the schmidt-czerny-turner...
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SPECTROSCOPY GROUP
2012 Advanced Materials Characterization Workshop
June 7, 2012
Jason McClure Chief Scientist
Princeton Instruments
The Schmidt-Czerny-Turner Spectrograph
SPECTROSCOPY GROUP
Outline
• Czerny-Turner imaging spectrograph
– Applications
– Limitations of the traditional design – image aberrations
• Schmidt-Czerny-Turner spectrograph
– Application Highlights
• Hyper-spectral imaging
SPECTROSCOPY GROUP
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
SPECTROSCOPY GROUP
Applications involving the CT-Spectrograph
• Where are the innovations occurring?
SPECTROSCOPY GROUP
Applications involving the CT-Spectrograph
• Where are the innovations occurring?
Nature Nanotechnology 4, 496 - 499 (2009) Published online: 26 July 2009
SPECTROSCOPY GROUP
Applications involving the CT-Spectrograph
• Where are the innovations occurring?
SPECTROSCOPY GROUP
Applications involving the CT-Spectrograph
• Where are the innovation occurring?
SPECTROSCOPY GROUP
Applications involving the CT-Spectrograph
• Where are the innovations occurring?
?
SPECTROSCOPY GROUP
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
SPECTROSCOPY GROUP
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
3#
1
fWI
Wavefront Aberration
SPECTROSCOPY GROUP
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
2#
1
fWII
Wavefront Aberration
SPECTROSCOPY GROUP
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
#
1
fWIII
Wavefront Aberration
Traditional CT focal plane
SPECTROSCOPY GROUP
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.
SPECTROSCOPY GROUP
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.
SPECTROSCOPY GROUP
Current state of the art Czerny-Turner spectrograph
f/4 class spectrograph Schmidt-Czerny-Turner
Row #
Wavelength
Dispersed image of a continuous source (QTH Lamp)
SPECTROSCOPY GROUP
SPECTROSCOPY GROUP
Application Highlight - Hyperspectral Imaging
• 1 um monodisperse polystyrene spheres
– Self assemble into 2D hcp arrays
– Dark field illumination
– Diffraction through multilayer
Olympus IX-71
100 X Illumination
10 mm
Annular aperture
Objective
PMMA array
SPECTROSCOPY GROUP
Application Highlight - Hyperspectral Imaging
• 10X dark field illumination of PMMA lattice
Witness camera on IX-71 0 order image seen through SCT
SPECTROSCOPY GROUP
Application Highlight - Hyperspectral Imaging
Row #
Wavelength Entrance Slit
Full 2D spectral image
SPECTROSCOPY GROUP
Application Highlight - Hyperspectral Imaging
Spectra from two differently oriented grains Resulting Hyperspectral
image
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
SPECTROSCOPY GROUP
Application Highlight - Hyperspectral Imaging
Data collected using NanoPhoton Confocal Microscope
SPECTROSCOPY GROUP
Acknowledgements
• Katsumasa Lab – Osaka University
– Isoplane testing with NanoPhoton
confocal microscope
• Acton Engineering
– Lloyd Wentzell
– Bob Fancy
– Mike Case
– Paulo Goulart
– Bob Jarratt
• Trenton Engineering
– Bill Asher
– Harry Grannis
– Bob Bolkus
– Bill Hartman
SPECTROSCOPY GROUP
Questions?
SPECTROSCOPY GROUP
Features
Feature Specification
Aperture ratio f/4.6
Focal length 320 mm
Wavelength Scan Range 0-1400 nm
CCD resolution 0.07nm *4mm x 10 um slit at 435nm
Astigmatism 0.0 um *any wavelength
Coma 0.0 um *at 500 nm with 1200 g/mm grating
Spherical Aberration 0.0 um *any wavelength
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