In some manufacturing applications the alignment of fine structures formed on the surface of a part such as micro-scribed patterns on solar panels can be critical to the panel performance. Variations in pattern uniformity may degrade the efficiency of the solar panel if the pattern deviates significantly from designed parameters. This paper will explore the use of moire patterns to interpret the angular alignment of such structures on 3 dimensional non-planar shapes. The moire interferometry pattern creates a beat between the scribed pattern and a reference pattern that is a function of both the shape of the part as well as the shape of the scribed pattern. Both the part shape variations and the patterns of interest are typically much smaller than can be seen visually. Similar challenges exist when inspecting specular models or testing low quality optics. The moire effect allows small displacements to be measured from patterns that are well below the resolution of the camera systems that are used to view the patterns. Issues such as the separation of the shape of the part from the alignment of the fine structure as well as resolution and robustness of the technique will be explored in this paper.
Characterization of a surface shape and finish has been vital for the manufacture of precision parts. Overall profile, surface finish and waviness of a part can be measured in two ways, contact and non-contact. In the contact method a stylus is dragged on the surface of a part to measure the profile and texture of the part for quantifying the surface characteristics. Non-contact methods applied z precision metrology include: microscopy, interferometry, chromatic confocal microscopy and laser profiling such as structured light methods. The chromatic confocal method offers flexibility because of its fiber optics probes that can be manipulated to accommodate many sample geometries. This flexibility provides a wide range of possible analysis dimensions such as cylindrical shapes of holes and the potential to provide both surface roughness and shape. This paper will discuss the setup and testing of a system specifically for measuring cylindrical shaped parts and present the performance of the technology as a precision metrology tool.
There are many visual inspection and sensing applications where both a high resolution image and a depth-map of the
imaged object are desirable at high speed. Presently available methods to capture 3D data (stereo cameras and structured
illumination), are limited in speed, complexity, and transverse resolution. Additionally these techniques rely on a
separated baseline for triangulation, precluding use in confined spaces. Typically, off the shelf lenses are implemented
where performance in resolution, field-of-view, and depth of field are sacrificed in order to achieve a useful balance.
Here we present a novel lens system with high-resolution and wide field-of-view for rapid 3D image capture. The design
achieves this using a single lens with no moving parts. A depth-from-defocus algorithm is implemented to reconstruct
3D object point clouds and matched with a fused image to create a 3D rendered view.
Measurement of surface finish in industrial manufacturing has traditionally been done by means of either visual
comparison with reference plates or by the use of contact stylus based profilers. There are many challenges associated with contact profilers such as stability during measurement in an industrial environment, damage and wear of the tip, measurement in tight spaces or on curved surfaces and just the limited amount of data obtained by a linear scan of the stylus. Many alternative methods have become available such as white light interferometry, focus based systems, and even laser scatter. This paper will present the result of testing of the commercially available methods with particular emphasis on the fine surface finishes demanded in today’s manufacturing, then presents some alternative methods that show strong potential to address some of the challenges mentioned above that are not in wide use today. The analysis will specifically explore some of the physical mechanisms that affect the stylus based measurement, as well as the limitations of many of the optical approaches related to view angle and diffraction limited resolution consequences. The area of confocal imaging will be specifically explored as to how it might be used to obtain more complete data on very fine surface finishes.
In this paper, the design and evaluation of a 3D stereo, near infrared (IR), defect mapping system for CZT inspection is
described. This system provides rapid acquisition and data analysis that result in detailed mapping of CZT crystal defects
across the area of wafers up to 100 millimeter diameter and through thicknesses of up to 20 millimeter. In this paper,
system characterization has been performed including a close evaluation of the bright field and dark field illumination
configurations for both wafer-scale and tile-scale inspection. A comparison of microscope image and IR image for the
same sample is performed. As a result, the IR inspection system has successfully demonstrated the capability of
detecting and localizing inclusions within minutes for a whole CZT wafer. Important information is provided for
selecting defect free areas out of a wafer and thereby ensuring the quality of the tile. This system would support the CZT
wafer dicing and assembly techniques that enable the economical production of CZT detectors. This capability can
improve the yield and reduce the cost of the thick detector devices that are rarely produced today.
The authors report on the feasibility of clinical neuroendovascular optical coherence tomography (OCT)
imaging as well as its efficacy and safety by comparing findings with histology in animal, cadaveric and
clinical studies. Catheter-based in vivo endovascular OCT imaging was carried out intracranially in four
patients, three in the anterior circulation and one in the posterior circulation (vertebral artery). The
neuroendovascular OCT device was delivered to the desired location using groin access and standard
endovascular procedures. In vivo findings were reproduced using ex vivo OCT imaging in corresponding
animal and human (cadaveric) harvested tissue segments with findings matched by histology. OCT images
correlated well with the images obtained after histologic sectioning, and visualized in vivo the laminar
vascular structure. Satisfactory imaging findings were obtained with no complications. Neuroendovascular
OCT imaging is thus feasible for clinical use and can detect with high resolution the structure of arterial
segments. Understanding OCT imaging in non-diseased arteries is important in establishing baseline
findings necessary for interpreting pathologic processes. This allows neuroendovascular optical biopsies of
vascular tissue to be obtained without the need for excision and processing, and potentially allows
prophylactic interventions against stroke and other cerebrovascular disease before they become