Patent US4938593A successfully refreshed from Google Patents.
US4938593A
Expired / Lapsed
US
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Photothermal densitometer for reading electrophoresis gels
Assignee: University of Michigan (System)
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Filing: 1988-08-01
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Granted: 1990-07-03
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Expires: 2008-08-01
Abstract
Abstract A densitometer apparatus for evaluating electrophoresis gel samples based on photothermal techniques. In accordance with this invention, electrophoresis gels are characterized by passing a heating light beam through the gel at a particular location. Light absorbed by the presence of staining dyes in that area causes heat evolution which generates a local index of refraction variation or a "thermal lens". A probe beam is passed through the sample in the area of the thermal lens a predetermined period of time after it is generated and the modification to the beam caused by the thermal lens is evaluated. For example, defocusing of the probe beam can be sensed by a detector which receives transmitted light through a limiting aperture. Various means of separating the heating and probe beams are disclosed, including use of separate lasers, crossed beams, modulation by plane of polarization, etc. One embodiment of this invention is particularly adapted for characterizing dry gels in which the heating beam is absorbed by the sample and the probe beam passes across the sample and is modified by a thermal lens generated in the air above the sample. Several embodiments are related to means for offsetting the probe beam from the heating beam for use with samples that are swept by the photothermal techniques in accordance with this invention offer advantages in terms of sensitivity over conventional transmission-type densitometers. These advantages enable increased sensitivity and facilitate the use of simplified staining techniques.
Inventors
- 👤 Michael D. Morris
- 👤 Konan Peck
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:18
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/171; G01N27/00; G01N27/26; G01N27/416; G01N27/447; G01N27/44704; G01N27/44717; G01N27/44721; G01N2021/1712; G01N21/59; G01N21/5907; G01N21/5911; G01N2201/00; G01N2201/10; G01N2201/108; G01N2201/1087
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
173 words
A desitometer apparatus for evaluating electrophoresis gel samples for characterizing a presence of a dye within said sample comprising: means for emitting a heating beam for passing into said sample such that said dye absorbs energy from said heating beam, thereby locally heating said sample and generating a local index of refraction variation within said sample, means for emitting a probe beam for passing through said sample, translation means for causing said beams to sweep relative to said sample, beam aiming means for offsetting said probe beam with respect to said heating beam along the direction of translation of said beams with respect to said sample so that said probe beam passes through an area of said sample a predetermined period of time after said area is subjected to said heating beam, and detector means for evaluating the modification of said probe beam as said probe beam passes through said area, whereby said modification caused by said local index of refraction variations is related to the concentration of said dye within said sample.
Claim 2
Dependent Claim
173 words
A desitometer apparatus for evaluating electrophoresis gel samples for characterizing a presence of a dye within said sample comprising: means for emitting a heating beam for passing into said sample such that said dye absorbs energy from said heating beam, thereby locally heating said sample and generating a local index of refraction variation within said sample, means for emitting a probe beam for passing through said sample, translation means for causing said beams to sweep relative to said sample, beam aiming means for offsetting said probe beam with respect to said heating beam along the direction of translation of said beams with respect to said sample so that said probe beam passes through an area of said sample a predetermined period of time after said area is subjected to said heating beam, and detector means for evaluating the modification of said probe beam as said probe beam passes through said area, whereby said modification caused by said local index of refraction variations is related to the concentration of said dye within said sample.
Claim 3
Dependent Claim
17 words
A densitometer apparatus according to claim 1 wherein said heating beam is produced by a laser source.
Claim 4
Dependent Claim
17 words
A densitometer apparatus according to claim 1 wherein said probe beam is produced by a laser source.
Claim 5
Dependent Claim
52 words
A desitometer apparatus according to claim 1 wherein said detector means comprises an aperture and a photodetector whereby the modification of said probe beam as it passes through said sample is evaluated by illuminating said aperture and said photodetector such that the intensity measured by said photodetector is function of said modification.
