Optical characterization of a reference instrument for gloss measurements in both a collimated and a converging beam geometry
2006
A reference instrument has been developed at the National Research Council of
Canada for rapid, reproducible specular gloss measurements. The design and
validation of this instrument for specular gloss measurements in accordance with
standard methods for paints and plastics at 20°, 60°, and 85° geometries [American Society for Testing and Materials (ASTM) D523
and the International Organization for Standards (ISO) 2813] have been recently reported. These standard methods require a collimated
beam geometry. Here we present the optical design considerations and characterization
of this instrument to extend its gloss measurement capabilities to specular gloss
measurements of paper samples at 75° geometry in accordance with standard test
methods requiring a converging beam geometry (ASTM D1223 and TAPPI T480). This
is, to the best of our knowledge, the first reported reference instrument that provides direct traceability for both types of standard gloss method and applications. The design challenge was to convert
from a collimated beam to converging beam geometry while meeting the rigorous
requirements of beam uniformity at the sample and receptor apertures specified in the 75°
geometry test methods. We describe the innovative design to achieve this degree
of functionality and reference instrument performance. The instrument's optical
performance has been characterized theoretically and by comparison with measurement
results. The light collection and detection systems have been analyzed via Monte Carlo
simulation and ray tracing. The instrument validation includes comparison of the
measurement results with theoretical gloss values for quartz, black glass, Vitrolite, and
mirror gloss working standards, giving agreement of better than
0.32%. Measurement
validation also involved participation in the Collaborative Testing Services program
interlaboratory comparison measurements of 75° gloss for white papers.
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
10
References
7
Citations
NaN
KQI