ILLUMINATION OF DIFFUSELY SCATTERING MEDIA
First Claim
1. A method of directing a beam of incident light into a diffusely scattering sample, comprising:
- locating a delivery filter adjacent to the sample, the delivery filter having characteristics such that reflection of said incident light is dependent upon angle of incidence of said light at the filter; and
directing a beam of said incident light through the delivery filter at a beam angle of incidence and to the sample,such that incident light diffusely scattered back out of the sample to arrive at the filter is preferentially reflected by the delivery filter back towards the sample.
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Accused Products
Abstract
The invention provides a technique for increasing the illumination intensity of probe light in a diffusely scattering sample without increasing the power of the probe beam. Generally, an optical filter is used which permits a collimated probe beam of light to pass through to the sample, but which reflects back towards the sample much of the backscattered scattered probe light emerging at a wider range of angles. In particular embodiments a collimated laser beam is delivered to the sample through a multi-layer dielectric filter covering a portion of the sample. The filter is transmissive to the laser light at normal incidence, but reflective at shallower angles of incidence characteristic of the backscattered light.
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Citations
51 Claims
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1. A method of directing a beam of incident light into a diffusely scattering sample, comprising:
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locating a delivery filter adjacent to the sample, the delivery filter having characteristics such that reflection of said incident light is dependent upon angle of incidence of said light at the filter; and directing a beam of said incident light through the delivery filter at a beam angle of incidence and to the sample, such that incident light diffusely scattered back out of the sample to arrive at the filter is preferentially reflected by the delivery filter back towards the sample. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. An optical enclosure for enhancing the intensity of incident light within a diffusely scattering sample comprising a delivery filter through which a beam of said incident light is directed to the sample at a beam angle of incidence with respect to said filter,
the delivery filter having characteristics such that reflection of said incident light increases at angles of incidence away from the beam angle of incidence, such that incident light scattered diffusely from the sample is preferentially reflected back into the sample by the delivery filter.
- 42. Apparatus for detecting one or more spectral features from a diffusely scattering sample, comprising a delivery filter adapted to allow an incident light beam to pass through at an incident beam angle of incidence to reach the sample, characterised in that the delivery filter is a multi-layer dielectric filter having a transmission characteristic coincident with the wavelength of the incident beam at said angle of incidence, but which shifts to shorter wavelengths at higher angles of incidence such that the filter preferentially reflects back towards the sample incident light diffusely scattered from the sample.
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47. A method of illuminating a diffusely scattering sample, comprising:
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covering a region of the sample with a delivery filter; and directing a beam of collimated light of a predetermined wavelength through the delivery filter and into said sample, wherein said delivery filter is adapted to preferentially reflect back to the sample light of said predetermined wavelength diffusively scattered out of the sample in said region. - View Dependent Claims (48, 49, 50)
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51. A method of collecting spectrally changed light from a diffusely scattering sample illuminated with light of an incident wavelength, comprising:
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covering a region of the sample with a collection filter; and collecting said spectrally changed light through the collection filter, wherein said collection filter is adapted to reflect back to the sample light of said incident wavelength diffusively scattered out of the sample in said region, and to preferentially allow said spectrally changed light to pass.
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Specification