Frequency division multiplexed fluorescence confocal microscopy

High-speed, frequency division multiplexed, multichannel fluorescence confocal microscopy imaging is achieved by encoding the spatial location information into the frequency domain. The technique provides high spatial resolution fluorescence imaging in real-time upto the nanosecond range when applied to the detection modules based on single or arrayed photomultiplier tubes. The crosstalk signal noise among various frequency channels is reduced by separating adjacent frequencies in the laser channels. For a Gaussian noise, the bandwidth of noise spectrum is estimated by observing the detected signal over a finite time interval. The maximum number of the frequency division multiplexed channels is limited by the response time of the fluorescence emission and the photomultiplier tube detector. The spatial resolution of the frequency division multiplexed fluorescence confocal microscope is same as conventional fluorescence confocal microscopes.