Objective optical system for endoscopes
First Claim
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1. An objective optical system for endoscopes comprising:
- in order from the object side, a first lens component being a negative meniscus lens, an aperture stop, a second lens component being a positive lens component, a third lens component being a positive lens component and a fourth lens component being a positive cemented doublet;
wherein an object side surface of said first lens component and an image side surface of said third lens component are aspherical surfaces.
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Abstract
An objective optical system for endoscopes consisting, in the order from the object side, of a front lens unit having negative refractive power, an aperture stop and a rear lens unit having positive refractive power and comprising at least one aspherical surface in each of said lens units. This objective optical system for endoscopes has distortion of a small absolute value, a distortion curve of natural shapes, favorably corrected aberrations, and is composed of lens elements easily manufacturable.
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Citations
7 Claims
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1. An objective optical system for endoscopes comprising:
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in order from the object side, a first lens component being a negative meniscus lens, an aperture stop, a second lens component being a positive lens component, a third lens component being a positive lens component and a fourth lens component being a positive cemented doublet; wherein an object side surface of said first lens component and an image side surface of said third lens component are aspherical surfaces. - View Dependent Claims (7)
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2. An objective optical system for endoscopes comprising:
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in order from the object side, a first lens component being a negative meniscus lens, a second lens component being a cemented doublet, an aperture stop, a third lens component being a positive cemented doublet and a fourth lens component being a positive lens component; wherein an object side surface of said first lens component and an image side surface of said fourth lens component are aspherical surfaces.
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3. An objective optical system for endoscopes comprising:
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in order from the object side, a first lens component being a negative meniscus lens, a second lens component being a cemented doublet, an aperture stop, a third lens component being a positive lens component, a fourth lens component being a positive lens component and a fifth lens component being a positive cemented doublet; wherein an object side surface of said first lens component and an image side surface of said fourth lens component are aspherical surfaces.
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4. An objective optical system for endoscopes comprising:
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in order from the object side, a first lens component being a negative meniscus lens, an aperture stop, a second lens component being a positive cemented doublet, a third lens component being a positive lens component and a fourth lens component being a positive cemented doublet; wherein an object side surface of said first lens component and an image side surface of said third lens component are aspherical surfaces.
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5. An objective lens system for endoscopes comprising:
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in order from the object side, a first lens component being a negative meniscus lens, a second lens component being a cemented doublet, and aperture stop, a third lens component being a positive cemented doublet, a fourth lens component being a positive lens and a fifth lens component being a positive cemented doublet; wherein an object side surface of said first lens component and an image side surface of said fourth lens component are aspherical surfaces.
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6. An objective optical system for endoscopes comprising:
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in order from the object side, a first lens component being a negative meniscus lens, an aperture stop, a second lens component being a positive lens component, a third lens component being a positive cemented doublet and a fourth lens component being a positive cemented doublet; wherein an object side surface of said first lens component and an object side surface of said fourth lens component are aspherical surfaces.
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Specification