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3. Set instrument parameters as desired. Set the Y Mode parameter on the Setup Dialog
Box of your WinUV application to %R.
4. Perform an instrument baseline correction.
5. Remove the calibrated standard from the reflectance port and load your sample.
6. Initiate the scan and record the measurement data.
7. Multiply the values recorded in the resulting scan by the known spectral reflectance
factor values of your standard to obtain the actual reflectance of the sample. If your
diffuse standard is calibrated, the reflectance factors are provided in the calibration
documentation. If your diffuse reflectance standard is uncalibrated, you can use the
reflectance values given in Appendix B.
0
°
/Diffuse Reflectance Factor Measurements
Although the DRA-CA-3300 integrating sphere does not have a specular exclusion port, the sam-
ple beam entrance port can serve the same purpose when taking 0° incidence measurements. When
the 0° wedge is in place, the specular component of reflection from the sample is redirected out of the
sphere through the transmittance port. The diffuse component of this reflection remains inside the sphere
and is sensed by the sphere detector. The procedure for diffuse reflectance factor measurement is as fol-
lows:
1. Replace the 8° sample wedge with the 0° wedge at the sample reflectance port.
2. Load the calibrated SRS-99-020 diffuse standard into the sample port and the uncali-
brated standard at the reference port.
3. Set instrument parameters as desired. Set the Y Mode parameter on the Setup Dialog
Box of your WinUV application to %R.
4. Run an instrument Baseline Correction.
5. Remove the standard from the sample reflectance port and load your diffuse sample.
6. Run the scan and record your measurement data.
7. Multiply the values recorded in the resulting scan by the known spectral reflectance
factor values of your standard to obtain the actual reflectance of the sample. If your
diffuse reflectance standard is calibrated, the reflectance factors are provided in the
calibration documentation. If your reflectance standard is uncalibrated, you can use
the reflectance values given in Appendix B.
Note: Measurements performed using the specular excluded geometry always should be inter-
preted with caution. The transmittance port may not be sufficient in size to exclude the entire
specular component.
Large Sample Reflectance Measurements
The sample holder and hinged sheet metal enclosure around the sample reflectance port may be
removed in order to accommodate large samples. Follow these directions to prepare the accessory
for large sample scans.
1. Using a 3/32" hex driver, loosen the three hex socket screws located along the black
bar beneath the enclosure.