Table 1. Comparison of automated tomographic software packages.
| Item | UCSF Tomography10 | Serial EM17 | Our software |
|---|---|---|---|
| TEM type | FEI, and JOEL | FEI, and JOEL | Zeiss Libra 120 |
| Model-based goniometer tracking | Yes | No | No |
| XY tracking value | Pre-calibration of model parameter | Exploration method | On-line feedback control |
| XY tracking actuator | Beam tilt or shift | Beam tilt or shift | Goniometer |
| XY tracking limitation | Yes, by objective aperture | Yes, by objective aperture | No |
| XY tracking image feedback | Yes, cross-correlation | Yes, cross-correlation of filtered image | Yes, modified cross-correlation |
| XY tracking additional image | Yes, 2 low-mag. images overall | Yes, 2 high-mag. images overall | Yes, 2 high-mag. images overall |
| Defocus tracking value | On-line update on the basis of pre-calibrated parameters | Beam-tilt-induced image displacement method | On-line feedback control |
| Defocus tracking actuator | Change objective lens current | Beam tilt and shift; change objective lens current | Change objective lens current |
| Defocus tracking limitation | Yes, by an acceptable image quality | Yes, by an acceptable image quality | Yes, by an acceptable image quality |
| Z tracking image feedback | No, predicted by the XY shift | Yes, cross-correlation of the additional image | Yes, CTF fitting of historical images |
| Z tracking additional images | No | Yes, 2 additional images at each tilt | No |
| Tilt range | Two loops (0° to +60°; 0° to −60°) | One loop at lower mag. and two loops at higher mag. | One loop (−60° to +60°) |
| Optical backlash (hysteresis) | Yes | Yes | No |
| Mechanical backlash | No | No | No, eliminated by moving strategy |
| Optical rotation compensation | Off-line identification | Off-line identification | Off-line identification |
| Keep magnitude unchanged during collection process | No, go to low mag. Between two tilting loops | No, go to low mag. for tracking when mag. is larger than 50,000× | Yes |
This table catalogs the basic ideas applied in our system compared with UCSF tomography and SerialEM software. Feature comparisons are listed with similarities and differences outlined.