1. SVOM MXT Lobster Eye Telescope Breadboard Model Testing Preliminary Results
Dick Willingale
Adrian Martindale, Jim Pearson, Charly Feldman, Julian Osborne
University of Leicester

2. SVOM MXT Breadboard F=1000 mm Aperture 210x210 mm2
Total mass of integrated optic ~1 kg (~250 kg/m2)

3. Narrow Field Lobster Eye Optimization
Maximize area at 1 keV
For wide field L/d≈50 constant
For narrow field
- maximum area on axis
L≈2.5dF/R
F=1150 mm
d=40 μm
21 square pore MCPs
- each plate has aperture
38 x 38 mm2
L 1.22 – 2.74 mm
L/d

4. Breadboard Model X-ray Testing
Testing 1 plate
Leicester TTF
Source at 27 m
F=1000 mm
Al support frame – spherical surface R=2000 mm
Machining accuracy ±10 μm
2x 20 μm plates, 2x 40 μm plates, 1x Ir coated plate

5. Measured Imaging 1.5 keV Single plate – off-axis
2 adjacent reflections - focus
0 reflection -
straight through
Single plate – off-axis
Set at nominal focal length
allowing for finite source distance
Focused spot
FWHM=6.0 arc mins
1 reflection - cross arm
Note: MXT detector 19.3x19.3 mm

6. Measured Imaging 1.5 keV Single plate – off-axis in vertical direction
2 adjacent reflections - focus
Edge of plate truncates cross arm
Single plate – off-axis in vertical direction
Set at nominal focal length
allowing for finite source distance
Length of cross-arm is the width of plate 38 mm, 2.18 degrees
1 reflection - cross arm

7. Results Single plate performance at nominal focus
FWHM 6.0 arc mins (c.f. 8.5x7.5 arc mins for MIXS-T)
Lobster eye performance better than Wolter I configuration but not as good as expected (4.5 arc mins) – possible explanation:
The finite source distance of 27 m not corrected for
Not at true focus
Combination of slumping, shear and surface roughness worse than expected
The measured efficiency ~70% of theoretical for the Ir coated plate
From the MIXS-T results (which used Ir coating) we expect 85% theoretical
The results are highly dependent on correct modeling of the test set up – the analysis is on-going
The available data are not consistent – maybe because of spectral contamination in the X-ray beam or maybe incorrect modeling – more analysis required
We hope to take more data early April 2015