WO1994024529A1

WO1994024529A1 - Fluorescence imaging with tunable detection

Info

Publication number: WO1994024529A1
Application number: PCT/SE1994/000352
Authority: WO
Inventors: Sune Svanberg; Sune Montan
Original assignee: Spectraphos Ab
Priority date: 1993-04-21
Filing date: 1994-04-20
Publication date: 1994-10-27
Also published as: SE9301313L; SE9301313D0

Abstract

The present invention is a fluorescence imaging system comprising a light source (1) for irradiating an object (2), an optical filter (3) for separating fluorescence radiation emitted by said object and detector means (5) to generate a respective signal for each image point and a recording and computing unit for the recording of said fluorescence radiation in a plurality of wavelength bands and executing a mathematical and/or logic operation on signals on the same image point corresponding to one and the same point on the object, therewith to obtain an expression for a weighted signal value and to produce an image of the object from the weighted signal values for the different points of the object; said optical filter being tunable to an arbitrary wavelength passband within a large wavelength range. The optical filter is an electronically tunable interference filter.

Description

FLUORESCENCE IMAGING WITH

TUNABLE DETECTION

Through previous patents (e.g. WO 86/02730), a device for simultaneous imaging of fluorescence in several wavelength bands is known. One of the purposes with the device is to enhance differences between differently fluorescing parts of the object under investigation by pointwise forming functions of the intensities in the different wavelength bands. An important advantage with the device is that it allows moving objects to be studied. Since the imaging is truly simultaneous, false results due to that images in different wavelength bands are detected at different times will be avoided.

However, when objects that are not moving or that are moving very slowly compared to the imaging rate, are to be studied, it may be advantageous to record the images in the different wavelength bands sequentially. The special optics required to create multiple images on the detector is no longer needed. Instead, commercially available camera optics can be used, which makes the system simpler, cheaper and faster. Also the subsequent processing of the images will be simpler since computer imaging systems generally are made for handling entire images.

Such a sequential recording can be realized by means of a rotating wheel holding the optical filters needed. A problem in that case is the synchronization of the wheel rotation with the recording. The wheel has to be in the correct position when the recording is made. This problem is now solved by utilizing electronically tunable liquid filters (produced by Cambridge Research & Instrumentation, Inc., Cambridge, USA). Using such filters, the detection no longer has to be carried out in a predetermined order or number of wavelength bands. Instead, these parameters can be adjusted to the situation. The present invention is a device utilizing such filters to sequentially detect fluorescence images in different wavelength bands.

The invention is outlined in Fig. 1. A light source (1), preferably emitting light in the blue, violet or ultra-violet wavelength range, illuminates the object (2) to be studied. The emitted fluorescence light passes through the filter mentioned above (3) and a lens (4) and finally reaches a detector (5). Thus an image of the object in the desired wavelength band has been achieved. When the image has been recorded, the passband of the filter is shifted to the next passband required. What passband is being used is controlled from a computer (7). The computer also steers the subsequent image processing (6).

CONFIRMATION COPY The light source may be a continuously working or pulsed laser, e.g. a nitrogen or an excimer laser, or a frequency-doubled alexandrite or Ti-Sapphire laser, or a lamp, the light of which is filtered to the desired wavelength range. The lamp may be a continuous lamp or a flashlamp. The filter is an electronically tunable filter that can be tuned as fast as the detection device requires. The lens may be any commercially available camera lens and the detector a CCD camera, equipped with an image intensifier if so needed. The device recording the images may be any ordinary frame grabber that digitizes the video signal and the computer a personal computer like an IBM PC/AT.

Claims

CLAIMS:

1. A fluorescence imaging system comprising a light source for irradiating an object, an optical filter for separating fluorescence radiation emitted by said object and detector means to generate a respective signal for each image point and a recording and computing unit for the recording of said fluorescence radiation in a plurality of wavelength bands and executing a mathematical and/or logic operation on signals on the same image point corresponding to one and the same point on the object, therewith to obtain an expression for a weighted signal value and to produce an image of the object from the weighted signal values for the different points of the object; said optical filter being tunable to an arbitrary wavelength passband within a large wavelength range.

2. A fluorescence imaging system according to Claim 1 , characterized in that the optical filter for separating the emitted fluorescence radiation is an electronically tunable interference filter.

3. A fluorescence imaging system according to Claim 2, the tunable filter of which can be tuned from 350 to 800 nm.

4. A fluorescence imaging system according to Claim 1, 2 or 3, characterized in that the detector is constituted by a CCD camera or a an image intensified CCD camera.

5. A fluorescence imaging system according to Claim 1, 2, 3 or 4, characterized in that the object illumination is carried out by means of an optical fiber.