The Schmidt-Czerny-Turner Spectrograph

Transcription

1 The Schmidt-Czerny-Turner Spectrograph 2012 Advanced Materials Characterization Workshop June 7, 2012 Jason McClure Chief Scientist Princeton Instruments

2 Outline Czerny-Turner imaging spectrograph Applications Limitations of the traditional design image aberrations Schmidt-Czerny-Turner spectrograph Application Highlights Hyper-spectral imaging

3 Applications involving the CT-Spectrograph Raman, PL, PLE Transmittance / Reflectance Spectral domain Optical Coherence Tomography (OCT) Fourier Domain Dispersive Spectroscopy There is a movement towards multimodality techniques that generate information rich data at the micro/nano scale Hyperspectral micro-raman imaging TERS, NSOM OCT/micro-Raman mapping cancer detection MRI/X-ray CT/Photoluminescence Small animal imaging

4 Applications involving the CT-Spectrograph Where are the innovations occurring?

5 Applications involving the CT-Spectrograph Where are the innovations occurring? Nature Nanotechnology 4, (2009) Published online: 26 July 2009

6 Applications involving the CT-Spectrograph Where are the innovations occurring?

7 Applications involving the CT-Spectrograph Where are the innovation occurring?

8 Applications involving the CT-Spectrograph Where are the innovations occurring??

9 The Czerny-Turner Spectrograph The CT spectrograph has not seen significant innovation in ~30 years! Strong movement towards multimodality techniques which require spatially resolved spectral data The CT spectrograph is the final optical element light sees before your detector does. There are three primary image aberrations that can be observed in any traditional CT type spectrograph Spherical Coma Astigmatism

10 Image Aberrations Spherical aberration Cause: Using a spherical mirrors to focus light to form an image Appearance: Diffuse symmetric blur about an image e.g. image of a fiber through a spectrograph will have a diffuse blur around a more intense center Affects on spectroscopy: Limits both spatial and spectral resolution of a spectrograph Example: Symmetric blur seen about a fiber optic image 150 um fiber core Wavefront Aberration W I 1 f # 3

11 Image Aberrations Coma aberration Cause: Using mirrors to image a source off axis Appearance: Comet shaped tail to focused images or spectral lines e.g. spectral lines are asymmetrically broadened Affects on spectroscopy: Limits spectral resolution of a spectrograph, however, is completely corrected at one grating angle or wavelength. Example: Asymmetry in spectral line profile Wavefront Aberration W II 1 f # 2

12 Image Aberrations Astigmatism aberration Cause: Using lenses or mirrors to image a source off axis Appearance: Vertical or horizontal elongation of an image e.g. The Bow-Tie effect, vertical distortion of fiber image Affects on spectroscopy: Limits both spectral and spatial resolution of a spectrograph. Is completely corrected at the center of the focal plane. Example: Elongation of Fiber core images Traditional CT focal plane Wavefront Aberration W III f 1 #

13 Image Aberrations Astigmatism aberration Cause: Using lenses or mirrors to image a source off axis Appearance: Vertical or horizontal elongation of an image e.g. The Bow-Tie effect, vertical distortion of fiber image Affects on spectroscopy: Limits both spectral and spatial resolution of a spectrograph. Is completely corrected at the center of the focal plane.

14 Image Aberrations Astigmatism aberration Cause: Using lenses or mirrors to image a source off axis Appearance: Vertical or horizontal elongation of an image e.g. The Bow-Tie effect, vertical distortion of fiber image Affects on spectroscopy: Limits both spectral and spatial resolution of a spectrograph. Is completely corrected at the center of the focal plane.

15 Current state Schmidt-Czerny-Turner of the art spectrograph f/4 class spectrograph Row # Wavelength Dispersed image of a continuous source (QTH Lamp)

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17 Application Highlight - Hyperspectral Imaging 1 um monodisperse polystyrene spheres Self assemble into 2D hcp arrays Dark field illumination Diffraction through multilayer Annular aperture PMMA array 10 mm Objective Olympus IX X Illumination

18 Application Highlight - Hyperspectral Imaging 10X dark field illumination of PMMA lattice Witness camera on IX-71 0 order image seen through SCT

19 Application Highlight - Hyperspectral Imaging Row # Full 2D spectral image Entrance Slit Wavelength

20 Application Highlight - Hyperspectral Imaging Spectra from two differently oriented grains Dark field QTH illumination, Line exposure time = 0.1 sec Objective lens = Olympus 10X APO Grating = 1200 g/mm blazed at 500 nm Spectrometer slit = 20 um Resulting Hyperspectral image

21 Application Highlight - Hyperspectral Imaging Data collected using NanoPhoton Confocal Microscope

22 Acknowledgements Acton Engineering Lloyd Wentzell Bob Fancy Mike Case Paulo Goulart Bob Jarratt Trenton Engineering Bill Asher Harry Grannis Bob Bolkus Bill Hartman Katsumasa Lab Osaka University Isoplane testing with NanoPhoton confocal microscope

23 Questions?

24 Features Feature Aperture ratio Focal length Wavelength Scan Range CCD resolution Astigmatism Coma Spherical Aberration Specification f/ mm nm 0.07nm *4mm x 10 um slit at 435nm 0.0 um *any wavelength 0.0 um *at 500 nm with 1200 g/mm grating 0.0 um *any wavelength