1. SNAP spectrograph demonstrator : Test Plan
Cedric CERNA
CNRS (IN2P3,INSU) FRANCE,

2. Performances requirements Functional requirement
INTRODUCTION
As explain in the specification requirements document :
The demonstrator should demonstrate the capability of the slicer technology to achieve the main performance requirements derived from the scientific requirements of the SNAP instrument.
Performances requirements
Functional requirement
November 15 & 16, 2005
Cerna, C.

3. Summary Functional requirements summary Test plan : Entrance PSF (R2)
Image quality (R3)
Pointing accuracy (R4)
Diffraction losses (R5)
Distortion correction (R6 + RP4)
Straylight measurement (R7)
November 15 & 16, 2005
Cerna, C.

4. Demonstrator summary stack of 5 slices, 10x0.5mm each
warm & cold tests are foreseen :
@ warm : 9x9mm pixels, 1 slice width imaged on 2 pixels
@ cold : 18x18mm pixels, 1 slice width imaged on 1 pixel
steering mirror relative positioning 1/10 of slice width
November 15 & 16, 2005
Cerna, C.

5. Functional requirements
2 detectors
R1 : wavelength coverage from 0.4 to 1.7 mm
R2 : PSF sampling  1mm = 1 slice width
 1rst Airy 1.7mm should contained in the FOV
R3 : Diffraction 1.7mm i.e. FWHMexp = FWHMth +/-5%
R4 : PSF Pointing : absolute 1/10 slice width
R5 : Diffraction losses : measure the diffraction losses due to the positioning of the PSF inside the slice
R6 : Distortions : correction of the distortions effects should be known at 1/10 of pixel
R7 : Straylight : must be measured < 10-3
Pupil & steering
5 slices
PSF measurements
November 15 & 16, 2005
Cerna, C.

6. Steering mirror test plan (R2)
Goal : verify the PSF shape and size in the visible range
250 mm
November 15 & 16, 2005
Cerna, C.

7. Diffraction limited (R3)
The diffraction have to be controlled at 1.7mm measuring the FWHM of the PSF with a precision of 5% to compare it with the simulation
(FWHMth~0.7mm)
November 15 & 16, 2005
Cerna, C.

8. Absolute pointing accuracy (R4)
We will already have a relative pointing accuracy
We are searching for an absolute one
Steering position
Intensity (%)
100
November 15 & 16, 2005
Cerna, C.

9. Diffraction losses (R5)
x,y,l scanning x y
intensity
diffraction losses y
November 15 & 16, 2005
Cerna, C.

10. Distortion correction 1/2 (R6)
Iso-lambda correction :
monochromatic sources
x,y,l scanning
detector y l
slicer x x
November 15 & 16, 2005
Cerna, C.

11. Distortion correction 1/2 (R6)
monochromatic flat field on one slice
monochromatic PSF multi-scan on one slice l
20 pxl width f l
FWHM
2-3 pxl
height
Fit with 1/10 pixel precision
achievable x y
slicer x
November 15 & 16, 2005
Cerna, C.

12. Distortion correction 2/2 (R6)
Iso-position correction :
large spectre sources
x,y,l scanning
November 15 & 16, 2005
Cerna, C.

13. Distortion correction 2/2 (R6)l
Fit with 1/10 pixel precision
achievable
~100 pixels
from 2 to 5 pixels x
November 15 & 16, 2005
Cerna, C.

14. Straylight measurement (R7)
Slits mirrors
Slices uniformly lighted
November 15 & 16, 2005
Cerna, C.

15. Straylight measurement (R7
PSF max = ADU
slit 1
Over exposure
CROSS-TALK
< 10-4
Proto 0, summer 2005
slit 0
slit -1
slice 1
slice 0
slice -1
SLIT 0
over exposition
PSF as small as possible
November 15 & 16, 2005
Cerna, C.

16. Test plan
This test plan will be almost the same for warm and cold test
It is in phase of finalization : illumination module (lamps, filters…) in course of definition
A detailed experience protocol document will be written for next spring
November 15 & 16, 2005
Cerna, C.

17. Spares slides
November 15 & 16, 2005
Cerna, C.

18. Photometry sphotometry l x f SNAP spectro simulation :
Star spectrum in the visible range
sphotometry f l
With an SNR=100
 sphotometry =5% is achievable x
November 15 & 16, 2005
Cerna, C.