High numerical aperture and long working distance objective system using diffraction-type optical elements
First Claim
1. An objective system comprising:
- a first diffraction type of optical element having a diffraction action;
a second diffraction type of optical element located at an image side of said first diffraction type of optical element; and
at least one cemented lens having a cemented surface, wherein said at least one cemented lens is located between said first and second diffraction type of optical elements.
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Abstract
The invention provides a high-magnification and high-NA objective having a long working distance, which is corrected for various aberrations, especially chromatic aberrations over a wide wavelength range and allowed to have an aligning pupil position without making much use of cemented lenses and anomalous dispersion glass. The objective comprises a first lens group G1 including a meniscus lens concave on the object side and having a positive power as a whole, two optical elements of the diffraction type (DOEs), and a second lens group G2 including at least one cemented lens, and satisfies the condition for ensuring the edge thickness of the front lens as well as either one of two conditions for making effective correction for longitudinal chromatic aberration and chromatic aberration of magnification.
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Citations
15 Claims
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1. An objective system comprising:
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a first diffraction type of optical element having a diffraction action; a second diffraction type of optical element located at an image side of said first diffraction type of optical element; and at least one cemented lens having a cemented surface, wherein said at least one cemented lens is located between said first and second diffraction type of optical elements. - View Dependent Claims (2, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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4. An objective system comprising, in order from an object side:
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a first lens group including a meniscus lens concave on the object side, said first lens group having a positive power as a whole; a first diffraction type of optical element having a diffraction action; and a second lens group divided into a front sub-group including at least one cemented lens having a cemented surface and a rear sub-group having at least one lens, wherein a second diffraction type of optical element is located between said front sub-group and said rear sub-group.
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Specification