Concave Diffraction Grating Groove Alignment via Intermediary Substrate

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Conventional manufacturing methods for concave diffraction gratings with unevenly spaced grooves face challenges in accurately matching the groove interval and position on a curved substrate, leading to variations in the groove pattern shape and reduced image forming capability.

Innovation Solution

A method involving the formation of alignment marks on both the metal thin film and convex fixing substrate, allowing for precise alignment and matching of the groove interval and curved surface during the fabrication of a master concave diffraction grating, ensuring high accuracy in image forming capability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a soft material is used to form the groove pattern and then transferred to a curved substrate, then the manufacturing process is simplified, but the groove pattern shape varies significantly

Engineering Contradiction:
Improveease of manufactureVSAvoidgroove pattern shape accuracy
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

A rigid intermediate substrate is introduced between the groove pattern formation and final curvature application. The groove pattern is first formed on the rigid substrate, then the entire assembly is curved together, ensuring the groove pattern geometry is preserved while achieving the required curved configuration.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The groove pattern is formed and fixed on the rigid substrate before the curvature is applied. This preliminary formation ensures that the groove geometry is established in a stable, rigid environment where precise dimensional control is possible, before the final curved configuration is achieved.

Inventive Principle:
Principle #10Preliminary action

2Shape

If a plane diffraction grating is transferred to a curved fixing substrate, then the curved diffraction grating is obtained, but the groove interval and position cannot be matched accurately

Engineering Contradiction:
Improvecurved shapeVSAvoidgroove interval and position matching
Core Design Contradiction:
ShapeVSManufacturing precision

Solution Approach 1:

The rigid substrate serves as an intermediary that maintains the groove pattern's geometric integrity during the curvature application process. This allows the groove interval and position to be precisely controlled relative to the curved surface, as the rigid substrate provides a stable reference framework.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The substrate rigidity parameter is changed from flexible/soft to rigid, which fundamentally alters how the groove pattern responds to curvature. This parameter change enables precise maintenance of groove interval and position relationships while achieving the desired curved shape.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If unequal groove intervals are used to achieve high image forming capability, then the image forming performance is improved, but the manufacturing complexity increases

Engineering Contradiction:
Improveimage forming capabilityVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The rigid substrate acts as a stable intermediary that simplifies the manufacturing of unequal groove intervals. Once the groove pattern is formed on the rigid substrate, the entire pattern can be curved as a single unit, reducing the manufacturing complexity compared to forming each groove position independently on a curved surface.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The unequal groove intervals are established in advance on the rigid substrate before curvature is applied. This preliminary arrangement of grooves at precise unequal intervals simplifies the overall manufacturing process, as the complex groove pattern is created in a stable, controllable environment before the final curved configuration is achieved.

Inventive Principle:
Principle #10Preliminary action

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 manufacturing of concave diffraction gratings with high image forming capability by accurately matching the groove interval and curved surface, enhancing the precision and performance of the diffraction grating.

Implementation Method 1

a metal thin film is formed on a plane diffraction grating

Methodology Applied
Scientific EffectElectroplating: Electroplating

Implementation Method 2

an alignment mark forming pattern is formed on a plane diffraction grating

Methodology Applied
Scientific EffectPhotolithography: Photography

Data Source

PatentEP3745166B1Manufacturing method of concave diffrraction grating
Publication Date: 2023.08.09 HITACHI HIGH TECH CORP
  • EP3745166B1 patent drawingFigure 1~1(h)
  • EP3745166B1 patent drawingFigure 2~2(f)
  • EP3745166B1 patent drawingFigure 3A~3B

AI summary

Easy and accurate mating of a groove interval of a groove pattern of a diffraction grating with a position on a convex fixing substrate is enabled. For this purpose, a concave diffraction grating 115 is fabricated by: transferring a groove pattern 103 formed on a plane diffraction grating 101 and having unequal groove intervals onto a metal thin film 105; forming a first alignment mark 109 on a convex surface of a fixing substrate 108 having the convex surface to fix the metal thin film 105; mating a second alignment mark 106 formed on an adhesive surface of the metal thin film 105 with the first alignment mark 109 to perform alignment; bonding the adhesive surface of the metal thin film and the convex surface of the fixing substrate to each other to fabricate a master 110; and transferring a groove pattern of a metal thin film of the master 110.