Brewster's angle flow cell for cavity ring-down spectroscopy
First Claim
1. An apparatus for measuring light absorption in a sample having a first index of refraction, the apparatus comprising:
- a ring-down optical cavity formed by at least first and second spaced apart light beam reflectors to receive and reflect a light beam having a selected wavelength width and to establish a resonant mode for the light beam, the light beam being measured after the light beam has been reflected at least once from each reflector to determine the absorption of the light beam by the sample, the optical cavity comprising a medium having a second index of refraction; and
a container positioned in the optical cavity for containing the sample, the container comprising;
an outer surface having opposing first and second outer faces that are oriented to receive and transmit the light beam, the container including a first portion forming the first outer face having a third index of refraction and a second portion forming the second outer face having a fourth index of refraction; and
an inner surface forming a void for containing the sample, the inner surface having opposing first and second inner faces that are oriented to receive and transmit the light beam,wherein the first and second outer faces of the container form first and second cavity/container interfaces, and the first and second inner faces of the container form first and second container/sample interfaces,wherein the first and second outer faces of the outer surface of the container are oriented at first and second angles, respectively, with respect to the light path of the light beam such that the light beam incident upon and exiting the first and second cavity/container interfaces is at approximately the Brewster'"'"'s angle of the respective first and second cavity/container interfaces, andwherein the first and second inner faces of the inner surface are oriented at third and fourth angles, respectively, with respect to the first and second outer faces of the outer surface such that the light beam incident upon and exiting the first and second container/sample interfaces is at approximately the Brewster'"'"'s angle of the respective first and second container/sample interfaces.
2 Assignments
0 Petitions
Accused Products
Abstract
A container to be positioned in a ring-down optical cavity for containing a sample includes an outer surface having opposing first and second outer faces and an inner surface forming a void for containing the sample and having opposing first and second inner faces. The container may include a first portion forming the first outer face having a second index of refraction and a second portion forming the second outer face having a third index of refraction. The container may be placed in an optical cavity including a medium. The first and second outer faces of the outer surface and the first and second inner faces of the inner surface are oriented so that the cavity-to-container interfaces and the container-to-sample interfaces of the container transmit and receive a light beam at an incidence angle approximately equal to the Brewster'"'"'s angle of the respective interface.
54 Citations
33 Claims
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1. An apparatus for measuring light absorption in a sample having a first index of refraction, the apparatus comprising:
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a ring-down optical cavity formed by at least first and second spaced apart light beam reflectors to receive and reflect a light beam having a selected wavelength width and to establish a resonant mode for the light beam, the light beam being measured after the light beam has been reflected at least once from each reflector to determine the absorption of the light beam by the sample, the optical cavity comprising a medium having a second index of refraction; and a container positioned in the optical cavity for containing the sample, the container comprising; an outer surface having opposing first and second outer faces that are oriented to receive and transmit the light beam, the container including a first portion forming the first outer face having a third index of refraction and a second portion forming the second outer face having a fourth index of refraction; and an inner surface forming a void for containing the sample, the inner surface having opposing first and second inner faces that are oriented to receive and transmit the light beam, wherein the first and second outer faces of the container form first and second cavity/container interfaces, and the first and second inner faces of the container form first and second container/sample interfaces, wherein the first and second outer faces of the outer surface of the container are oriented at first and second angles, respectively, with respect to the light path of the light beam such that the light beam incident upon and exiting the first and second cavity/container interfaces is at approximately the Brewster'"'"'s angle of the respective first and second cavity/container interfaces, and wherein the first and second inner faces of the inner surface are oriented at third and fourth angles, respectively, with respect to the first and second outer faces of the outer surface such that the light beam incident upon and exiting the first and second container/sample interfaces is at approximately the Brewster'"'"'s angle of the respective first and second container/sample interfaces. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A container to be positioned in a ring-down optical cavity for containing a sample having a first index of refraction, the container to be used to facilitate measurement of light absorption in the sample, the container comprising:
