[Blueboard] Ateneo Physics News

Quirino Jr. M. Sugon qsugon at ateneo.edu
Mon May 8 17:29:53 +08 2017

The Department of Physics of Ateneo de Manila University cordially invites
you to a Physics Dissertation Defense:

Student name: Caironesa Pada
Schedule and venue: 10 May 2017, 4 PM, F-106


Dr. Raphael A. Guerrero (Physics), Dissertation Adviser
Dr. Percival F. Almoro (UPD), Dissertation Examiner
Dr. James Bernard Simpas (Physics), Dissertation Examiner
Dr. Maria Obiminda Cambaliza (Physics), Dissertation Reader
Dr. Christian Lorenz Mahinay (Physics), Dissertation Reader


A tunable diffraction grating shows promise in applications from beam
steering to spectroscopy due to the versatility of its design. A
diffraction grating made of polydimethylsiloxane (PDMS) is replicated using
simple soft lithography. Tunable diffraction is accomplished by modifying
groove spacing through the application of strain on the elastomeric grating
replica. The range of strain-variable diffraction angles is extended by
adding a refracting liquid layer to the grating. The scanning of the
1st-order diffraction angles as the grating pitch is tuned is demonstrated
when the grating operates in transmission and reflection mode. In
transmission mode, using a water layer, the diffraction angle is tuned from
38o to 33.4o with an applied strain of 17.7%. With an equal amount of
strain, adding a glycerol layer results in the diffraction angle varying
from 38.8o to 34.4o. When the grating operates in reflection mode, with a
water layer, effective diffraction angle is 24.85o with 8.86% strain. This
is equivalent to the output at an applied mechanical strain of 12.8% of an
unmodified grating. The addition of glycerol as a refracting element to the
tunable grating yields 27.8o with an applied strain of 8.86%. Without
glycerol, this angle can be achieved at a strain level of approximately
14.76%. The addition of liquid layer proves an efficient way to extend the
range of the 1st-order diffraction output. The experimental results are
accurately described by the combined effects of diffraction by a deformable
grating and refraction by a fluid with a curved surface.


Dr. Quirino Sugon Jr.

Assistant Professor, Department of Physics, Ateneo de Manila University
Program Manager, Upper Atmosphere Dynamics, Manila Observatory
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