Determination of dominant color of light emitting objects using spectrophotometric analysis

Date

11-2001

Degree

Bachelor of Science in Applied Physics

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Nelio C. Altoveros

Abstract

A spectrophotometer was used to determine the dominant color of a light-emitting object such as tungsten. An analog-to-digital converter (PCADCl2) card was used to facilitate the data acquisition system. The set-up used a photosensor (Hamamatsu #S7505) as the detector of the emitted light of a body and outputs a corresponding voltage signal for each wavelength color. The study makes use of a tungsten lamp as the source of radiated light. The ADC was calibrated by feeding analog signals ranging from 66mV to 913mV at I mV interval to its input channels namely channels 0, 1 and 2 of the ADC. The voltmeter reading of the analog signal was compared to the reading of the ADC and the resulting slope and intercept for channels 0, 1 and 2 are 0.8742 and 0.5026, 0.8742 and 0.5537, and 0.8742 and 0.6348, respectively. The spectral response of the photosensor was determined using a spectrophotometer. The tungsten lamp's power supply ranges from 15 ± 0.10 V to 24 ± 0.10V. The spectral response of the red filter was determined within 720nm to 520nm, for the green between 620nm to 420nm and 550nm to 350nm for the blue filter where in the sensor is sensitive. The spectral distributions acquired were used to compute the tristimulus values (X, Y, and Z). The dominant wavelengths were determined using the CIE Chromaticity system by computing the chromaticity coordinates (x, y) using the tristimulus values earlier computed. These coordinates were plotted to the CIE 1931 Chromaticity diagram where the dominant wavelength was determined. Based from the results, it was observed that the dominant wavelength shifted to shorter wavelength as the input voltage of the tungsten lamp was increased. The study shows that color of the dominant light was light orange at 15V and it becomes lighter as the power supply was increased.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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