Using Adaptive Optics to Perform Deep-Tissue Cell Imaging
- Monday, 01 July 2013
One of the main analysis tools used in this project was the Vision Development Module. This LabVIEW add-on made it simple to perform image data analysis and display results to the user. The Vision Development Module also makes use of the multicore PC so the user can make feedback adjustments as the images are acquired.
In addition to image processing, we used the Vision Development Module to drive another very important component of the system, the SLM. The SLM is the active element in the microscope used to cancel out sample aberrations, which reduces image blur and increases image brightness. The SLM can be thought of as a 1,920 × 1,080 pixel “mirror” that we use to reflect the excitation laser beam into the microscope objective. By addressing sections of pixels on the SLM, the laser beam is divided into multiple beams, or “beamlets,” that can be independently controlled. Each beamlet can then be redirected back to the focus point if it was scattered in the wrong direction by tissues covering the cells of interest.
Similarly, the phase of each beamlet can also be adjusted. This correction compensates for any index of refraction differences each beamlet might experience while passing through the sample. The goal is to configure the SLM so that all beamlets meet exactly at the focal point, perfectly in phase. When this occurs, we acquire the sharpest and brightest images possible (Figure 3).
To configure the SLM, we needed specific patterns. Using the Vision Development Module, it was simple to generate the images necessary for the adaptive optics algorithms and to send them to the SLM via a standard digital visual interface video cable. The tight integration of the Vision Development Module and the LabVIEW development environment was also key to making the SLM updates fast and in synch with the microscope’s scanning.
Using the adaptive optics microscope with NI technology, researchers can obtain deeper tissue images with greater clarity than ever before. In addition, these images are several times brighter than those taken without using the adaptive optics corrections. This means less excitation power is needed, significantly reducing photo bleaching and allowing for the performance of longer and deeper scans.