Opto-ceramic optical elements for compact imaging optics

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Solution Overview

Problem

Current optical materials, such as glasses and polycrystalline ceramics, face limitations in achieving high refractive index, Abbe number, and relative partial dispersion, which are essential for producing compact, lightweight imaging optics with nearly apochromatic behavior, especially in visible and infrared ranges, while maintaining high transparency and resistance to mechanical and thermal influences.

Innovation Solution

Development of opto-ceramics with a single-phase polycrystalline structure based on oxides, specifically zirconium oxide or garnet structures, stabilized by additives like yttrium oxide, which allows for the creation of optical elements with high refractive index, Abbe number, and relative partial dispersion, enabling nearly apochromatic imaging behavior and high transparency across visible and infrared spectra.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional glass or polycrystalline ceramics are used, then manufacturing is easier, but optical quality (refractive index, Abbe number, transparency) is insufficient

Engineering Contradiction:

Improveoptical qualityVSAvoidmanufacturing difficulty

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent uses composite materials by combining crystalline phases (providing high refractive index and Abbe number) with controlled amorphous phases, creating opto-ceramics that achieve superior optical quality. The composite structure allows simultaneous optimization of refractive index (1.8-2.2), Abbe number (30-55), and transparency, which cannot be achieved with conventional single-phase materials.

Inventive Principle:

Principle #40Composite materials

2Volume of moving object

If materials with high refractive index and low dispersion are used, then imaging optics can be made more compact, but material stability decreases

Engineering Contradiction:

Improveoptics sizeVSAvoidmaterial stability

Core Design Contradiction:

Volume of moving objectVSStability of the object's composition

Solution Approach 1:

The patent changes material parameters by developing opto-ceramics with specific refractive indices (1.8-2.2) and Abbe numbers (30-55) that occupy a stable region in the Abbe diagram. This parameter optimization allows compact imaging optics design while maintaining material stability, resolving the contradiction between miniaturization and material reliability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by creating regions with different optical properties within the opto-ceramic material. By controlling the distribution and size of crystallites (1-500 μm) and their optical characteristics, the material achieves both the high refractive index/low dispersion needed for compact optics and the stability required for practical application.

Inventive Principle:

Principle #3Local quality

3Reliability

If single-phase polycrystalline opto-ceramics are used, then optical quality improves, but manufacturing precision requirements increase

Engineering Contradiction:

Improvetransparency and optical uniformityVSAvoiddensity and crystallite uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent utilizes phase transitions in the manufacturing process, controlling the transformation of precursor materials into the final single-phase polycrystalline opto-ceramic structure. By carefully managing sintering temperatures and atmospheres, the process achieves uniform crystallite formation (1-500 μm) and high density (>99% theoretical), meeting both optical quality and manufacturing precision requirements.

Inventive Principle:

Principle #36Phase transitions

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

The opto-ceramics provide optical elements with improved refractive indices, Abbe numbers, and relative partial dispersion, enabling the design of compact, lightweight imaging optics with nearly apochromatic behavior and high transparency, overcoming the limitations of conventional materials in terms of stability and spectral range.

Implementation Method 1

The opto-ceramic has a refractive index nD of between about 1.8 and about 2.2 and an Abbe number νd in the range of between about 35 and 55

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

The optical element may furthermore have a diffractive structure

Methodology Applied

Scientific EffectDiffraction: Diffraction

Data Source

PatentUS7324285B2Optical elements and imaging optics comprising them

Publication Date: 2008.01.29 SCHOTT AG

AI summary

The optical elements are made from an opto-ceramic material that is characterized by high density, transparency for visible light and IR, high refractive index, high Abbe number and outstanding relative partial dispersion. Mixed oxides are sintered to obtain the opto-ceramic material. The mixed oxides contain zirconium oxide and hafnium oxide mixed with one or more oxides of yttrium, scandium, lanthanide elements, and optionally mixed with one or more of SiO2, Na2O, and TiO2. Alternatively the mixed oxides contain zirconium oxide and hafnium oxide mixed with CaO and/or MgO and optionally mixed with one or more of SiO2, Na2O, and TiO2. In addition, the mixed oxides can also include one or more oxides of Al, Ga, In, and Sc; optionally one or more oxides of yttrium, some lanthanide elements; and optionally one or more of SiO2, Na2O, MgO, CaO, and TiO2.