Abstract: A measuring head includes a light source unit, a first image pickup element, a second image pickup element, an objective optical system, an optical path splitting element, a common optical path, a first optical path, and a second optical path. The common optical path is located on one side of the optical path splitting element, and the first optical path and a second optical path are located on the other side. The optical path splitting element is disposed at a position where the first optical path and the second optical path intersect. The light source unit and the first image pickup element are disposed at predetermined positions. The second image pickup element is disposed at a position different from the predetermined positions. Each of the predetermined positions is a focal position of the objective optical system or a position conjugate to the focal position of the objective optical system.

Abstract: According to one aspect, an eccentricity amount obtainment method is a method of obtaining shift eccentricity amounts of lens frames through in a lens barrel that includes the plurality of lens frames having lens cells, the eccentricity amount obtainment method including arranging, in each of the lens cells, a flat plate member on which an index is formed and which has optical transparency and arranging the lens frames in the lens barrel in a prescribed order so as to assemble an assembly, a emitting illumination light to the flat plate members, obtaining pieces of information related to positions of the indexes formed on the flat plate members, and obtaining, as the shift eccentricity amounts of the lens frames, the positional displacement amounts with respect to the indexes formed on the flat plate members with respect to an arbitrary position.

Abstract: A measuring head includes a light source unit, a first image pickup element, a second image pickup element, an objective optical system, an optical path splitting element, a common optical path, a first optical path, and a second optical path. The common optical path is located on one side of the optical path splitting element, and the first optical path and a second optical path are located on the other side. The optical path splitting element is disposed at a position where the first optical path and the second optical path intersect. The light source unit and the first image pickup element are disposed at predetermined positions. The second image pickup element is disposed at a position different from the predetermined positions. Each of the predetermined positions is a focal position of the objective optical system or a position conjugate to the focal position of the objective optical system.

Abstract: According to one aspect, an eccentricity amount obtainment method is a method of obtaining shift eccentricity amounts of lens frames through in a lens barrel that includes the plurality of lens frames having lens cells, the eccentricity amount obtainment method including arranging, in each of the lens cells, a flat plate member on which an index is formed and which has optical transparency and arranging the lens frames in the lens barrel in a prescribed order so as to assemble an assembly, a emitting illumination light to the flat plate members, obtaining pieces of information related to positions of the indexes formed on the flat plate members, and obtaining, as the shift eccentricity amounts of the lens frames, the positional displacement amounts with respect to the indexes formed on the flat plate members with respect to an arbitrary position.

Abstract: Provided are a variable power optical system in which the value of the entire length with respect to the image height is reduced and the aberration is well corrected, and an image pickup device comprising the same. Specifically provided is a variable power optical system comprising, in order from the object side, at least a first lens group having negative refractive power, a variable power group having positive refractive power, and a final lens group having positive refractive power, wherein the variable power group is provided with, in order from the object side, a first lens element having positive refractive power, a second lens element, and a third lens element, the second lens element has a convex shape on the object side, and the final lens group comprises a positive lens, the variable power optical system satisfying the following conditional expression: 10?VdLg?45 ?1.0<(R2a?R2b)/(R2a+R2b)<1.

Abstract: Provided are a variable power optical system in which the value of the entire length with respect to the image height is reduced and the aberration is well corrected, and an image pickup device comprising the same. Specifically provided is a variable power optical system comprising, in order from the object side, at least a first lens group having negative refractive power, a variable power group having positive refractive power, and a final lens group having positive refractive power, wherein the variable power group is provided with, in order from the object side, a first lens element having positive refractive power, a second lens element, and a third lens element, the second lens element has a convex shape on the object side, and the final lens group comprises a positive lens, the variable power optical system satisfying the following conditional expression: 10?VdLg?45 ?1.0<(R2a?R2b)/(R2a+R2b)<1.

