1. Manosque, 25 February 2003 University of Durham Astronomical Instrumentation Group IFU Progress Meeting 2 Slit/Pupil Mirror Development NGST IFU Prototype Slit/Pupil Mirror Design

2. Manosque, 25 February 2003 University of Durham Astronomical Instrumentation Group IFU Progress Meeting 2 Slit/Pupil Mirror Development 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

3. Manosque, 25 February 2003 University of Durham Astronomical Instrumentation Group IFU Progress Meeting 2 Slit/Pupil Mirror Development 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

4. Manosque, 25 February 2003 University of Durham Astronomical Instrumentation Group IFU Progress Meeting 2 Slit/Pupil Mirror Development Interim Design – Pupil Mirror Pupil Array Design –Zerodur Substrate –Monolithic Construction –Toleranced –Full Specification produced –Cost Estimate ~€12,000

5. Manosque, 25 February 2003 University of Durham Astronomical Instrumentation Group IFU Progress Meeting 2 Slit/Pupil Mirror Development Interim Design – Pupil Mirror Slit Design –Construction as for pupil mirror –Fully Toleranced and specification produced –Cost estimate ~€12,000

6. Manosque, 25 February 2003 University of Durham Astronomical Instrumentation Group IFU Progress Meeting 2 Slit/Pupil Mirror Development 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…)

7. Manosque, 25 February 2003 University of Durham Astronomical Instrumentation Group IFU Progress Meeting 2 Slit/Pupil Mirror Development 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)

8. Manosque, 25 February 2003 University of Durham Astronomical Instrumentation Group IFU Progress Meeting 2 Slit/Pupil Mirror Development Line Contact Grinding (Spherical)

9. Manosque, 25 February 2003 University of Durham Astronomical Instrumentation Group IFU Progress Meeting 2 Slit/Pupil Mirror Development Line Contact Grinding (Toroidal)

10. Manosque, 25 February 2003 University of Durham Astronomical Instrumentation Group IFU Progress Meeting 2 Slit/Pupil Mirror Development Raster Grinding

11. Manosque, 25 February 2003 University of Durham Astronomical Instrumentation Group IFU Progress Meeting 2 Slit/Pupil Mirror Development Grinding Setup (Line Contact)

12. Manosque, 25 February 2003 University of Durham Astronomical Instrumentation Group IFU Progress Meeting 2 Slit/Pupil Mirror Development

13. Manosque, 25 February 2003 University of Durham Astronomical Instrumentation Group IFU Progress Meeting 2 Slit/Pupil Mirror Development Rougness Measurement (test Component) Ra=10nm

14. Manosque, 25 February 2003 University of Durham Astronomical Instrumentation Group IFU Progress Meeting 2 Slit/Pupil Mirror Development 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

15. Manosque, 25 February 2003 University of Durham Astronomical Instrumentation Group IFU Progress Meeting 2 Slit/Pupil Mirror Development 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

16. Manosque, 25 February 2003 University of Durham Astronomical Instrumentation Group IFU Progress Meeting 2 Slit/Pupil Mirror Development 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

17. Manosque, 25 February 2003 University of Durham Astronomical Instrumentation Group IFU Progress Meeting 2 Slit/Pupil Mirror Development 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

18. Manosque, 25 February 2003 University of Durham Astronomical Instrumentation Group IFU Progress Meeting 2 Slit/Pupil Mirror Development GNIRS IFU Slit Mirror

19. Manosque, 25 February 2003 University of Durham Astronomical Instrumentation Group IFU Progress Meeting 2 Slit/Pupil Mirror Development