Canon Kabushiki Kaisha

Hiroto Yasui

Fumihito Wachi

Provided is an optical system including, in order from an object side to an image side, a front lens unit, an aperture stop, and a rear lens unit. The front lens unit consists of a positive lens and a diffractive optical element, which are arranged in order from the object side to the image side. The diffractive optical element consists of a plurality of lenses that are cemented to each other, and at least one of cemented surfaces of the plurality of lenses is a diffractive surface. An interval on an optical axis between the positive lens and the diffractive optical element is the largest among intervals on the optical axis between two lenses that are adjacent in the optical system.

Optical system and image pickup apparatus including the same

Provided is an optical system including a front unit, an aperture stop and a rear unit which are arranged in order from an object side to an image side. The front unit includes a diffractive optical element, at least one first refractive optical element having a power in the same sign as a sign of a power at a diffractive surface of the diffractive optical element, and at least one second refractive optical element having a power in a different sign from the sign of the power at the diffractive surface. A partial dispersion ratio between a d-line and a C-line and a partial dispersion ratio between a g-line and the d-line of the at least one first refractive optical element and the at least one second refractive optical element are appropriately set.

An optical system includes a diffractive surface and at least one aspherical surface, an aspherical surface of at least one aspherical surface closest to the diffractive surface is referred to as a first aspherical surface, a phase function &#x3c8;(r) and an aspherical function X(r) of the first aspherical surface increase with different signs from each other in a height direction with increasing a distance from an optical axis, and a condition below is satisfied: where f is a focal length of the optical system when focusing on an infinite object, and Fno is an F number of the optical system.

Optical system and optical apparatus with diffractive optical element

The optical system includes, in order from an object side, a front lens unit LF, an aperture stop S, a rear lens unit LR. The front lens unit includes a diffraction optical element Ldoe. A stop side positive lens Lsp disposed closest to the aperture stop among the rear lens unit satisfies 1.55&#x2266;Nd&#x2266;1.70, 30.0&#x2266;&#x3bd;d&#x2266;50.0, and 5.0&#xd7;10&#x2266;&#x394;&#x3b8;dC&#x2266;5.0&#xd7;10. Ndand &#x3bd;drepectively represent a refractive index and an Abbe number of the stop side positive lens for a d-line, and &#x394;&#x3b8;dCis represents a value defined by &#x394;&#x3b8;dC=&#x3b8;dC&#x2212;(&#x2212;0.17041&#xd7;&#x3b8;gd+0.513577) where Ng, NCand NFrespectively represent refractive indices of the stop side positive lens for a g-line, a C-line and an F-line. &#x3b8;dCand &#x3b8;gdare respectively defined by &#x3b8;dC=(Nd&#x2212;NC)/(NF&#x2212;NC) and &#x3b8;gd=(Ng&#x2212;Nd)/(NF&#x2212;NC).

Optical system including diffractive optical element and optical apparatus

The optical system includes plural lens groups, a negative lens included in one lens group among the plural lens groups and formed of a first medium, a diffractive grating formed on at least one lens surface of the negative lens and being in contact with a second medium different from the first medium, and a positive lens included in the one lens group and formed of a third medium different from the first medium and the second medium. The first medium satisfies ndA&#x2267;1.7 and 40&#x2266;&#x3bd;dA&#x2266;55 where ndA represents a refractive index of the first medium for a d-line, and &#x3bd;dA represents an Abbe number of the first medium for the d-line. The third medium satisfies ndC&#x2266;1.55 and &#x3bd;dC&#x2267;60 where ndC represents a refractive index of the third medium for the d-line, and &#x3bd;dC represents an Abbe number of the third medium for the d-line.

Optical system including diffractive grating and optical apparatus

Provided are an optical element in which a thickness of a refractive optical portion having an extraordinary partial dispersion characteristic is suitably specified to minimize flare generated by a diffraction optical portion, to thereby sufficiently correct chromatic aberrations to obtain excellent optical performance, and an optical system including the optical element. The optical system includes a cemented portion in which the refractive optical portion made of a solid material and has a refractive action is brought into intimate contact with at least one of light incident and exiting surfaces of the diffraction optical portion having a plurality of diffraction gratings which are layered. An Abbe (&#x3bd;d), a partial dispersion ratio (&#x3b8;gF), and an extraordinary partial dispersion ratio (&#x394;&#x3b8;gF) of the solid material are suitably set.

Optical element and optical system including the same

An optical system includes a front lens group, a stop, and a rear lens group arranged successively in order from the object side toward the image side. The front lens group includes a solid material element having a refractive action. The rear lens group includes a diffractive optical element. The solid material element is formed on at least one transmissive surface of a refractive optical element. An Abbe number of a solid material of the solid material element with respect to the d line, a partial dispersion ratio of the solid material with respect to the g line and the F line, respective thicknesses of the solid material element and the refractive optical element when measured on the optical axis, and respective focal lengths of the diffractive optical portion of the diffractive optical element and the solid material element in air satisfy predetermined conditional expressions.

