Stop-action Images Research Articles

Low-Cost Optical Measurement for Micro-Displacement with High Accuracy

Micro-displacement measurement with high accuracy plays a vital role in micro/nano manufacturing technology. In this paper, three low-cost techniques for micro-displacement measurement with high accuracy are discussed, and they are the methods based on DVD optical head, burred images and stop-action images. The techniques based on the DVD optical head and burred images are very attractive for many applications where the low cost is indispensable, and the method based on stop-action images has also better performance when measuring the static micro-displacement. Then, an application based on the stop-action images approach is given, and this method can measure the micro-displacement with nanometer accuracy. In addition, these discussions show that the methods based on the DVD optical head and burred images are a possible direction for low-cost micro-displacement measurement with high accuracy.

Advances in Comparative Physiology from High-Speed Imaging of Animal and Fluid Motion

Since the time of Muybridge and Marey in the last half of the nineteenth century, studies of animal movement have relied on some form of high-speed or stop-action imaging to permit analysis of appendage and body motion. In the past ten years, the advent of megapixel-resolution high-speed digital imaging with maximal framing rates of 250 to 100,000 images per second has allowed new views of musculoskeletal function in comparative physiology that now extend to imaging flow around moving animals and the calculation of fluid forces produced by animals moving in fluids. In particular, the technique of digital particle image velocimetry (DPIV) has revolutionized our ability to understand how moving animals generate fluid forces and propel themselves through air and water. DPIV algorithms generate a matrix of velocity vectors through the use of image cross-correlation, which can then be used to calculate the force exerted on the fluid as well as locomotor work and power. DPIV algorithms can also be applied to images of moving animals to calculate the velocity of different regions of the moving animal, providing a much more detailed picture of animal motion than can traditional digitizing methods. Although three-dimensional measurement of animal motion is now routine, in the near future model-based kinematic reconstructions and volumetric analyses of animal-generated fluid flow patterns will provide the next step in imaging animal biomechanics and physiology.

Computer Microvision for MEMS

Abstract Computer Microvision is a microscopy technique originally developed to study sound-induced motions of sensory cells in the inner ear - motions that are on the order of picometers-i.e., smaller than the radius of a hydrogen atom. Three-dimensional micrornovies of inner ear cells moving in response to sound were analyzed to quantify motions with nanometer precision. Recently we have adapted the technique for in situ measurement of motions of micro-electron mechanical (MEMS) devices. In Computer Microvision systems, images of MEMS are magnified with an optical microscope and projected onto a CCD camera. Stroboscopic illumination is used to obtain stopaction images of the moving structures. Stop-action images from multiple focal planes provide information about 3D structure and 3D motion. Image analysis algorithms determine motions of all visible structures with nanometer accuracy. The system can measure motions at frequencies as high as 5 MHz with nanometer resolution, i.e., well below the wavelength of light.

Computer Microvision for MEMS

AbstractWe have developed a versatile instrument for in situ measurement of motions of MEMS. Images of MEMS are magnified with an optical microscope and projected onto a CCD camera. Stroboscopic illumination is used to obtain stop-action images of the moving structures. Stopaction images from multiple focal planes provide information about 3D structure and 3D motion. Image analysis algorithms determine motions of all visible structures with nanometer accuracy.Hardware for the system includes the microscope, CCD camera and associated frame grabber, piezoelectric focusing element, and a modular stimulator that generates arbitrary periodic waveforms and synchronized stroboscopic illumination. These elements are controlled from a Pentium-based computer using a graphical user interface that guides the user through both data collection and data analysis. The system can measure motions at frequencies as high as 5 MHz with nanometer resolution, i.e., well below the wavelength of light.

