New mirror interferometers for the testing of the optical systems are discussed. Interferometers consist of the light source, very small convex mirror or lens, two small flat or spherical mirrors and optics under test. In the first new interferometer, radial shearing interferometer, a laser's light reflects from the spherical semiball mirror and goes to an optical system (or mirror) under test. The optical system (or mirror) reflects the light back and forms an image near spherical semiball mirror. Another part of beam of laser reflects from the small spherical semiball mirror, and then reflects from a small reference mirror (or reference small part of mirror under test), another small semisphere mirror, and flat mirror with central hole -- it is a reference beam. In the second new interferometer, demountable interferometer, a light passes of optical system under test, focused, passes semitransparent convex lens; the other part of the light reflects back on two small flat mirrors, reflects and both part of beam interfered. Both part of beam forms the interference pattern on a screen or CCD receiver. A modifications of the interferometers can be used also for testing ellipsoidal mirrors or another aspherical mirrors with the providing of special optical compensation and interference filters for better accuracy. An interferometers can be used at any spectral line from the far ultraviolet up to the far infrared. The interferometers are very simple, cheap and easily can be manufactured in quantity. The interferometers can be especially recommended for optics testing in space and manufacturing.