Optical parallel beam tomography
The contrast mechanism of X-ray tomography is based on the differences of X-ray absorbance of materials. However, soft tissues consist of mainly light elements, produce very poor contrast under conventional short wavelength X-rays, therefore, a tomographic system utilizing the visible and NIR spectrum could be useful for 3D imaging of living tissues. The optical parallel-beam tomography using visible light could minimize scattering and refraction effects using refractive index matched specimen. The system consists of a basic Schlieren optical setup using two lenses/mirrors with a point light source and a pinhole detector. The pinhole acts as a spatial filter. Arranging multiple Schlieren optics in a circular fashion provides an imaging system capable of capturing number of projection images simultaneously. This reduced the number of specimen rotation steps needed for tomographic reconstruction. The imaging model for optical tomography is set up in AMIL.