A battery powered near infrared (NIR) camera for the MIT HelioDome

Abstract

Research in advanced fenestration systems has led to the development of the Heliodome project at the Massachusetts Institute of Technology Daylighting Laboratory. The MIT Heliodome project is dedicated to goniophotometry and the assessment of bidirectional photometric properties of light- (or heat-)redirecting facade systems by using digital cameras as multiple-points photosensors, that cover the visible and near infrared portions of the sunlight spectrum. Two cameras are used in this device: a charge couple device (CCD) camera using silicon detectors and a near infrared (NIR) camera using InGaAs sensors. Both cameras are mounted to a table which has two degrees of rotational freedom, altitude and azimuth. Using the rotating table and cameras in combination with an ellipsoidal dome, which is coated with a semi-transparent specula coating, allows a time-efficient and continuous measurement of bidirectional transmission (or reflection) density functions (BTDFs or BRDFs). This thesis seeks to enhance current Heliodome operations by developing a portable power source for the NIR camera. A portable power system has been designed and constructed to operate the NIR camera during measurement sessions. The portable power system allows the rotating table to rotate completely free of constraints caused by weight, imbalance, power and light path obstruction issues. This contribution to the Heliodome project provides the user with more reliable data and relief from disorderly setup.