Acousto-Optic Deflector Thermal Distortion Control
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Solution Overview
Problem
The existing laser working apparatuses face challenges in achieving high accuracy due to thermal distortion in acousto-optic devices caused by continuous RF application, leading to errors in laser beam deflection and non-uniform output, which affects productivity and precision in forming fine holes and grooves on semiconductor wafers.
Innovation Solution
A laser beam irradiation apparatus is designed with a pulse laser beam oscillator, cycle frequency setting means, acousto-optic deflection means, and control means that output a driving pulse signal with a predetermined time width, minimizing the duration of RF application to acousto-optic devices, thereby suppressing thermal distortion and ensuring high accuracy working.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RF is continuously applied to the acousto-optic device for laser beam deflection, then the laser beam can be continuously deflected to perform working, but thermal distortion appears on the acousto-optic device causing deflection angle errors and non-uniform output
Solution Approach 1:
The patent applies periodic pulsed action by outputting driving pulse signals with predetermined time widths to the acousto-optic devices only during the periods when laser beam oscillation and deflection are required. This periodic activation allows the devices to cool down between pulses, preventing thermal distortion while maintaining deflection functionality during active working periods.
Solution Approach 2:
The patent dynamically adjusts the operating state of the acousto-optic devices by switching between active (during laser pulse) and inactive (between pulses) states. This dynamic control optimizes the balance between productivity and precision by activating the devices only when needed for deflection while allowing thermal recovery during idle periods.
2Manufacturing precision
If pulse laser beam is irradiated multiple times on the same position to form fine holes, then high precision holes can be formed, but the workpiece must be moved multiple times reducing productivity
Solution Approach 1:
The patent uses periodic pulsed laser beam irradiation at the same position to accumulate energy and form precise fine holes. By maintaining the workpiece in a fixed position and applying multiple controlled pulses, the system achieves high precision hole formation without requiring repeated workpiece movements, thus improving productivity.
Solution Approach 2:
The patent performs preliminary positioning of the workpiece to the exact target location before initiating multiple pulsed laser irradiations. This preliminary action ensures that all subsequent pulses are delivered to the correct position, enabling precise hole formation without the need for repeated repositioning of the workpiece.
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 effectively eliminates thermal distortion in acousto-optic devices, enabling high accuracy and precise laser beam deflection, improving productivity and precision in forming fine holes and grooves on semiconductor wafers without the need for repeated workpiece movement.
Implementation Method 1
an acousto-optic device configured to deflect the pulse laser beam oscillated from the laser beam oscillation means
Data Source
AI summary
A laser beam irradiation apparatus includes a laser beam oscillation unit including a pulse laser beam oscillator for oscillating a pulse laser beam and a cycle frequency setting unit for setting the cycle frequency, an acousto-optic deflection unit for deflecting the optical axis of the pulse laser beam oscillated from the laser beam oscillation section, and a control unit for controlling the acousto-optic deflection unit. The control unit outputs a driving pulse signal having a predetermined time width including a pulse width of the pulse laser beam oscillated from the pulse laser beam oscillator to the acousto-optic deflection unit based on the cycle frequency setting signal from the cycle frequency setting section.