Optical contact

The most recent development is the video extensometer which claims to overcome all of the disadvantages of the contact, optical and laser types. A... 

Variation in sample height on a non contact optical unit can be a major analytical limitation. There are at least three American and three European near-infrared moisture monitoring systems which use water absorption at 1940 nm with one or more reference wavelengths. These are designed to be mounted above a conveyor belt with clearance between the optical window and the sample surface. Since water is a strong absorber the coefficients used in the analytical expression are small and the uncertainty associated by multiplying the sampling noise may be acceptable. For analytes where absorbance differences are less, the precision may not be sufficient. 

Since the introduction of the STM a number of variations have been devised, such as ATM (atomic force microscope). The basic concept is that piezoelectric actuators move a miniature cantilever arm (with a nm-sized tip) across the sample while a non-contact optical system measures the deflection of the cantilever caused by atomic scale features. The deflection is proportional to the normal force exerted by the sample on the probe tip and images are generated by raster scanning the sample [201]. One application of this technique was to measure the thickness and size distribution of sub-micron clay particles with diameters in the 0.1 to 1 pm size range and thickness from 0,01 to 0.12 pm [202]. 

T.-W. Lee et al.. Soft-contact optical lithography using transparent elastomeric stamps Application to nanopattemed organic light-emitting devices, Adv. Funct. Mater, 15, 1435, 2005. 

The majority of pulse calorimetric measurements use pyrometry, which is non-contact (optical) measurement of the thermal radiation emitted fi om any heated body or substance according to Planck s radiation law for black body radiation. Planck s law describes the spectral distribution of black body radiance which provides the basis for the International Temperature Scale (ITS-90) [76], especially above the freezing point of silver [77]. Because Planck s law is only... 

Use of non-contact optical probes (measurements through glass, quartz, safflre flow-through cells) real-time observation... 

Non-contact optical technologies can be used to obtain the full rail profile at speeds up to 350 km/h. Rail profile measurement systems (RPMS) can use high level laser and video technology to provide accurate and instantaneous report on the rail profile condition. The video cameras capture full cross-sectional rail profiles from the base to the top of the rail surface to allow useable and accurate measurements. Such a system can measure the following parameters rail profile vertical and horizontal wear, rail inchnation and head width. By comparison with a reference profile, parameters out of tolerance can be identified immediately. 

Observations of nerve mechanical motions during the action potential have been performed with various contact and combined contact/optical techniques, including piezoelectric sensors (2P), volume change measurements 30 measurements of scattering of attached beads (75) and optical lever recordings... 

Figure 2-10. (a) Diagram illustrating an extensometer (strain gauge) attached to the test specimen. (Courtesy of Instron Corporation.) (b) Non-contact optical extensometer (Courtesy Zwick USA). 

E2208-02(2010)e1 Standard Guide for Evaluating Non-Contacting Optical Strain Measurement Systems... 

A positive image was obtained with contact optical mqiosure at 250 nm (6 mJ/cm ) and development for 15 seconds in a 0.1% TMAH aqueous solution. 

A great variety of experimental techniques has been developed to measure film thickness in EHL contacts. Optical interferometry is the most commonly used technique and has significantly contributed to a better understanding of the way an EHL contact works [9]. The recently developed colorimetric interferometry techniques that combine optical interferometry and computer image analysis allow the mapping of film thickness distributions... 

Huls AG Applications Electrical contacts, optical waveguide buffer tubes. Vestodur PBT... 

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