Optical Element Laminate with Isotropic Layer for Oblique Inspection
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Solution Overview
Problem
Optical elements such as diffraction elements and lenses with optically anisotropic layers have insufficient mechanical strength and are difficult to handle, and their optical characteristics are not accurately inspected when light is incident from an oblique direction.
Innovation Solution
A laminate structure comprising a sticky adhesive layer, an optically isotropic layer, and a first peelable protective layer, where specific retardation relationships and adhesive strengths are established to allow accurate optical characteristic inspection from oblique directions and facilitate easy peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If various members are bonded to the optical element to protect its surface and impart mechanical strength, then mechanical strength is improved, but the optical characteristics cannot be accurately inspected when light is incident from an oblique direction
Solution Approach 1:
An optically isotropic layer is introduced as an intermediary between the optical element and the protective member. This layer has specific optical properties (in-plane retardation Re1 and thickness direction retardation Rth1 satisfying |Rth1| ≤ 0.05×|Re1| and Re1 ≥ 10 nm) that compensate for the optical path differences caused by oblique light incidence, enabling accurate optical characteristic inspection while the protective member provides mechanical strength
Solution Approach 2:
The patent controls specific optical parameters of the optically isotropic layer, namely the in-plane retardation Re1 and thickness direction retardation Rth1, to satisfy specific mathematical relationships. By adjusting these parameters, the layer compensates for optical path differences and enables accurate inspection from oblique directions
2Strength
If a protective layer is bonded to the optical element, then mechanical strength is improved, but the protective layer may interfere with optical inspection
Solution Approach 1:
The optically isotropic layer serves as a mediator that allows optical inspection light to pass through without being significantly affected by the protective member. Its specific retardation properties enable it to compensate for optical path differences, making the protective layer transparent to inspection purposes while maintaining mechanical protection
3Reliability
If the adhesive strength between the protective layer and optically isotropic layer is too strong, then bonding reliability is improved, but peeling difficulty increases
Solution Approach 1:
The patent creates different adhesive strength characteristics at different interfaces: the interface between the optically isotropic layer and the protective member has strong bonding (adhesive strength ≥ 1.0 N/25mm) for reliability, while the interface between the optically isotropic layer and the optical element has weak bonding for easy peeling. This spatial differentiation of adhesive properties resolves the contradiction
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 laminate structure enhances mechanical strength and enables accurate optical characteristic inspection of optical elements even when light is incident from an oblique direction, while allowing easy peeling of protective layers.
Implementation Method 1
an in-plane retardation Re1(550) of the optically isotropic layer at a wavelength of 550 nm and a thickness direction retardation Rth1(550) of the optically isotropic layer at a wavelength of 550 nm satisfy a relationship of expressions (1A) and (1B)
Data Source
AI summary
The present invention provides a laminate in which optical characteristics of an optical element can be accurately inspected even in a case where inspection light is incident from an oblique direction with respect to a bonded body obtained by bonding the optical element; and an optical element-containing laminate. The laminate of the present invention includes a sticky adhesive layer, an optically isotropic layer, and a first peelable protective layer in this order, in which an in-plane retardation Re1(550) of the optically isotropic layer at a wavelength of 550 nm and a thickness direction retardation Rth1(550) of the optically isotropic layer at a wavelength of 550 nm satisfy a predetermined relationship, and an in-plane retardation Re2(550) of the first peelable protective layer at a wavelength of 550 nm and a thickness direction retardation Rth2(550) of the first peelable protective layer at a wavelength of 550 nm satisfy a predetermined relationship.