General SDR-1 Frequently Asked Questions

FAQ Legend:

All Products Product Class (Rotating Shadowband Radiometers) This Product (SDR-1)

1. General

1. What kind of optical interference filters do the MFR, UVMFR, and SPUV use?

The MFR, UVMFR, and SPUV all use new technology "Ion Assisted Deposition" interference filters. The slit width and effective center wavelength are exceptional and stable. However, while the throughput/transmission of IAD filters is far superiror compared with previous generations of optical filter technologies, we still recommend that yearly factory calibrations.

2. Can I replace my standard filters for custom MFR/UVMFR/SPUV filters later on?

Yes. You will also need to recalibrate at the time these factory modifications are made.

3. Can I get non-standard filters for the MFR, UVMFR, or SPUV?

Yes, at additional cost and only as long as the filters are 10 nm FWHM wide and on 10 nm increments. For the MFR-7 and SPUV, the longest practical wavelength is 1040 nm due to the silicon detector's lack of quantum efficiency beyond this. Remember that the radiometric calibration accuracy may suffer as the bandwidth increases. Beyond 40 nm wide, calibration with FEL lamps becomes a problem.

The RSS/UVRSS instruments provide continuous spectral measurements and are excellent solutions for special requirements.

4. What do I need to know before selecting an radiometer for outdoor use?

You need to know whether you want spectral or broadband data, and whether you want measurements in the thermal Infrared, NIR/visible, UV-A or UV-B.

Next, decide whether you want direct-normal and/or total (global) radiation measurements.

Finally, decide if you need continuous unatended measurements of "campaign mode" measurements. In campaing mode, the instrument is kept out of inclement weather and setup for brief periods of time, such as making ground-truth measurements during a a satellite fly-by. All YES systems work well in both applications because they are weatherproof and thermally stabilized. However, other instruments (e.g. telescopes) are only suitable for campaign mode.

5. The internal operating temperature of the UVB, MFR, UVMFR, SPUV, RSS is about 45° C. Why is this?

To eliminate effects of changing ambient air temperature and solar loading, we thermally stabilize the internal optics of our instruments to above ambient temperature, between 38° C and 45° C, depending on the instrument. The exact temperature is not as important as knowing that the temperature is stable and has been stable since the most recent calibration.