Integral Field Spectrograph Integral Field Spectrograph

Eric PRIETO

CNRS,INSU,France,Project Manager

11 November 2003

2

Spectrograph characteristicsSpectrograph characteristics

Property Visible IR

Wavelength coverage (m) 0.35-0.98 0.98-1.70

Field of view 3.0" 6.0" 3.0" 6.0"

Spectral resolution, 70-200 70-100

Spatial resolution element (arc sec) 0.15 0.15

detectorsLBL CCD

10 mHgCdTe

18 m

Efficiency with OTA and QE >40% >30%

3

Spectrograph: Functional OverviewSpectrograph: Functional Overview

RelayOptics

SlicerUnit

Collimator

PrismsDichroics

NIRCAM

VISCAM

NIRFocal plane

VisibleFocal plane

Shutter

Dithering

Thermal control

Interface Electronics

Science Software

Calibration lamps

OCU

4

• optics with 7 mirrors • two arms configuration• Two prisms

Pre optical design

Visible detector

IRdetector

slicerprisms

entrance

5

Entrance beam

IR detector

Visible detector

Floppy interface

Fix point

180 mm

dL=180 x (300-140) x 1,3.10-6 = 0,038 mm

420 mm

dL= 0,02 mm

dL = 0,09

6

Optical bench(Invar)weight =2,3Kg

Structural support

(Molibdenum)

weight =2,7Kg

Floppy interface

Fix point (nearest of the entrance beam point)

Structural support

fix on the cold plate

Displacement is amplify

7

Instrument road mapInstrument road map

Primary SNAP specifications

Concept definition

Pre conceptual

design

Detailed simulation

New requirements

Conceptual

design

Define system

requirements

Prove the feasibility

Verify performances

Budget errors

2002

2003

2004

First requirements

Interface control

document

8

Implementation:Implementation:

Telescope

Telescopefocal plane

IFS

Dark zone

9

Optical design (option1)Optical design (option1)

10

Slicer Design:Slicer Design:

11

Focal plan developmentFocal plan development

No ‘single point failure’

=> Only detectors are to be duplicate:

two detectors and their electronic:•Field of view of 3’’X6‘’ instead of 3’’X3’’ Field of view of 3’’X6‘’ instead of 3’’X3’’

•Need 40 slicesNeed 40 slices

•No effect on opticNo effect on optic

12

Performance: efficiencyPerformance: efficiency

# elementsEfficiency/elements

Cumulative efficiency

Telescope 4 0.98 0.92

Relay optic 1 0.98 0.90

Slicer(mirrors + straylight +

diffraction)0.82 0.71

SpectrographMirrors 2

PrismDichroic

0.980.810.95

0.57

Visible Detector 1 0.9 0.52

IR Detector 1 0.8 0.42

13

PerformancesPerformances

Spectral resolution for the visible detector

7595

115135155175195215235255275295

0,4 0,5 0,6 0,7 0,8 0,9 1

lambda Spectral resolution for the IR detector

70

75

80

85

90

95

100

105

110

1 1,1 1,2 1,3 1,4 1,5 1,6 1,7

lambdaZeemax optimisation

Simulation result

Integral Field Spectrograph:Integral Field Spectrograph:

R&T Slicer R&T Slicer

Eric PRIETO

CNRS,INSU,France,Project Manager

11 November 2003

(on behalf: ESA Slicer Prototype Team: LAM/CRAL/Durham

More specifically: Charles Maccaire and Florence Laurent)

15

SCOPESCOPE

• ESA Funded prototyping work

• JWST/NIRSPEC development• Previously MEMS back-up• Currently IFU option

• Collaboration LAM/CRAL/DURHAM

• Aim: Technical Readiness Level 6

16

Slicer PrincipleSlicer Principle

1. Field divided by

slicing mirrors in

subfields (40 for

SNAP)

2. Telescope pupil on

the pupil mirrors

3. Aligned pupil

mirrors

4. Sub-Field imaged

along an entrance

slit

Field beforeslicing

Pseudo-slit

Slicing mirror (S1)

Spectrogram

Pupil mirrors(S2)

To spectrograph

Field optics (slit mirrors S3)

From telescopeand fore-optics

1

2

3

4

How to rearrange 2D field to enter spectrograph slit:

