Shutter assembly for calibration

• US 10,436,641 B2
• Filed: 05/16/2016
• Issued: 10/08/2019
• Est. Priority Date: 02/10/2011
• Status: Active Grant

• Current Assignee: DIRAmed LLC
• Original Assignee: DIRAmed LLC
• Inventors: Higgins, Richard J., Lipp, Brian, Caudy, Don Warren
• Primary Examiner(s): Porta, David P
• Assistant Examiner(s): Malevic, Djura
• Application Number:
  US15/156,291
• Publication Number:
  US 20170131145A1
• Time in Patent Office: 1,240 Days
• CPC Class Codes: G01J 3/0232 using shutters
• CPC Class Codes: G01J 3/0297 Constructional arrangements for removing other types of optical noise or for performing calibration
• CPC Class Codes: G01J 3/28 Investigating the spectrum using colour filters G01J3/51
• CPC Class Codes: G01J 3/44 Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry
• CPC Class Codes: G01N 21/274 Calibration, base line adjustment, drift correction

Abstract

Described are a shutter assembly, a spectrometer, and a method for calibrating a spectrometer. For example, the method may include positioning a shutter including a mirror into a first position in an illumination path of an excitation light beam such that a measurement window is blocked. The mirror may be operable to direct at least one of: (1) the illumination path to a spectral calibration material, (2) a first collection path extending from the spectral calibration material, and (3) a second collection path of a spectral calibration light beam. The method may include directing a returned light from the receiving optics unit to an imaging device; processing the returned light at the imaging device into one or more image signals; analyzing and comparing the image signals with approved image signals; and providing an indication of whether the comparative results of the analysis are within acceptable tolerances.

Claims

1. A spectrometer operable to perform an internal calibration check, the spectrometer comprising:

at least one source of optical radiation operable to generate at least one of;

(1) an excitation light beam, wherein the excitation light beam comprises an illumination path and at least one of a first collection path and a second collection path, and

(2) a spectral calibration light beam, wherein the spectral calibration light beam comprises a desired spectral feature and a third collection path;

a receiving optics unit operable to receive a spectrum of wavelengths derived from at least one of the first collection path and the second collection path, and operable to receive the desired spectral feature derived from the third collection path;

an imaging device operable to produce image signals from the received spectrum of wavelengths and from the received desired spectral feature;

a shutter comprising at least one of;

(1) a first spectral calibration material, the first spectral calibration material operable to alter the excitation light beam in order to generate a first consistent spectrum within wavelengths utilizable by the receiving optics unit and the imaging device in the spectrometer, and

(2) a mirror, the mirror operable to direct at least two of;

(a) the illumination path to a second spectral calibration material at a location distinct from the shutter, the second spectral calibration material operable to alter the excitation light beam in order to generate a second consistent spectrum within wavelengths utilizable by the receiving optics unit and the imaging device in the spectrometer,

(b) the second collection path extending from the second spectral calibration material toward the receiving optics unit, and

(c) the third collection path toward the receiving optics unit; and

a mechanism operatively connected to the shutter and operable to move the shutter into;

(1) at least a first, closed position in the illumination path of the excitation light beam such that a measurement window is blocked and at least one of;

(a) the excitation light beam strikes the first spectral calibration material wherein the first collection path, comprising the first consistent spectrum, is directed toward the receiving optics unit,

(b) the excitation light beam is directed by the mirror to the second spectral calibration material,

(c) the second collection path, comprising the second consistent spectrum, is directed by the mirror toward the receiving optics unit, and

(d) the third collection path, comprising the desired spectral feature, is directed by the mirror toward the receiving optics unit; and

(2) a second, open position out of the illumination path of the excitation light beam to allow the excitation light beam to strike a sample through the measurement window;

provided that the spectrometer excludes a beam splitter.

2. The spectrometer of claim 1, wherein the source of optical radiation is capable of generating substantially coherent light.

3. The spectrometer of claim 1, wherein the excitation light beam has one of:

a wavelength in the range of 700 nanometers to 1100 nanometers; and

a focal length set for a measurement site located proximate to the measurement window, and in the first, closed position of the shutter, the excitation light beam strikes the first spectral calibration material at a position that is different than the focal length.

4. The spectrometer of claim 1, wherein the spectrometer is capable of performing Raman spectroscopy.

5. The spectrometer of claim 1, wherein the first and second spectral calibration material comprises a polymer.

6. The spectrometer of claim 1, wherein the first and second spectral calibration material comprises polystyrene.

7. The spectrometer of claim 1, wherein the shutter carries at least two different calibration materials, each at a different locus on the shutter, and the mechanism is capable of successively positioning the shutter in different calibration positions, each calibration position corresponding to one of each different locus.

8. A method for calibrating a spectrometer, the method comprising:

positioning a shutter into a first, closed position in an illumination path of an excitation light beam such that a measurement window is blocked, wherein the shutter comprises a mirror, the mirror operable to direct at least two of;

(1) the illumination path of the excitation light beam to a spectral calibration material at a location distinct from the shutter, the spectral calibration material operable to alter the excitation light beam in order to generate a consistent spectrum within wavelengths utilizable by a receiving optics unit and an imaging device in the spectrometer,

(2) a first collection path of the excitation light beam extending from the spectral calibration material, and

(3) a second collection path of a spectral calibration light beam, the spectral calibration light beam comprising at least one desired spectral feature utilizable by the receiving optics unit and the imaging device in the spectrometer;

generating at least one of the excitation light beam and the calibration light beam from one or more light sources such that at least one of;

(1) the illumination path of the excitation light beam strikes the mirror and is directed to the spectral calibration material,

(2) the first collection path of the excitation light beam is directed by the mirror toward the receiving optics unit as a first returned light comprising the consistent spectrum,

(3) the second collection path of the spectral calibration light beam is directed by the mirror toward the receiving optics unit as a second returned light comprising the desired spectral feature;

directing at least one of the first returned light and the second returned light from the receiving optics unit to the imaging device;

processing at least one of the first returned light and the second returned light at the imaging device into one or more image signals;

analyzing and comparing the one or more image signals with approved image signals;

generating comparative results of the analysis; and

providing an indication of whether the comparative results of the analysis are within acceptable tolerances.

9. The method of claim 8, wherein the excitation light beam has one of:

a wavelength in the range of 700 nanometers to 1100 nanometers; and

a focal length set for a measurement site located proximate to the measurement window.

10. The method of claim 8, wherein the spectrometer is capable of performing Raman spectroscopy.

11. The method of claim 8, wherein the spectral calibration material comprises a polymer.

12. The method of claim 8, wherein the spectral calibration material comprises polystyrene.

13. The method of claim 8, further comprising placing a sample at a measurement site located proximate to the measurement window and moving the shutter into a second, open position out of the illumination path of the excitation light beam to take a measurement of the sample.