Materials Research Activities

Electron microscopy in the 1960s

Electron microscopy in the 1960s

by Tim Palucka

In 1969 RCA dropped out of the electron microscope business, having decided that they could make more money selling record albums and consumer electronic devices.  General Electric had never become a major power in the electron microscope business. This left the field wide open for companies such as JEOL, Hitachi, and Akashi in Japan, and Philips, Siemens, and Zeiss in Europe.

TEMs

The resolution of the best TEMs was now approximately 0.3 nm (3 Å); JEOL claimed a resolution of 0.2 nm (2 Å) for its 1968 model JEM-100B. Accelerating voltages were still typically in the 100 kV range, although JEOL marketed a 200 kV instrument in 1967 called the JEM-200. Philips marketed a very popular 100 kV microscope called the EM 300 in 1966. They claimed that this was the ‘first fully-transistorized electron microscope,' and that it could attain a point resolution of 0.5 nm (5 Å). More than 1,850 units of the EM 300 were sold.

Ultrahigh voltage electron microscopes

Another approach to the study of materials that emerged in the 1960s involved increasing the accelerating voltage of the electron gun to extreme levels—up to 3 MeV—in an effort to penetrate more deeply into thicker samples. CEMES-LOE/CNRS at Toulouse, France, developed a 3MeV instrument around 1965, followed closely by JEOL, which released a 1 MeV microscope, the JEM-1000, in 1966. (One MeV represents a million electron volts, while one kV is a thousand electron volts. So 1,000 kV= 1 MeV.) Hitachi eventually came to dominate this field. Starting in 1954 with a 300 kV microscope, Hitachi followed this up with the HU-500 (500 kV) instrument in 1964, the HU-650 (650 kV) in 1968, and the HU-1000 (1 MeV) in 1969. It would continue this pursuit with the HU-3000 (3 MeV) Ultrahigh Voltage EM in 1970 and the H-1250 (1250 kV) in 1976.

These ultrahigh voltage EMs were so large that they typically occupied their own two-story building. The electron gun and its associated high voltage electronics were located near the ceiling of the second story, while the operator sat at the bottom of the microscope column looking at the fluorescent screen. Hitachi's 1964 model HU-500 stood 4 meters tall; later, higher MeV versions eventually made this look small. On the left is a photograph of the 1 MeV Atomic Resolution Microscope (ARM) at the Lawrence Berkeley Laboratory.

SEMs

From 1966 to 1969 JEOL produced four commercial SEM units, the JSM-1, JSM-2, JSM-U, and the JSM-U3. Accelerating voltages could be adjusted from 5 to 50 kV on these instruments. The resolution improved from 50 nm on the JSM-1 to 20 nm on the JSM-U3.

Hitachi called its 1966 XMA-5b an “EPMA with SEM.” This was more of an electron probe microanalyzer than an SEM, and was most likely Hitachi's attempt to quickly join in the SEM business. They did not really get involved until the introduction of the HSM-2A in 1971; their attention was focused more on the UHV EM market during the 1960s.

Philips' only foray into scanning microscopy came in 1968 with the development of a “scanning attachment” for its 1966 model EM 300. This attachment turned the TEM into an STEM. Their first dedicated SEM was the PSEM 500, introduced in 1972.

  • Electron microscopy in the 1960s
  • Electron microscopy in the 1970s
  • Electron microscopy in the 1980s
  • Electron microscopy in the 1990s
This page was updated on 19 July 2002 by Arne Hessenbruch.