FAQ: “Do we have to keep the white tile at the reflectance port during transmission readings?”The answer is yes, you need to keep the white tile at the reflectance port of HunterLab sphere instruments whenever you perform transmission measurements in TTRAN Total Transmission or RTRAN Regular Transmission modes.
In colorimetric sphere instruments, the same fixed light path is used for color measurements in both reflectance and transmission.
When you measure in transmission, the lens is looking where the sample is (TTRAN port in this case) but also continues to view through the sphere to the reflectance port so it has to be filled in with a white tile. The white tile is not functioning as an instrument standard in this situation, but still becomes part of the optical path during transmission measurements. This white tile standard needs to be left at the reflectance port for all subsequent sample readings because it is effectively part of the optical path.
FAQ: “We only measure samples in transmission. Should we put the white calibrated tile back in the standards box when the instrument is not in use?
The calibrated white tile is well protected at the reflectance port and could be left there all the time. Pressed flush against the reflectance port, the tile is as well protected here as if it were in the standards box. It is only exposed to light during the brief duration that a flash measurement is taken, so fading is not a problem. And you will not have to remember to put it back for measurements… 🙂
Similarly, I suggest you leave the instrument power on. With a pulsed xenon lamp, the only power that is consumed is to power the LED light and minimal electronics. The only time power is consumed is when a measurement is being taken. Powered up, the unit is ready to take measurements at any time.