Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Tandem Fabry-Perot Spectrometer SQUEAN: Spectrometer for QUasar in EArly uNiverse Presented at The 2nd Survey Science Group Workshop, High1 Resort on 2012 Feb 14 by Soojong Pak (Kyung Hee University) Classification of Spectrometers Types of Dispersing Elements Mechanism Type refraction Prism Spec. diffraction, interference Grating Spec. reflection, interference Image Slit (1D) Fourier Transform Spec. Imaging (2D) Fabry-Perot Spec. Slit Sp. vs. Imaging Sp. Imaging Spectrometer Slit Spectrometer Top View Spatial L d Side View Spec tr W al DATA Format Imaging Spectrometer Slit Spectrometer io ct ire n SpectralDirection Direction Spatial lD Spectral Direction tra ec Spatial Direction Direction Spatial Sp Spatial Direction Spatial Direction Other Kinds of Imaging Spectrometer: Integral Field Unit Other Kinds of Imaging Spectrometer: Multi-Object Spectrometer What is Fabry-Perot Spectrometer? Fabry-Perot Parameters Path Difference 2 d o cos m o Finesse d R F 1 R m=1 Instrument Profile I(, ,d , ) I ( T 1 R )2 4R 2 d cos 2 1 sin ( ) 2 (1 R ) 2 3 …. Basic Etalon Equations • • Conventions – – 𝑅 = 𝑚𝐹 : Spectral Resolution We assumed that the incident angle is zero, 𝜃 = 0, and the mirror space is in vacuum, 𝑛 = 1. – It is convenient to use wave numbers, 𝜆 = . – – – – – 𝑑𝜆,𝑚 : mirror distance for 𝜆 at order m Δ𝜆𝐹𝑆𝑅 : Free Spectral Range in units of wave number Δ𝑑𝐹𝑆𝑅,𝑚 : Corresponding mirror distance for FSR at m Δ𝜆𝐹𝑊𝐻𝑀 : Full Width at Half Maximum of the instrument profile in units of wavelength Δ𝑑𝐹𝑊𝐻𝑀 : Corresponding mirror distance for Δ𝜆𝐹𝑊𝐻𝑀 1 𝜆 Etalon Equations 2𝑑𝜆,𝑚 = 𝑚𝜆 2𝑑𝜆,𝑚 𝜆 = 𝑚 Δ𝜆𝐹𝑆𝑅 = 𝜆𝑚+1 − 𝜆𝑚 = Δ𝑑𝐹𝑆𝑅,𝑚 = = 1 2𝜆𝑚 𝑚 2𝜆𝑚+1 − 1 𝜆 1 = = 2𝑑 𝑚 𝑚𝜆 𝑚 2 𝜆𝑚 = 𝑚 1 1 𝑚 1 − = −1 2 𝜆𝑚 − Δ𝜆𝐹𝑆𝑅 𝜆𝑚 2 𝜆𝑚 1 − 1 𝑚 𝑚 1 1 𝜆𝑚 𝑚 1 = = =𝑑 𝑚−1 2 𝑚−1 𝑚−1 2Δ𝜆𝐹𝑆𝑅 𝑚 − 1 Δ𝜆𝐹𝑊𝐻𝑀 = 𝜆 𝜆 = 𝑅 𝑚𝐹 Δ𝑑𝐹𝑊𝐻𝑀 = 𝑚 𝜆 Δ𝜆 = 2 𝐹𝑊𝐻𝑀 2𝐹 Simulated Spectra Δ𝜆𝐹𝑆𝑅 = 𝜆𝑚+1 − 𝜆𝑚 1 𝜆 1 = = = 2𝑑 𝑚 𝑚𝜆 1.0 0.9 m=7 m=8 m=9 m=10 m=11 m=12 m=13 0.8 Relative Intensity 0.7 FSR 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0.1000 10 um 0.1200 0.1400 0.1600 1/wavelength [1/um] 0.1800 0.2000 5 um Simulated Spectra Order Sorting Filter 1.0 0.9 0.8 Relative Intensity 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0.1000 10 um 0.1200 0.1400 0.1600 1/wavelength [1/um] 0.1800 0.2000 5 um Simulated Spectra 1.0 0.9 0.8 Relative Intensity 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0.1000 10 um 0.1200 0.1400 0.1600 1/wavelength [1/um] 0.1800 0.2000 5 um Order Sorting Method of Tandem Fabry-Perot Telescope Collimator Camera Lens Detector FP-A FP-B (m=20) (m=250) Disadvantage of FP io ct ire Takes Long Time for Wide Spectral Band n SpectralDirection Direction Spatial lD Spectral Direction tra ec Spatial Direction Direction Spatial Sp Spatial Direction Spatial Direction Advantage of FP io ct ire n SpectralDirection Direction Spatial lD Spectral Direction tra ec Spatial Direction