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LCLV and Adaptive Optics
Amar IUCAA
Advisor: Prof. Ramprakash
AO Test Bench Flowchart
Sky simulator Atmospheric distortion simulator
Telescope simulator
Laser guide star
Tip-tilt open/close loop
DM open/close loop, higher order correction
Science instrument
The AO test bench (correct this schematic)
LCLV as a prospective AO substitute
Stating the problem for higher order corrections
• The writing light has intensity variations and this intensity variations is transformed into phase variations in the reading side.
• Need to convert the phase changes to intensity changes effectively.
Who are the proposed candidates
• Brewster angle concept. • Internal reflection concept. • Moire’ and Fourier transformation concept.
Whom do I prefer
• Moire’ and Fourier transformation concept.
Brewster angle and internal reflection concept
Moire’ and Fourier concept to convert the phase in a 2D wavefront
into intensity variations.
What is needed ??
For a wave front with no higher order aberrations
Transformation Intensity
What is needed ??
For a wave front with higher order aberrations
Transformation Intensity
Trying Moire’ and Fourier concepts
Incident LGS wavefront with distortions
This is the image plane
Trying Moire’ and Fourier concepts
Reference wavefront
Spatial negative grid
This is the image plane
Trying Moire’ and Fourier concepts
Superimpose
A Break
A Micro Channel Plate
The setup LGS wavefront
Reference wavefront in lab
Superimposed output
Low intensity High intensity
suitable for LCLV write side
MC
P
Optics
How does the flow chart look now
AO Test Bench Flowchart
Sky simulator Atmospheric distortion simulator
Telescope simulator
Laser guide star
Tip-tilt open/close loop
DM open/close loop, higher order correction
Science instrument
Reference laser wavefront
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MC
P
Science 11
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(1) Sky Simulator Screen (2) Optics (3) Wedge (4) Transparency sheet or a hot plate (5) Optics (6) Optics (7) LGS mirror (8) Cassegrain secondary mirror (9) Cassegrain primary mirror (10) Folding mirror (11) Reference laser (12) Optics for reference laser (13) Narrow band laser frequency filter (14) Optics (15) Spatial grid (16) Spatial negative grid (17) Superimposing optics (18) Wavefront with local phase distortions shown up as
intensity distortions. (19) Microchannel Plate for light amplification suitable for
LCLV system. (20) Wavefront with optimum light amplification for
LCLV system (21) Optics (22) LCLV system (23) Folding mirror (24) Tip-tilt mirror (25) Optics (26) Off axis optics to shift the target light (27) Fold mirror (28) Tip-Tilt sensor
(29) Electronics for algorithm (30) Optics (31) Optics (33) Fold mirror
Thank You