Abstract: Provided are a variable power optical system in which the value of the entire length with respect to the image height is reduced and the aberration is well corrected, and an image pickup device comprising the same. Specifically provided is a variable power optical system comprising, in order from the object side, at least a first lens group having negative refractive power, a variable power group having positive refractive power, and a final lens group having positive refractive power, wherein the variable power group is provided with, in order from the object side, a first lens element having positive refractive power, a second lens element, and a third lens element, the second lens element has a convex shape on the object side, and the final lens group comprises a positive lens, the variable power optical system satisfying the following conditional expression: 10?VdLg?45 ?1.0<(R2a?R2b)/(R2a+R2b)<1.

Abstract: In an image forming optical system which includes in order from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power, a refractive index for a d-line of a positive single lens having the largest refractive power among all lenses in the second lens group, is the smallest of a refractive index of lenses in the second lens group.

Abstract: Provided are a variable power optical system in which the value of the entire length with respect to the image height is reduced and the aberration is well corrected, and an image pickup device comprising the same. Specifically provided is a variable power optical system comprising, in order from the object side, at least a first lens group having negative refractive power, a variable power group having positive refractive power, and a final lens group having positive refractive power, wherein the variable power group is provided with, in order from the object side, a first lens element having positive refractive power, a second lens element, and a third lens element, the second lens element has a convex shape on the object side, and the final lens group comprises a positive lens, the variable power optical system satisfying the following conditional expression: 10?VdLg?45 ?1.0<(R2a?R2b)/(R2a+R2b)<1.

Abstract: A variable power optical system includes, in order from the object side, a first lens group having negative refractive power, a variable power group having positive refractive power, and a final lens group having positive refractive power. The variable power group is provided with, in order from the object side, a first lens element having positive refractive power, a second lens element, and a third lens element. The second lens element has a convex shape on the object side. The final lens group includes a positive lens. The variable power optical system satisfies the following conditions: 10?VdLg?45 ?1.0<(R2a?R2b)/(R2a+R2b)<1.0 where VdLg is the Abbe number of the positive lens of the final lens group with respect to the d line, R2a is the curvature radius of the object-side surface of the second lens element, and R2b is the curvature radius of the image-side surface of the third lens element.

Abstract: The invention provides a zoom optical system comprising at least three lens groups and designed to implement zooming by varying a separation between the respective lens groups. The zoom optical system includes, on an image plane side with respect to a stop, a lens group comprising a plurality of lenses and having positive refracting power throughout. The lens group having positive refracting power includes therein a first lens and a second lens in order from the object side, an image plane side surface of the first lens being convex toward the object side, and an object side surface of the second lens being concave toward the object side.

Abstract: A focus position control apparatus includes a lens for forming an image from light from a subject, an imaging element and an imaging controller for performing photoelectric conversion on the subject image, lights having at least two different wavelengths or wavelength bands, on an imaging plane to generate at least a visible-region image signal and an infrared-region image signal, a focus-position movement mechanism for moving the lens in a direction along an optical axis relative to the imaging plane, a focusing state evaluator for evaluating a focusing state in each wavelength or wavelength band based on the generated visible-region image signal and infrared-region image signal, and a movement controller for driving the focus-position movement mechanism based on the evaluation result from the focusing state evaluator.

Abstract: A variable power optical system includes, in order from the object side, a first lens group having negative refractive power, a variable power group having positive refractive power, and a final lens group having positive refractive power. The variable power group is provided with, in order from the object side, a first lens element having positive refractive power, a second lens element, and a third lens element. The second lens element has a convex shape on the object side. The final lens group includes a positive lens. The variable power optical system satisfies the following conditions: 10?VdLg?45 ?1.0<(R2a?R2b)/(R2a+R2b)<1.0 where VdLg is the Abbe number of the positive lens of the final lens group with respect to the d line, R2a is the curvature radius of the object-side surface of the second lens element, and R2b is the curvature radius of the image-side surface of the third lens element.

