Viscous Flow Structuring of Glass Substrates for Inclined Optical Surfaces
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Solution Overview
Problem
Existing viscous flow processes for producing optical components are limited in creating arbitrarily inclined planar surfaces, such as mirrors or optical prisms, and cannot produce surfaces with inclinations like equiangular or oblique plane-parallel pyramid segments.
Innovation Solution
A method involving a planar substrate with a depression, where the vitreous material is converted into a flowable state and flows over a wetting surface with a line-like edge, allowing for the formation of planar surfaces with controlled inclination and curvature, using techniques like anodic bonding and pressure control in a tempering furnace.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a two-dimensional structural plane is used to define the basic shape of the optical component, then the production process is simple and spherical profiles can be easily produced, but arbitrarily inclined planar surfaces such as mirrors or optical prisms cannot be created
Solution Approach 1:
The invention transitions from using a two-dimensional structural plane to a three-dimensional structured substrate with vertical walls and inclined surfaces. The mold substrate is structured to include vertical walls extending downward from the surface, forming cavities with inclined bottom surfaces. This dimensional extension enables the glass material to form arbitrarily inclined planar surfaces during viscous flow, while maintaining the simplicity of the viscous flow process itself.
2Device complexity
If only physical effects of surface wetting and surface tension are used to form three-dimensional structures, then the process is simple, but surfaces with controlled inclination angles and specific curvature cannot be precisely produced
Solution Approach 1:
The invention prepares the mold substrate in advance with precisely structured vertical walls and inclined surfaces before the viscous flow process. The cavities are pre-formed with specific geometries including inclined bottom surfaces at predetermined angles. When the glass material flows into these pre-structured cavities, it reproduces the precise inclination angles and curvature requirements, combining process simplicity with manufacturing precision.
3Ease of operation
If the glass material flows freely into cavities determined by surface tension, then the process is straightforward, but planar surfaces with specific inclination angles cannot be formed
Solution Approach 1:
The invention introduces a structured mold substrate with vertical walls and inclined surfaces as an intermediary between the simple viscous flow process and the desired complex optical surfaces. The mold substrate acts as a template that guides the freely flowing glass material to form the required planar surfaces with specific inclination angles. The vertical walls and inclined surfaces of the mold cavity mediate the transformation from simple flow to precise geometric formation.
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
Enables the production of flat, non-contact glass surfaces with adjustable inclination angles from 10° to 80° and varied curvature, enhancing optical integration capabilities and allowing for the creation of complex optical components.
Implementation Method 1
the planar substrate made of vitreous material is converted into a viscous, flowable state in the course of a subsequent tempering process, in which at least portions of the flowable vitreous material of the planar substrate flow over the peripheral edge into the depression of the planar substrate
Implementation Method 2
the at least one depression of which has at least one wetting surface which is lower than the surface of the planar substrate and is at least partially delimited by a line-like edge, which at the same time is an edge of a trench structure provided within the depression
Implementation Method 3
The flow process stops as soon as the internal pressure equalizes with the ambient pressure, when the cavity is completely filled if it was previously evacuated, or when the viscosity of the glass material is no longer sufficient for flow. The latter is usually the case when processing glass by lowering the process temperature below a critical temperature value.
Data Source
Figure 1a~1d
Figure 1e~1h
Figure 2a~2d
AI summary
The invention describes a method for structuring a flat substrate composed of glass-type material in the course of a viscous flow process, in which the glass-type flat substrate is joined to a surface of a flat substrate, preferably a semiconductor flat substrate, which has at least one depression bounded by a circumferential edge located in the surface and, in the course of a subsequent tempering process, is changed to a viscous pre-flowing state, in which at least proportions of the free-flowing glass-type material of the flat substrate flow over the circumferential edge into the depression in the flat substrate. The invention is characterized in that a flat substrate is provided of which the at least one depression has at least one wetting surface that is countersunk with respect to the surface of the flat substrate and is at least partly bounded by a line-type edge which, at the same time, is an edge of a trench structure provided within the depression and countersunk with respect to the wetting surface and/or is determined by a discontinuous change in a wetting property for the free-flowing glass-type material that could be assigned to the wetting surface, in that, during the tempering process, the free-flowing glass-type material is brought into contact with the wetting surface in such a way that a wetting front forms along the line-type edge, and in that the tempering process is ended with the formation of a surface of the glass-type material that extends between the wetting front and the circumferential edge without contact with the flat substrate and that encloses a cavity with a sub-region of the depression.