Concave Diffraction Grating Structure for Thermal Shape Stability
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Solution Overview
Problem
Conventional diffraction gratings face issues with deformation and deterioration of optical characteristics due to temperature and humidity, particularly when a reflection film is affixed to a resin substrate, and when a metal film is coated on grating grooves, leading to rounded tops and compromised performance.
Innovation Solution
A concave diffraction grating design featuring a holding film made of metal with a reflection film, affixed to a concave substrate via an affixing layer, which maintains the shape and optical integrity by preventing deformation and heat accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the reflection film is affixed to a resin substrate, then the device configuration can be simplified, but the reflection film deforms when the resin expands and contracts due to temperature and humidity changes
Solution Approach 1:
The patent uses a composite structure consisting of a resin substrate, a reflective film, and a metal holding film. The metal holding film is bonded to both the reflective film and the resin substrate, creating a composite material system that combines the advantages of each material: the resin substrate provides simplicity in device configuration, while the metal holding film provides dimensional stability and prevents deformation of the reflective film due to thermal and humidity expansion of the resin.
2Reliability
If the reflection film is coated on the surface of grating grooves, then the reflection film is resistant to temperature and humidity changes, but the top of each grating groove becomes rounded, deteriorating optical characteristics
Solution Approach 1:
The patent divides the functional requirements into separate components: the metal holding film provides thermal and humidity stability, while the reflective film is deposited only on the grating groove surfaces to maintain precise optical shapes. The holding film acts as a stable substrate that doesn't interfere with the precise formation of grating groove tops, allowing each component to fulfill its specific function without compromising the other.
Solution Approach 2:
The metal holding film serves as an intermediary layer between the resin substrate and the reflective film. It provides a stable, dimensionally invariant surface that supports the reflective film without transmitting thermal or humidity-induced deformations to it, thereby preventing rounding of the grating groove tops while maintaining the reflective film's resistance to environmental changes.
3Device complexity
If the reflection film is disposed on a resin, then the device configuration can be simplified, but the reflection film deforms affecting optical characteristics
Solution Approach 1:
The patent creates a composite structure where a metal holding film is bonded between the resin substrate and the reflective film. This composite material system allows the device to maintain simplified configuration using a resin substrate while the metal holding film provides dimensional stability that prevents deformation of the reflective film, thereby preserving optical characteristics.
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 design prevents deformation of the reflection film due to temperature and humidity, maintains optical characteristics, and effectively dissipates heat, ensuring stable spectral performance.
Implementation Method 1
an affixing layer that is provided between the concave surface and the other surface of the holding film and affixes the holding film and the reflection film to the concave substrate
Implementation Method 2
a holding film formed of metal... effectively dissipates heat, ensuring stable spectral performance
Implementation Method 3
a concave diffraction grating... has a function of dispersing and condensing light for each wavelength
Data Source
AI summary
The present invention provides a concave diffraction grating and an optical device using the concave diffraction grating, the concave diffraction grating being capable of preventing deformation of a reflection film due to the influence of temperature, and preventing deterioration in optical characteristic due to temperature. This concave diffraction grating is provided with: a reflection film (22) having a plurality of grating grooves (21); a holding film (25) comprising metal and having one surface on which the reflection film (22) is provided; a concave substrate (24) having a concave surface (24a); and an affixing layer (23) provided between the concave surface (24a) and the other surface of the holding film (25), and affixing the holding film (25) and the reflection film (22) to the concave substrate (24).