Context imaging raman spectrometer

Patent metadata

Field	Value
Publication number	US-10048130-B2
Application number	US-201614989749-A
Country	US
Kind code	B2
Filing date	Jan 6, 2016
Priority date	Jan 9, 2015
Publication date	Aug 14, 2018
Grant date	Aug 14, 2018

Abstract

Methods and systems for Raman spectroscopy and context imaging are disclosed. One or two lasers can be used to excite Raman scattering in a sample, while a plurality of LEDs can illuminate the sample at a different wavelength. The LED light is collected by a lenslet array in order to enable a high depth of field. Focusing of the image can be carried out at specific points of the image by processing the light collected by the lenslet array.

First claim

What is claimed is:

1. A device comprising:
a first laser to emit a first laser light at a first wavelength;
a plurality of LEDs to emit LED light at a second wavelength different from the first wavelength;
a plurality of optical elements to convey the first laser light from the first laser onto a sample and collect a Raman shifted light and the LED light from the sample;
a Raman detector to collect the Raman shifted light; and
a context imager detector to collect the LED light,
wherein:
the first laser is a frequency doubling green laser comprising a birefringent crystal to modulate the first wavelength,
the birefringent crystal is a Lyot filter,
the plurality of optical elements comprises:
first, second, third, fourth, fifth, sixth and seventh lenses;
first and second dicroic beam splitters;
a multiplexed holographic grating;
a split;
first and second detectors; and
a lenslet array,

the first and second lens are to transmit the first laser light from the first laser to the first dicroic beam splitter,
the first dicroic beam splitter is to reflect the first laser light to the second dicroic beam splitter and transmit the LED light from the second dicroic beam splitter to the seventh lens,
the second dicroic beam splitter is to reflect the first laser light from the first dicroic beam splitter to the third lens and transmit the Raman shifted light from the third lens to the fourth lens,
the third lens is to focus the first laser light from the second dicroic beam splitter to the sample and collect the Raman shifted light from the sample,
the fourth lens is to transmit light through the split to the fifth lens,
the multiplexed holographic grating is to refract the Raman shifted light from the fifth lens to the sixth lens,
the sixth lens is to focus the Raman shifted light onto the Raman detector,
the seventh lens is to focus the LED light onto the lenslet array, and
the lenslet array is to focus the LED light onto the context imager detector.

2. The device of claim 1 , wherein the lenslet array comprises lenslets having a diameter between 20 and 40 micrometers.

3. The device of claim 1 , wherein the lenslet array comprises lenslets having a diameter between 240 and 260 micrometers.

4. The device of claim 2 , wherein the Raman detector is a charged coupled device.

5. The device of claim 4 , wherein at least one of the first, second, third, fourth, fifth, sixth and seventh lenses comprises a plurality of composite lenses.

6. The device of claim 4 , further comprising a second laser to emit a second laser light at a third wavelength different from the first and second wavelengths.

7. The device of claim 6 , wherein the second laser is a red laser.

8. The device of claim 7 , wherein the first wavelength is 532 nm, the second wavelength is between 450 and 250 nm, and the third wavelength is between 660 nm and 790 nm.

9. The device of claim 8 , further comprising a heater to control a temperature of the Lyot filter, thus modulating the wavelength of the first laser.

10. A method comprising:
emitting a first laser light at a first wavelength by a first laser, the first laser being a frequency doubling green laser comprising a birefringent crystal to modulate the first wavelength;
emitting LED light at a second wavelength different from the first wavelength by a plurality of LEDs;
by a plurality of optical elements, conveying the first laser light from the first laser onto a sample and collecting a Raman shifted light and the LED light from the sample;
detecting the Raman shifted light by a Raman detector;
detecting the LED light by a context imager detector;
sweeping the first wavelength through a wavelength range in a plurality of first wavelength steps, by modulating the birefringent crystal in the first laser;
detecting the Raman shifted light at each wavelength step; and
deriving a Raman spectrum for the sample from the detected Raman shifted light at each wavelength step,
wherein:
the birefringent crystal is a Lyot filter,
the plurality of optical elements comprises:
first, second, third, fourth, fifth, sixth and seventh lenses;
first and second dicroic beam splitters;
a multiplexed holographic grating;
a split;
first and second detectors; and
a lenslet array,

the first and second lens are to transmit the first laser light from the first laser to the first dicroic beam splitter,
the first dicroic beam splitter is to reflect the first laser light to a second dicroic beam splitter and transmit the LED light from the second dicroic beam splitter to the seventh lens,
the second dicroic beam splitter is to reflect the first laser light from the first dicroic beam splitter to the third lens and transmit the Raman shifted light from the third lens to the fourth lens,
the third lens is to focus the first laser light from the second dicroic beam splitter to the sample and collect the Raman shifted light from the sample,
the fourth lens is to transmit light through the split to the fifth lens,
the multiplexed holographic grating is to refract the Raman shifted light from the fifth lens to the sixth lens,
the sixth lens is to focus the Raman shifted light onto the Raman detector,
the seventh lens is to focus the LED light onto the lenslet array, and
the lenslet array is to focus the LED light onto the context imager detector.

11. The method of claim 10 , further comprising emitting, by a second laser, a second laser light at a third wavelength different from the first and second wavelengths.

12. The method of claim 11 , wherein detecting the Raman shifted light comprises taking a difference between a Raman spectrum detected while emitting first laser light and a Raman spectrum detected while emitting the second laser light.

13. The method of claim 11 , further comprising:
sweeping the third wavelength through a wavelength range in a plurality of third wavelength steps, by modulating a birefringent crystal in the second laser;
detecting the Raman shifted light at each third wavelength step; and
deriving a Raman spectrum for the sample from the detected Raman shifted light at each first and third wavelength step.

14. The method of claim 10 , wherein the first wavelength is 532 nm.

15. The method of claim 13 , wherein the first wavelength is 532 nm, the second wavelength is between 450 and 250 nm, and the third wavelength is between 660 nm and 790 nm.

16. The method of claim 10 , further comprising focusing an image of the sample at a desired point of the sample by processing the LED light captured by the lenslet array.

17. A device comprising:
a first laser to emit a first laser light at a first wavelength;
a plurality of LEDs to emit LED light at a second wavelength different from the first wavelength;
a plurality of optical elements to convey the first laser light from the first laser onto a sample and collect a Raman shifted light and the LED light from the sample;
a Raman detector to collect the Raman shifted light; and
a context imager detector to collect the LED light,
wherein:
the first laser is a frequency doubling green laser comprising a birefringent crystal to modulate the first wavelength,
the plurality of optical elements comprises:
at least one lens;
first and second dicroic beam splitters; and
a lenslet array;

the first dicroic beam splitter is to reflect the first laser light to the second dicroic beam splitter and transmit the LED light from the second dicroic beam splitter to the at least one lens,
the at least one lens is to focus the LED light onto the lenslet array, a

Assignees

• California Inst Of Techn

Inventors

• Lambert James L

Classifications

• G01J3/10

  Arrangements of light sources specially adapted for spectrometry or colorimetry · CPC title

• G01J3/0208

  using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction · CPC title

• G01J3/108

  for measurement in the infrared range · CPC title

• G01J3/44 Primary

  Raman spectrometry; Scattering spectrometry {; Fluorescence spectrometry} · CPC title

• G01J2003/104

  Monochromatic plural sources · CPC title