SPECTROSCOPY GROUP
An Aberration Free Spectrograph for
Improved Imaging and Spectra of Biological Samples
Photonics West
February 3, 2013
Brian C. Smith, Ph.D. ,Princeton Instruments
Jason McClure, Ph.D. Princeton Instruments
Dan Heller, Ph.D. Memorial Sloan-Kettering Cancer Center
Ed Gooding, Ph.D. Princeton Instruments
The Traditional Czerny-Turner (CT) Spectrograph
• Has seen little design change in ~30 years
– Light Path: Collimating Mirror => Grating => Focusing Mirror => Detector
– Mirrors were originally spherical, are now toroidal
• Three primary image distortions observed in CT spectrographs
– Field Astigmatism
– Coma
– Spherical Aberration
• Caused by the laws
of physics
• Are present in ALL
manufacturer’s CT
spectrographs
SPECTROSCOPY GROUP
Traditional CT Spectrographs = Blurred Images
• The optical aberrations inherent in Czerny-Turner designs cause
distorted images
• Note decent imaging in the center. Blurring gets progressively
worse towards sensor edges
- Vertical stack of fourteen 200 micron optical fibers stepped across the focal plane of a
traditional CT spectrograph. 435 nm light, 1200 groove/mm grating, 300 mm focal length
SPECTROSCOPY GROUP
Traditional CT Spectrographs = Poor Spectra
An asymmetrically broadened
spectral line measured on a
traditional
Czerny-Turner
spectrograph
1. Distorted Line Shapes
2. Poor Spectral Resolution
3. Reduced Signal-to-Noise Ratio (SNR)
SPECTROSCOPY GROUP
The Schmidt-Czerny-Turner (SCT) Spectrograph
Collimating
mirror
On-axis
grating
drive
Entrance Slit
Proprietary
Mirror
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Focusing
mirror
Traditional CT Spectrograph
IsoPlane SCT Spectrograph
Reduced aberrations = Great Focal Plane Imaging
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IsoPlane = Great Spectroscopy
IsoPlane vs. CT
Pixis 400BR
1200 gr/mm HVIS
grating
CT 1 Row
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The MicroSpec Interface
• Interfaces the IsoPlane to an inverted microscope’s UDP Port
• Olympus, Nikon, and Zeiss microscopes are supported
• No optics involved
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NIR Fluorescence of Carbon Nanotubes
• Single-walled nanotubes 0.6-1.3 nm in diameter
• ~100-2000 nm long, averaging ~500nm
• Nanotubes are wrapped in a polymer
- Can vary polymer functionality
- Proteins and nucleic acids can bind to the polymer
SPECTROSCOPY GROUP
Imaging Nanotubes in Live Cells: NIRvana
The NIRvana is PI’s new TE cooled InGaAs focal plane array camera
HeLa Cells, Amine-rich polymer-encapsulated carbon nanotubes, 640 nm ex, 410 um slit. 1 frame/second.
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Nanotubes are Transported Within Living Cells
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NIR Fluorescence Spectrum of a Nanotube
Image of carbon
nanotube centered on
the IsoPlane slit
640 nm excitation,20 sec
exposure time, 410
micron slits
SPECTROSCOPY GROUP
Acknowledgements
• Acton Engineering
• Ed Gooding
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–
–
–
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Lloyd Wentzell
Bob Fancy
Mike Case
Paulo Goulart
Bob Jarratt
• Memorial Sloan Kettering
Cancer Center
– Januka Budhathoki-Uprety
SPECTROSCOPY GROUP
• Trenton Engineering
–
–
–
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Bill Asher
Harry Grannis
Bob Bolkus
Bill Hartman
Outline
• The Traditional Czerny-Turner (CT) imaging spectrograph and its
limitations
• The Schmidt-Czerny-Turner (SCT) spectrograph: The IsoPlane
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–
–
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Instrumentation
Data showing Reduction or Elimination of image aberrations
Improved imaging
Improved spectroscopy
• Near Infrared Fluorescence of Carbon Nanotubes in Live Cells
SPECTROSCOPY GROUP
Field Astigmatism
• Cause: Using lenses or mirrors to image a source off axis
• Affects on Imaging: Vertical or horizontal elongation of an image
e.g. The dreaded “Bow-Tie” effect
• Affects on spectroscopy: Limits both spectral and spatial resolution of a
spectrograph. Is completely corrected only at the center of the focal plane.
Fourteen 200 micron diameter optical fibers, 1200 g/mm grating, 300 mm focal length.
SPECTROSCOPY GROUP
Coma
• Cause: Using mirrors to image a source off axis
• Affects on Imaging: Comet shaped tail on focused images or spectral lines
• Affects on spectroscopy: spectral lines are asymmetrically broadened Limits
spectral resolution of a spectrograph
• Can only be completely corrected at one grating angle or wavelength
An asymmetrically broadened spectral line
SPECTROSCOPY GROUP
These are images of optical fibers,
not Halley’s Comet!
Spherical Aberration
• Cause: Using spherical mirrors to focus light to form an image
• Affects on Imaging: Diffuse symmetric blur about an image
• Affects on spectroscopy: Limits both spatial and spectral resolution of a
spectrograph
Symmetric blur around the image
of a 150 micron diameter optical -fiber
SPECTROSCOPY GROUP
Traditional CT Spectrograph
IsoPlane SCT Spectrograph
Minus astigmatism, the Dreaded Bow Tie Effect is Gone
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IsoPlane: Better SNR = Increased Sensitivity
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