Measurement uncertainty of phase measuring deflectometry.

Phase measuring deflectometry (PMD) is a proven optical measurement method for measuring the shapes of objects. This method is suitable for measuring the shape of an object with an optically smooth (mirror-like) surface. The measured object is used as a mirror through which the camera observes a defined geometric pattern. We derive the theoretical limit of measurement uncertainty using the Cramér-Rao inequality. It shows that the measurement uncertainty is expressed in the form of an uncertainty product. The factors of the product are the angular uncertainty and lateral resolution. The magnitude of the uncertainty product depends on the mean wavelength of the light used and the number of photons detected. The calculated measurement uncertainty is compared with the measurement uncertainty of other deflectometry methods.

Optically smooth and optically rough surface in the view of optical 3D sensors based on imaging.

An optical 3D sensor is a device intended to measure the geometric shape of objects using optical methods. When designing an optical 3D sensor, it is necessary to consider whether the surface to be measured is smooth or rough. This is because the signal formation process is different for each of the two cases. Moreover, it turns out that the signal formation process is not only influenced by the roughness of the measured surface but also by other parameters of both the measured surface and the optical measuring system. The additional parameter of the measured surface is the surface correlation length. The parameters of the optical measuring system are the wavelength of the light used and the radius of the resolution cell. Based on the knowledge of the parameter values of the surface to be measured and the measuring system, the surface to be measured can be classified as optically smooth or optically rough. We present an analysis to determine whether a given surface measured by a given optical measuring system will behave as an optically smooth or optically rough surface.

Damage Analysis of Composite CFRP Tubes Using Acoustic Emission Monitoring and Pattern Recognition Approach.

The acoustic emission method has been adopted for detection of damage mechanisms in carbon-fiber-reinforced polymer composite tubes during the three-point bending test. The damage evolution process of the individual samples has been monitored using the acoustic emission method, which is one of the non-destructive methods. The obtained data were then subjected to a two-step technique, which combines the unsupervised pattern recognition approach utilizing the short-time frequency spectra with the boundary curve enabling the already clustered data to be additionally filtered. The boundary curve identification has been carried out on the basis of preliminary tensile tests of the carbon fiber sheafs, where, by overlapping the force versus time dependency by the acoustic emission activity versus time dependency, it was possible to identify the boundary which will separate the signals originating from the fiber break from unwanted secondary sources. The application of the presented two-step method resulted in the identification of the failure mechanisms such as matrix cracking, fiber break, decohesion, and debonding. Besides the comparison of the results with already published research papers, the study presents the comprehensive parametric acoustic emission signal analysis of the individual clusters.

Coherence scanning interferometry with a focus-tunable lens.

Coherence scanning interferometry is an established optical method that is able to measure the shape of objects with high precision. The surface of the object to be measured can be both optically smooth and optically rough. However, a major limitation of coherence scanning interferometry is that the object to be measured must mechanically move relative to the measuring device during the measurement procedure. We introduce an optical measurement method based on coherence scanning interferometry that is able to measure without the mechanical movement between the measured object and the measuring device. The suggested solution is that the reference plane moves. The imaging system includes an electrically focus-tunable lens. This lens ensures that the measured part of the object is sharply imaged during the measurement procedure.

Shape from focus for large image fields.

Shape from focus is a method for the accurate measurement of the geometrical shape of objects. The measurement principle is the local focus search. The method is suitable only for objects with a texture (optically rough surface). The longitudinal coordinate of a surface point is determined from the maximum of the focus measure function. The focus measure function expresses the quality of focus in a small image area. The measurement is fast because the focus measure function shows no oscillations. Thus, a large sampling step can be used. We present experimental results that demonstrate the capability of the proposed method.

White-light interferometry on rough surfaces--measurement uncertainty caused by noise.

White-light interferometry on rough surfaces is an optical method for the measurement of the geometrical form of objects. The longitudinal coordinate of the measured surface is obtained from the measured interferogram by means of an evaluation method. However, the longitudinal coordinate cannot be determined completely accurately because the interferogram is affected by noise. We calculate the lower limit of the longitudinal measurement uncertainty caused by noise by use of the Cramer-Rao inequality. Additionally, we calculate the lower limit of the longitudinal measurement uncertainty caused by shot noise only.

Spatial coherence profilometry on tilted surfaces.

