Focus™

Additional Information

Figure 1. Schematic of the Focus.
The Focus™ is an excellent tool for analyzing coated materials of a variety of sizes and shapes. Such samples include coated mirrors, thin film on metals, coatings on semicondutors, wafers, and disks. Coatings on flat, machined metals can also be effectively examined.

This grazing angle accessory, shown in Figure 1, utilizes a planar mirror to direct the FT-IR beam to a parabolic reflector (M2) that focuses through a Si polarizing plate onto the sample. The reflected radiation is directed from the parabolic reflector and a second plane mirror to the detector of the spectrometer.

The Focus™ features a convenient horizontal sampling stage to accommodate a wide range of sample sizes. The Focus also includes a built-in Si polarizer for optimal spectral contrast. The accessory is enclosed in a purgable box for rapid sample exchange without interrupting the purge of the FT-IR spectrometer.

Representative infrared spectra recorded with the Focus™ are shown in Figures 2 through 4. Figure 2 is the grazing angle reflectance from a golden film on a Si wafer. Note that the high level of the baseline indicates that the sample is a better reflector than the reference mirror used.



Figure 2. Grazing Angle Reflectance of a Golden Coating on Si.

Figure 3 shows the grazing angle reflectance spectra of two SiO2 coated aluminum mirrors. The band intensities in the two spectra differ, indicating that the two coatings are not the same thickness.

Figure 4 shows the grazing angle FT-IR infrared spectrum recorded from a machined surface coated with polyethylene. This demonstrates the effectiveness of the Focus™ for examining samples for coatings on flat, non-polished materials.




Figure 3. Grazing Angle Reflectance from two SiO2
coated Aluminum Mirrors.




Figure 4. Grazing Angle Specular Reflectance
of Polyethlyene on Machined Metal.

This accessory records grazing angle spectra quickly and accurately, allowing the user to focus on the results. Furthermore, the Focus™ is ATR-ready. Simply exchange its sampling plate with the optional ConcentratIR™ top plate for multiple reflection ATR studies!