ZnSe Diffraction Grating on ZnS Substrate for Infrared Spectroscopy

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Solution Overview

Problem

Manufacturing diffraction gratings from crystalline materials like ZnS and ZnSe is challenging due to tool wear and achieving precise shape accuracy, especially when processing in the brittle mode, which affects optical performance and efficiency.

Innovation Solution

A diffraction device comprising a ZnS member coupled with a ZnSe member, where the ZnSe member has a diffraction grating formed using a processing apparatus with a diamond tool, minimizing tool wear by operating within the critical cutting thickness and utilizing optical contact bonding or deposition methods for coupling, and incorporating antireflection or reflection films for improved performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If diamond tool is used to process ZnS material in brittle mode, then shape accuracy and surface roughness can be achieved, but tool wear occurs and processing efficiency decreases

Engineering Contradiction:

Improveshape accuracyVSAvoidprocessing efficiency

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent changes the material parameter from ZnS to ZnSe, which has different mechanical properties. ZnSe allows ductility mode processing with larger critical cutting thickness, enabling faster material removal while maintaining shape accuracy and surface quality, thus resolving the contradiction between precision and productivity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies different materials to different functional regions: ZnSe for the diffraction grating surface requiring precision, and ZnS for the body providing infrared transmittance. This local differentiation allows each material to optimize its performance for the specific requirements of that region

Inventive Principle:

Principle #3Local quality

2Duration of action of stationary object

If critical cutting thickness is reduced to prevent tool wear, then tool life increases, but processing time increases significantly due to multiple passes

Engineering Contradiction:

Improvetool lifeVSAvoidprocessing time

Core Design Contradiction:

Duration of action of stationary objectVSLoss of time

Solution Approach 1:

By changing from ZnS to ZnSe material, the critical cutting thickness increases from sub-micrometer to several micrometers. This parameter change allows using larger cutting thickness while maintaining ductility mode, reducing the number of passes needed and thereby reducing total processing time while preserving tool life

Inventive Principle:

Principle #35Parameter changes

3Illumination intensity

If ZnS material is used for the entire diffraction device, then infrared transmittance is improved, but tool wear and processing difficulty increase

Engineering Contradiction:

Improveinfrared transmittanceVSAvoidprocessing difficulty

Core Design Contradiction:

Illumination intensityVSEase of manufacture

Solution Approach 1:

The patent applies ZnS to the body portion where infrared transmittance is critical, and ZnSe to the diffraction grating surface where precision machining is critical. This local quality differentiation allows each material to excel at its specific function, resolving the contradiction between optical performance and manufacturability

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent creates a composite structure combining ZnS and ZnSe materials. The ZnS layer provides infrared transmittance while the ZnSe layer provides ease of precision machining for the diffraction grating, achieving both high transmittance and ease of manufacture through material composition

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 approach enables the production of high-quality diffraction gratings with enhanced optical characteristics, including high transmittance in the infrared range, reducing tool wear and maintaining accuracy, thus improving the efficiency and resolution of spectroscopic apparatuses.

Implementation Method 1

the brittle mode processing face unique to the material tends to be dominant in processing. In order to obtain the shape accuracy, the dimensional accuracy, and the surface roughness required for the diffraction grating, it is necessary to implement the processing under the processing conditions in the ductility mode.

Methodology Applied

Scientific EffectBrittle mode processing: Fracture Mechanics

Implementation Method 2

utilizing optical contact bonding or deposition methods for coupling

Methodology Applied

Scientific EffectOptical contact bonding: Adhesive

Implementation Method 3

A phase diffraction grating is a diffraction grating in which the shape of each grating groove is formed to be a sawtooth shape (blazed shape), a sine wave shape, a rectangular wave shape, or the like to give a phase difference to incident light within one period of the grating

Methodology Applied

Scientific EffectDiffraction: Diffraction