Direction Spatial Sp Spatial Direction Spatial Direction Takes Many Targets for Short Spectral Band Suggested Fabry-Perot Spectrometer Specifications • Target Emission Lines at Optical Bands – [OII] 372.7nm – H 486.1nm – [O III] 495.9 500.7nm – H 656.2 nm – [SII] 671.6 673.1 nm • Spectral Resolutions – The spectral resolution R = Finesse X m, where Finesses comes from the FP mirrors reflectivity and the order of interference, m, from the mirrors distance. – If Finesse=40 and m=50-250, we can expect that R • FOV (in case we use CQUEAN CCD) – 13 um 1024 X 1024 – Total FOV 5 X 5 arcmin with 0.27 arcsec/pixel = 2000 – 10000 Sciences (1/2) • Emission Lines of Star Forming Regions in the Galaxy (Soojong Pak) • Emission Lines of Star Forming Regions in the nearby galaxies (Luis Ho suggested) • Emission Lines of Merging AGNs (Julia Comerford suggested) – Ref. Comerford et al. 2012, ApJ, 753, 42, Kpc-Scale Spatial Offsets in DoublePeaked Narrow-Line AGN. I – Ref. Liu et al. 2011, ApJ, 737, 101, AGN Pairs from the SDSS. I. • Narrow Emission Line Survey of Galaxies at z=1. – H_beta 486nm, [OII] 372.7nm – Ref. Glazebrook et al. 2004, AJ, 128, 2652, Cosmic Star Formation History to z=1 from Narrow Emission Line Selected Tunable Filter Survey Sciences (2/2) • Dark Matter in Globular Clusters (Karl Gebhardt) – 1000 Stellar velocities at the edges of the visible clusters in order to constrain the dark matter distributions. – R=10000 for velocity accuracy of 1 km/s – m_R = 20 – 21 mag • Chemical Composition Studies in Globular Cluster (Chris Sneden) – a search for (the rare) Li-rich giant stars. The Li I resonance line is at 6708A – characterizing Na variations in clusters. One could choose Na D lines, but probably I would be happier with one of the 5680A doublet lines. – searching for Ba abundance variations. Probably the 6496A or 6141A lines are best. – finding out the level of metallicity variations as a function of evolutionary state. One could use one of the Ca IR triplet lines, for example. McDonald Observatory Otto Struve 2.1m telescope 2011-02-08 2011 IR Workshop CQUEAN at 2.1m telescope Science CCD Filter Wheel Control PC Guide CCD Motor for guide CCD field rotator 2011-02-08 Guide CCD field 2011 IR Workshop rotator Science CCD Camera (Andor iKon-M 934 BR-DD) CCD E2V Deep Depletion Chip Pixels 1024 x 1024, 13μm Readout Speed QE Fringe RD Noise (Measured) 2011-02-08 2011 IR Workshop 2.5 MHz (0.4 sec) 1 MHz (1 sec) 50 kHz (20 sec) Better than 25% at 1 μm None 8.1 electrons/pixel Possible Designs of Tandem Fabry-Perot Serial Configuration of 2 etalons FP-A FP-B (m=20) (m=250) Integrated Configuration of 3 mirrors Etalon Specifications for Tandem Fabry-Perot • Basic Specifications – We use two etalons for high spectral resolution (ET-H) and low spectral resolution (ET-L). – The ET-L will sort the overlapped orders of ET-H. – We also need broad band filters for the overlapped orders of ET-L. – The