SPECTROSCOPY GROUP

Photonics WestFebruary 3, 2013

Brian C. Smith, Ph.D. ,Princeton Instruments Jason McClure, Ph.D. Princeton Instruments

Dan Heller, Ph.D. Memorial Sloan-Kettering Cancer CenterEd Gooding, Ph.D. Princeton Instruments

An Aberration Free Spectrograph for Improved Imaging and Spectra of Biological Samples

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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 ALLmanufacturer’s CTspectrographs

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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

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1. Distorted Line Shapes2. Poor Spectral Resolution3. Reduced Signal-to-Noise Ratio (SNR)

Traditional CT Spectrographs = Poor SpectraAn asymmetrically broadened spectral line measured on a traditional Czerny-Turner spectrograph

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The Schmidt-Czerny-Turner (SCT) Spectrograph

Focusing mirror

Entrance S

lit

On-axis gratingdrive

Collimating mirror

ProprietaryMirror

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Reduced aberrations = Great Focal Plane Imaging

Traditional CT Spectrograph

IsoPlane SCT Spectrograph

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IsoPlane = Great Spectroscopy

IsoPlane vs. CTPixis 400BR

1200 gr/mm HVIS grating

CT 1 Row

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• Interfaces the IsoPlane to an inverted microscope’s UDP Port

• Olympus, Nikon, and Zeiss microscopes are supported

• No optics involved

The MicroSpec Interface

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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

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The NIRvana is PI’s new TE cooled InGaAs focal plane array cameraImaging Nanotubes in Live Cells: NIRvana

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

640 nm excitation,20 sec exposure time, 410 micron slits

Image of carbon nanotube centered on the IsoPlane slit

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Acknowledgements

• Trenton Engineering– Bill Asher– Harry Grannis– Bob Bolkus– Bill Hartman

• Acton Engineering• Ed Gooding

– Lloyd Wentzell– Bob Fancy– Mike Case– Paulo Goulart– Bob Jarratt

• Memorial Sloan Kettering Cancer Center– Januka Budhathoki-Uprety

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Outline• The Traditional Czerny-Turner (CT) imaging

spectrograph and its limitations

• The Schmidt-Czerny-Turner (SCT) spectrograph: The IsoPlane– Instrumentation– Data showing Reduction or Elimination of image aberrations– Improved imaging– Improved spectroscopy

• Near Infrared Fluorescence of Carbon Nanotubes in Live Cells

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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.

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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

These are images of optical fibers, not Halley’s Comet!

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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 imageof a 150 micron diameter optical -fiber

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Traditional CT Spectrograph

IsoPlane SCT Spectrograph

Minus astigmatism, the Dreaded Bow Tie Effect is Gone

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IsoPlane: Better SNR = Increased Sensitivity