Dual CCDs Realize Fast Structured Illumination Microscopy With Large Measurement Range

For fast structured illumination microscopy (FSIM), the linear region of the axial modulation response curve is used to map modulation to height directly, thereby avoiding time-consuming axial scanning and improving detection efficiency significantly. However, the linear range of the modulation response curve is minimal, which means that the measurement range of the measurement system is limited. Later, differential fast structured illumination microscopy (DFSIM)was proposed, which added a CCD to the measurement system and constructed a new modulation response function to increase the range of the linear region. In this letter, a square root differential fast SIM modulation response function (SDFSIM)is proposed. It can increase the range of the measurement system by two times compared with the traditional DFSIM. Simulation and experimental results will demonstrate the improvement of SDFSIM.