Optical measurement for illuminating a sample with filtered light and measuring fluorescence from the sample

Abstract

An optical measurement system for illuminating a sample with filtered light and measuring fluorescence from the sample, which system includes a broadband light source arranged to provide a broadband beam; a first tunable element arranged to filter at least a portion of the broadband beam thereby providing filtered light; and a control unit arranged to provide a control signal to said first tunable element, wherein the first tunable element includes an acousto-optic filter (AOTF) and the control signal to the AOTF includes an acoustic RF signal provided by a Voltage Controlled Oscillator (VCO) arranged so the AOTF provides an out-of-band suppression of more than or equal to 25 dB.

1 . An optical measurement system for illuminating a sample with filtered light and measuring sample fluorescence, comprising
 a. a broadband light source arranged to provide a broadband beam;   b. a first tunable element arranged to filter at least a portion of said broadband beam thereby providing filtered light; and   c. a control unit arranged to provide a control signal to said first tunable element,   
       wherein said first tunable element is an acousto-optic filter (AOTF) and said control signal to said AOTF is an acoustic RF signal provided by a Voltage Controlled Oscillator (VCO) arranged so said AOTF provide an out-of-band suppression of more than or equal to 25 dB. 
     
     
         2 . The system of  claim 1  wherein said system is arranged to
 a. Illuminate a sample with light filtered by said AOTF; and 
 b. measure a fluorescent response to said illumination from said sample in a wavelength range in which said AOTF provides said out-of-band suppression. 
 
     
     
         3 . The system of  claim 1 , wherein said system is selected from the group of
 a. a fluorescence microscope,   b. an epifluorescence microscopy,   c. a STED microscope,   d. a 4 pi microscope,   e. a SPDM localization microscope,   f. a SMI microscope,   g. a Vertico SMI microscope,   h. fluorescence imaging, and   i. Fluorescence Lifetime Imaging Microscope (FLIM).   
     
     
         4 . The system of  claim 2 , wherein the said system further comprises a photon counter arranged to detect the fluorescent response from said sample. 
     
     
         5 . The system of  claim 4 , wherein said system is arranged to measure said fluorescent response as a function of time. 
     
     
         6 . The system according to  claim 1 , wherein multiple RF control signals provided by multiple VCOs are multiplexed in order to allow the AOTF to output multiple spectral lines in said filtered light. 
     
     
         7 . The system according to  claim 1 , wherein said control unit is arranged to provide that said control signal vary in time such that the central wavelength of said filtered light is scanned though a part of the wavelength range of said incoming broadband beam. 
     
     
         8 . The system according to  claim 1 , wherein said control unit is arranged to provide that the amplitude of said control signal vary in time such that the spectral width of said filtered light varies in time. 
     
     
         9 . The system according to  claim 1 , wherein said out-of-band suppression is provided at a wavelength more than or equal to 5 nm from the illumination wavelength. 
     
     
         10 . (canceled) 
     
     
         11 . An optical filter for illuminating a sample with filtered light, comprising:
 an input for receiving an incoming beam from a light source;   a first tunable filter;   a second tunable filter; and   a splitter arranged before the filters, wherein the splitter comprises
 a spectral splitter arranged to split the incoming beam into two beams of which one beam has light at wavelengths in a higher wavelength range and one beam has light at wavelengths in a lower wavelength range, 
 or wherein the splitter comprises 
 a polarization splitter arranged to split the incoming into two beams of which one beam has a first polarization and one beam has a second polarization, 
   wherein the filter is arranged such that one of the two beams is directed into the first filter and the other one of the two beams is directed into the second filter.   
     
     
         12 . The optical filter for illuminating a sample of  claim 11 , wherein said beam splitter comprises said polarization beam splitter. 
     
     
         13 . The optical filter for illuminating a sample of  claim 11 , wherein said beam splitter comprises said spectral beam splitter. 
     
     
         14 . The optical filter for illuminating a sample of  claim 11 , wherein said first tunable filter comprises an element arranged to change its refractive index in response to a stimulus. 
     
     
         15 . The optical filter for illuminating a sample of  claim 11 , comprising a combiner arranged to combine the filtered beams exiting from the first and the second filters.