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Design Review Spartan IR Camera E Loh, Physics-Astronomy Department, Michigan State University East Lansing, 22 May 2001 1 Science Goals (ref: NSF proposal)

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Presentation on theme: "Design Review Spartan IR Camera E Loh, Physics-Astronomy Department, Michigan State University East Lansing, 22 May 2001 1 Science Goals (ref: NSF proposal)"— Presentation transcript:

1 Design Review Spartan IR Camera E Loh, Physics-Astronomy Department, Michigan State University East Lansing, 22 May 2001 1 Science Goals (ref: NSF proposal) 2 Optical Design (ref. “Optical Design”) –Optical alignment (ref: “Alignment” & “SOBER”) 3 System Design & Electronics (ref. “Electronics”) 4 Mechanical Design (ref. “Mechanical Design”) 5 Budget & Schedule (ref. “Budget & Schedule”)

2 22 May 2001DR SOAR Spartan IR Camera2 The Team Jason Biel, technician –Measurements for vacuum design –Electronics designer & technician Mike Davis, graduate student –Optics Owen Loh, Okemos High, volunteer –Finite-element analysis –Drafting Tom Palazzolo, head, Phys-Ast shop –Mechanical shop, design advice, contact for mechanical designers & job shops Jack Baldwin, Brooke Gregory, Ron Probst, Dan Edmunds, Phys-Ast EE, advisors E Loh

3 22 May 2001DR SOAR Spartan IR Camera3 1. Science Goals Tip-tilt corrected imaging in the J, H, & K bands To cover the wide, corrected field (5’) To resolve FWHM of median seeing (0.15–-0.23”) To resolve high-contrast features at the diffraction limit (0.08” @H & 0.11” @K)

4 22 May 2001DR SOAR Spartan IR Camera4 Point-spread Function with Tip-Tilt Correction Point spread function is not a gaussian Diffraction spike Median seeing Top quartile

5 22 May 2001DR SOAR Spartan IR Camera5 Image Width Sub 0.5” images w/o tip-tilt 0.15-0.23” images w tip-tilt Telescope optics preserves images Telescope degradation. Goodyear CDR

6 22 May 2001DR SOAR Spartan IR Camera6 2. Optical Design Concept Image Quality Tolerances

7 22 May 2001DR SOAR Spartan IR Camera7 Optical Concept Requirements –Large number of pixels [ 2 x 5’ / 0.08” = 7500 pixels ] –Large telescope image [ 5’ x 4.2m x 16 = 100mm square] Rockwell 2048x2048 HgCdTe detector –4 detectors & 7500 pixels  two plate scales Reflective optics  large telescope image Off-axis collimator & camera mirror –Parent design: two paraboloids Perfect image for 1:1 & small field –Real design for change in plate scale Adjust conic constants, distances Field flattening lens

8 22 May 2001DR SOAR Spartan IR Camera8 Design Four 2048 2 detectors Two plate scales: 0.08 & 0.04”/pixel 20 filters near pupil Focal plane mask –coronagraphy –spectroscopy

9 22 May 2001DR SOAR Spartan IR Camera9 Image Quality: Spot Diagram 9 Field points in a grid. Corners are corners of 4 detectors. H band f/11 f/21 Airy disk

10 22 May 2001DR SOAR Spartan IR Camera10 Image Quality: Strehl Ratio 9 Field points in a grid. Corners are corners of 4 detectors. Strehl is very high for diffraction sampled cases, f/21 in H and K bands Sampled for diffraction limit

11 22 May 2001DR SOAR Spartan IR Camera11 Tolerances Error budget –Loss of Strehl of ~0.07mag Alignment Manufacturing

12 22 May 2001DR SOAR Spartan IR Camera12 Alignment Tolerances 1mil over 6in 6mil

13 22 May 2001DR SOAR Spartan IR Camera13 Manufacturing Tolerances Focal lengths are absorbed in focus SORL can manufacture conic constants Surface irregularity –Peak-to-valley is /16 to /4.  = 633nm

14 22 May 2001DR SOAR Spartan IR Camera14 Alignment with SOBER Align at room temperature with point source, SOBER, & CCD SOBER –f/16 beam –Move SOBER & shift stop to mimic pupil at 10m –z stage mimics curved focal surface of telescope –Tolerances 1mm & 1º –Image in IR? TBD Soar Beam Simulator LED & pinhole Lenses R-  stage ISB surface Sliding stop z stage

