Maynooth University Department of Experimental Physics MODAL MODAL Maynooth Optical Design and Analysis Laboratory Uses Physical Optics and GBM Verified against GRASP 1 Farfield pattern of Horn w M ID: 813413
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Slide1
Optical Simulations
David Burke
Maynooth University
Department of Experimental Physics
Slide2MODAL
MODAL (Maynooth Optical Design and Analysis Laboratory)
Uses Physical Optics and GBM
Verified against GRASP
Slide31. Farfield pattern
of Horn (w/ M.
Zannoni
)
Mario measured the pattern of the horn in the far field in the Lab (at 60 cm)In MODAL the beam profile was investigated at 10, 20, 30, 40, 50 and 60 cm
The 60 cm data was compared to the data that was obtained by Mario
Results obtaine
d by e
xciting horn
with an on-axis plane wave
Slide4Farfield pattern of
Horn: 220 GHz
Slide5Farfield pattern of Horn: Comparison with Mario’s result
Slide6Farfield pattern of Horn:150 GHz
Slide7Farfield pattern of Horn: Asymmetry
of th
e E and H planes
150 GHz
220 GHz
Slide82. Spreading of beams due to bandwidth
Due to QUBIC operating at a broad range of frequencies the spread of the beam was investigated
Specifically looked at the lower range (130-170 GHz)
Compared the spread with the central frequency in the lower band
Slide9Spreading of beams due to bandwidth:
Results
Slide10Spreading of beams due to bandwidth:
Central cut
The spread data provided a reduction of the FWHM of the central
peak
Slide113. Coldstop
Restricted to
200
mm diameter (maximum)
circular coldstop due to filter size that can be made in CardiffPerformed tests in MODAL, only including the mirrors and the
coldstop
, to see if this smaller coldstop would have much of an effect on the beams on the focal plane
Also tested to see what is the minimum circular diameter at which the instrument shows measurable difference
This occurred at 165 mm diameter
Slide12Coldstop footprint
Slide13Coldstop affected beams
Some beams are affected when the
coldstop
gets small enough (specifically at 165 mm)
Slide14Coldstop: X21Y06
Slide15Coldstop: X17Y02
Slide164. Horn ring radii tolerance
Created geometry files with radii variations
of
0.05 mm
SCATTER was used to generate the far field plots and these were compared with the ‘perfect’ far field patternThe lower and higher frequency bands were examined
Slide170.05 mm tolerance: 130 and 190 GHz
0.05 mm tolerance: 150 and 220 GHz
Slide190.05 mm tolerance: 170 and 250 GHz
Slide20240 GHz 0.05 mm
Also Lateral shifts, thicker plates
Slide215. Calibration source simulation (w/ M. De Petris)
Winston cone (calibration
source) was put on the edge of the horn array
The specifications were obtained from D.
Buzi and M. De
Petris
Positioned at (0,-181.11,0) mm in GRF
50
º
FWHM
Simulations were performed in MODAL only including the mirrors
Results were compared with GRASP
Slide22Calibration source simulation
Simulated results in MODAL matched the results obtained from GRASP
6.57% power from emitted beam captured at focal plane
Slide23Calibration source
simulation
When the source was rotated (24
º
as recommended by D. Buzi and M. De
Petris
) to be centred on the primary, the
power
on the focal plane was still
low (only
3.37% of the emitted power captured)
Slide24Calibration source simulation
Source
was put in centre of the horn array to check the power
Power on the primary – 80.18%Power on the secondary – 73.98%Power on the focal plane
– 9.51
%
Slide25Calibration source (30 º FWHM)
Investigated the power collected by a cone that had a beam with a FWHM of 30
º
This gave a collected power
of 15.58%
Slide26Future Work
Examine the effect of a raised ring on the mirrors
Test tolerance/
allignment
of the mirror positions in the technical demonstrator at room temperature.Most urgent, using
Zemax