A dispersion interferometer for measurements of line plasma density has been developed with a sensitivity 〈nel〉min = 1013 cm-2 and a temporal resolution of 10 μs. The main advantages of the interferometer are compactness and minimal sensitivity to vibrations. The interferometer does not require specific vibration isolation structure and can be mounted directly on the working chamber of the plasma device. The use of short-wave radiation (λ=1.06 μm) eliminates the influence of refraction and enables one to use quartz windows, which are the most resistant to neutron and gamma radiation. The above-mentioned advantages have been successfully demonstrated in a gas-dynamic trap experiment. These properties make the dispersion interferometer a very attractive diagnostic tool for large tokamaks.