Abstract: There is provided a zoom lens including broad picture angle of 60 to 100 degrees as photographic picture angle of the wide-angle end state, and having magnification ratio of about three to six times, small front gem diameter, excellent compactness and high image formation performance, which is used in video camera or digital still camera, and an image pick-up apparatus using such a zoom lens. A zoom lens (20), consisting of plural groups and serving to change group spacing or spacings to thereby perform magnification changing or adjusting operation, comprises a first lens group GR1 having positive refractive power, a second lens group GR2 having negative refractive power and a third lens group GR3 having positive refractive power which are arranged in order from the object side, and a last group GRR arranged at the side closest to the image surface and having negative refractive power, wherein the first lens group GR1 is constituted by single positive lens G1, and satisfies the following conditional formulas.

Abstract: There is provided a zoom lens system including at least a first lens group GR1 having a positive refractive power, a second lens group GR2 having a negative refractive power, a third lens group GR3 having a positive refractive power, a fourth lens group GR4 having a negative refractive power, a fifth lens group GR5 having a positive refractive power, and a sixth lens group GR6 having a negative refractive power, arranged sequentially from the object side. Zoom ratio is varied by changing the distance between the adjacent lens groups.

Abstract: A zoom lens of rear focus type in which a total lens system is able to be miniaturized by further miniaturizing a prism, without deteriorating an optical performance. The zoom lens has a first lens group (GR1) to a fifth lens group (GR5) having refraction powers of a positive, negative, positive, positive and negative from the object side in this order, respectively, and is configured to carry out a zooming operation by moving the second lens group (GR2) and the fourth lens group (GR4). In addition, the first lens group has a front-side lens group having an negative refracting power, an optical element for folding an optical path, and a backside lens group having a positive refracting power, from the object side in this order, and further a condition of 1.3<?5<2.2 is satisfied, provided that an imaging magnification of the fifth lens group (GR5) at where an object distance is at infinity is ?5.

Abstract: A zoom lens is disclosed which has a macro mode wherein the magnifying power is higher than 0.5. The zoom lens includes a first positive lens group, a second negative lens group movable upon power variation, and a plurality of movable lens groups cooperable with the second group to form a macro lens group, disposed in order from an object side. The movable lens groups include a single focusing group, and an additional negative lens group disposed further on the image side. The zoom lens has a macro mode in which it can be focused at a shorter distance than an ordinary region by moving the macro lens group integrally from a telephoto end position toward the object side while the first lens group is fixed at the telephotograph end.

Abstract: A zoom lens is proposed, which includes a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power, which are arranged in order from an object side, performing zooming by moving the second lens group and the fourth lens group, wherein the first lens group includes a front lens group having negative refractive power, an optical member refracting a light path, and a rear lens group having positive refractive power, which are arranged in order from the object side, wherein the fourth lens group includes one single lens, and if an image forming power of the fifth lens group at an object distance of infinity is ?5, a conditional formula (1) 1.0<?5<1.8 is satisfied.

Abstract: A zoom lens of rear focus type in which a total lens system is able to be miniaturized by further miniaturizing a prism, without deteriorating an optical performance. The zoom lens has a first lens group (GR1) to a fifth lens group (GR5) having refraction powers of a positive, negative, positive, positive and negative from the object side in this order, respectively, and is configured to carry out a zooming operation by moving the second lens group (GR2) and the fourth lens group (GR4). In addition, the first lens group has a front-side lens group having an negative refracting power, an optical element for folding an optical path, and a backside lens group having a positive refracting power, from the object side in this order, and further a condition of 1.3<?5<2.2 is satisfied, provided that an imaging magnification of the fifth lens group (GR5) at where an object distance is at infinity is ?5.

Abstract: A zoom lens is disclosed which has a macro mode wherein the magnifying power is higher than 0.5. The zoom lens includes a first positive lens group, a second negative lens group movable upon power variation, and a plurality of movable lens groups cooperable with the second group to form a macro lens group, disposed in order from an object side. The movable lens groups include a single focusing group, and an additional negative lens group disposed further on the image side. The zoom lens has a macro mode in which it can be focused at a shorter distance than an ordinary region by moving the macro lens group integrally from a telephoto end position toward the object side while the first lens group is fixed at the telephotograph end.

