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| Just Another Big, Bulky Sample |
Sample – The coated window material of an intact photo-multiplier tube, viewed end-on
There are many “real world” coatings that do not reside on nice flat one inch sized substrates. Many modern quality control specular reflectance samples are the finished manufactured part.
The picture at left shows such a sample.
The placement of this type of large sample on the Universal Reflectance Accessory is shown in the bottom left picture. Since the sampled area is flat and covers the entire beam entry aperture, there is no need for additional light cover. There spectra of the window coating are shown at bottom right. The PMT contents behind the window are far enough removed from the window (1 cm) so as not to interfere.
Sample Preparation
1) Sample is placed on the URA stage with the coated side contacting the opening in the sample stage.
2) The internal Common Beam Depolarizer was used to prevent polarization artifacts at incidence angles higher than 20 degrees.
Placement of the sample on the URA accessory is seen below.
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| Sample on URA |
The spectral results of an angular study of the reflectance of the PMT widow coating is seen below.
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| URA Specular Reflectance Results |
Conclusion: The design of the URA , with it’s gravity held sample placement and lack of either width or height obstructions, makes it the reflectance accessory of choice for large, bulky, irregular shaped samples. For more info go to http://www.perkinelmer.com
