Expanded Project Information & Concept Introduction
Table of Contents
What is Goniophotometry?
- This is merely a combination of a gloss measurement + an angle measurement. Measuring both of these properties allows the creation of a more useful metric than standard gloss meters on the market. In creating a data set of gloss levels with a corresponding angular component a far more accurate and descriptive indicator of gloss is created.
Introduction to Gloss and Goniophotometry
- The measurement of gloss is essential in a wide variety of industries. Gloss is an optical phenomenon caused when evaluating the appearance of a surface. The evaluation of gloss describes the capacity of a surface to reflect directed light. Goniophotometry is a field that integrates the measurement of gloss from a variety of angles. In doing so, far more information can be obtained about the actual gloss properties of the item. Gloss is often used as a criterion to evaluate the quality of a product, especially in the case of products where the aesthetic appearance is of importance. This includes products such as automotive coatings, furniture coatings, plastics, metals and paper. A visual gloss evaluation includes many subjective sources of error and is not sufficient. Therefore, to be objective, it is necessary to put a measured value on the degree of gloss. A complete evaluation of gloss is dependent on several factors. Since the 1930's, measuring instruments have been used to associate reflection behavior and a defined measurement value under defined conditions. Gloss when perceived by the human eye is a subjective evaluation. However, visually observed differences can not always be measured physically by using, for example, glossmeters.
Current Technological State of Goniophotometry at RIT
- The printing and imaging science department at RIT is the primary information source of information, expertise, and experimentation on goniophotometry. The current system is an experimental device that resides in the college of imaging science. The current device requires a substantial amount of experience to operate and interpret. This project is aimed at creating a system that isn't as cumbersome, is easy to operate, and has useful and easy to interpret data output. Scientists and researchers from RIT are researching the field and have various systems in place that can successfully measure gloss with respect to varying angles. The goal of this project is to take the scientific knowledge and lab setting system onto the next stage. Developing a compact system that doesn't require substantial training or a degree in advanced optics to operate is the overall goal of this project. The product should be scaled down and be in as many ways as possible self calibrating, self functional, and provide easy to interpret but robust technical measurements. In addition, the system should provide repeatable output and the overall manufacturing of the system should be fully documented in order for repeat devices to be produced from the teams engineering specifications.
Current Systems In UsePortable Gloss Meter
This is an example of a fixed angle gloss measuring device used in industry, Although it can measure gloss, it only does so from one fixed position.
- Information Taken From: http://www.paint-test-equipment.co.uk/Gloss%20Meters.htm
The sample is mounted on the goniometer and rotated around a pivot point through two axes of rotation. This presents the different orientations of the test item towards a detector, mounted at a distance across the room. Through this way the luminous flux and luminous intensity distribution (beam characteristics) of the test item is measured.
- Information Taken From: http://www.ferret.com.au/articles/73/0c03fc73.asp
Sphere Measuring Goniophotometer
NPL has developed the use of goniophotometers that mimic integrating spheres, for photometric measurements. Goniophotometric measurements are made using a photometer, mounted on the end of an arm that is free to scan the surface of a notional sphere, with the source mounted at the centre of this sphere. They are primarily used for the measurement of the luminous intensity distribution of lamps and luminares, but it is also possible to determine luminous flux from the directional, SI base unit, of luminous intensity. This is achieved by mapping the illuminance over the surface of a sphere surrounding the source and summing over the total solid angle of 4 PIE steradian.
- Information Taken From: http://www.npl.co.uk/optical_radiation/instrumentation/gonio_fac.html