The influence of tilted surfaces on the measurement of shape by spatial coherence profilometry is investigated. Based on theoretical analysis and experimental results, the systematic measurement error caused by surface tilt is determined. The systematic measurement error depends not only on the tilt angle but also on the parameters of the experimental setup. The theoretical analysis and the experiments show the similarities and differences between spatial coherence profilometry and white-light interferometry. We also suggest the conditions to obtain correct measurements by use of spatial coherence profilometry.

Effective treatment of mild-to-moderate nasal polyposis with fluticasone delivered by a novel device.

OBJECTIVE: To assess the efficacy and safety of fluticasone propionate administered using OptiNose's novel delivery device (Opt-FP) in subjects with bilateral mild-to-moderate nasal polyposis. METHODS: A prospective, multicentre, randomized, double-blind, placebo-controlled, parallel group study was conducted in adult subjects (n = 109) with mild-to-moderate bilateral nasal polyposis. Subjects received Opt-FP 400 microg or placebo twice daily for 12 weeks. Endpoints included endoscopic assessment of polyp size using Lildholdt's Scale, peak nasal inspiratory flow (PNIF), symptom scores and use of rescue medication. RESULTS: The proportion of subjects with improvement in summed polyp score >or= 1 (Lildholdt\'s Scale) was significantly higher with Opt-FP compared with placebo at 4, 8 and 12 weeks (22% vs 7%, p = 0.011, 43% vs 7%, p < 0.001, 57% vs 9%, p < 0.001). After 12 weeks the summed polyp score was reduced by 35% (-0.98 vs +0.23, p < 0.001). PNIF increased progressively during Opt-FP treatment (p < 0.05). Combined symptom score, nasal blockage, discomfort, rhinitis symptoms and sense of smell were all significantly improved. Rescue medication use was lower (3.1% vs 22.4%, p < 0.001). Opt-FP was well tolerated. CONCLUSIONS: Fluticasone propionate (400 microg b.i.d.) administered using OptiNose's breath actuated bi-directional delivery device was an effective and well tolerated treatment for mild-to- moderate bilateral nasal polyposis.

White-light interferometry on rough surfaces--measurement uncertainty caused by surface roughness.

White-light interferometry measuring an optically rough surface commonly does not resolve the lateral structure of the surface. This means that there are height differences within one resolution cell that exceed one-fourth of the wavelength of the light used. Thus the following questions arise: Which height is measured by white-light interferometry? How does the surface roughness affect the measurement uncertainty? The goal of the presented paper is to answer these questions by means of numerical simulations. Before the aforementioned questions can be answered, the distribution of the intensity of individual speckles, the influence of surface roughness, and the spectral width of the light source used are discussed.

White-light interferometer with dispersion: an accurate fiber-optic sensor for the measurement of distance.

We present a fiber-optical sensor for distance measurement of smooth and rough surfaces that is based on white-light interferometry; the sensor measures the distance from the sample surface to the sensor head. Because white light is used, the measurement is absolute. The measurement uncertainty depends not on the aperture of the optical system but only on the properties of the rough surface and is commonly approximately 1 microm. The measurement range is approximately 1 mm. The sensor includes no mechanical moving parts; mechanical movement is replaced by the spectral decomposition of light at the interferometer output. The absence of mechanical moving parts enables a high measuring rate to be reached.

Measurement of the influence of dispersion on white-light interferometry.

White-light interferometry is a well-established method for measuring the height profiles of samples with rough as well as with smooth surfaces. Because white-light interferometry uses broadband light sources, the problem of dispersion arises. Because the optical paths in the two interferometer arms cannot be balanced for all wavelengths, the white-light correlogram is distorted, which interferes with its evaluation. We investigate the influence of setup parameters on the shape of the correlogram. Calculated values are compared with experimental results.

Theoretical measurement uncertainty of white-light interferometry on rough surfaces.

A great advantage of the white-light interferometry is that it can be used for profile objects with a rough surface. A speckle pattern that arises in the image plane allows one to observethe interference; however, this pattern is also the source of the measurement uncertainty. We derive the theoretical limits of the longitudinal uncertainty by virtue of the first-order statistics of thespeckle pattern. It is shown that this uncertainty depends on the surface roughness of the measured object only; it does not depend on the setup parameters.