Method to remove the spectral components of illumination energy from a sample spectrum without the use of optical barrier filters, and apparatus for the same

A method to remove the spectral components of illumination energy from a sample spectrum without the use of optical barrier filters, the method comprising:

• directing energy outputted from a reference chamber and a sample chamber to a diffraction grating that diffracts the received energy onto a CCD chip to generate a first set of illumination spectra when illumination energy is simultaneously provided to said reference chamber and to said sample chamber while said sample chamber is empty;
• determining from said first set of illumination spectra the intensity differences between the illumination spectrum from said reference chamber and the illumination spectrum from said empty sample chamber at each wavelength across the illumination wavelength range;
• directing energy outputted from said reference chamber and said sample chamber to said diffraction grating that diffracts the received energy onto a CCD chip to generate a second set of illumination spectra when illumination energy is simultaneously provided to said reference chamber and to said sample chamber, the spectrum from the reference chamber contains only illumination spectral components and the spectrum from said sample chamber contains both illumination and sample spectral components;
• adjusting the intensities of the illumination spectrum from said reference chamber of the second set of spectra across the wavelength range of the illumination by subtracting or adding the previously determined intensity difference at each corresponding wavelength to the intensities of said illumination spectrum wavelength from said reference chamber of the second set of spectra to make the illumination intensities from said chambers equal across the illumination wavelength range;
• and
• subtracting said adjusted illumination spectrum of said second set of spectra from the spectrum from said sample chamber of the second set of spectra that contains both illumination and sample components, effectively removing the spectral component of illumination energy from a sample spectrum.