Device for selecting lightwave ranges via computer control for studying building material properties via goniophotometer

Abstract

To enable the fast and accurate cataloging of material samples, I designed a filtration device for selecting specific visible and near-infrared light wavelengths related to the red, green, and blue sensitivity peaks of a visible detection camera and the pixel response for a near-infrared camera. This filter device functions in conjunction with the Department of Architecture's Daylighting Laboratory goniophotometer to profile the complete reflection and transmission properties for sample building materials. The resulting data is used in computer simulations and material optimization. The goniophotometer uses two types of detection cameras, color and infrared, to measure the light that is transmitted or reflected off a sample of material. The spectral sensitivity variances of the cameras create inaccuracies in the resulting data when full-spectrum light is used. To remove these inaccuracies, the light is filtered into smaller sections of the full spectrum and the data is recombined by software, to remove these inaccuracies. The device to filter the light is the subject of this thesis. The final filter design uses a geneva drive to index wheels containing pairs of high-pass and low-pass filters into the light path between the light source and the test specimen.

(cont.) The device satisfies the design specifications dictated by the usability, function and spatial constraints. This design should prove to be very reliable and flexible through its continued use in studying building materials. As the project is advanced, future work includes installation of the control system and integration into the software used to coordinate the goniophotometer components.