Improved Optical Imaging Employing Integrated Photonic Technology

摘要

Noninvasive diagnostic techniques have been explored in past for detecting tissue abnormalities. Near infrared and long wavelength visible light can penetrate deep into biological tissues with minimum absorption, however light traversing biological tissues undergoes multiple elastic scattering events. The objective of the photon migration studies is to reduce or eliminate the resulting turbidity, which obscures embedded lesions. A richer information can be achieved with time resolve/time gated spectroscopy, where light is pulsed and detected luminescence is time gated to collect only early arriving photons. Our experimental set-up enhances the current state of art techniques for time resolved spectroscopy and imaging by providing alternative source that can be modulated at desired frequencies and repetition rates. In this paper we explore use of an array of Vertical Cavity Surface Emitting Lasers (VCSELs) as emitter (excitation source) as an integral part of bio-optical imaging system. In this paper we describe the effect of Laser (excitation source) Jitter on the performance of time resolved/time gated spectroscopy and imaging system. In diffusion, trans-illumination and fluorescence tomographic techniques, the timing jitter of an excitation source itself seriously degrades the temporal resolution of the collected luminescence, which significantly effects the detection and localization of tumor or other desired regions of interest. The discussed technology promises high performance, better spatial resolution and signal to noise ratio without compromising sensitivity. The structure of excitation source also allows for on-wafer testing and easy integration with other photonic components and high channel capacity free space diffractive micro-optical elements.