15 22 May 2001DR SOAR Spartan IR Camera15 Alignment Indicator Intensity of 9 field points indicates error Y-decenter of collimator  0.34mmX-tilt of fold #1 of  0.2mrad

16 22 May 2001DR SOAR Spartan IR Camera16 Test of Alignment x-position of collimator; wrong y-tilt of lens; right Defect: I 7 { "@context": "http://schema.org", "@type": "ImageObject", "contentUrl": "http://images.slideplayer.com/13/4008353/slides/slide_16.jpg", "name": "22 May 2001DR SOAR Spartan IR Camera16 Test of Alignment x-position of collimator; wrong y-tilt of lens; right Defect: I 7

17 22 May 2001DR SOAR Spartan IR Camera17 3. System Design & Electronics System Electronics Software Motors Vacuum

18 22 May 2001DR SOAR Spartan IR Camera18 System Design PC Stages Detector Data ArchiveObserverTelescope Control Pressure Sensor Umbilical Camera Controller Motor Controller Legend Camera Controller Detector DeviceNet NI 6533 RS232 Fiber optic Ethernet RS232 On camera In vacuum In control rack Elsewhere Camera Controller Custom Commercial

19 22 May 2001DR SOAR Spartan IR Camera19 Umbilical Card Provenance –CCD system DRV11 interfaceNI 6533 interface Laptop-type power supply Master clock Test pod FIFO NI 6533 Camera card Serializer deserializer Fiber-optic tranceiver Logic Analyzer Existing CCD Software on Alpha In FPGA One of 4 channels shown For debugging

20 22 May 2001DR SOAR Spartan IR Camera20 Camera Card Provenance: CCD camera 4 analog channels for 4 quadrants Laptop-type power supply Phase-locked loop Test pod Umbilical card Serializer deserializer In FPGA Detector Fiber-optic tranceiver Amplifier &16-bit ADC (2 12-bit ADC) Buffer Fixed voltages (digital pot) Timer & clock generator TemperatureDiodes Logic Analyzer Instruction

21 22 May 2001DR SOAR Spartan IR Camera21 Umbilical Card 3U 100  160 mm Tested w/ CCD software 160mm NI 6533 Fiber optic to 4 detectors FPGA 7V in To logic analyzer To existing computer

22 22 May 2001DR SOAR Spartan IR Camera22 Camera Card 3U 100  160 mm Low crosstalk –5-mil between signal & ground layers Delivery expected in 2 weeks FPGA Signal chains Fiber optic 7V in Flex cables to detectorNeck between analog & digital circuits 2.5  s/pixel 4 channels Power: 1.4W

23 22 May 2001DR SOAR Spartan IR Camera23 Noise Detector noise is about 10e – ; noise on amplifier glow is 5e –. Electronics noise is 6e –. Coupling from a saturated channel is about 2e –. Coupling from clocks on cable is large. –Sampling signal must wait 100ns after clock transition.

24 22 May 2001DR SOAR Spartan IR Camera24 Detector Card Card butts on 2 sides Connects to camera card with 5 flex cables, which are thermal resistors. 3 layers with 5-mil G10. Electrically isolated straps to nitrogen dewar Flex cables Detector ZIF socket

25 22 May 2001DR SOAR Spartan IR Camera25 Software Functions [copied from Optical Imager] –Control detector –Scripting –Communicate with motors –Communicate with telescope control system –Communicate with user ArcView –Used for all SOAR instruments –CTIO will debug ArcView with Optical Imager, the commissioning instrument LabView, “visual programming” –Independent of hardware  obsolescence is obsolete –Self documenting –Easy to do. ArcView costs < 1 man-year

26 22 May 2001DR SOAR Spartan IR Camera26 Software Tasks Design –Use commercial parts with LabView drivers Modify ArcView –Computer send commands and receives data from camera controller through NI 6533 card. Replace Leach controller & driver with NI 6533 card. Our card has a 4k sample FIFO –0.6ms margin for 4 detectors reading simultaneously –Write software for summing pictures –Change software for formatting picture –Change motor controls –Add temperature & vacuum sensing

27 22 May 2001DR SOAR Spartan IR Camera27 Motion Phytron stages DT-90 & MT-85 –Vacuum compatible –Stepper motor –Indexing switch –Limit switches –Open loop; controller stores position Controller –RS232 to computer –LabView –Heat Shutoff power? Cooler?

