Mantis 5000 Especificaciones descargar pdf (Pagina 5)

integrating sphere usually depends on the wavelength capabilities demanded by the

reflectance application.

The integrating sphere configuration offers some distinct advantages over the standard

sample compartment. The changes made in sample beam and reference beam geometry

on your accessory do not compromise the transmission and absorption measurement

capabilities already inherent to the spectrophotometer the traditional sample transmission

and absorbance measurements can be performed in the same manner, with or without the

DRA. Because of the geometry of the integrating sphere, it has the ability to collect most

reflected or transmitted radiation, remove any directional preferences, and present an

integrated signal to the detector.

The DRA accessories each include an optical bench composed of double beam transfer

optics in combination with a six-inch (150 mm) diameter integrating sphere. The

integrating spheres are machined from SpectralonTM a highly diffuse reflectance

material. The accessory is equipped with a movable mirror in the sample beam optics to

allow the beam to be focused at the transmission, reflectance, or centre-mount sample

positions. This feature adds versatility for measuring various size samples. The external

DRA accessories are designed to perform reflectance, transmission, or absorbance

measurements of diffuse, specular, or mixed samples. The Scan application of the Cary

WinUV software is usually used when operating the accessory.

Reflectance measurements

First, a baseline is recorded with the PTFE reference disk covering the reflectance port.

The sample is then mounted over the port and the reflection off the sample surface is

collected by the sphere. The reflectance is therefore measured relative to the PTFE disk.

This is the ’substitution’ method.

The total (diffuse and specular) or the diffuse-only reflectance may be measured by using

either the specular plug (specular included) or the light trap (specular excluded). The

specular component may be calculated from the difference of these two, or the Cary

Absolute Specular Reflectance Accessory (SRA) may be used to give an absolute value

of the specular component.

A variety of sample types and sizes may be used with the accessory, in conjunction with

different sample holders. For powders, pastes or other material requiring a sample

container, a powder cell is available for use in the DRA.

If only very small amounts of powder or paste are available, or if measurements

extending beyond the range of 250–2500 nm are required, the DRA cannot be used. The

'Praying Mantis' accessory (P/N 00 100469 00) is used for these measurements.

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Mantis 5000 Especificaciones Pagina 5