Abstract: The zoom of this invention comprises a first lens group having a positive refracting power, a second lens group having an negative refracting power, a third lens group having a positive refracting power, a fourth lens group having a positive refracting power, and a fifth lens group having a negative refracting power from an object side in this order, wherein a zooming is carried out by moving the second and the fourth lens groups, wherein the first lens group comprises, a foreside lens group having an negative refracting power, an optical element for folding an optical path, and a backside lens group having a positive refracting power from the object side, and a condition of 1.0<?5<1.9 is satisfied, provided that an imaging power of the fifth lens group where an object distance is at infinity is ?5.

Abstract: A zoom lens has an optical axis and includes: a negative first lens group capable of being moved for zooming and disposed nearest to the front end; a positive second lens group capable of being moved for zooming, and disposed behind the first lens group; and a positive third lens group disposed behind the second lens group. The zoom lens meets conditions expressed by inequalities: 0.02<D12/fw<0.13??(1) 0.5<D2G/fw<0.95??(2) 5<TLW/fw<8??(3) where D12 is a minimum distance on the optical axis between a back surface of the first lens group and a front surface of the second lens group, D2G is a distance between front and back surfaces of the second lens group, TLW is optical length of the zoom lens as set in the shortest focal length, and fw is the shortest focal length.

Abstract: A zoom lens is proposed, which includes a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power, which are arranged in order from an object side, performing zooming by moving the second lens group and the fourth lens group, wherein the first lens group includes a front lens group having negative refractive power, an optical member refracting a light path, and a rear lens group having positive refractive power, which are arranged in order from the object side, wherein the fourth lens group includes one single lens, and if image forming power of the fifth lens group at an object distance of infinity is ?5, a conditional formula (1) 1.0<?5<1.8 is satisfied.

Abstract: A zoom lens has an optical axis and includes: a negative first lens group capable of being moved for zooming and disposed nearest to the front end; a positive second lens group capable of being moved for zooming, and disposed behind the first lens group; and a positive third lens group disposed behind the second lens group. The zoom lens meets conditions expressed by inequalities: 0.02<D12/fw<0.13 ??(1) 0.5<D2G/fw<0.95 ??(2) 5<TLW/fw<8 ??(3) where D12 is a minimum distance on the optical axis between a back surface of the first lens group and a front surface of the second lens group, D2G is a distance between front and back surfaces of the second lens group, TLW is optical length of the zoom lens as set in the shortest focal length, and fw is the shortest focal length.

Abstract: The zoom of this invention comprises a first lens group having a positive refracting power, a second lens group having an negative refracting power, a third lens group having a positive refracting power, a forth lens group having a positive refracting power, and a fifth lens group having a negative refracting power from an object side in this order, wherein a zooming is carried out by moving the second and the forth lens groups, wherein the first lens group comprises, a foreside lens group having an negative refracting power, an optical element for folding an optical path, and a backside lens group having a positive refracting power from the object side, and a condition of 1.0<?5<1.9 is satisfied, provided that an imaging power of the fifth lens group where an object distance is at infinity is ?5.

Abstract: In this invention, in order to realize an interferometer apparatus which can correct a measurement error caused by a change in refractive index due to a fluctuation of a gas such as air with high precision, and can assure a high-precision, stable measurement, first and second interferometer means are arranged, and two measurement reflection means are integrally moved while a predetermined relationship is held between measurement optical path lengths and reference optical path lengths formed by the two interferometer means.

Abstract: An interferometric distance measuring interferometer comprises a light source (11) for irradiating a main light beam (L), a beam splitting member (56) for splitting the main light beam into a first light beam (MR1, MR2) and a second light beam (MM1, MM2), a first reflection member (28) and second reflection member (14) for reflecting the first light beam and the second light beam, respectively, an optical composition member (25) for compositing the first light beam reflected by the first reflection member (28) and the second light beam reflected by the second reflection member (14), and a photoelectric converter (19) for receiving the composited light beam from the optical composition member. Whereby, a relative displacement between the first reflection member (28) and the second reflection member (14) is detected based on a photoelectric conversion signal from the photoelectric converter (19).

Abstract: An interferometer apparatus includes a prism member provided with a polarization beam splitter surface and a reflecting surface. A light beam from a laser source is split into first and second light beams by the polarization beam splitter surface. The first light beam passes through a quarter wave plate and is incident on a first movable mirror. The second light beam is incident on a rectangular prism and reflected therefrom. The reflected second light beam passes through a half wave plate and is incident on an upper portion of the polarization beam splitter surface. The second light beam having passed through the surface is passed through the quarter wave plate and is incident on a second movable mirror.