Ateneo Physics student builds low-cost polarimeter from LEGO and simple circuitry

Mr Ryan Joseph Felicidario, a BS Applied Physics student, together with his thesis adviser Dr Ramon delos Santos, of the Ateneo Physics Department Photonics laboratory built a low-cost polarimeter using LEGO bricks for testing the purity of two brands of ascorbic acid. 

A polarimeter is an instrument that is used to measure the direction and angles of rotation of polarized light after passing through a compound and typically costs around PhP 70,000 or more, depending on the accuracy, wavelength capabilities, and automation features of the device. The one developed by the Ateneo researchers only costs around PhP 8,000. Their design is composed of an LED light source, a protractor, a polarizer, and a simple circuitry.  

Moreover, their results show that one sample of the ascorbic acid exhibited specific rotations close to theoretical values, indicating high purity, while the other sample showed significant deviations from the expected specific rotation, indicating the presence of impurities in the sample. Their results were supplemented by melting point determination experiments, where the sample with high purity exhibited narrow melting ranges, while the other significantly diverged from literature value. 

This innovative and low-cost device may be used for classroom demonstrations and research contributing to the advancement of our Science education in the country.

The full link to their article can be found here: Measurement of Ascorbic Acid Samples' Optical Rotation via an Improvised Polarimeter for Purity Assessment.