Error Causes and Magnitudes in Thermochromic Liquid Crystal Thermometry

Abstract

This paper investigates experimentally and assesses the errors that may be incurred in the hue-based thermochromic liquid crystal (TLC) method, and their causes. The errors include response time, hysteresis, aging, surrounding illumination disturbance, direct illumination and viewing angle, illumination light intensity, TLC thickness, digital resolution of the image conversion system, and measurement noise. Some of the main conclusions are that (1) the 3×8 bits digital representation of the red, green and blue TLC color values produces a temperature measurement error of typically 1% of the TLC effective temperature range, (2) an 8-fold variation of the light intensity into the camera produced variations, which were not discernable from the digital resolution error, (3) this temperature depends on the TLC film thickness, (4) thicker films are less susceptible to aging and thickness nonuniformities.