Small laser interferometer are designed. Interferometer consists of two very small convex or concave mirrors and small flat mirror attached. Well-known Dall method of testing concave aspherical mirrors can be used with this interferometer. Concave ellipsoid mirrors can be tested as well as spherical one. It is possible to design very simple modification of the interferometer using only one very small convex mirror. A few interferometers can be used in a very large spectral range as they consist of mirror surfaces only. It is possible to use the interferometers to test optics, for testing transparent matter, to watch gas or liquid streams. Interferometers are very cheap and easily can be made in quantity. The interferometers are very small that is why they are especially recommended for testing optics in the Space.