We present a transmission-mode confocal laser scanning microscope system based on the use of second-harmonic generation (SHG) for signal detection. Our method exploits the quadratic intensity dependence of SHG to preferentially reveal unscattered signal light and reject out-of-focus scattered background. The SHG crystal acts as a virtual pinhole that remains self-aligned without the need for descanning.
© 2003 Optical Society of America
C. Yang and J. Mertz, "Transmission confocal laser scanning microscopy with a virtual pinhole based on nonlinear detection," Opt. Lett. 28, 224-226 (2003)