We have designed, constructed, and tested an optical polarimeter for use with the Virginia Military Institute (VMI) 0.5 m, f/13.5 Cassegrain telescope. Our instrument is based on the common dual-beam design that utilizes a rotatable half-wave plate and Wollaston prism to image starlight onto a CCD detector after it has passed through a broadband filter. The usable field of view is ≲10′′ and the operational range of the instrument is 400–700 nm. Measurements of unpolarized stars demonstrate that the instrumental polarization is ≲0.05%. Observations of seven standard stars were in agreement with their accepted values by an order of Δp(%) ≲ 0.23 for the degree of polarization and Δθ(°) ≲ 0.94 for the position angle.

No abstract

No abstract

This study presents the long time effects of varying temperature conditions on pH-responsive films deposited on glass slides. The films were fabricated from Brilliant Yellow and poly (allylamine hydrochloride) through ionically self-assembled monolayer technique using an automated slide strainer. The absorbance of the films was monitored and the effect of varying temperature on the optical properties of the films was studied. We found that as the films are maintained at increasing temperatures their absorbance slightly decreased. As the temperature increased the percent change decreased reaching a plateau. Films kept at low temperatures of 3.24 °C and below freezing (-9.02 °C) had a small increase in absorbance. Finally, we monitored the absorbance of films kept at room temperature over a long time (128 days) and found that the films showed decreased absorbance by 19%.

Students experience the entire process of designing, fabricating and testing thin films during their capstone course. The films are fabricated by the ionic-self assembled monolayer (ISAM) technique, which is suited to a short class and is relatively rapid, inexpensive and environmentally friendly. The materials used are polymers, nanoparticles, and small organic molecules that, in various combinations, can create films with nanometer thickness and with specific properties. These films have various potential applications such as pH optical sensors or antibacterial coatings. This type of project offers students an opportunity to go beyond the standard lecture and labs and to experience firsthand the design and fabrication processes. They learn new techniques and procedures, as well as familiarize themselves with new instruments and optical equipment. For example, students learn how to characterize the films by using UV-Vis-NIR spectrophotometry and in the process learn how the instruments operate. This work compliments a previous exercise that we introduced where students use MATHCAD to numerically model the transmission and reflection of light from thin films.