Japan Science and Technology Agency (JST) announced April 26, 2012, that a Japanese research group developed a scanning electron microscope (SEM) capable of showing a 3D image in real time and a high-resolution naked-eye 3D monitor for the SEM.
The group consists of researchers from Hitachi High-Technologies Corp, Eizo Nanao Corp, Niigata University, Shizuoka University, etc. The new SEM is expected to be used not only for analyzing the structure of an object but for microanatomy using a manipulator and measuring electrical characteristics of inorganic materials.
Scanning while switching direction of electron beam
With an SEM, three-dimensional structures (convex and concave structures) on the surface of an object are observed by emitting a narrowed electron beam to the object and two-dimensionally scanning it. Normal SEMs show images that are observed from one direction. Therefore, those images are two-dimensional as if they are seen by one eye.
For obtaining three-dimensional images by using normal SEMs, it is necessary to synthesize still images equivalent to images seen by the right and left eyes (parallax images) after taking those images from different angles by tilting the stage and to observe them with red/blue glasses, etc. However, with this method, it takes time to obtain and make adjustment to parallax images, and it is not possible to observe the SEM image of a specimen in real time.
This time, the research group developed a technology to scan a specimen at high speeds while switching the angle of an electron beam directed at a specimen and succeeded in instantly obtaining right and left parallax images. Specifically, an electron beam is slanted by the converging effect of the electromagnetic lens.
Though the aberration caused by slanting an electron beam lowers resolution, the group developed a new electro-optical system and a scan control technology for electron beam and applied them for the SEM.
The control of the direction of electron beam's tilt is conducted by using a special magnet coil and switching among left-leaning scanning, normal scanning, right-leaning scanning, etc for each line and frame. As a result, the research group realized a high scanning speed of 33ms/frame and real-time 3D observation.
The focus and astigmatism of the right and left parallax images are different from those of normal SEM images because of the use of the converging effect of the lens. But they can be adjusted for each line and frame.