The 4 mm Port Plate (A02-1010-838 ) masks down the 6 mm viewed sample area in Small Area of View (SAV) to a 4 mm diameter aperture. It is intended to be used only when the sample is smaller than the 9.5 mm diameter of the normal SAV port.
For the ColorQuest XE and UltraScan XE diffuse d/8 sphere instruments, the Port and Sample View diameters in RSIN/RSEX reflectance modes are:
- Large Area View (LAV) 25 mm (1 in) illuminated/19 mm (0.75 in) measured
- Small Area View (SAV) 9.5 mm (0.375 in) illuminated/6 mm (0.25 in) measured
The instrument still measures a 6 mm diameter area in SAV mode when the 4 mm port plate is being used.
Coupled with the SAV mode, the viewed area of the sample using the 4 mm port is about 50% of the total viewed area by the instrument. The rest of the viewed area is the inside of the port, masking the sample measurement.
For this reason, a 6 mm circle inside the port read by the SAV lens as well as the internal edge of the port opening (ocular) are painted black to minimize scattering and interference with the 4 mm diameter sample area being measured (If the ocular was white, there would be more scattering).
If using the 4 mm port, standardize the sphere instrument in RSIN SAV mode with the 4 mm port plate in place. This will negate most of the photometric effects due to sample masking.
This 4 mm masked port measurement is suitable for RSIN color difference measurements of samples relative to a product standard, all of which should be read using this same 4 mm port. It is not intended for the best agreement between LAV and SAV ports, use in Reflectance Specular-excluded mode (RSEX), or to perform diagnostic tests for instrument performance.
All Diagnostic Tests for instruments which compare to factory baseline values must be performed in the Large Area of View mode, Reflectance Specular-Included (RSIN), UV Filter Nominal mode. This requires use of the 25 mm open port, not the 4 mm Port Plate (A02-1010-838).