pinholes for each wavelength;
• a thickness calculation unit which calculates a thickness between the first surface and the second surface of the measurement object based on the intensities of the plurality of first and second light for each wavelength acquired by the acquisition unit;
• and
• a control device which is configured to be able to adjust optical axes of the first and second optical members using a reference member having the first and second surfaces parallel to each other instead of the measurement object,
• wherein the first head unit is configured such that a first primary light having one wavelength, which is emitted to the first surface through the first optical member, is reflected by the first surface and passes the first pinhole through a path of a first multi-order light having the one wavelength when an optical axis of the first optical member is orthogonal to the first surface,
• wherein the second head unit is configured such that a second primary light having one wavelength, which is emitted to the second surface through the second optical member, is reflected by the second surface and passes the second pinhole through a path of a second multi-order light having the one wavelength when an optical axis of the second optical member is orthogonal to the second surface, and
• wherein the control device includes an intensity information display control unit, when adjusting the optical axis, causing a display unit to display, as first intensity information, information on an intensity of a first determination light acquired from the first primary light having been reflected by the first surface and having passed the first pinhole through the path of the first multi-order light from among the intensities of the plurality of light that the acquisition unit acquires, and to display as second intensity information, information on an intensity of a second determination light acquired from the second primary light having been reflected by the second surface and having passed the second pinhole through the path of the second multi-order light from among the intensities of the plurality of light that the acquisition unit acquires, in a state where the reference member is disposed between the first head unit and the second head unit.