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an outer surface having opposing first and second outer faces that are oriented to receive and transmit a light beam, the container including a first portion forming the first outer face having a second index of refraction and a second portion forming the second outer face having a third index of refraction; an inner surface forming a void for containing the sample, the inner surface having opposing first and second inner faces that are oriented to receive and transmit the light beam; the first and second outer faces of the container forming first and second cavity/container interfaces; and the first and second inner faces of the container forming first and second container/sample interfaces, wherein the first and second outer faces of the outer surface of the container are to be oriented in the optical cavity such that the first and second cavity/container interfaces transmit and receive the light beam at an incidence angle approximately equal to the Brewster'"'"'s angle of the respective first and second cavity/container interfaces, and wherein the first and second inner faces of the inner surface are oriented at first and second angles, respectively, with respect to the first and second outer faces of the outer surface such that the first and second container/sample interfaces transmit and receive the light beam at an incidence angle approximately equal to the Brewster'"'"'s angle of the respective first and second container/sample interfaces. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A method for measuring light absorption in a sample having a first index of refraction, the method comprising:
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providing a light beam having a selected wavelength width that includes at least one selected wavelength λ
;receiving the light beam in a ring-down optical cavity formed by at least first and second spaced apart light beam reflectors to receive and reflect the light beam and to establish a resonant mode for the light beam, the optical cavity comprising a medium having a second index of refraction; positioning a container in the optical cavity for containing the sample, the container having opposing first and second outer faces that are oriented to receive and transmit the light beam, and opposing first and second inner faces forming a void for containing the sample which inner faces are oriented to receive and transmit the light beam, the first and second outer faces forming first and second cavity/container interfaces and the first and second inner faces forming first and second container/sample interfaces, wherein positioning the container in the optical cavity comprises; orienting the first and second outer faces of the container at first and second angles, respectively, with respect to the light path of the light beam such that the first and second cavity/container interfaces transmit and receive the light beam at an incidence angle approximately equal to the Brewster'"'"'s angle of the respective first and second cavity/container interfaces; and orienting the first and second inner faces of the container at third and fourth angles, respectively, with respect to the first and second outer faces such that the first and second container/sample interfaces transmit and receive the light beam at an incidence angle approximately equal to the Brewster'"'"'s angle of the respective first and second container/sample interfaces; and receiving the light beam after the light beam has been reflected at least once from each reflector to determine the absorption of the light beam by the sample. - View Dependent Claims (28)
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29. A method for measuring light absorption in a sample having a first refractive index, the method comprising:
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providing a light beam having a selected wavelength width that includes at least one selected wavelength λ
;receiving the light beam in a ring-down optical cavity formed by at least first and second spaced apart light beam reflectors to receive and reflect the light beam and to establish a resonant mode for the light beam, the optical cavity comprising a medium having a second index of refraction; positioning a container in the optical cavity for containing the sample, the container having first and second outer faces that are oriented to receive and transmit the light beam, and first and second inner faces forming a void for containing the sample which inner faces are oriented to receive and transmit the light beam, the first and second outer faces forming first and second cavity/container interfaces and the first and second inner faces forming first and second container/sample interfaces; transmitting and receiving the light beam at the first cavity/container interface at an incidence angle approximately equal to the Brewster'"'"'s angle of the first cavity/container interface; transmitting and receiving the light beam at the first container/sample interface at an incidence angle approximately equal to the Brewster'"'"'s angle of the first container/sample interface; transmitting and receiving the light beam at the second container/sample interface at an incidence angle approximately equal to the Brewster'"'"'s angle of the second container/sample interface; transmitting and receiving the light beam at the second cavity/container interface at an incidence angle approximately equal to the Brewster'"'"'s angle of the second cavity/container interface; and receiving the light beam after the light beam has been reflected at least once from each reflector to determine the absorption of the light beam by the sample. - View Dependent Claims (30, 31, 32, 33)
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Specification