Week 4 Log

June 22nd - June 26th

The Spectro-Polarimeter project has a few hold ups from the previous week, particularly regarding the challenge of detecting SWIR. However, this week I worked to solve this problem using a couple of methods.

First, I started taking successive measurements in two minute intervals. During the two minute intervals, I am able to obtain about 20 measurements. This will permit me to average the 20 different measurements together in hopes of canceling out noise that may be concealing the SWIR data.

A second method has been to make adjustments in the integration time and gain settings of the Spectro-Polarimeter and make comparisons in order to find the optimal settings.

The Spectro-Polarimeter is not able to detect light over the range of 350 nm to 2500 nm with a single detector. Consequently, within the instrument are three separate detectors as follows. A silicon photodiode detector covers the range of 350 nm to 1050 nm and two indium gallium arsenide detectors cover ranges of 900 nm to 1850 nm and 1700 nm to 2500 nm respectively.

The graphs above illustrate the differences between a single measurement and an average of 20 measurements.

As an additional note, the discontinuities in the graphs are due to the different detectors within the Spectro-Polarimeter.

While the averaging technique noticeably helped, adjusting the integration time and gain settings produced the most noticable change. The integration time was reduced so that the measurements over the visible spectrum (VIS) did not overwhelm those of the SWIR and the gain setting was adjusted to its maximum in order to boost the signal.

I have also continued on the Solar Radiometer project. This week I started soldering the components of Solar Radiometer circuit together.