Non-contact optical three dimensional liner metrology
We optically captured the "as-built" liner geometry of NTLX (near term liner experiments) for Shiva Star using ultra-precision ranging lasers. We subsequently verified the resulting digitized geometry against the 3D CAD model of the part. The results confirmed that the Liner contours are within designed tolerances but revealed subtle fabrication artifacts that would typically go undetected. These features included centimeters long waviness and saddle and bulge regions of 1 micron or less in magnitude. The laser technology typically provided 10 micron spatial resolution with /spl plusmn/12 nanometer ranging precision. Atlas liners in the future may have to be diamond turned and will have the centimeter wavelength and 100 angstrom amplitude requirements. The advantages of using laser technology are (1) it avoids surface damage that may occur with conventional contact probes and (2) dramatically improves spatial resolution over CMM, capacitance and inductance type probes. Our work is the result of a perceived future need to develop precision, non-contact, liner inspection techniques to verify geometry, characterize machining artifacts and map wall thickness on delicate diamond turned surfaces. Capturing "as-built" geometry in a non-contact way coupled with part-to-CAD verification software tools creates a new metrology competency for MST-7.
Fabrication of an ultra smooth liner for Ranchero
Calculations indicate that Atlas liners must have waviness amplitudes less than 10 nm over spatial wavelengths near 1 cm. A liner for Ranchero has been produced, on equipment at LANL, with waviness amplitudes as close to 10 nm as was possible. A lathe, with air bearing slideways and spindle, was used in concert with a single crystal diamond tool to produce this part. Since the dimensional characterization of this liner can be as challenging as the production, on-machine gauging techniques were used for much of the dimensional inspection. This paper discusses the fabrication and metrology of this ultra smooth liner.
Development of new analytical methods for the determination of caffeine content in aqueous solution of green coffee beans
BackgroundThis study was conducted to develop fast and cost effective methods for the determination of caffeine in green coffee beans. In the present work direct determination of caffeine in aqueous solution of green coffee bean was performed using FT-IR-ATR and fluorescence spectrophotometry. Caffeine was also directly determined in dimethylformamide solution using NIR spectroscopy with univariate calibration technique.ResultsThe percentage of caffeine for the same sample of green coffee beans was determined using the three newly developed methods. The caffeine content of the green coffee beans was found to be 1.52 ± 0.09 (% w/w) using FT-IR-ATR, 1.50 ± 0.14 (% w/w) using NIR and 1.50 ± 0.05 (% w/w) using fluorescence spectroscopy. The means of the three methods were compared by applying one way analysis of variance and at p = 0.05 significance level the means were not significantly different. The percentage of caffeine in the same sample of green coffee bean was also determined by using the literature reported UV/Vis spectrophotometric method for comparison and found to be 1.40 ± 0.02 (% w/w).ConclusionNew simple, rapid and inexpensive methods were developed for direct determination of caffeine content in aqueous solution of green coffee beans using FT-IR-ATR and fluorescence spectrophotometries. NIR spectrophotometry can also be used as alternative choice of caffeine determination using reduced amount of organic solvent (dimethylformamide) and univariate calibration technique. These analytical methods may therefore, be recommended for the rapid, simple, safe and cost effective determination of caffeine in green coffee beans.