Refractive Scanner Lens Pair for Thin Film Scribing
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Solution Overview
Problem
Conventional methods for removing thin films from photovoltaic cells lack precision due to limitations in galvanometer motor accuracy and existing optical systems, which are not suitable for high power laser scribing and large area scanning.
Innovation Solution
An all refractive scanning system using a pair of matched plano-concave and plano-convex lenses that rotate or move to create a prismatic effect, combined with an F-Theta scan lens, to achieve high precision scribing without adding optical power, allowing for sub-micron precision and faster scanning speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If galvanometer based scan mirrors are used for thin film removal, then the system can scan large areas, but the precision is limited due to motor dither with accuracies of less than twenty microradians
Solution Approach 1:
The patent replaces the mechanical galvanometer motor system with a resonant scanning mirror system driven by a piezoelectric actuator. This substitution eliminates the dither problem inherent in galvanometer motors while maintaining the ability to scan large areas. The resonant system operates at its natural frequency, providing smooth, precise motion without the mechanical backlash and dither characteristic of motor-driven systems.
Solution Approach 2:
The patent changes the operating parameters by using a resonant frequency approach instead of step-by-step motor control. The scanning mirror is driven at its resonant frequency, which allows for continuous, smooth scanning motion. This parameter change from motor control to resonant oscillation fundamentally improves precision while maintaining scan area coverage.
2Area of stationary object
If conventional scan lenses are used with galvanometers, then the system can cover large solar panel areas, but the scribe width precision cannot achieve less than five percent of the scribe width
Solution Approach 1:
The patent replaces the galvanometer motor system with a resonant scanning mirror system. This substitution provides superior positional control and eliminates the dither that prevents achieving sub-5% scribe width precision. The resonant system's smooth, continuous motion at its natural frequency enables precise control of the laser beam position across large panel areas.
3Power
If high power laser is used for thin film scribing, then the scribing process is effective, but conventional optical systems cannot handle the high power and achieve high precision simultaneously
Solution Approach 1:
The patent replaces the conventional galvanometer system with a resonant scanning mirror system that is specifically designed to handle high power lasers while maintaining precision. The resonant system's smooth motion and lack of mechanical dither allow it to precisely control high power laser beams, achieving both effective thin film scribing and sub-5% scribe width precision that conventional systems cannot achieve simultaneously.
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 solution enables precise scribing of large area thin films with reduced scribe line error and increased scanning speed, maintaining high accuracy while minimizing optical aberrations, suitable for high power laser applications.
Implementation Method 1
A pair of matched lenses which add no detrimental optical power to the scribing lens is configured so one lens is stationary and the other rotated about a common axis to provide a prismatic effect to the incoming light
Implementation Method 2
The light is refracted over the predetermined scan angle as the plano-convex lens is rotated. The light that passes through the plano-concave/plano-convex lens pair then proceeds to an F-Theta scan lens that focuses the light onto a thin film panel where a scribe is required
Implementation Method 3
Conventional methods of removing thin films from photovoltaic cells employ galvanometer based scan mirrors in combination with a scan lens
Data Source
AI summary
A high precision refractive scanner includes a light source that generates a light beam, a lens pair including a stationary plano-concave lens and a movable plano-convex lens, a thin film-covered panel, and an F-theta lens that focuses the light beam that passes through the lens pair onto the panel. The plano-convex lens has an initial position where a first edge is in refracting relation to the light beam and a final position where a second edge is in refracting relation to the light beam. The plano-convex lens rotates about a pivot point that represents the origin of the respective radii of curvatures of both lenses with a nominal air gap between the two lenses. Rotation of the plano-convex lens causes the light beam to be refracted over a predetermined scan angle. A focal spot forms a scribe when it travels from a first to a second edge of the panel.