The detection limit for linear (fluorescence) and nonlinear (stimulated fluorescence or Raman) imaging can be improved by reducing noise. One way to reduce the noise in these types of imaging is to modulate the signal at a certain frequency and only detect signals at that frequency. Since most noise sources have a 1/f dependence, higher modulation frequencies result in less noise. Typically cameras used for imaging have frame rates of 50 or 100 Hz; however, a new time-of-flight camera developed for the gaming industry has a modulation frequency of 20 MHz, allowing for a substantial reduction in noise. In this study, the improved detection limit of this camera was applied to three different experiments: the detection of fluorescent dyes used for tracing cancer cells, the detection of biological material (e.g. saliva) using autoflorescence which has applications in forensics, and the detection of otherwise non-fluorescent materials (e.g. hemoglobin) using stimulated fluorescence.
Available at: http://works.bepress.com/brian-vanhoozen/4/