Figure 1 shows a schematic of the experimental system. A broadband Ti: Sapphire laser (MICRA, center wavelength: 800 nm, bandwidth: 120 nm, Coherent Inc.) was used as the fundamental light source. The fundamental laser light was focused into a frequency doubling crystal (BBO, Castech, Fujian, China) by a lens of (L1) and converted to the visible. The light exiting the BBO crystal (bandwidth ) was first collimated with an achromatic lens of (L2) and then reflected by a long-pass filter (FEL0700, Thorlabs) to separate the visible light from the residual fundamental light. The visible light beam was coupled into the source arm of a single-mode optical fiber-based Michelson interferometer. After exiting the sample arm, the light was collimated, reflected by a dichroic mirror (NT69-887, cut on wavelength: 450 nm, Edmund Optics, Inc.), scanned by an galvanometer scanner, and then focused on the sample by an achromatic lens (L3, ). When imaging the retina in vivo an objective lens (L4, ) was added. In the detection arm, the reflected light from the sample and reference arms was collimated and detected by a spectrometer, which consisted of an transmission grating, a multi-element imaging lens (), and a line scan CCD camera (Aviiva-SM2-CL-2010, 2048 pixels with 10 μm pixel size operating in 12-bit mode, e2V). An image acquisition board (NI IMAQ PCI 1428) acquired the image captured by the camera and transferred it to a workstation (HP xw4600, 4 GB memory) for signal processing and image display.