TY - JOUR
T1 - 650 GHz imaging as alignment verification for millimeter wave corneal reflectometry
AU - Hu, Yong
AU - Baggio, Mariangela
AU - Dabironezare, Shahab
AU - Tamminen, Aleksi
AU - Toy, Brandon
AU - Ala-laurinaho, Juha
AU - Brown, Elliot
AU - Llombart, Nuria
AU - Deng, Sophie X.
AU - Wallace, Vincent
AU - Taylor, Zachary D.
PY - 2022
Y1 - 2022
N2 - A system concept for online alignment verification of millimeter-wave, corneal reflectometry is presented. The system utilizes beam scanning to generate magnitude-only reflectivity maps of the cornea at 650 GHz and compares these images to a precomputed/measured template map to confirm/reject sufficient alignment. A system utilizing five off-axis parabolic mirrors, a thin film beam splitter, and two-axis galvanometric mirror was designed, simulated, and evaluated with geometric and physical optics. Simulation results informed the construction of a demonstrator system which was tested with a reference reflector. Similarity metrics computed with the aligned template and 26 misaligned positions, distributed on a 0.5 mm x 0.5 mm x 0.5 mm mesh, demonstrated sufficient misalignment detection sensitivity in 23 out of 26 positions. The results show that positional accuracy on the order of 0.5 mm is possible using 0.462 mm wavelength radiation due to the perturbation of coupling efficiency via beam distortion and beam walk-off.
AB - A system concept for online alignment verification of millimeter-wave, corneal reflectometry is presented. The system utilizes beam scanning to generate magnitude-only reflectivity maps of the cornea at 650 GHz and compares these images to a precomputed/measured template map to confirm/reject sufficient alignment. A system utilizing five off-axis parabolic mirrors, a thin film beam splitter, and two-axis galvanometric mirror was designed, simulated, and evaluated with geometric and physical optics. Simulation results informed the construction of a demonstrator system which was tested with a reference reflector. Similarity metrics computed with the aligned template and 26 misaligned positions, distributed on a 0.5 mm x 0.5 mm x 0.5 mm mesh, demonstrated sufficient misalignment detection sensitivity in 23 out of 26 positions. The results show that positional accuracy on the order of 0.5 mm is possible using 0.462 mm wavelength radiation due to the perturbation of coupling efficiency via beam distortion and beam walk-off.
KW - Biological and medical imaging
KW - THz imaging of cornea
KW - medical diagnostics
KW - clinical instruments
UR - http://www.scopus.com/inward/record.url?scp=85122558009&partnerID=8YFLogxK
U2 - 10.1109/TTHZ.2021.3140199
DO - 10.1109/TTHZ.2021.3140199
M3 - Article
AN - SCOPUS:85122558009
SN - 2156-342X
VL - 12
SP - 151
EP - 164
JO - IEEE Transactions on Terahertz Science and Technology
JF - IEEE Transactions on Terahertz Science and Technology
IS - 2
M1 - 9669169
ER -