Claim 6
Dependent Claim
78 words
A densitometer apparatus according to claim 1 wherein said heating beam emanates from a first laser source and said probe beam emanates from a second laser source, and further comprises means for orienting said heating beam and said probe beam in a parallel offset relationship as they pass through said sample, and filter means for absorbing said heating beam after said beams pass through said sample such that only said probe beam is sensed by said detector means.
Claim 7
Dependent Claim
37 words
A densitometer apparatus according to claim 1 wherein said heating beam and said probe beam are derived from a single laser source and further comprising beam splitter means for providing a separated heating beam and probe beam.
Claim 8
Dependent Claim
52 words
A densitometer apparatus according to claim 1 wherein said heating beam and said probe beam are derived from a single laser source and further comprising means for separating the output from said laser by plane of polarization thereby providing said heating beam and said probe beam having orthogonally oriented axes of polarization.
Claim 9
Dependent Claim
22 words
A densitometer apparatus according to claim 7 further comprising filter means for absorbing light polarized in the direction of said heating beam.
Claim 10
Dependent Claim
32 words
A densitometer apparatus according to claim 1 further comprising chopper means for interrupting said heating beam and lock-in amplifier means for detecting the alternating component of the output from said detector means.
Claim 11
Dependent Claim
23 words
A densitometer apparatus according to claim 1 wherein said translation means comprises a translation stage for moving said sample relative to said beams.
Claim 12
Dependent Claim
39 words
A densitometer apparatus according to claim 1 wherein said beam aiming means comprises a glass plate positioned along said probe beam and tilted from a plane normal to said probe beam to cause said offsetting of said probe beam.
Claim 13
Dependent Claim
39 words
A densitometer apparatus according to claim 11 further comprising an actuator for varying the angle of tilt of said glass plate relative to said normal plane thereby varying the offset of said probe beam relative to said heating beam.
Claim 14
Dependent Claim
39 words
A densitometer apparatus according to claim 11 wherein said translation means provides bidirectional translation and further comprising an actuator for tilting said glass plate in opposite directions relative to said normal plane to enable bidirectional offsetting of said beam.
Claim 15
Dependent Claim
30 words
A densitometer apparatus according to claim 1 wherein said team aiming means comprises a cylinder lens positioned along said probe beam and displaceable to cause offsetting of said probe beam.
Claim 16
Dependent Claim
32 words
A densitometer apparatus according to claim 14 further comprising an actuator for adjusting the position of said cylinder lens thereby varying the offset of said probe beam relative to said beating beam.
Claim 17
Dependent Claim
34 words
A densitometer apparatus according to claim 14 wherein said translation means provides bidirectional translation and further comprising an actuator for adjusting the position of said cylinder lens to enable bidirectional offsetting of said beams.
Claim 18
Dependent Claim
40 words
A densitometer apparatus according to claim 1 wherein said beam aiming means comprises a lens conforming to surfaces of revolution generated about an axis and said axis being displaced from said probe beam to cause offsetting of said probe beam.
Claim 19
Dependent Claim
38 words
A densitometer apparatus according to claim 17 further comprising actuator means for enabling the position of said lens to be displaced relative to said axis along two orthogonal axes thereby displacing said probe beam along two orthogonal axes.
Claim 20
Dependent Claim
25 words
A densitometer apparatus according to claim 1 wherein said translation means causes said beams to sweep across said sample at a rate of 10-100 millimeters/seconds.
Claim 21
Dependent Claim
38 words
A densitometer apparatus according to claim 1 wherein the amount of said offset and the rate of translation of said beams relative to said sample are so related such that said predetermined period of time is 1-5 milliseconds.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-07-02 | 1994-01-01 | 1994-07-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-07-02 | 1998-01-01 | 1998-07-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-07-02 | 2002-01-01 | 2002-07-03 | $7700.00 | Window Closed / Lapsed |