maxim webster cash university of colorado. capella 0.0001”
TRANSCRIPT
MAXIM
Webster CashUniversity of Colorado
Sne
SNR
Log
Dia
met
er (
cm)
Log Distance (pc)0 1 2 6543 987 10
6
8
10
12
14
16
18
Maxim
PathfinderHSTChandra
NS Disks
XRB Disks
Stellar Coronae
AGNJets
AGN BLR
AGNEvent
Horizons
GRBAfterglow
InteractingBinaries
CV
XRBOrbits
20
22Star
Clusters
GalaxiesClusters ofGalaxies
Capella 0.0001”
Capella 0.000001”
AR LacSimulation @ 100as
AGN Accretion DiskSimulations @ 0.1as
Courtesy of Phil Armitage, U. Colorado and C. Reynolds, U. Maryland
Need Resolution and Signal
If we are going to do this, we need to support two basic capabilities:
• Signal
• Resolution
X-ray Sources Are Super Bright
Example: Mass Transfer Binary1037ergs/s from 109cm object
That is ~10,000L from 10-4A = 108 B
where B is the solar brightness in ergs/cm2/s/steradian
Brightness is a conserved quantity and is the measure of visibility for a resolved object
Note: Optically thin x-ray sources can have very low brightness and are inappropriate
targets for interferometry. Same is true in all parts of spectrum!
Artist’s impression of Cyg X-1 (NASA)
My Impression
Status of X-ray Optics
• Modest Resolution– 0.5 arcsec telescopes
– 0.5 micron microscopes
• Severe Scatter Problem– Mid-Frequency Ripple
• Extreme Cost– Millions of Dollars Each
– Years to Fabricate
sin1B
2cos12 BB
sin2
sin
2cos121
BBOPD
sin20
cossin20
Baselined
2sin20
focald
Pathlength Tolerance Analysis at Grazing Incidence
A1 A2
S1S2
A1 & A2 in Phase Here
C
If OPD to be < /10 then
A Simple X-ray Interferometer
Flats
Detector
Wavefront Interference
d/L
=s (where s is fringe spacing)
d
Ls
s
Optics
Each Mirror Was AdjustableFrom Outside Vacuum
System was covered by thermal shroud
X-ray Fringes
1.25keVCash et al March 1999
0.5keVGendreau, October 2002
Flats Held in PhaseSample Many Frequencies
As More Flats Are UsedPattern Approaches Image
2 4 8
16 3212
Parallel to Source Direction
To focus
Periscope Configuration
Reduces Sensitivity to BaselineEach Periscope in the array is held to sin
Keeps beam pointedin constant directionlike thin lens
focus
Periscopes allow for delay in eachchannel. Can sample full UV plane.
Periscope Requirements
• Even Number of Reflections
With odd number ofreflections, beam direction shiftswith mirror tilt
With even number, the mirrorscompensate and beam travels in samedirection.
Phase Shift
Path Delay = h sin
h
so h < /10 for phase stability
if h~1cm then < 10-8 (2 milli-arcsec)
This can be done, but it’s not easy.
Phase Delay
)cot(cot2coscot)22sec(sincotsin22seccos(cos 2111122121 dP
d1
d2
)cot(cot2coscot)22sec(sincotsin22seccos(cos 43333424234222 d
There are Solutions
This solution can be direction and phase invariant
Dennis Gallagher has verified this by raytrace!
Pointing can wander arcseconds, even arcminutes, and beamholds fixed!
Array Pointing
• 4 mirror periscopes solve problem of mirror stability
• But what about array pointing?
• Doesn’t the array have to be stable to 1as if we are to image to 1as?
Thin Lens Behavior
As a thin lens wobbles, the image in space does not movePosition on the detector changes only because the detector moves
Formation Flying
If detector is on a separate craft, then a wobble in the lens has no effect on the image.
But motion of detector relative to Line of Sight (red) does!
Much easier than stabilizing array.Still the toughest nut for full Maxim.Variety of solutions under development.
Mirror FEMMirror Face Mirror Back
3pt Ti Flexure Mount
Optic w/FaceSheet Removed
Mirror Analysis SummaryAnalysis Goal/Req. Result Comments
1oc Bulk Temp Load min surface deformation PtoV=6.2nm, RMS=1.2nm
1oc X Gradient min surface deformation PtoV=3.2nm, RMS=0.6nm Gradient across mirror surface
1oc Y Gradient min surface deformation PtoV=3.1nm, RMS=0.6nm Gradient across mirror surface
1oc Z Gradient min surface deformation PtoV=17.0nm, RMS=3.8nm Gradient through mirror thicknessFixed Base Dynamics FF > 100 Hz FF=278 Hz Mirror on flexures, but not entire mount20g Quasi Static Load Mount Stress < Yield 35 MPa maximum 20g Y Loading20g Quasi Static Load Low Mirror Stress 7.6MPa maximum 20g Y Loading
1cZ Mirror Deformations (mm) 20gY Mirror Back Stresses (MPa) Mirror First Mode = 278 Hz
MAXIM Position Tolerances =1nm, F=20,000km, D=1km, m=30cm, =1deg, h=1m
DOF Mirror Equation Periscope Equation
MirrorTolerance
PeriscopeTolerance
X ±1.7nm ±4m
Y ±0.3mm ± 0.5mm
Z ±94.7nm ±0.32m
X-rot(yaw)
±6.9arcmin
± 7.8arcmin
Y-rot(pitch)
±2.3marcsec
± 10arcsec
Z-rot(roll)
±0.13arcsec
±18.5arcsec2D5
F2
)cos()sin(320
D5
F
10
)sin( m
310
)sin( m
)(sin320
)2cos(2
2
2
D5
F4
35
)sin( 15
)sin(
h20
22
10
sin
sin103
1
F
m
m
22
10
sin
sin10sin3
1
F
m
m
Optical Bench FEM
Flexure Fixed Mount
Simplified Optics Mounts
Main Bench
“Daughter” Benches
Periscope Assembly
Entrance Aperture(Thermal Collimator)
Shutter Mechanism(one for each aperture)
Assy. Kinematic Mounts (3)
Launch Configuration LayoutDelta IV ø5m x L14.3m 24 Free Flyer Satellites (4 Apertures ea.)1 Hub Satellite (12 Apertures)1 Detector Satellite
Ø4.75m
Aperture Locations (central area)
26
12
3
45
6
7
8
9
10
11
12
13
14
15
16
17
18
On the left is the probability distribution function for two sources in the same field of view. The central source has an energy half that of the source that is displaced to the lower left. The image on the right shows 9000 total events for this system with the lower energy source having twice the intensity of the higher energy source. Even though the higher energy source is in the first maxima of the other, the two can still be easily distinguished.
Stars
Simulation with Interferometer
Sun with SOHO
Black hole imager
black hole census
black hole physics
space interferometry
The Beyond Einstein Program
LIGO
Chandra
Swift
MAP
Hubble
Science and Technology Precursors
Dark EnergyProbe
optical imaging
Constellation-X
x-ray imaging
LISA
gravitational wave detectors
InflationProbemicrowave background detection
Black HoleSurveyProbehard x-ray detectors
Big BangObserver
dark matter physics
space interferometry, gravitational wave detection
dark energy physics
Bottom Line
• Maxim can be built in an affordable way
• Achieving 0.1mas can be done with modest control in free-flying
• Full black hole imaging for under $900M
• Maxim is in the planning
• NRA for “Vision Mission Studies” coming out this week.