Abstract: It is preferable that for an image forming optical system a basic structure which includes a first lens group having a negative refracting power, which is made of one cemented lens component, a second lens group having a positive refracting power, a third lens group having a positive refracting power, which is made of one lens component, and is movable for focusing, and a fourth lens group which is made of one lens component having an aspheric surface, and at the time of zooming from a wide angle end to a telephoto end, the second lens group moves only toward the object side, and the first lens group and the third lens group move while following a trajectory of movement different from a trajectory of movement of the second lens group is adopted, and that the image forming optical system satisfies predetermined conditional expressions.

Abstract: The invention provides a zoom optical system comprising at least three lens groups and designed to implement zooming by varying a separation between the respective lens groups. The zoom optical system includes, on an image plane side with respect to a stop, a lens group comprising a plurality of lenses and having positive refracting power throughout. The lens group having positive refracting power includes an air double-convex positive lens in it.

Abstract: An image forming optical system has a positive lens group disposed closer to its object side than an aperture stop, and the values of ?gF1 and other constants of at least one lens LA included in the positive lens group fall within three ranges including a range bounded by the straight lines given by the equation ?gF1=?1×?d1+?gF1 (where ?1=?0.00566) into which the lowest and highest values in the range given by a first conditional expression are substituted respectively, a range bounded by the straight lines given by the equation nd1=a1×?d1+b1 (where a1=?0.0267) into which the lowest and highest values in the range given by a second conditional expression are substituted respectively, and a range defined by a third conditional expression.

Abstract: In an image forming optical system which includes in order from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power, a refractive index for a d-line of a positive single lens having the largest refractive power among all lenses in the second lens group, is the smallest of a refractive index of lenses in the second lens group.

Abstract: An image forming optical system according to the present invention is characterized in that, in an image forming optical system having a positive lens group, a negative lens group, and an aperture stop, the positive lens group is disposed at an object side of the aperture stop, the positive lens group has a cemented lens which is formed by cementing a plurality of lenses, in a rectangular coordinate system in which a horizontal axis is let to be Nd and a vertical axis is let to be ?d, when a straight line indicated by Nd=?×?d+? (where, ?=?0.017) is set, Nd and ?d of at least one lens forming the cemented lens is included in both of areas namely, an area which is determined by a line when a lower limit value is in a range of a following conditional expression (1a), and a line when an upper limit value is in a range of the following conditional expression (1a), and of an area determined by following conditional expressions (2a) and (3a). 1.45<?<2.15??(1a) 1.30<Nd<2.

Abstract: An image forming optical system according to the present invention is characterized in that, in an image forming optical system having a positive lens group, a negative lens group, and an aperture stop, the positive lens group is disposed at an object side of the aperture stop, the positive lens group has a cemented lens which is formed by cementing a plurality of lenses, in a rectangular coordinate system in which a horizontal axis is let to be Nd and a vertical axis is let to be ?d, when a straight line indicated by Nd=?×?d+? (where, ?=?0.017) is set, Nd and ?d of at least one lens forming the cemented lens is included in both of areas namely, an area which is determined by a line when a lower limit value is in a range of a following conditional expression (1a), and a line when an upper limit value is in a range of the following conditional expression (1a), and of an area determined by following conditional expressions (2a) and (3a). 1.45<?<2.15??(1a) 1.30<Nd<2.

Abstract: In an image forming optical system having a positive lens group, a negative lens group, and an aperture stop, the positive lens group being disposed at an image-plane side of the aperture stop and having a cemented lens, and when a straight line indicated by Nd=?×?d+? (where, ?=?0.017) is set, Nd and ?d of at least one lens forming the cemented lens are included in both an area which is determined by a line when a lower limit value is in a range of a following conditional expression (1), and a line when an upper limit value is in a range of the following conditional expression (1), and in an area determined by following conditional expressions (2) and (3) 1.45<?<2.15??(1) 1.30<Nd<2.20??(2) 3<?d<25??(3) Here, Nd denotes a refractive index, and ?d denotes an Abbe's number.