Abstract

The laser phase plate (LPP) is now approaching readiness for applications in biomedical science. I present the design and how we have overcome teething problems such as resolution loss by thermal noise. Our first steps toward automation resulted in reliable, reproducible, and stable operation over the time needed to take large datasets. As a first step towards applications, we show that the strong contrast increase reveals surprising structural variation in protein particles (apoferritin and rubisco). We have even generated a tomogram with the LPP , showing that it is in principle possible to maintain laser/electron beam alignment when tilting the specimen. Installation of Theia, our new microscope, is currently advancing well. With a useful resolution of _{1-Å (as opposed to} 3-Å in our old microscope), along with spherical-aberration correction (enabling us to recover more information across all scales) and a long effective focal length (for phase contrast out to the largest specimen features) together with high throughput, Theia will allow our collaborators and us to use the LPP in its ideal environment. We have constructed its “T-1” LPP and demonstrated it on the optical bench at the needed high power. We are thus expecting first phase-contrast images from Theia this Fall.