Radiant energy – Luminophor irradiation – With ultraviolet source
Patent
1986-06-23
1988-11-22
Howell, Janice A.
Radiant energy
Luminophor irradiation
With ultraviolet source
2504581, 2504612, G01N 2164
Patent
active
047868139
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a fluorescence imaging system of the kind which comprises a light source for irradiating a fluorescent object, a filter for separating fluorescence radiation emitted by the object as a result of irradiation, and detector means for detecting radiation transmitted through the filter, there being arranged between the object and the detector means an imaging optical system having an object image plane located adjacent the detector means.
Systems which fall within this general group are known to the art. Examples of such systems include fluorescence microscopy systems, which are often used in research work. These instruments provide an image produced by fluorescent substances in the object under examination, these substances being either natural substances or fluorescent dyes.
Many solid and liquid substances emit fluorescence radiation when irradiated with ultraviolet light, which radiation may fall within wide wavelength bands of but low structural profiles, and hence identification on the basis of spectroscopy is difficult. However, in conventional fluorescence analysis, e.g. in fluorescence microscopy, there is normally incorporated in the optical system a filter for a selected wavelength band. In the case of slightly complex situations, observations are often disturbed by contributions emanating from the many different compounds present in the sample under examination.
An object of the present invention is to provide a fluorescence imaging system with which fluorescence reproduction can be achieved with improved significance, by eliminating irrelevant fluorescence radiation, even when a certain spectral overlap prevails between the fluorescence radiation desired to be imaged and the disturbing fluorescence radiation.
This object is achieved in accordance with the invention by providing a fluorescence imaging system of the kind described in the introduction with a beam-splitting system arranged to split the fluorescence radiation passing through the optical system into at least three parts, each of which parts forms a respective image of the object, which image is displaced in the image plane relative to the other imges and falls on a respective detector-area in the detector means, the various parts of the beam being led through a respective filter, each filter being of mutually different frequency pass-band, there being obtained thereby an image of the object within each respective wavelength region in the form of a plurality of image points for each, the detector means being arranged to produce a respective signal for each of said points, means being provided for performing a mathematical and/or logic operation for signals deriving from each image point corresponding to one and the same point on the object, so as to obtain a weighted signal value and to produce an image of the object from the weighted signal values of the various points on the object.
The imaging system should be achromatic. Consequently, in accordance with a preferred embodiment, the beam splitting system comprises a mirror which is incorporated in the optical system and divided into a plurality of parts, each positioned at a mutually different angle to reproduce the object on different parts of the detector plane. Both planar and spherical mirrors can be used, as can also other beam-splitting systems of a known kind.
The filters used should be filter constructions capable of producing well defined band-pass curves, and particular benefit is obtained in this respect when interference filters are used.
In order to understand the difference between ordinary fluorescence imaging and that of the invention, it is suitable to consider the spectrum illustrated in FIG. 2a. Tumor cells have the ability to retain the substance hematoporphyrine-derivative (HPD). The characteristic fluorescence spectrum for this substance lies within the range of 610-700 nm, which corresponds to the peaks referenced A and C in the figure. Other substances in the cells, however, fluoresce much more strongly, and produce a broader band spectru
REFERENCES:
patent: 3872312 (1975-03-01), Hirschfeld
patent: 4019060 (1977-04-01), Woodman
patent: 4144452 (1979-03-01), Harte
patent: 4272684 (1981-06-01), Seachman
patent: 4407008 (1983-09-01), Schmidt et al.
patent: 4573195 (1986-02-01), de France
Montan Sune
Svanberg Sune
HighTech Network SCI AB
Howell Janice A.
Rauchholz William F.
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