Optical configuration and method for differential refractive index measurements
First Claim
1. An optical configuration for use in measuring a difference in refractive index between a first sample and a second sample, said optical configuration comprising:
- a first optical interface associated with said first sample;
a second optical interface associated with said second sample;
an illumination beam traveling along an optical path, light from said illumination beam being incident upon said first and second optical interfaces to provide a first partial beam defined by the refractive index of said first sample and a second partial beam defined by the refractive index of said second sample;
a linear scanned array comprising a plurality of photoelectric cells each providing an output pulse during a scan having an amplitude determined by the amount of illumination of the corresponding cell by incident light; and
optical multiplexing means upstream of said linear scanned array for receiving said first and second partial beams and defining first and second optical channels, said first optical channel containing optical signal information associated with said first partial beam and said second optical channel containing optical signal information associated with said second partial beam, said first partial beam exhibiting a feature indicative of said refractive index of said first sample on said array and said second partial beam exhibiting a feature indicative of said refractive index of said second sample on said array.
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Abstract
An optical configuration for measuring a difference in refractive index between a first sample and a second sample comprises partitioned first and second optical interfaces symmetrically illuminated by an illumination beam to provide first and second partial beams defined by the refractive index of the first and second samples, respectively. A linear scanned array is aligned in a meridional plane of the optical configuration for detection purposes, and an optical multiplexor is provided upstream of the linear scanned array for receiving the first and second partial beams and defining first and second optical channels carrying optical signal information corresponding to the first and second partial beams. The optical multiplexor switches between optical channels, such that the linear scanned array detects either the first or second optical channel at a given time. Thus, differential measurements are possible using a single linear array. Embodiments for critical angle and surface plasmon resonance refractive index measurements are disclosed. The disclosure also relates to methods for measuring a difference in refractive index between a first sample and a second sample in accordance with the described optical configuration embodiments.
45 Citations
35 Claims
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1. An optical configuration for use in measuring a difference in refractive index between a first sample and a second sample, said optical configuration comprising:
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a first optical interface associated with said first sample;
a second optical interface associated with said second sample;
an illumination beam traveling along an optical path, light from said illumination beam being incident upon said first and second optical interfaces to provide a first partial beam defined by the refractive index of said first sample and a second partial beam defined by the refractive index of said second sample;
a linear scanned array comprising a plurality of photoelectric cells each providing an output pulse during a scan having an amplitude determined by the amount of illumination of the corresponding cell by incident light; and
optical multiplexing means upstream of said linear scanned array for receiving said first and second partial beams and defining first and second optical channels, said first optical channel containing optical signal information associated with said first partial beam and said second optical channel containing optical signal information associated with said second partial beam, said first partial beam exhibiting a feature indicative of said refractive index of said first sample on said array and said second partial beam exhibiting a feature indicative of said refractive index of said second sample on said array. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A method for measuring a difference in refractive index between a first sample and a second sample, said method comprising the steps of:
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A) providing a transparent medium having a sample surface;
B) contacting a first area of said sample surface with said first sample and a second area of said sample surface with said second sample;
C) illuminating an interface of said transparent medium and said first sample and an interface of said transparent medium and said second sample with a beam of light having obliquely incident divergent rays to provide a first partial beam defined by the refractive index of said first sample and a second partial beam defined by the refractive index of said second sample;
D) defining first and second optical channels, said first optical channel containing optical signal information associated with said first partial beam and said second optical channel containing optical signal information associated with said second partial beam;
E) arranging a single linear scanned array of photoelectric cells to detect said optical signal information contained by said first optical channel and said optical signal information contained by said second optical channel;
F) determining a location of a first sample critical angle shadowline on said linear scanned array using said first optical channel, and a location of a second sample critical angle shadowline on said linear scanned array using said second optical channel; and
G) calculating said difference in refractive index based on a distance between said location of said first sample critical angle shadowline and said location of said second sample critical angle shadowline on said linear scanned array. - View Dependent Claims (25, 26, 27, 28, 29)
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30. A method for measuring a difference in refractive index between a first sample and a second sample, said method comprising the steps of:
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A) providing a transparent medium having a metal film adhered thereto;
B) contacting a first area of said metal film with said first sample and a second area of said metal film with said second sample;
C) illuminating an interface of said transparent medium and said metal film with a beam of light having divergent rays obliquely incident to said interface, said beam of light simultaneously irradiating said interface at a first region opposite said first area and a second region opposite said second area to provide a first partial beam defined by the refractive index of said first sample and a second partial beam defined by the refractive index of said second sample;
D) defining first and second optical channels, said first optical channel containing optical signal information associated with said first partial beam and said second optical channel containing optical signal information associated with said second partial beam;
E) arranging a single linear scanned array of photoelectric cells to detect said optical signal information contained by said first optical channel and said optical signal information contained by said second optical channel;
F) determining a location of a first resonance induced flux minimum associated with said first sample on said linear scanned array using said first optical channel, and a location of a second resonance induced flux minimum associated with said second sample on said linear scanned array using said second optical channel; and
G) calculating said difference in refractive index based on a distance between said first resonance induced flux minimum and said second resonance induced flux minimum on said linear scanned array. - View Dependent Claims (31, 32, 33, 34, 35)
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Specification