ngst ifu prototype
DESCRIPTION
NGST IFU Prototype. Slit/Pupil Mirror Design. Original Design. Both Pupil and Slit mirrors required raster grinding to produce freeform surfaces in monolithic substrate Full tolerance analysis and specification produced. Pupil Mirror. Slit Mirror. Interim Design. - PowerPoint PPT PresentationTRANSCRIPT
Manosque, 25 February 2003
University of Durham Astronomical Instrumentation GroupAstronomical Instrumentation Group
NGST IFU Prototype
Slit/Pupil Mirror Design
Manosque, 25 February 2003
University of Durham Astronomical Instrumentation GroupAstronomical Instrumentation Group
Original Design
• Both Pupil and Slit mirrors required raster grinding to produce freeform surfaces in monolithic substrate
• Full tolerance analysis and specification produced
Pupil Mirror
Slit Mirror
Manosque, 25 February 2003
University of Durham Astronomical Instrumentation GroupAstronomical Instrumentation Group
Interim Design
• IFU re-designed to eliminate need to use raster (freeform) grinding
• Compromise in output slit performance (each “slitlet” focuses in different position in focal plane)
• Considered easier by LFM to manufacture
Manosque, 25 February 2003
University of Durham Astronomical Instrumentation GroupAstronomical Instrumentation Group
Interim Design – Pupil Mirror
• Pupil Array Design– Zerodur Substrate– Monolithic
Construction– Toleranced– Full Specification
produced– Cost Estimate
~€12,000
Manosque, 25 February 2003
University of Durham Astronomical Instrumentation GroupAstronomical Instrumentation Group
Interim Design – Pupil Mirror
• Slit Design– Construction as for
pupil mirror– Fully Toleranced and
specification produced– Cost estimate
~€12,000
Manosque, 25 February 2003
University of Durham Astronomical Instrumentation GroupAstronomical Instrumentation Group
Issues With Manufacture
• Development of Raster Grinding of Zerodur still in early stages of development
• Proposed a “simplified” IFU design to use line contact method of grinding
• IFU re-designed to accommodate line contact method of manufacture (but…)
Manosque, 25 February 2003
University of Durham Astronomical Instrumentation GroupAstronomical Instrumentation Group
Issues Still Remaining• Steps between Pupil/Slit
facets will cause problems when grinding (unable to control quality/shape of surface close to step)
• Either:– Larger gaps between facets– Modified grinding wheel
(experimental)
Manosque, 25 February 2003
University of Durham Astronomical Instrumentation GroupAstronomical Instrumentation Group
Line Contact Grinding (Spherical)
Manosque, 25 February 2003
University of Durham Astronomical Instrumentation GroupAstronomical Instrumentation Group
Line Contact Grinding (Toroidal)
Manosque, 25 February 2003
University of Durham Astronomical Instrumentation GroupAstronomical Instrumentation Group
Raster Grinding
Manosque, 25 February 2003
University of Durham Astronomical Instrumentation GroupAstronomical Instrumentation Group
Grinding Setup (Line Contact)
Manosque, 25 February 2003
University of Durham Astronomical Instrumentation GroupAstronomical Instrumentation Group
Manosque, 25 February 2003
University of Durham Astronomical Instrumentation GroupAstronomical Instrumentation Group
Rougness Measurement (test Component)
Ra=10nm
Manosque, 25 February 2003
University of Durham Astronomical Instrumentation GroupAstronomical Instrumentation Group
Interferometry (test component)
• This should have a picture of the interferometry data however including it crashes my laptop
• Aperture 4mm x 6mm• Spherical – ROC = 66.2mm• PV : 0.174• rms : 0.023
Manosque, 25 February 2003
University of Durham Astronomical Instrumentation GroupAstronomical Instrumentation Group
Next Stages (Zerodur Optics)
• Produce spherical “proof of concept” monolithic mirror
• Toroid production tests• Tackle issue of stepped facets• Produce line contact ground
components• Develop raster grinding techniques
Manosque, 25 February 2003
University of Durham Astronomical Instrumentation GroupAstronomical Instrumentation Group
Timescale For Development
• To develop repeatable/reliable process for production of monolithic components in Zerodur (line contact method with steps between facets)
– not possible before August 03• This gives a problem with IFU
schedule
Manosque, 25 February 2003
University of Durham Astronomical Instrumentation GroupAstronomical Instrumentation Group
Proposal
• Develop IFU system with replacement metal (Aluminium) Pupil and Slit arrays
• Perform all warm/vibration tests with metal components – replace with Zerodur when techniques fully developed
• Durham shall provide metal components (already have much experience with GNIRS IFU)
• Pursue Zerodur components in parallel
Manosque, 25 February 2003
University of Durham Astronomical Instrumentation GroupAstronomical Instrumentation Group
GNIRS IFU Slit Mirror
Manosque, 25 February 2003
University of Durham Astronomical Instrumentation GroupAstronomical Instrumentation Group