Laser Device Pulse Timing Control for Stable Switching
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Solution Overview
Problem
Conventional laser devices face challenges in achieving high-speed and stable switching of output light due to time constants in high-frequency circuits, leading to unstable emission of short pulse lights, particularly in semiconductor lasers and EO intensity modulators, which affects precision in applications like exposure and inspection devices.
Innovation Solution
A laser device comprising a laser light source generating a pulse waveform, an intensity modulator driven by a transmittance waveform that changes at a predetermined frequency, and a control unit that adjusts the relative timing of the transmittance waveform to output a pulse light with specific waveforms, enabling high-speed and stable switching by differing peak intensities, wavelengths, and polarization states at the wavelength conversion optical element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high-frequency circuits are used for rapid switching of laser output, then switching speed is improved, but stability deteriorates due to time constants causing unstable emission
Solution Approach 1:
The patent applies preliminary action by continuously outputting pulse lights from the laser light source at a predetermined frequency before switching is needed. This maintains the laser in a ready state, allowing rapid switching between high and low wavelength conversion efficiencies without requiring the laser to be turned on/off, thus avoiding stability issues from high-frequency circuit time constants while achieving fast switching response
2Power
If pulse duration is shortened to achieve high peak power, then wavelength conversion efficiency is improved, but circuit response time becomes insufficient
Solution Approach 1:
The patent applies parameter changes by varying the pulse duration and peak power of the laser light source to optimize wavelength conversion efficiency. By continuously outputting pulses with adjusted parameters and controlling the timing relative to the intensity modulator, the system achieves high peak power for efficient wavelength conversion while maintaining adequate pulse duration for circuit response
3Ease of operation
If intensity modulator is used to extract laser light, then light emission control is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by having the laser light source continuously output pulse lights that serve multiple functions: maintaining amplifier inversion, providing timing reference for switching, and enabling wavelength conversion control. The intensity modulator and control unit work together to achieve light emission control by adjusting the relative timing between continuous pulses and the modulator's transmittance waveform, reducing the need for separate control mechanisms
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
This configuration allows for high-speed and stable on/off operation of output light, improving the precision and accuracy of exposure and inspection devices by maintaining constant amplifier states and optimizing wavelength conversion efficiencies.
Implementation Method 1
a wavelength conversion optical element which converts the wavelength of the laser light which is amplified by the amplifier
Implementation Method 2
an intensity modulator which extracts and emits the laser light which is outputted from the laser light source
Data Source
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AI summary
A laser device includes: a laser light source which generates a laser light in a pulse waveform of a preset predetermined frequency; an intensity modulator which is driven with a transmittance waveform wherein transmittance changes at either the predetermined frequency or an integer-multiple frequency thereof and which extracts and outputs the laser light which is outputted from the laser light source; a control unit which controls an operation of the intensity modulator; an amplifier which amplifies the laser light which is outputted from the intensity modulator; and a wavelength conversion optical element which converts a wavelength of the laser light which is amplified by the amplifier, wherein the control unit changes relative timing of the transmittance waveform with respect to the pulse waveform, thereby changing the pulse waveform of the laser light which is emitted from the intensity modulator, to output a pulse light of a predetermined waveform from the wavelength conversion optical element.