Using a light microscope to measure motions with nanometer accuracy

A system for measuring nanometer motions of microscopic structures is demonstrated. Stop-action images of a target are obtained with a light microscope, CCD camera, and stroboscopic illuminator. Mo- tions are determined directly from measured images using algorithms from computer vision. The accuracy of motion measurements using the system is assessed using a moving target with calibrated displacements. Accuracy is determined for specimens viewed under our most optimal conditions as well as for a number of suboptimal conditions that illustrate important degradation mechanisms. Measured errors are compared to predictions based on computer simulations of theoretical models. Re- sults show that the most important hardware factors include substrate vibrations and camera imperfections. Measurement errors for the most optimal hardware conditions are primarily due to systematic bias in the computer vision algorithms. For our most optimal conditions, the system can resolve motions as small as nanometers. Thus, errors in motion measurements are small compared to both the wavelength of the light used to obtain the images and the pixel spacing of the video microscope. © 1998 Society of Photo-Optical Instrumentation Engineers. (S0091-3286(98)03904-X) Subject terms: video microscopy; stroboscopic illumination; motion measure- ment; fixed-pattern noise; shot noise; substrate vibration.

Mixed light imaging system for recording bioluminescence behaviours

Video recordings of bioluminescence have depended on the use of image-intensified systems, which generally suffer from poor resolution and image persistence. These characteristics, coupled with the restriction that any illumination must be dimmer than the bioluminescence, have complicated efforts to record behaviours associated with bioluminescent displays. The Mixed Light Imaging System (Mlis), described here, uses (1) an intensified video camera, (2) an infra-red (IR) sensitive video camera (3) a dichroic beam splitter, (4) strobed IR illumination and (5) a video mixer to record stop-action images of organisms superimposed on intensified images of their bioluminescence. With the MLIS, behaviours associated with bioluminescent emissions, including rapid escape responses, were recorded from the mesopelagic copepods Euaugaptilus magnus and Gaussia princeps.

Soft x-ray microscopes

Recent advances in sources, optics, and detectors for soft x rays have led to rapid developments in applications to microscopy. The history of the field and the advantages of soft x rays for the examination of biological specimens are briefly described. Limitations in resolution and radiation induced damage are mentioned before embarking on a survey of the various approaches in use. Contact microscopy is the highest resolution technique available today. It is particularly powerful when used with flash sources for stop-action imaging. Imaging with Fresnel zone plates provides direct magnification, high resolution, and short exposure times. Scanning microscopy leads naturally to digitally recorded images, with minimal radiation exposure to the specimen. The focused beam for scanning can be generated with multilayer mirrors, or with zone plates. This last approach is treated in greater detail. Extensions of soft x-ray imaging to three dimensions, and to elemental mapping, are considered as important areas under active development.

A method for stop-action imaging of the heart using gated computed tomography.

A new method for the reconstruction of limited angle projection data in rotary fan-beam X-ray computed tomography (CT) is presented. Missing views resulting from ECG-gated cardiac CT are estimated, and the standard fan-beam reconstruction algorithm is used to convolve and backproject both measured and estimated views. The estimation of the missing views takes place in three stages: first, the projection data is augmented by incorporating into each missing view the line integrals that do not pass through the heart, and which otherwise would be considered missing due to ECG-gating; second, line integrals corresponding to source positions in the range 180°±fan angle away from missing view angles are reflected; third, those line integrals that remain missing are estimated by interpolation. This method has been applied to ECG-gated cardiac imaging in dogs without requiring extensive interpolation; end-systolic and end-diastolic images were generated with short-interval gating (?cycle) and total scan time (breath holding period) of 12 s. An important advantage of this method over other proposed limited angle reconstruction techniques is that it uses the existing fan-beam convolution-backprojection algorithm for image reconstruction.

Cardiovascular and pulmonary dynamics by quantitative imaging.

The accuracy and range of studies on cardiovascular and pulmonary functions can be greatly facilitated if the motions of the underlying organ systems throughout individual cycles can be directly visualized and readily measured with minimum or preferably no effect on these motions. Achievement of this objective requires development of techniques for quantitative noninvasive or minimally invasive dynamic and stop-action imaging of the organ systems. A review of advances in dynamic quantitative imaging of moving organs reveals that the revolutionary value of cross-sectional and three-dimensional images produced by various types of radiant energy such as X-rays and gamma rays, positrons, electrons, protons, light, and ultrasound for clinical diagnostic and biomedical research applications is just beginning to be realized. The fabrication of a clinically useful cross-section reconstruction device with sensing capabilities for both anatomical structural composition and chemical composition may be possible and awaits future development.