Portable Optical Measurement Research Articles

Portable optical fiber probe for in vivo brain temperature measurements.

This work reports on the development of an optical fiber based probe for in vivo measurements of brain temperature. By utilizing a thin layer of rare-earth doped tellurite glass on the tip of a conventional silica optical fiber a robust probe, suitable for long-term in vivo measurements of temperature can be fabricated. This probe can be interrogated using a portable optical measurement setup, allowing for measurements to be performed outside of standard optical laboratories.

Advances in photogrammetric measurement solutions

In recent years, industrial photogrammetry has emerged from a highly specialized niche technology to a well established tool in industrial coordinate measurement applications with numerous installations in a significantly growing market of flexible and portable optical measurement systems. This is due to the development of powerful, but affordable video and computer technology. The increasing industrial requirements for accuracy, speed, robustness and ease of use of these systems together with a demand for the highest possible degree of automation have forced universities and system manufacturers to develop hard- and software solutions to meet these requirements. The paper will show the latest trends in hardware development, especially new generation digital and/or intelligent cameras, aspects of image engineering like use of controlled illumination or projection technologies, and algorithmic and software aspects like automation strategies or new camera models. The basic qualities of digital photogrammetry-like portability and flexibility on one hand and fully automated quality control on the other—sometimes lead to certain conflicts in the design of measurement systems for different online, offline or real-time solutions. The paper will further show, how these tools and methods are combined in different configurations to be able to cover the still growing demands of the industrial end-users.

Evaluation of Portable Optical Property Measurement Equipment for Solar Selective Surfaces

The operation and accuracy of portable optical measurement equipment for determining the solar absorptance, αs, and emittance, ε, of solar selective surfaces are presented. The optical equipment includes a Gier Dunkle Solar Reflectometer (Model MS-251) and a Willey Alpha Meter (Model 2150) for αs measurements and a Gier Dunkle Infrared Reflectometer (Model DB-100) and a Willey Ambient Emissometer (Model 2158) for ε measurements. The accuracy of the MS-251 for measurements of αs for electrodeposited black chrome coatings was determined to be better than ±0.03 absorptance units. For the same coatings, the Willey Alpha Meter accuracy was limited by deviations up to 0.11 absorptance units. The accuracy of the Gier Dunkle Infrared Reflectometer for ε(100°C) measurements is better than ±0.02 emittance units. Values for ε(100°C) determined with the Willey Emissometer using black chrome coatings are higher than the actual 100°C emittance. However, since the relationship is linear, the correct emittance can be calculated by multiplication by a constant factor.