Topography Measurement for Monitoring Manufacturing Processes in Harsh Conditions

High precision manufacturing, e.g. milling and grinding, which have manufacturing tolerances in the range of <10 μm require microscopic measurement techniques for the inspection of the manufactured components. These measurement techniques are very sensitive to cooling liquids and lubricants which are essential for many manufacturing processes. Therefore, the measurement of the components is usually conducted in separate and clean laboratories and not directly in the manufacturing machine. This approach has some major drawbacks, e.g. high time consumption and no possibility for online process monitoring. In this article, a novel concept for the integration of high precision optical topography measurement systems into the manufacturing machine is introduced and compared to other concepts. The introduced concept uses a reservoir with cooling liquid in which the measurement object is immersed during the measurement. Thereby, measurement disturbance by splashing cooling liquids and lubricants can effectively be avoided.BMBF/03V047

On the development of a low-cost rigid borescopic fringe projection system

Examining the geometry of complex industrial free form objects, like a blade integrated disk (blisk) of a jet engine compressor, is currently subject to research. High measurement precision and speed are required and the complex geometry poses a challenge for state of the art measurement systems. In order to fulfill typical inspection requirements, the fringe projection methodology was adapted in this work to accomplish the task of fast and precise geometry examination. A low cost borescopic fringe projection system for 3D shape measurement based on consumer electronics combined with state of the art optics was developed. Nevertheless, it is able to provide measurement uncertainties comparable to professional systems. We are using a portable consumer LED-beamer, which we have modified to fit the optics of the borescope and a Raspberry Pi single-board computer with a 5 megapixel camera to capture the fringe patterns. With this setup and fringe projection algorithms, which have been developed by this institute over the last years, we were able to perform high quality measurements while still being suitable for a compact inspection system. Measurements with high point densities are possible even in narrow areas of parts with complex geometries like blisks. The measuring system and first measurement results will be presented at the conference. © 2015 SPIE.DFG/SFB/87

Inzidenz und epidemiologische Charakteristika des Mayer-Rokitansky-Küster-Hauser-Syndroms in Deutschland - eine bundesweite populationsbezogene Studie

MRKHS ist eine seltene genitale Fehlbildung. Ziel der vorliegenden Arbeit war es, durch verschiedene methodische Ansätze die Häufigkeit dieser seltenen Erkrankung in Deutschland zu erfassen und weitere epidemiologische Daten zu gewinnen

Single image geometry inspection using inverse endoscopic fringe projection

Fringe projection is an important technology for the measurement of free form elements in several application fields. It can be applied to measure geometry elements smaller than one millimeter. In combination with deviation analysis algorithms, errors in fabrication lines can be found promptly to minimize rejections. However, some fields cannot be covered by the classical fringe projection approach. Due to shadowing, filigree form elements on narrow or internal carrier geometries cannot be captured. To overcome this limitation, a fiberscopic micro fringe projection sensor was developed [1]. The new device is capable of resolutions of less than 15 m with uncertainties of about 35 m in a workspace of 3x3x3 mm. Using standard phase measurement techniques, such as Gray-code and cos-patterns, measurement times of over a second are too long for in-situ operation. The following work will introduce an approach of applying a new single image measuring method to the fiberscopic system, based on inverse fringe projection [2]. The fiberscopic fringe projection system employs a laser light source in combination with a digital micro-mirror device (DMD) to generate fringe patterns. Fiber optical image bundles (FOIB) are used as well as gradient-index lenses to project these patterns on the specimen. This advanced optical system creates high demands on the pattern generation algorithms to generate exact inverse patterns for arbitrary CAD-modelled geometries. Approaches of optical simulations of the complex beam path and the drawbacks of the limited resolutions of the FOIBs are discussed. Early results of inverse pattern simulations using a ray tracing approach of a pinhole system model are presented.DFG/CRC/TR 7

Multiscale optical inspection systems for the regeneration of complex capital goods

The inspection of capital goods with complex geometries is a challenging task due to the limited maneuvering and measuring space available. We developed a set of optical measurement systems for the inline inspection of such machines and capital goods. At first we introduce a borescopic fringe projection system based on of-the-shelf components. It is capable of detecting geometric variances in hard to reach areas, e.g. inside machines or in between parts with highly complex geometries like blade integrated discs (blisks). Single parts like compressor blades are measured with an inverse fringe projection system, which uses fully adaptable fringe patterns. The adaptable patterns lead to a high sensitivity and high speed. Results can be achieved with only one fringe pattern per measurement. In order to perform microscopic measurements and surface characterizations, we use a michelson interferometer with advanced 3D reconstruction algorithms to detect microscopic variances of the objects surface. These newly developed algorithms lead to higher sensitivity and improved results. Together these three inspection systems enable us to detect and to quantify geometric defects or variances of different industrial parts. Based on this information the prediction of the reliability of a part can be improved and the lifetime of an industrial part can be extended leading to a reduction of maintenance costs.DFG/SFB/87

