Developing an Automatic Measuring Instrument for the Prismatic Refractive Power of Lenses
Ching-Huang Lin a, Cheng-Chung Lee b, Wen-Hong Wu c, Fu-Kuei Chan d and Shun-Yuan Chien e
aDepartment of Electronic Engineering, National Yunlin University of Science and Technology, Yunlin, Taiwan, 640, ROC
bGraduate School of Engineering Science and Technology, National Yunlin University of Science and Technology, Yunlin, Taiwan, 640, ROC,
cTaiwan Instrument Research Institute, National Applied Research Laboratories, Hsinchu, Taiwan, 300, ROC
dYIN-TSUNG Co., Ltd., Tainan, Taiwan, 717, ROC
eProject, Hardline Laboratory, SGS Taiwan Ltd., Kaohsiung, Taiwan, 806, ROC.
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Abstract:
With improvements in quality of life, the demand
for high-quality safety glasses and sunglasses has
increased. Prismatic refractive power is a crucial
aspect of eyewear testing. According to ISO 18526-
1:2020, this testing procedure involves focusing an
inspection beam on a scale target 2 m away after it
passes through the glasses. Subsequently, the
prismatic refractive power of the lenses is determined
by observing the displacement of the focal point.
Nevertheless, human observation errors may occur
during testing. Therefore, in this study, a machine
vision module was developed to obtain target images,
and image processing and recognition techniques were
used to automatically determine the position of the
focused spot of light and calculate each lens’s
prismatic refractive power. This instrument eliminates
the need for human observation, manual calculation,
and record-keeping, and it reduces the workforce
required for inspection.
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