Triana epic stray light evaluation
Download
1 / 21

Triana EPIC Stray Light Evaluation - PowerPoint PPT Presentation


  • 77 Views
  • Uploaded on
  • Presentation posted in: General

Triana EPIC Stray Light Evaluation. Preliminary Analysis and Results Dennis Charles Evans Optics Branch, Code 551 Instrument Synthesis & Analysis Laboratory 301-286-6237 / 301-262-2230 / ee@erols.com February 27, 2002. EPIC Optical & Mechanical Models. Optical Models GTRIANA.SEQ

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha

Download Presentation

Triana EPIC Stray Light Evaluation

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Triana EPIC Stray Light Evaluation

Preliminary Analysis and Results

Dennis Charles Evans

Optics Branch, Code 551

Instrument Synthesis & Analysis Laboratory

301-286-6237 / 301-262-2230 / ee@erols.com

February 27, 2002

EPIC ASAP RESULTS.ppt


EPIC Optical & Mechanical Models

  • Optical Models

    • GTRIANA.SEQ

      • Failed to load successfully in Code-V

      • Converted to ZEMAX OK using SEQ2ZMX.exe

    • GTRIANA-00.ZMX

      • Good optical performance

        • Strehl Ratio 0.66-0.60 for all wavelengths over FOV

  • Mechanical Model

    • Epic.igs (provided)

    • Epic-IGS-02.dwg (converted, edited AutoCAD)

EPIC ASAP RESULTS.ppt


EPIC Optical & Mechanical Models

  • Reasonable Agreement Mechanical & Optical Models

    • Telescope Optics and Focal Plane within 0.01 inch

      • As good as fabrication and assembly tolerances

    • Filter position different by up to 1.74 inch (ZMX=aft of IGES)

      • Not expected to have any significant effect

    • No IGES Lenses, but ZMX lenses centered in “Lens Holder”

  • No printed copy ICD drawings of optical system

    • There have been obvious design changes from concept to build

    • No really good optics illustration available, especially baffle system

EPIC ASAP RESULTS.ppt


ZEMAX Model

EPIC ASAP RESULTS.ppt


ASAP 3D Model (Telescope & Detector)

View from behind Telescope

View looking into telescope.

Note Green Detector.

EPIC ASAP RESULTS.ppt


Full ASAP Model

View from behind Telescope

View looking into telescope.

Note: Lenses & Filter covers Detector.

EPIC ASAP RESULTS.ppt


ASAP 3D Model as Traced

EPIC ASAP RESULTS.ppt


View from Detector

Smooth Cylinder Wall

that can be illuminated

EPIC ASAP RESULTS.ppt


ASAP Optical Model

  • IGES Conversion Problems

    • Did not trim extended flat surfaces correctly

    • Typical problem with IGES flavors

    • Not likely to be a problem in model construction

  • ASAP Model constructed by selective modeling

    • Typical procedure, usually better than blind IGES insertion in both speed and quality

EPIC ASAP RESULTS.ppt


Baffling Observations

  • Does not meet definition of well baffled system

    • Detector can see space [through lenses & filter]

    • No significant space sources likely (Moon occasionally)

    • Missing Primary central baffle tube an academic concern

  • Limited Vane implementation

    • None detected on Barrel Baffle

    • None on Spider arms or inner ring (cylinder)

      • Spider arms not modeled, but inner ring cylinder was modeled

    • None inside Secondary Housing

    • Limited to none on cylinder near Detector

  • Dominate Stray Light

    • From optical surface ghosts [at 1/600 level]

    • Missing vanes unlikely to be significant for EPIC

    • Would not be good low light level instrument, but doesn’t need to be.

EPIC ASAP RESULTS.ppt


ASAP Surface Models

  • Mirrors

    • Reflectivity, 0.98

    • BRDF, none applied, unlikely to be a problem

  • Three Lenses & Single Filter

    • Coating Per Surface: (ARF05)

      • 0.95 Transmission, 0.05 Reflection

  • Detector Cover

    • 0.80 Transmission, 0.20 Reflection

  • All other surface

    • 0.00 Transmission, 0.05 Reflection (Lambertian)

  • EPIC ASAP RESULTS.ppt


    Floor at 1E-3

    Near ghost < 1/1000

    EPIC ASAP RESULTS.ppt


    Floor at 1E-4

    Near ghost between 1/1000 and

    1/10,000

    EPIC ASAP RESULTS.ppt


    Floor at 1E-5

    Near ghost between 1/1000 and

    1/10,000.

    General ghosting obvious.

    EPIC ASAP RESULTS.ppt


    Floor at 1E-6

    Near ghost between 1/1000 and

    1/10,000.

    General ghosting obvious.

    EPIC ASAP RESULTS.ppt


    Floor at 1E-3

    Near ghost is about 1/600

    EPIC ASAP RESULTS.ppt


    Floor at 1E-4

    Near ghost is about 1/600.

    General ghosts between

    1/600 to 1/1000.

    All look like surface ghosts.

    EPIC ASAP RESULTS.ppt


    Floor at 1E-5

    Near ghost is about 1/600.

    General ghosts between

    1/600 to 1/1000.

    All look like surface ghosts.

    No new ghosts.

    EPIC ASAP RESULTS.ppt


    Floor at 1E-6

    Near ghost is about 1/600.

    General ghosts between

    1/600 to 1/1000.

    All look like surface ghosts.

    EPIC ASAP RESULTS.ppt


    ASAP Spot Plot Displays

    • Point Sources:

      • At combinations of 6371 and 3186 km referenced to Earth

        • Each, 5 rings of 36 rays for 180 rays,

    • Extended Source:

      • 102 mm radius, shifted 300 mm up (+Y)

      • 150 meters from Secondary Vertex

      • (1/2916)-(1/150000)=(1/2861); 55 mm image shift

      • f/9 implies ± 2.5 mm edge blurring (unlikely to mask any problems)

      • ASAP low flux limit.

        • Intended source; 2000 km diameter at 1.5E6 km distance, 3000 km offset.

    • Result

      • Stray light (ghosting) begins at the 1/600 to 1/1000 level.

    EPIC ASAP RESULTS.ppt


    ASAP Spot Plot Displays

    • Displays

      • Adjusted for peak flux (logarithmic) density [Flux/sq-mm]

      • Lower level truncation at 3, 4, 5, and 6 decades below peak

      • Pixilation is 256 x 256 over 36 mm square. [0.140 mm pixels]

    • Point Source Ray Statistics

      • 5 rings of 36 rays each; 180 rays

      • 1620 rays starting from 9 field points

      • 554,937 rays traced (ray splits at transmission surfaces)

      • 120,659 rays absorbed by detector

    • Extend Source Ray Statistics

      • 200,000 rays left source aimed for oversized entrance edge

      • 3,193,734 rays traced (ray splits at transmission surfaces)

      • 1,053,293 rays absorbed by detector

    EPIC ASAP RESULTS.ppt


    ad
  • Login