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Most TEMs employ side-entry specimen stages because it allows more versatility in positioning the specimen, and the design of the device (goniometer) for tilting the specimen is also simpler.
The maximum achievable sample-tilt angles in TEMs are normally smaller than ±30° with commercial single- and double-tilt holders. Note that these angles are barely higher than the tilt required for lattice parameter measurements as indicated by the standard indexed diffraction patterns for fcc, bcc, and hcp crystals.
However, the tilt angles are usually much higher (e.g. ±70°) with tomography holders.
On the other hand, for TEMs with top-entry specimen holders, in order to insert a tilting holder, the top entry pole piece requires a relatively large upper bore. In some designs, the maximum tilting angle can be about 30°.
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