A method for direct phase measurement of radiation, more particularly light radiation, which is reflected by a body or object with a diffusely reflecting surface. In order to make possible measurement of the phase with the production of a single image, the object or body is irradiated with coherent radiation having a predetermined frequency. The reflected radiation is used to produce an image in an image plane using an image forming optical system, a sensor with a plurality of preferably regularly arranged sensor elements being located in the plane. There is a superimposition of reference radiation on the sensor with the same frequency and with a defined phase relationship. In the case of directed object rays coming from a mirror-like body or object, the reference beam is set so that one period of the interference field produced on the sensor by the superimposition of the object and reference beams covers at least three sensor elements. The image forming optical system is designed and set so that the images of the speckles produced by the radiation on the object or body cover at least three sensor elements in the image plane. The phase of the radiation from the object or body is determined on the basis of the intensity signals of the at least three sensor elements.