Machining Mold for Microlens Array with Variable Azimuth Angle
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Solution Overview
Problem
Conventional methods of machining molds for microlens arrays suffer from significant form errors, particularly around the central axis, leading to variance in illuminance when used in optical applications.
Innovation Solution
A method of machining a mold for a microlens array involves defining an xyz orthogonal coordinate system and adjusting the angles θ and ϕ to distribute form errors uniformly across the mold surfaces, thereby reducing variance in illuminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional machining methods are used with a rotating cutting tool, then the mold surfaces can be machined, but form errors appear particularly at positions machined by the central axis portion of the cutting tool due to disagreement between the central axis and rotation axis
Solution Approach 1:
The invention changes the machining parameters by varying the tilt angle θ and azimuth angle φ of the cutting tool relative to the mold surface normal. By adjusting these angular parameters during machining, the method compensates for form errors that would otherwise occur at specific positions, particularly around the central axis region where conventional fixed-angle machining produces the greatest deviations.
2Device complexity
If the same angle φ is used for all surfaces, then the machining process is simple, but form error at specific positions accumulates across multiple microlens surfaces
Solution Approach 1:
The invention applies local quality by assigning different azimuth angles φ to different microlens surfaces based on their positional characteristics. Rather than using a uniform angle for all surfaces, the method selectively varies the angle φ for surfaces located at different positions in the array, thereby distributing and reducing form error accumulation across the entire microlens array while maintaining manageable process complexity.
3Ease of manufacture
If conventional machining methods are used, then molds can be produced, but variance in illuminance on the illuminated surface becomes relatively great due to accumulated form errors
Solution Approach 1:
The invention varies the machining parameters (tilt angle θ and azimuth angle φ) according to the positional coordinates of each microlens surface. This parameter variation strategy directly addresses the illuminance variance problem by compensating for position-dependent form errors, thereby producing molds that generate more uniform illuminance distributions on illuminated surfaces while maintaining ease of manufacture through systematic parameter control.
Data Source
AI summary
A method of machining a mold for a microlens array, wherein for a surface of the mold corresponding to a microlens surface, an xyz coordinate system is defined such that a z-axis is parallel to the central axis of the surface, an angle φ is defined as an angle around a straight line passing through a point on the rotation axis and parallel to the z-axis, of a plane containing the rotation axis of a cutting tool and the straight line, in machining of a surface of the mold, the angle φ is kept constant and in machining of the surfaces of the mold, values of the angle φ for the surfaces of the mold are distributed so as to make variance of the values of the angle φ greater than a predetermined value.