17

Optical DesignOptical Design

Slice mirrorsSlit mirrors array

Pupil mirrors array

Steering mirror

18

Design OverviewDesign Overview

Active Stack

Heel

Stack support

Steering mirror

Pupil mirror array

Slit mirror array

Main structure

Substructure

Thrust cylinders

Dummy Stack

19

RealityReality

20

Reality: Image Slicer (uncoated)Reality: Image Slicer (uncoated)

Support

18 “Flat” Slices (Dummies)

10 “Curved” Slices (Actives)

2 “Flat” Slices (Dummies)

21

Slicing-mirror stack measurementsSlicing-mirror stack measurements

Images of the two scans• common reference surface• one slicing mirror is present in both scans and can be used to check results

22

Slicing-mirror stack measurementsSlicing-mirror stack measurements

Results• positioning accuracy includes both assembly and manufacturing errors

•Xc within +/- 22 µm from nominal

• Yc within +/-22 µm (except n°6) from nominal (measurement errors contribute to probably ~10 µm) to be compared to the +/-20 µm requirement

Slices mirrors curvature center DX default measured w ith the STIL machine

-0,025-0,020-0,015-0,010-0,0050,0000,0050,0100,0150,0200,025

1 2 3 4 5 6 7 8 9 10

slice number (1: sclice 28; 10: slice19)

DX

c (m

m)

Slices mirrors curvature center DY default measured with the STIL machine

-0,030

-0,020

-0,010

0,000

0,010

0,020

0,030

0,040

0,050

1 2 3 4 5 6 7 8 9 10

slice number (1: sclice 28; 10: slice19)

DX

c (m

m)

23

Pupil/slit mirrors linesPupil/slit mirrors lines

Opto-Mech. Mount

5 Pupil Mirrors

1 Broken Mirror

Glass Bar

•Optical contact released during manipulation

•New assembly will be produced compatible with vibration specifications

•Back-up solution from monolithic solution

24

Pupil-mirror line measurementsPupil-mirror line measurements

• damaged mirror to the right• scratches on the left-mirror are outside the usefull area (pupil size)

25

Pupil-mirror line measurementsPupil-mirror line measurements

Comparing the curvature center locations• remove a slope• compare with expected positions

MP_regresse

-0,005

0

0,005

0,01

1 2 3 4 5

x

y

Results• positioning accuracy includes both assembly and manufacturing errors • both Xc and Yc are within +/- 5-6 µm from their nominal positions (probably need to add a few µm of measurement accuracy)• to be compared to the +/- 20 µm requirement

the pupil mirror line meets the relative alignment requirements

26

Slit-mirror line measurementsSlit-mirror line measurements

• 5 identical mirrors• overall slope (will be removed during analysis)

27

Slit-mirror line measurementsSlit-mirror line measurements

Comparing the curvature center locations• remove a slope• compare with expected positions

Results• positioning accuracy includes both assembly and manufacturing errors • both Xc and Yc are within +/- 8 and even 1 µm from their nominal positions (probably need to add a few µm of measurement accuracy)• to be compared to the +/- 20 µm requirement

the pupil mirror line meets the relative alignment requirements

MF_RégressionLinéaire

-0,008

-0,006

-0,004

-0,002

0

0,002

0,004

0,006

1 2 3 4 5x

y

28

First Results: Pupil planeFirst Results: Pupil plane

• Impressive alignment of the pupils on the pupil mirrors

• Positioning alignment within 50µm (pitch: 2.75mm)

• Surface defect and edges are due to manipulation accident (assembly weakness)

• New line will be produced (stronger)

29

First PSF resultsFirst PSF results

• Preliminary results

• PSF Size in agreement with simulation

• Astigmitism & coma (as theory)

• Rotation along the slice

• TBD: deconvolve with instrumental PSF

30

First Results: Slit planeFirst Results: Slit plane

• Impressive alignment of the virtual slits on the slit mirrors

• Positioning alignment within 20µm (pitch: 2.75mm)

31

Thermal / Structural testsThermal / Structural tests

• Low level vibration tests performed: first mode 185hz

• Sinusoidal tests will be performed 20g (40g if possible)

• Random tests will be performed 15g (30 if possible)

• First test of optical mount at 77°K performed

• Full prototype will be tested @ 30-40°K (dec 03)

Insi

de L

iqui

d N

itro

gen

32

Current outputCurrent output

• System expertise demonstrated

• Optical manufacturing demontrated

• Optical performance compliant

• To be done: thermal qualification (Dec 03)

• To be done: vibration qualification (Dec 03)

• Re-manufacture pupil line for vibration (April 04)