Dual-wavelength imaging is used in several scientific and practical applications. One of the most common applications is
dual-wavelength thermography which has many advantages over single wavelength thermal imaging. Optical imagesplitters
can be used to turn any imaging equipment into a dual-wavelength imaging system. In this paper, a new design
of an image-splitting optic, for use in dual-wavelength imaging, is presented. The new design evades the limitations
encountered with the basic image-splitter design where images can be captured at higher resolutions and frame rates. The
new design also facilitates the adjustment of the image magnification. With very minor changes in the optical
components, the image-splitter can be used in different thermal imaging techniques such as Infrared (IR) imaging and
Laser Induced Fluorescence (LIF) imaging or any other technique that utilizes dual-wavelength imaging. Furthermore,
with some modifications in the optical path, the image splitter can be used for imaging
Multi-channel gated-intensified cameras are commonly used for capturing images at ultra-high frame rates. However, the image intensifier reduces the image resolution to such an extent that the images are often unsuitable for applications requiring high quality images, such as digital image correlation. We report on the development of a new type of non-intensified multi-channel camera system that permits recording of image sequences at ultra-high frame rates at the native resolution afforded by the imaging optics and the cameras used. This camera system is based upon the use of short duration light pulses of different wavelengths for illumination of the target and the use of wavelength selective elements in the imaging system to route each particular wavelength of light to a particular camera. A prototype of this camera system comprising four dual-frame cameras synchronized with four dual-cavity lasers producing laser pulses of four different wavelengths is described. The camera is built around a stereo microscope such that it can capture image sequences usable for 2D or 3D digital image correlation. The camera described herein is capable of capturing images at frame rates exceeding 100 MHz. The camera was used for capturing microscopic images of the chip-workpiece interface area during high speed machining. Digital image correlation was performed on the obtained images to map the shear strain rate in the primary-shear-zone during high speed machining.
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