3D geometry measurement of hot cylindric specimen using structured light

We present a fringe projection system to measure glowing hot hybrid components in between production processes. For this a high power green light projector, based on TI DLP technology, is used to create the highest possible contrast between fringes on the red glowing specimen. It has a resolution of 1140 x 912 pixels with a maximum frame rate of 120 images per second for fast measurement. We use a green bandpass filter (525 nm) on the camera lens to block unwanted incoming radiation from the specimen caused by self-emission. Commercial measurement standards are not calibrated for temperatures other than 20° C, so they cannot be used to validate measurement data at the required temperatures of up to 1000°C since thermal expansion invalidates the geometry specification from the calibration data sheet. In our first development we use a uniformly heated pipe made of stainless steel as a dummy specimen to examine the measured geometry data. A pyrometer measures the temperature of the pipe so the expansion can be easily calculated using the thermal expansion coefficient. Different impact and triangulation angles are investigated to identify the effects of hot ambient air on the measurement. The impact of the induced refractive index gradient is examined to check the need for pre-processing steps in the measurement routine. © 2017 SPIE

Advanced Characterization Techniques for Turbine Blade Wear and Damage

This paper presents four complementary non-destructive measurement techniques for material characterization and damage detection of turbine blades. The techniques are macroscopic fringe projection with inverse fringe projection algorithms, robot guided microscale fringe projection, high frequency eddy current and pulsed high frequency induction thermography, both in the megahertz range. The specimen on which the measurements were carried out is a blade of the 1st stage high pressure turbine of a modern airplane jet engine. The turbine blade was characterized with regard to the macroscopic and microscopic geometry, cracks in the base material as well as the condition of the protective layer system

Light section measurement to quantify the accuracy loss induced by laser light deflection in an inhomogeneous refractive index field

In the manufacturing process of Tailored Forming components, the inline inspection of the joining zone directly after each single process step can yield advantages - such as early error detection and real-time process control. Since measuring times need to be synchronized with the production chain, there is no time to cool down the components in between two hot forming processes. On the one hand, the chosen measurement technique needs to be non-tactile due to the heat of the measurement object. On the other hand, the object's areal surface texture needs to be captured rapidly to realize a fast inline inspection. These requirements are only matched by optical 3d measurement systems. Additional challenges arise due to the high temperature of the Tailored Forming components: The ambient air is heated up and the air's temperature increase results in an inhomogeneous refractive index field surrounding the hot workpiece, effecting the light's path emitted by the illumination unit of the optical sensor. We present a simple measurement setup based on the laser light section method to visualize the measurement accuracy loss induced by the convectional heat flow from a hot cylindrical measurement object. To attain a direct validation of the measurement results, the measurements are performed with and with reduced influence of the inhomogeneous refractive index field induced by the hot object. © 2017 SPIE

Enhanced measurement routine for optical 3D geometry measurement of hot specimen by reduction of ambient pressure

Optical 3d geometry measurement is a vital part of the process control when manufacturing hybrid components. These so-called Tailored Forming components are meant to be inspected fast, in hot state and with high accuracy. In this paper, we examine the effect of a pressure reduction on the optical measurement data of hot objects, obtained with a self-developed fringe projection system. For this purpose, the fringe projection system has been attached to the window of vacuum chamber, housing a heatable cylinder as measurement object. Additionally, basic information on light propagation in inhomogeneous refractive index fields is provided next to a short review of previous work – including a theoretical analysis of a pressure reduction on the refractive index of air

Molecular cloning, tissue expression and regulation of Liver X Receptor (LXR) transcription factors of Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss)

Fish are important sources of high quality protein, essential minerals such as iodine and selenium, vitamins including A, D and E, and omega-3 fatty acids in the human diet. With declining fisheries worldwide, farmed fish constitute an ever-increasing proportion of fish in the food basket. Sustainable development of aquaculture dictates that diets will have to contain increasing levels of plant products that are devoid of cholesterol, but contain phytosterols that are known to have physiological effects in mammals. Liver X receptors (LXR) are transcription factors whose activity is modulated by sterols, with activation inducing cholesterol catabolism and de novo fatty acid biosynthesis in liver. Transcriptomic analysis has shown that substitution of fish meal and oil with plant products induces genes of cholesterol and fatty acid metabolism in salmonids. Here we report the cloning of LXR cDNAs from two species of salmonid fish that are important in aquaculture. The full-length cDNA (mRNA) of LXR obtained from salmon was shown to be 3766 bp, which included a 5’-untranslated region (UTR) of 412 bp and a 3’-UTR of 1960 bp and an open reading frame (ORF) of 1394 bp, which specified a protein of 462 amino acids. The trout LXR full-length cDNA was 2056 bp, including 5’- and 3’-UTRs of 219 and 547 bp, respectively, and an ORF of 1290 bp, which specified a protein of 427 amino acids. The protein sequences included characteristic features of mammalian LXRs, including the DNA binding (DBD), containing P-box, ligand binding (LBD) and activation function-2 (AF-2) domains, D-box, D (hinge) region, and eight cysteines that belong to the two zinc fingers. Phylogenetic analysis clustered the salmonid LXRs together, more closely with zebrafish and more distantly from medaka and stickleback. A pair-wise comparison among vertebrate LXR sequences showed the amino acid sequence predicted by the salmon LXR ORF showed greatest identity to that of trout 97%, and 97%, 87% and 81% identity to LXRs of zebrafish, frog and human (LXRα). The trout LXR ORF showed 96%, 92% and 82% identity to LXRs of zebrafish, frog and human (LXRα). Surprisingly, the expression of LXR was lowest in liver of all tissues examined and in salmon the greatest expression was observed in pyloric caeca with liver showing intermediate expression. It is likely that tissue expression was affected by the physiological status of the sampled animals. Certainly, nutritional, environmental and/or developmental regulation was evident in salmon, where the expression of LXR in liver was higher in fish in seawater than in freshwater, and higher in fish fed fish oil compared to fish fed vegetable oil in adult salmon