Telescope Optical System Diffractive Cemented Lens Aberration Correction

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Solution Overview

Problem

Conventional telescope optical systems with diffractive elements fail to adequately correct axial and lateral chromatic aberrations in a balanced manner.

Innovation Solution

The telescope optical system incorporates a combination of diffractive optical elements and cemented lenses, with specific power ratios and configurations in both the objective and eyepiece lens systems, including contact multi-layer diffractive optical elements and cemented lenses with positive and negative refractive powers, to correct axial and lateral chromatic aberrations effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a diffractive optical element is used in the objective lens system and eyepiece lens system, then axial chromatic aberration and lateral chromatic aberration can be reduced, but the aberrations are not sufficiently corrected in a balanced manner

Engineering Contradiction:
Improveaberration correction qualityVSAvoidbalanced correction performance
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent combines a diffractive optical element with a cemented lens containing a negative lens in the eyepiece lens system. The diffractive optical element corrects axial chromatic aberration while the cemented lens with negative lens corrects lateral chromatic aberration, achieving balanced correction of both aberration types simultaneously.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent uses a composite optical system combining different optical elements with distinct properties: a diffractive optical element for axial chromatic aberration correction and a cemented lens system with specific positive and negative lenses for lateral chromatic aberration correction. This composite approach enables balanced aberration correction that neither element could achieve alone.

Inventive Principle:
Principle #40Composite materials

2Manufacturing precision

If conventional cemented lenses are used to correct chromatic aberration, then aberration correction is achieved, but the correction is not sufficient across all wavelength regions

Engineering Contradiction:
Improvechromatic aberration correctionVSAvoidwavelength region coverage
Core Design Contradiction:
Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The patent changes the optical parameters by introducing a diffractive optical element with specific diffraction characteristics that complement the refractive properties of the cemented lenses. This parameter change enables effective aberration correction across a broader wavelength region including visible and near-infrared ranges.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite optical system combining diffractive and refractive elements. The diffractive optical element works in conjunction with the cemented lenses to extend the effective correction range across multiple wavelength regions, achieving both visible and near-infrared correction capability.

Inventive Principle:
Principle #40Composite materials

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration allows for satisfactory correction of axial and lateral chromatic aberrations across a wide wavelength region, enhancing image quality and visual field while maintaining manufacturing efficiency and productivity.

Implementation Method 1

diffractive optical elements having a configuration that is drastically different from conventional optical lenses are used in a variety of optical systems in order to, e.g., reduce various aberrations

Methodology Applied
Scientific EffectDiffraction: Diffraction

Implementation Method 2

The cemented lens generates and cancels out positive and negative aberrations, thereby correcting axial chromatic aberration

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP2579081B1Telescope optical system and optical device provided therewith
Publication Date: 2019.08.07 NIKON CORP
  • EP2579081B1 patent drawingFigure 1
  • EP2579081B1 patent drawingFigure 2
  • EP2579081B1 patent drawingFigure 3

AI summary

A telescope optical system having an objective lens system and an eyepiece lens system; wherein: the objective lens system includes a multi-layer-type diffractive optical element (PFo), and cemented lenses (So1) provided with a lens having positive refractive power and a lens having negative refractive power; the eyepiece lens system includes a multi-layer-type diffractive optical element (PFe), and cemented lenses (Se1) provided with a lens having negative refractive power and a lens having positive refractive power; and the condition represented by: 2 ≤ |(Po/FNO)/{Pe/(θ × m)}| ≤ 15 is satisfied, where Ko represents the power of the objective lens system, Kodoe represents the power of the diffractive optical element (PFo) of the objective lens system, and Po is defined as Po = Kodoe/Ko; Ke represents the power of the eyepiece lens system, Kedoe represents the power of the diffractive optical element (PFe) of the eyepiece lens system, and Pe is defined as Pe = Kedoe/Ke;, and FNO represents the F-number of the objective lens system, e represents the real field of view of the telescope optical system, and m represents the magnification of the telescope optical system.