Ultrafast Imaging Optics Using Wavelength-Time Segmentation
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Solution Overview
Problem
Conventional high-speed cameras have limited optical resolution, making it difficult to sufficiently verify mechanisms such as machining marks or crack propagation, which requires an ultrafast imaging apparatus with higher resolution.
Innovation Solution
An ultrafast imaging apparatus featuring a chuck table, an imaging unit with an objective lens, beam splitter, image processing unit, and illumination unit using a broadband pulsed light source and spectrometer to divide light into multiple wavelengths, producing a time lag between them, allowing for the capture of images at 10 ns intervals with high resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional high-speed cameras are used, then the device complexity is low, but the measurement precision is limited to several tens thousands of frames/sec
Solution Approach 1:
The broadband pulsed light is segmented into multiple wavelength components by the diffraction grating, with each wavelength corresponding to a specific time point. This segmentation allows simultaneous capture of multiple time points in a single exposure, achieving ultrafast temporal resolution without requiring extremely high frame rates from the camera.
Solution Approach 2:
A dispersive element (diffraction grating) is introduced as an intermediary between the object and the image sensor. This grating spatially separates different wavelengths of light, creating a spectrum across the sensor plane where each spatial position corresponds to a specific wavelength and thus a specific time point in the ultrafast process.
2Productivity
If the cutting blade rpm is increased to 30,000 rpm for high-speed cutting, then the productivity is improved, but the measurement precision of the cutting mechanism becomes insufficient with conventional cameras
Solution Approach 1:
The system uses periodic pulsed illumination at ultrafast time intervals (e.g., 10 ns between wavelengths) to capture the periodic rotation of the high-speed cutting blade. Each pulse illuminates the blade at a specific rotational position, and the diffraction grating disperses the reflected light by wavelength, allowing reconstruction of the blade's motion through the high-speed process.
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
Enables the capture of ultrafast images at 10 ns/sec, providing a resolution of one one-hundred-millionth, allowing for precise verification of high-speed processes like machining mark formation and crack propagation.
Implementation Method 1
a spectrometer configured to divide a single pulse of light, which has been emitted from the broadband pulsed light source, into a plurality of wavelengths and to produce a time lag between each two adjacent ones of the plurality of wavelengths
Implementation Method 2
a diffraction grating configured to divide and diffract return light, which has been reflected by the workpiece supported on the chuck table after application of illumination light onto the workpiece with the time lag from the illumination unit, at different angles according to the wavelengths
Data Source
AI summary
An imaging unit for an ultrafast imaging apparatus includes an objective lens opposing a workpiece supported on a chuck table, a beam splitter disposed in a first optical path extending from the objective lens, an image processing unit disposed in a second optical path extending from the beam splitter, and an illumination unit disposed in a third optical path extending from the beam splitter. The illumination unit includes a broadband pulsed light source, and a spectrometer configured to divide a single pulse of light, which has been emitted from the broadband pulsed light source, into a plurality of wavelengths and to produce a time lag between each two adjacent ones of the plurality of wavelengths.