Wavelength-coded volume holographic imaging endoscope for multidepth imaging.

A wavelength-coded volume holographic imaging (WC-VHI) endoscope system capable of simultaneous multifocal imaging is presented. The system images light from two depths separated by 100  μm in a tissue sample by using axial chromatic dispersion of a gradient index probe in combination with two light-emitting diode sources and a multiplexed volume hologram to separate the images. This system is different from previous VHI systems in that it uses planar multiplexed gratings and does not require curved holographic gratings. This results in improved lateral imaging resolution from 228.1 to 322.5  lp/mm. This letter describes the design and fabrication of the WC-VHI endoscope and experimental images of hard and soft resolution targets and biological tissue samples to illustrate the performance properties. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).