Fluorometer having an improved optical system

#The subject invention is directed to an improved high efficiency fluorometer and comprises a device for determining the relative fluorescence of test samples in miniature polystyrene test wells which are designed for use in fluorescent immuno assays, and especially to the illuminating optical system for this fluorometer.

#Fluorometers have been designed and are known for measuring fluorescent levels of samples in a series of tests known as fluorescent immuno assays. Fluorometers have been extensively used to measure the relative fluorescence of light emmitted by samples in wells as an indication of the presence of antibodies in the wells. In a typical application, an ultraviolet lamp projects a beam through a lens to an excitation filter. The excited beam passes the excitation filter and is reflected by a mirror downward into the solution sample well, causing the sample substance to fluoresce. The emitted light passes upward from the well, and is passed through emission filters which are specifically selected to pass light only within a certain band width to a photomultiplier tube. The emitted light is then enhanced, processed and the information comprising relative fluorescent units relative to a base line established by a sample well containing a known substance is then sent to a printer.

#Typically, such systems have been very expensive, and only capable of being used by highly trained personnel. One of the major problems with such prior art systems has been the optical system which often consists of a lamp and photomultiplier which must be placed at least 90.degree. apart or on opposite sides of the sample in order to separate the excitation and emission beams. This has lead to complex optical systems of both considerable expense and size.

#A fluorometer of the present invention may be better understood with reference to FIG. 1 which is a cross-sectional view of the optical system of the fluorometer shown in combination with a block diagram of the basic data analysis elements of the fluorometer.

#To briefly summarize the critical elements of the fluorometer shown in FIG. 1, ultraviolet radiation from an ultraviolet lamp 10 passes through a shield 12 and is focused into a sample well 14 after passage through an optical excitation filter 16. This filter selects a narrow band of ultraviolet wavelength suitable for excitation of the fluorescent substance used in the assay contained in the well 14. The fluorescent radiation emitted by the material in the sample well 14 is reflected by a beam splitter 16 into an emission filter 18 where scattered and reflected ultraviolet radiation from the ultraviolet source 10 is rejected. A precisely defined band of longer wave length radiation is passed from the emission filter 18 to the photomultiplier tube 20 via the shield 22.

#The intensity of the radiation passing through the emission filter 18 is measured by multiplier tube 20 which provides a current output signal on line 24 proportional to a strength of the light emission received by photomultiplier tube 20. The signal from the photomultiplier tube 20 is amplified by amplifier 26, converted to a digital form at analog to digital converter 28, and sent through a microprocessor 30 where fluorescence levels are computed and temporarily stored. The levels of the critical components in the sample are then computed based upon calibration wells which are also included in the carousel. The thermal printer 32 then prints out a tabulation of fluorescence units for each well in the set. The printer may also print out a correlation coefficient describing how well the calibration data defines a standard calibration curve using the data reduction software incorporated in software package 34.

#The techniques of amplification, conversion data reduction and printing are well known in the art and are not described in detail herein.