Optical system and optical apparatus using the same

The diffractive optical element includes two diffraction gratings made of different materials and being in contact with each other at their grating surfaces. The materials satisfy the following conditions, and the second material is obtained by mixing a resin material with a particulate material satisfying the following conditions: nd1&#x2267;1.48, &#x3bd;d1&#x2267;40, (&#x2212;1.665E&#x2212;07&#xd7;&#x3bd;d1+5.213E&#x2212;05&#xd7;&#x3bd;d1&#x2212;5.656E&#x2212;03&#xd7;&#x3bd;d1+0.675)&#x2266;&#x3b8;g,F1&#x2266;(&#x2212;1.665E&#x2212;07&#xd7;&#x3bd;d1+5.213E&#x2212;05&#xd7;&#x3bd;d1&#x2212;5.656E&#x2212;03&#xd7;&#x3bd;d1+0.825), (&#x2212;1.687E&#x2212;07&#xd7;&#x3bd;d1+5.702E&#x2212;05&#xd7;&#x3bd;d1&#x2212;6.603E&#x2212;03&#xd7;&#x3bd;d1+1.400)&#x2266;&#x3b8;g,d1&#x2266;(&#x2212;1.687E&#x2212;07&#xd7;&#x3bd;d1+5.702E&#x2212;05&#xd7;&#x3bd;d1&#x2212;6.603E&#x2212;03&#xd7;&#x3bd;d1+1.580), nd2&#x2266;1.6, &#x3bd;d2&#x2266;30, &#x3b8;g,F2&#x2266;(&#x2212;1.665E&#x2212;07&#xd7;&#x3bd;d2+5.213E&#x2212;05&#xd7;&#x3bd;d2&#x2212;5.656E&#x2212;03&#xd7;&#x3bd;d2+0.675), &#x3b8;g,d2&#x2266;(&#x2212;1.687E&#x2212;07&#xd7;&#x3bd;d2+5.702E&#x2212;05&#xd7;&#x3bd;d2&#x2212;6.603E&#x2212;03&#xd7;&#x3bd;d2+1.400), nd1&#x2212;nd2&#x3e;0, ndb2&#x2267;1.70, &#x3bd;db2&#x2266;20. The element achieves a high diffraction efficiency in a specific diffraction order over a wide wavelength range.

Contacting two-layer diffractive optical element

An image-pickup optical system includes, from the object side to the image side, a first lens unit having positive optical power, an aperture stop, and a second lens unit. A diffractive optical element and a lens composed of extraordinary partial dispersion material are appropriately disposed in the optical system. The image-pickup optical system is capable of reducing the generation of flare and ghosts at the diffractive optical element and effectively correcting chromatic aberration.

Image-pickup optical system

A zoom lens system includes a frontmost first lens unit having a negative optical power and a plurality of lens units on the rear side thereof. The first lens unit consists of a negative lens element. The zoom lens system includes five or less lens elements in total. The Abbe number of the negative lens element and the exit pupil distance of the zoom lens system at a wide-angle end are appropriately adjusted.

Zoom lens system and image pickup apparatus including the same

Among a plurality of lens units constituting an optical system, at least one of the plurality of lens units includes a refractive optical element made of a solid material that satisfies the following conditions:3&#x3c;&#x3bd;d&#x3c;300.10&#x3c;&#x3b8;gd&#x3c;1.250.10&#x3c;&#x3b8;gF&#x3c;0.60where &#x3bd;d is an Abbe number of the solid material and &#x3b8;gd and &#x3b8;gF represent partial dispersion ratios of the solid material. The refractive optical element made of the solid material has refractive power with a sign opposite to a sign of refractive power of the lens unit including the refractive optical element.

Optical system

There are provided a zoom lens system comprising, in order from a more distant conjugate point, a first lens unit of a negative refractive power, a second lens unit of negative refractive power which moves during zooming, third, fourth and fifth lens units, and at least one diffraction optical element.

Zoom lens system, image projecting and image pick-up devices using the same

A zoom lens system which allows a reduction in size. This zoom lens makes two points at different distances have an optically conjugate relationship, and sequentially includes, from a first conjugate point side at a longer distance to a second conjugate point side at a shorter distance, a first lens unit having a negative optical power, a second lens unit, a third lens unit, a fourth lens unit, a fifth lens unit, and a sixth lens unit. A plurality of lens units of the first to sixth lens units move for zooming, and at least one lens unit of the first to sixth lens units has a diffractive optical element.

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Saitama, Japan

Hiroto Yasui