摘要 |
<p>In a probe system which enables high sensitivity to be achieved in a differential phase contrast optical or electron microscope, a focused beam is periodically deflected over the surface of an object and resulting phase modulation of the beam (related to the phase structure of the object) is sensed. In one embodiment, the beam (18) is derived from a laser (10) and light reflected from the irradiated object (24) is received by a photodetector (26), where it interferes with a reference beam (28) also derived from the laser (10) but shifted in frequency by means of a Bragg cell (30); the detection system includes a vector voltmeter (40) sensing the amplitude and phase of a signal component at the deflection frequency. Also described are other optical embodiments utilizing different forms of interferometer and/or detection system, and an embodiment using an electron probe instead of a laser probe.</p> |