Документ взят из кэша поисковой машины. Адрес оригинального документа : http://site2010.sai.msu.ru/static/doc/VOrlov_site2010.pdf Дата изменения: Mon Oct 18 13:30:52 2010 Дата индексирования: Mon Oct 1 20:07:40 2012 Кодировка:

Dynamic Shack-Hartmann System "RAPID"
V. G. Orlov, V. V. Voitsekhovich Instituto de AstronomМa, UNAM, MИxico

CONACYT project E9507-1020P

UNAM
PAPIIT IN104910


Telescopes OAN
OAN-SPM
2.1m telescope 1.5m telescope 0.84m telescope

2.1m telescope

OAN-Tonanzintla 1m telescope


Astronomical site SPM
Observing statistics 1982-2002 (Tapia+ 2007 )
"Photometric" nights: 64.1% "Spectroscopic" nights: 80.2% "Bad weather " nights: 21.2% Sky Transparency

0.84m telescope

Extinction coefficients: Visible: ky = 0.14 Red: KR = 0.05
SPM confirmed have largest fraction of clear nights of any site in the Northern Hemisphere


Sky Brightness in SPM
Brightness magnitudes

mU =21.7 mB =22.4 mV =21.5

mR =20.7
mI =19.2


Astronomical site SPM
San Pedro Martir
Good sky transparency Big number of clear nights Excellent image quality Photometric stability SPM is one of the darkest

1.5m telescope

sites in the Northern Hemisphere SPM is good for IR observing So, we are looking for big telescopes


Telescopio Optico-Infrarrojo Mexicano (TIM)
alt-azimuth mount Segmented mirror 6.5m > BTA (1996-2004)


SPM-Twin
Copy of Magellan 2 x 6.5m telescopes f/4.5 : WF-Spectroscopic Telescope WF AO telescope (2005-2008)


Synoptic All-Sky Infrared Survey (SASIR)
Magellan-inspired 6.5m mirror At least we have the

mirror. (2008-...)


Rapid - Dynamic Shack-Hartmann
All modern telescopes

demand installation of adaptive system. So, we have to study of spatial and temporal characteristics of the wavefront distortions. We have chosen a ShackHartmann wavefront sensor :
It is simply Compact data


Rapid - Dynamic Shack-Hartmann
1. Collimator:


Focal distance 200mm

2. Lenslet-Array. Shack­

Hartmann diaphragm:
Consists of 48 lenses with a

focal distance of 150 mm Hexagonal arrangement to minimize the wavefront measurement errors


Rapid - Dynamic Shack-Hartmann
Image Intensifier Tube Generation 2 (-10) Photocathode diameter, mm 24.5 Resolution, lp/mm 33,8 Photocathode sensitivity, A/lm 280 Light gain, 30,000 Dark background brightness, max, cd/m2 2.5x10-3 Signal-to-noise ratio 4 Consumption, max, mA 35 Mean time before failure, hours 2,000


Rapid - Dynamic Shack-Hartmann
Light intensifier
Generation 2 (-10)

3

Photocathode operating




diameter, mm 24.5 18 Resolution, lp/mm 33,8 58 Photocathode sensitivity, A/lm 280 1500 Light gain, 30,000 42,000 Dark background brightness, max, cd/m2 2.5x10-3 0.4 Signal-to-noise ratio 4 21 Consumption, max, mA 35 20 Mean time before failure, hours 2,000 10,000


Rapid - Dynamic Shack-Hartmann
·

High-speed CCD
·

· · ·

Based on SONY ICX055AL 1/3-inch CCD Image Sensor for CCIR B/W Camera 25,50,100,200 fr./sec. 200 is possible only for 256*288 Electronic shutter Calculate coordinates of the center of mass for each spot.

·
·

Special processor


Rapid - Dynamic Shack-Hartmann
Rapid Software:
Creation, saving or loading of

RAPID protocols Viewing and addition copies of the camera image, with tuning and textual comments saving Execution of operation of data accumulation in "Master" (Wizard) mode .


steps
First step:





choose of parameters of the camera assignment of the dark current. choose a video mode for reading data amount of frames, used for a dark level calculation. Shutter on/off amplification


steps
Second step:


Parameters for Hartmann picture place calculation : frequencies 200/100/50 (for 256*288 ) 100/50/25 (for 512*288 ) Hertz are available, amount of averaged frames: from 2 up to 1024 Amplification of the camera Amplification of the II "Preview" for previewing the image.


steps
Third step:
Choice of threshold meanings for Hartmann picture calculation. appropriate buttons

Fourth step:
Save data on the memory

Fifth step:
Save on the hard disk


Rapid Software
In the same protocol also it is possible:


write text of the comment save up to 50 mages directly from ccd.



The phase reconstruction

is very fast and simple.


Hartmann method