ao:lab_ao
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ao:lab_ao [2018/07/07 10:08] (current) jones |
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| * After e.g. 300mm, the beam hits the dichroic. | * After e.g. 300mm, the beam hits the dichroic. | ||
| * After e.g. 300mm, the beam hits the LDC | * After e.g. 300mm, the beam hits the LDC | ||
| - | The thin-lens formula simple script that Mike used to make these calculations is {{ao: | + | The thin-lens formula simple |
| - | + | import numpy as np | |
| - | | + | import matplotlib.pyplot as plt |
| - | | + | |
| - | | + | f1 = 1280. |
| - | .\\ \\ The wavefront sensor could be built around the 18-00079 microlens array from SUSS - 53 Euro each. These have a 30 micron pitch, meaning that with a 5 lenslet sampling across the pupil (19 lenslets altogether), | + | f2 = 192. |
| + | | ||
| + | | ||
| + | smallpsize=19.0 | ||
| + | # focus_from_secondary | ||
| + | ffs = 1.0/(1.0/(f2-dz) - 1.0/f2) | ||
| + | #pupil distance (in mm) | ||
| + | pd = 200000. | ||
| + | #pupil distance to secondary | ||
| + | pds = 1.0/(1.0/f1 - 1.0/pd) - (f1 - f2 + dz) | ||
| + | | ||
| + | pfs = 1/(1/pds - 1/f2) | ||
| + | psize = smallpsize*(f2-dz)/ | ||
| + | #19mm collimator from pupil | ||
| + | frat = ffs/ | ||
| + | colfs = ffs + smallpsize*frat | ||
| + | colfdm = colfs - pfs | ||
| + | #plt.plot(pfs, | ||
| + | \\ The wavefront sensor could be built around the 18-00079 microlens array from SUSS - 53 Euro each. These have a 30 micron pitch, meaning that with a 5 lenslet sampling across the pupil (19 lenslets altogether), | ||
| * A 25mm diameter, 150mm focal-length achromat that forms a new pupil image. | * A 25mm diameter, 150mm focal-length achromat that forms a new pupil image. | ||
| * A 1-2mm focal-length lens to collimate, the microlens array, and a 2nd <10mm focal-length lens in a lens tube, or possibly a double | * A 1-2mm focal-length lens to collimate, the microlens array, and a 2nd <10mm focal-length lens in a lens tube, or possibly a double | ||
| * A Thorlabs DCC1545M CMOS detector, reading out a ~320x240 subarray at >200Hz (this doesn' | * A Thorlabs DCC1545M CMOS detector, reading out a ~320x240 subarray at >200Hz (this doesn' | ||
| - | An example Zemax for this that almost works is:\\ [[/ | + | An example Zemax for this that almost works is:\\ [[http://chara.gsu.edu/wiki/data/pages/ao/files/ |
| - | + | [[http://chara.gsu.edu/wiki/data/pages/ao/files/ | |
| - | * [[/ | + | \\ An issue with this design is that a focal-plane shift of 0.18mm is required for a 0.5 lenslet shift, because the pupil-plane is located very close to one 2mm focal-length from the 2mm lens. This both causes poor image quality and possibly vignetting, depending on how the mounts are arranged. This means that pupil alignment can not be done by tilting the beamsplitter, |
| - | * [[/ | + | \\ The Thorlabs parts for this option without the DM mount are below:\\ {{ao:Thorlabs_-_My_Shopping_Cart.pdf|Thorlabs - My Shopping Cart.pdf}}\\ |
| - | * 89 KB | + | \\ {{ao:shoppingCart.xls|shoppingCart.xls}}\\ |
| - | [[/ | + | \\ The advantage of the larger micro lens arrays is that no XY translation is needed for alignment. Moving the focus spot by 130 microns moves the pupil image by 75 microns or half a lenslet. This is 180 arc sec in lab-units, or about 3 arc sec on-sky. Stability is needed at the level of 0.1 lenslets, i.e. 36 arc min, or 173 micro-radians. According to Thorlabs, this is way within spec for the mirror mount.\\ \\ The z-translation of the lens tube moves the outer lenslets by 0.5 lenslets at 2.5mm, and the 0.1 lenslet tolerance is a 0.5mm motion of the lens tube. This kind of adjustment precision is possible without any z-translation mounts.\\ \\ Finally - Laszlo suggested that the optical tolerances would be easier if focal-lengths were longer. This Zemax is given below, with a a shopping cart that includes both options.\\ |
| - | + | [[http://chara.gsu.edu/wiki/data/pages/ao/files/ | |
| - | * [[/ | + | [[http://chara.gsu.edu/wiki/data/pages/ao/files/ |
| - | * [[/ | + | {{ao:Thorlabs_-_CHARA_AO.pdf|Thorlabs - CHARA AO.pdf}}\\ |
| - | * 89 KB | + | {{ao: |
| - | \\ An issue with this design is that a focal-plane shift of 0.18mm is required for a 0.5 lenslet shift, because the pupil-plane is located very close to one 2mm focal-length from the 2mm lens. This both causes poor image quality and possibly vignetting, depending on how the mounts are arranged. This means that pupil alignment can not be done by tilting the beamsplitter, | + | |
| - | + | ||
| - | * [[/ | + | |
| - | * [[/ | + | |
| - | * 87 KB | + | |
| - | \\ The Thorlabs parts for this option without the DM mount are below: | + | |
| - | + | ||
| - | * [[/ | + | |
| - | * [[/ | + | |
| - | * 333 KB | + | |
| - | \\ [[/ | + | |
| - | + | ||
| - | * [[/ | + | |
| - | * [[/ | + | |
| - | * 9 KB | + | |
| - | \\ The advantage of the larger micro lens arrays is that no XY translation is needed for alignment. Moving the focus spot by 130 microns moves the pupil image by 75 microns or half a lenslet. This is 180 arc sec in lab-units, or about 3 arc sec on-sky. Stability is needed at the level of 0.1 lenslets, i.e. 36 arc min, or 173 micro-radians. According to Thorlabs, this is way within spec for the mirror mount.\\ \\ The z-translation of the lens tube moves the outer lenslets by 0.5 lenslets at 2.5mm, and the 0.1 lenslet tolerance is a 0.5mm motion of the lens tube. This kind of adjustment precision is possible without any z-translation mounts.\\ \\ Finally - Laszlo suggested that the optical tolerances would be easier if focal-lengths were longer. This Zemax is given below, with a a shopping cart that includes both options.\\ [[/ | + | |
| - | + | ||
| - | * [[/ | + | |
| - | * [[/ | + | |
| - | * 87 KB | + | |
| - | [[/ | + | |
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| - | * [[/ | + | |
| - | * 99 KB | + | |
| - | [[/ | + | |
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| - | * [[/ | + | |
| - | * [[/ | + | |
| - | * 371 KB | + | |
| - | [[/ | + | |
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| - | * [[/ | + | |
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| - | * 10 KB | + | |
ao/lab_ao.1530970140.txt.gz · Last modified: 2018/07/07 09:29 by jones
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