Development of an integral field unit (IFU) with an image slicerShinobu Ozaki, Satoshi Miyazaki, Takuya Yamashita, Takashi Hattori, Norio Okada, Kenji Mitsui (NAOJ)2011/01/18 Subaru Future Instrumentation Workshop

Integral Field Spectroscopy is a powerful tool3D data (XY+) is simultaneously obtained.Science exampleDetailed studies of AGN emission line regionsVelocity structureExcitation structureNGC1068 [OIII]l5007 channel map (Gerssen et al. 2006)

Project outlineFOCAS @ SubaruWFOS @ TMT

Why image slicer type IFU?AdvantageDead space on a detector is the smallest.DrawbackDifficulty of fabrication.Diminishing thanks to technology progressFrom ifu wiki

IFU optical layoutSlicerPupil mirrorsPseudo slitsPickup mirrorEnlargerField opticsTop viewSide viewFrom telescopeTo spectrographBased on GNIRS at Gemini observatory.We are considering another possible layout.We select the better layout, comparing these two.

IFU parameters*: Aspect ratio of FOV is fixed to be about 1.4.

Manufacturing methods for mirrorsHigh precision machining for metalAdvantageFast fabrication speedEasy to fabricate an aspheric surfaceCan make monolithic moduleDrawbackOnly a few experiences in astronomical instrumentation

Polishing for glassAdvantageAchievable low surface roughnessDrawbackSlow fabrication speedDifficult to fabricate an aspheric surfaceCannot make monolithic moduleManufacturing methods are closely coupled with optical layout.We choose the method after the decision of the optical layout.

Fabrication sample of high precision machiningTOSHIBA MACHINE CO.,LTDSurface roughness : Ra 0.7nmDiamond turning

Comparison with other instruments* (Information amount) = (Spatial element #) x (Spectral element #)

Comparison with future instruments* (Information amount) = (Spatial element #) x (Spectral element #)

ScheduleFY2010Parameter search (Done)Decision on optical layout ( till end of Jan.)Test fabrications of each modules (from Feb.)

FY2011IFU for FOCASDetailed designFabricationsAssemblePerformance verifications

FY2012Test observations with FOCAS+IFUStart developing the IFU for TMT/WFOS

BudgetsApplied for Grants-in-Aid for Scientific Research (Kiban-B)Applied for NAOJ internal budget

SummaryWe are developing the slicer type optical IFU.1st step: IFU for FOCAS/Subaru2nd step: IFU for WFOS/TMT

FY2012: First light of IFU for FOCAS