Spatial Light Modulation for Temporal Waveform Shaping in Focused Pulsed Light
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Solution Overview
Problem
Conventional simultaneous spatial and temporal focusing (SSTF) techniques have limited freedom in adjusting the temporal waveform of pulsed light in the focusing region due to aberration and wavelength dispersion, making it difficult to achieve the desired temporal waveform.
Innovation Solution
A light irradiation apparatus and method that uses a dispersive element to disperse pulsed light, a spatial light modulator to modulate the phase or intensity spectrum, and a focusing element to focus the light on a common region, with the spatial light modulator compensating for wavelength dependency and aberration to achieve high flexibility in temporal waveform adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional SSTF is used to focus pulsed light, then light energy density increases in the focusing region, but the degree of freedom for adjusting temporal waveform is low due to optical path aberration and wavelength dispersion
Solution Approach 1:
A spatial light modulator is introduced as an intermediary device between the dispersive element and focusing element. This modulator can independently control the phase and/or amplitude of each wavelength component, serving as a mediator that compensates for optical path differences and enables precise temporal waveform shaping without being constrained by traditional optical aberrations
Solution Approach 2:
The patent changes the control parameters from simple mechanical adjustment of dispersive elements to electronic control of spatial light modulator pixels. By independently modulating the phase and amplitude parameters for each wavelength component through the SLM, the system achieves high-degree freedom in temporal waveform adjustment while compensating for wavelength dispersion and optical path variations
2Ease of operation
If dispersive element is used to disperse light by wavelength, then temporal waveform can be adjusted, but light energy density decreases in the optical path before reaching the focusing region
Solution Approach 1:
The spatial light modulator applies local quality control by independently modulating each wavelength component's phase and amplitude at specific spatial locations. This allows energy to be concentrated precisely where needed in the optical path while maintaining low energy density elsewhere, achieving both temporal waveform control and energy efficiency
3Power
If multiple wavelengths are focused through different optical paths, then light energy density increases in the focusing region, but aberration and wavelength dispersion affect temporal waveform accuracy
Solution Approach 1:
The spatial light modulator acts as a compensatory intermediary that measures and corrects optical path differences for each wavelength component. By introducing controllable phase and amplitude modulation through the SLM, the system compensates for aberrations and wavelength dispersion effects, maintaining temporal waveform precision even when multiple wavelengths are focused through different paths
Solution Approach 2:
The system implements feedback control by using the spatial light modulator to actively compensate for measured optical path differences and aberrations. The SLM adjusts phase and amplitude parameters based on feedback about actual optical conditions, ensuring accurate temporal waveform formation despite variations in optical paths for different wavelengths
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 allows for high freedom in adjusting the temporal waveform of pulsed light in the focusing region, enabling the realization of desired waveforms and reducing light energy density outside the focus, thus minimizing object influence while enabling precise processing.
Implementation Method 1
pulsed light output from the light source is dispersed by a dispersive element, and is output to an optical path different according to a wavelength
Implementation Method 2
the light of each wavelength output from the spatial light modulator is focused on a common region via the optical path different according to the wavelength, by the focusing element
Data Source
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AI summary
A light irradiation apparatus 1A includes a light source 10, a dispersive element 20, a spatial light modulator 30, and a focusing element 50. The dispersive element 20 disperses pulsed light output from the light source 10 and outputs the light. The dispersive element 20 includes, for example, prisms 21 and 22. The spatial light modulator 30 modulates a phase spectrum or an intensity spectrum of the light output from the dispersive element 20 and outputs the light. The focusing element 50 receives the light output from the spatial light modulator 30 in a dispersing state, and focuses the light on a common region (focusing region) in a surface or an inside of an object 9. As a result, a light irradiation apparatus in which a degree of freedom for adjustment of a temporal waveform of the pulsed light in the focusing region is high and a desired temporal waveform can be easily realized is realized.