28 22 May 2001DR SOAR Spartan IR Camera28 Vacuum Measurement Granville-Phillips ion gauge –Computer readout via DeviceNet –LabView –12W; need to shut off

29 22 May 2001DR SOAR Spartan IR Camera29 4 Mechanical Design Cryogenic optical box –A-frame attachment to vacuum enclosure –Analysis of flexure Vacuum enclosure –Analysis of stress –Transfer of forces from A-frame to instrument mounting box (ISB) Mechanisms using warm stages –Layout –Proof of concept Flexure Heat load Operating temperature of stage & optics

30 22 May 2001DR SOAR Spartan IR Camera30 Cryogenic Optical Box Symmetric box having two plates equidistant from optics. –Gravity vector is in plane. –Optics supported by both plates. Torque perpendicular to plates Box is attached near focal surface of telescope –Rotation of optical box causes no boresight error.

31 22 May 2001DR SOAR Spartan IR Camera31 A-frame Attachment Connect cold optical box to warm vacuum enclosure Complies with shrinkage of optical box –Web weak in z Hold box w/o sag –Web strong in x & y Heat load is 0.7 W for 4 A- frames. G10 ring G10 web Al leg Section removed for clarity Bolt to optical box Bolt to warm vacuum enclosure Weak for thermal compliance Strongest; max sag: 14  or 0.04” Safety stop

32 22 May 2001DR SOAR Spartan IR Camera32 Rotation of Optical Box Gravity parallel to mounting plate. (Causes boresight error) First approximation –Optical box rotates 40  rad as a unit –Sag is 14  at telescope focus. More precisely –Error is greater for gravity perpendicular to mounting plate. –Rotation within box is 2.3  rad peak-to-peak –Boresight shifts 0.007”. 34–46  rad0–155  rad

33 22 May 2001DR SOAR Spartan IR Camera33 Vacuum Enclosure Aluminum plate, mostly 1/2” Max stress is here –Max is tensile strength / 2.2. –Code for pressure vessels is 3.5. –Is this OK?

34 22 May 2001DR SOAR Spartan IR Camera34 Transfer of Forces to Bolts on ISB Does the vacuum enclosure transfer forces between the A- frames and the bolts on the instrument mounting box (ISB) without sag? Yes. Sag is 2 . Bolts to A-frames Bolts to ISB Sides of vacuum enclosure Optical box

35 22 May 2001DR SOAR Spartan IR Camera35 Mechanisms Two filter wheels –Loose tolerances Focal-plane mask –300  along optic axis, 18  in transverse direction Collimator insertion –Tilt 5  rad (1”) as instrument turns for boresight with tip-tilt sensor Camera mirror insertion –Tilt 5  rad as instrument turns Rotate lens-detector by 112.7±0.6mrad –Tilt 0.2mrad (30  over 150mm) Move lens-detector assembly for focusing Difficult

36 22 May 2001DR SOAR Spartan IR Camera36 Layout of Mask & Filter Wheel Load is balanced  Easy to meet tolerances. Phytron DT-90 rotational stages –Integrated stepper motor, indexing switch, limit switch –Spring constant 2  rad/(N-m). Wobble is ±15  rad (Clarification needed.) Vacuum enclosure Optical box Rotation stage Mask wheelFilter wheel

37 22 May 2001DR SOAR Spartan IR Camera37 Layout of Mirror Insertion Mirrors must be balanced to meet 5  rad tolerance. Vacuum enclosure Optical box Rotation stage Mirror Counterweight Background mirror f/21 collimatorf/11 camera

38 22 May 2001DR SOAR Spartan IR Camera38 Proof of Concept: Insert f/21 Mirror Requirements. Cold mirror — warm stage — cold optical box –Support with tilt < 5  rad –Keep mirror cold –Keep stage warm –Minimize heat load –Comply with thermal expansion Precepts –Balance load –Use G10 A-frames to control conduction & comply with thermal expansion –Shield stage from cold to control radiation –Allow stage to absorb radiation from warm vacuum enclosure

