Positioning systems for high resolution tissue imaging

Tissue handling systems position ex-vivo samples to a required accuracy that depends on the features to be imaged. For example, to resolve cellular structure, micron pixel spacing is needed. 3D tissue scanning at cellular resolution allows for more complete histology to be obtained and more accurate diagnosis to be made. However, accurate positioning of a light beam on the sample is a significant challenge, especially when fine spacing between scan steps is desired or large, inconsistently shaped samples need to be imaged. Optical coherence tomography (OCT) is an application where accurate positioning systems are required to reap the full benefit of the technology. By simultaneously manipulating the light beam position and sample location, a 3D image is reconstructed from a series of depth profiles produced. To automate image acquisition, a fully integrated and synchronised system is necessary. A tissue handling and light delivery system for free-space optical devices is described. Performance characteristics such as resolution, uncertainty, and repeatability are evaluated for novel hardware configurations of OCT. Typical scanning patterns with associated synchronisation requirements are discussed.