Title: Method of increasing power within an optical cavity with long path lengths

Abstract

A cavity-enhanced absorption spectroscopy instrument has an optical cavity with two or more cavity mirrors, one mirror of which having a hole or other aperture for injecting a light beam, and the same or another mirror of which being partially transmissive to allow exit of light to a detector. A spherical-spherical configuration with at least one astigmatic mirror or a spherical-cylindrical configuration where the spherical mirror could also be astigmatic prevents a reentrant condition wherein the injected beam would prematurely exit the cavity through the aperture. This combination substantially increases the number of passes of the injected beam through a sample volume for sensitive detection of chemical species even in less than ideal conditions including low power laser or LED sources, poor mirror reflectivity or detector noise at the wavelengths of interest, or cavity alignment issues such as vibration or temperature and pressure changes.

Inventors:

Leen, John Brian; Bramall, Nathan E.

Issue Date:

2018-03-13

Research Org.:

ABB, Inc., Cary, NC (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1426789

Patent Number(s):

9915562

Application Number:

15/235,401

Assignee:

ABB, Inc., Cary, NC

Patent Classifications (CPCs):

G - PHYSICS G01 - MEASURING G01J - MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRA-RED, VISIBLE OR ULTRA-VIOLET LIGHT

G - PHYSICS G01 - MEASURING G01N - INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES

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G - PHYSICS G01 - MEASURING G01J - MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRA-RED, VISIBLE OR ULTRA-VIOLET LIGHT

G01J3/0208 - {using focussing or collimating elements, e.g. lenses or mirrors
G01J3/021 - {using plane or convex mirrors, parallel phase plates, or particular reflectors}
G01J3/0243 - {having a through-hole enabling the optical element to fulfil an additional optical function, e.g. a mirror or grating having a throughhole for a light collecting or light injecting optical fiber}
G01J3/0286 - {Constructional arrangements for compensating for fluctuations caused by temperature, humidity or pressure, or using cooling or temperature stabilization of parts of the device
G01J3/0291 - {Housings
G01J3/42 - Absorption spectrometry

G - PHYSICS G01 - MEASURING G01N - INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES

G01N2021/391 - {Intracavity sample}
G01N2021/399 - {Diode laser}
G01N21/3504 - for analysing gases, e.g. multi-gas analysis
G01N21/39 - using tunable lasers
G01N2201/06113 - Coherent sources

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DOE Contract Number:  

SC0007654

Resource Type:

Patent

Resource Relation:

Patent File Date: 2016 Aug 12

Country of Publication:

United States

Language:

English

Subject:

47 OTHER INSTRUMENTATION