39 22 May 2001DR SOAR Spartan IR Camera39 Mirror Insertion f/21 collimator Counterweight DT90 rotational stage Bracket attaches to optical box 4 A-frames 4 A-frames between stage & bracket (hidden) Center mass

40 22 May 2001DR SOAR Spartan IR Camera40 Results for f/21 Insertion A-frames have 1x1x5mm legs. Balance within 1mm. Wrap stage in 10 layers of aluminized mylar. Results –Conduction is 170mW –Tilt is 2  rad; tolerance for boresight alignment is 5  rad. –Sag with mirror vertical is 8  ; tolerance for internal alignment is 0.8mm. –Sag with mirror horizontal is 4  ; tolerance for focus is 15 . –Temperature of mirror is 88K. –Temperature of stage is 2K below ambient. (Area of radiator is 10% that of the stage.)

41 22 May 2001DR SOAR Spartan IR Camera41 5 Budget & Schedule Budget Contingency Descope Risk to budget Schedule

42 22 May 2001DR SOAR Spartan IR Camera42 Budget Not allocated or charged: Majority of electrical engineer, mechanical engineer, project management, drafting (done so far), and finite-element analysis.

43 22 May 2001DR SOAR Spartan IR Camera43 Contingency vs Remaining Tasks Tracking of tasks since budget of Aug 2000 –Electronics design is 17% over budget. ($5k of $29k) –Design of telescope simulator is 65% over budget. ($5k of $8k) –Optics design is 31% under budget. ($6k of $19k) –Overall budget dropped $100k because mechanical design firmed up, optics shortened, and mirror quotes dropped. Contingency is 36% of remaining tasks.

44 22 May 2001DR SOAR Spartan IR Camera44 Descope Descope 2nd plate scale, J, H, K, Ks filters only, spectroscopy & coronagraphy. Descope will be treated as contingency. –Descoped items will be added as contingency allows. –Possible formula: spend if Budgeted Contingency > 1.5 Actual Contingency

45 22 May 2001DR SOAR Spartan IR Camera45 Risk to Project Number of risks covered –A big item is $100k. –Labor for optical box, mechanisms, enclosure is $70k with $30k contingency Drafting: 3 mo. Internal shop: 7 mo. External shop: 1 mo. Technician: 6 mo. –Contingency, $193k, covers 2 big risks –Descope, $175k, covers 2 big risks. Descope & contingency  remaining tasks of descoped instrument

46 22 May 2001DR SOAR Spartan IR Camera46 Schedule Overview

47 22 May 2001DR SOAR Spartan IR Camera47 Detector Multiplexer & engineering-grade device delivered. Long slack time before science-grade detector is needed.

48 22 May 2001DR SOAR Spartan IR Camera48 Electronics 7 mo. slack

49 22 May 2001DR SOAR Spartan IR Camera49 Optical Box, Enclosure, & Mechanisms Optical box & enclosure will soon be a critical task. Plans for mechanisms have changed. –Swales Aerospace’s estimate is 3 times higher than that of 1998. –New plan is to purchase high quality, warm stages & design non- precision parts. –Short slack.

50 22 May 2001DR SOAR Spartan IR Camera50 Optics Optics & filters are behind schedule. –Estimated time is 2–3 times longer than vendors’ quotes of 26 weeks, because of word-of-mouth tales. –Schedule could be made up with immediate requisitions and on- time deliveries

51 22 May 2001DR SOAR Spartan IR Camera51 Software ArcView will be fully tested by CTIO with the Optical Imager. Scope of software task is uncertain. –No experience with LabView. –Need to see ArcView. If task is beyond students’ capability, we will seek vendor such as Imaginetics.

52 22 May 2001DR SOAR Spartan IR Camera52 Integration & Installation There is a 16 week period for fixing problems. Delivery is scheduled for 3/28/03.

53 22 May 2001DR SOAR Spartan IR Camera53 Risk to Schedule Tasks on the critical path –Optics are delayed. –Optical box & enclosure have little slack. –Mechanisms have a short slack. Delay of funding is the greatest risk. –Without starting on the critical tasks, we cannot test our estimates. We cannot set accurate bounds on the task.


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