AQ-00275-000, Rev. 3
17
Transmittance Sample Holder
Labsphere offers a clasp-style sample holder and a cuvette-style sample holder that fit over the
dovetail mount at the transmittance port of the DRA-CA-3300 integrating sphere. The clasp-style
device, shown in Figure 9, is best suited for solid samples large enough to completely fill the trans-
mittance port.
8
°
/Hemispherical Reflectance Factor Measurements
For reflectance measurements, make sure that mirror M3 is placed in the reflectance position, clos-
est to the sphere. Repeat the alignment procedure if the mirror has been moved. This mirror config-
uration provides a focused spot size of approximately 6.5 mm wide x 15 mm high. If a large
reflectance spot is desired, such as for the measurement of fabrics or other non-homogenous sam-
ples, place mirror M3 in the transmittance mirror position. This mirror configuration provides an
unfocused spot size of approximately 20 mm wide x 25 mm high. Place the mirror in the center-
mount position if an intermediate beam size is desired.
The 8° reflectance measurement capability of the DRA-CA-3300 accessory is limited to the total hemi-
spherical reflectance from a sample surface. The DRA-CA-3300 has no specular exclusion port - the dif-
fuse and specular reflectance components cannot be separated. The following procedure should be used to
measure total reflectance of a sample.
1. Install the 8° wedge at the sample reflectance port.
2. Place the uncalibrated USRS-99-020 standard in the reference port. Place a calibrated
SRS-99-020 Spectralon diffuse standard or a calibrated specular standard at the sam-
ple reflectance port. If your sample is mostly diffuse, you should use the diffuse stan-
dard; if your sample is mostly specular, use a specular standard such as a calibrated
first-surface aluminum mirror.
Clips
Transmittance Sample
Figure 9. The standard Labsphere transmittance
sample holder can handle sample sizes up to
approximately 4" x 4".