spectroscopy group photonics west february 3, 2013 brian c. smith, ph.d.,princeton instruments jason...

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