mirror sets and housing of ET-H and ET-L are identical. The only difference is the mirror distances. • Etalon Specs Etalon Finesse 𝜆𝑜 [nm] m R d [nm] 𝜆𝐹𝑆𝑅 𝑑𝐹𝑆𝑅 𝜆𝐹𝑊𝐻𝑀 𝑑𝐹𝑊𝐻𝑀 ET-H 15 650 250 3750 81,250 2.60 325 0.17 21.7 ET-L 15 650 20 300 6,500 32.5 325 2.17 21.7 ET-H 40 650 250 10000 81,250 2.60 325 0.065 8.1 ET-L 40 650 6,500 32.5 325 0.813 8.1 20 800 Fore-Optics Design • We need collimator units and camera units • before and after the Fabry-Perot. Telescope Collimator Camera Lens Detector FP-A FP-B (m=150) (m=10) Fore-Optics Design with Traditional Lens System Example from CQUEAN Focal Reducer Fore-Optics Design with Off-Axis Mirrors • We can apply the off-axis mirror design of Dr. Seunghyuk Chang. Eccentric section of an on-axis parent system The mirrors of a confocal system do not need to have a common axis for a perfect image at the system focus Re-imaging Optics for KASINICS (cf. Offner System) Schwartzschild-Chang Type Telescope - from "Inverse Cassegrain" ellipsoid paraboloid off-axis (Schwartzschild-Chang Type) on-axis D=50mm, F/D=2 et al. 2011 (Schwartzschild Type) (Kim, Pak, Chang et al. 2010) Off-Axis Design for SQUEAN (by Chang) Off-Axis Design for SQUEAN (by Chang) (x,y) Spot Diagrams 13um Project Roadmap and Required Resources GS Labor [year] Work Definition Cost [M KRW] Etalon Development 3 60 Fore-Optics (Off-Axis Mirrors or Lens) 2 30 Telescope Interface and Structure 0.5 10 Instrument Operation Software 0.5 Data Reduction Software 1 Telescope Installation and Commissioning 0.5 30 7.5 130 TOTAL Comments Karl Gebhardt Cost includes HW and Travel. Appendix Fabry-Perot Etalon Vendors • Bristol Instruments – They make the replacement FP mirrors for OLD Burleigh RC series. – The basic price for one set of mirrors starts from $8,000. – The man in the company recommends www.lightmachinery.com for custommade etalons. • LightMachinery.com Etalon • LightMachinery.com – They make customized Etalon mirrors. – Piezo Tunable Etalons with clear aperture of 4 mm. – Ian Miller, Director of R&D, gives very kind detailed technical supports. PZT Tunable Etalon Housing • ThorLabs.com – – – – Scanning Fabry-Perot Interferometer: SA210-5B • 535-820 nm, 10 GHz FSR • $2,533 • This is for laser, but we can use this for scanning test. PZT Drives & Actuator: PE4 • Micrometer Travel Range = 4mm with 1 um resolution • PZT Travel Range = 15 um with 10 nm resolution • 3 X $479.60 / unit Open-Loop PZT Controllers: MDT693A • 3 Channel • $1,580 Piezoelectric Actuators • Open Loop Piezo Actuator, 17um/150V: AE0505D16F, $153 • Full Bridge Strain Gauge Piezo Actuators, AE0505D16F: PZS001, $175 • Strain Gauge Amplification Circuit, AMP002, $161 • www.PhysikInstrumente.com Coefficient of Thermal Expansion • Fused Silica – CTE = 0.55 ppm/K • Invar – CTE = 0-2 ppm/K • Piezo Material – CTE = 6E-3/K http://www.piceramic.com/datasheet/Piezo_Material_Datasheet_Cofefficients_Te mperature_Measurements.pdf