In Zemax we represented a symplified version of the FLAO and LUCI optical systems:
  1. The Pyramid arm of the FLAO WFS up to the detector pupil plane (w/o pyramid). This configuration is highligthd in blue color.
  2. The Pyramid arm of the FLAO WFS up to the F45 focus. This configuration is highligthed with green color in figures below.
  3. The F15 focus of the telescope behind the LUCI window (red color in figures).

20140731_FLAO_LUCI_alignment_3DLayout.JPG 20140731_FLAO_LUCI_alignment_3DLayout2.JPG 20140731_FLAO_LUCI_alignment_3DLayout3.JPG

The system also considers the LUCI rotator DoF. This variable is picked-up to accordingly move the pupil rerotator on board of the WFS unit (configurations 1 and 2).

After having offsetted the optical surface properly the analysis procedure sets the LUCI rotator to different angles and it records the position of the PSF on both F15 and F45 planes and the chief-ray position on the pupil plane in the W unit. At each rotation angle the ASM tip-tilt is optimiezed to recenter the PSF on the F45 plane simulating closed loop operation.

LUCI window tilted by 0.5deg

PtV of LUCI PSF wobble of 2.5mm = 4.2" over a 360deg rotatot angle


From the above Zemax calculation we retrieve the PSF wobble vs rotator angle in function of an incoming beam tilt of 1deg (0.5deg error on LUCI window) = 4.2" / 2 * 2 * PI / 360deg = 36.6mas/deg

SPEC is to have 5mas/2.5deg = 2mas/deg so 18.3 times less than 0.5deg on LUCI window = 0.027deg = 1.7' maximum tilt.

Considering a pupil wobble diameter of 0.35mm introduced by 0.5deg of LUCI window tilt we estimate the pupil wobble diameter to be 20um for a 1.7' of window tilt.

Board tilted by 0.5deg

PtV of LUCI PSF wobble of 1.75mm = 2.9" => 5.8"/deg


M3 tilted by 0.005deg

No wobble noticable


-- MarcoBonaglia - 31 Jul 2014
Topic revision: r4 - 29 Sep 2015, MarcoBonaglia
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