RU2000125117A - METHOD FOR INTERFEROMETRIC MEASUREMENT OF DEFLECTION OF OPTICAL SURFACES FORM AND SYSTEM FOR ITS IMPLEMENTATION - Google Patents

Claims (3)

1. The method of interferometric measurement of the deviation of the shape of the optical surfaces, based on the formation using the interferometer of the first shifting phase interferogram by interference of the first beam reflected from the controlled surface and the beam with a periodically changing phase reflected from the reference surface, designing the interferogram on the recording unit, measuring for the time of one cycle of changing the optical path length of the beam of three or more values of the intensity of the interferogram at the field which determine the position of the photodetector elements, and the calculation of the phase of the interferogram at these points, on the basis of which the wavefront deformation is determined, characterized in that two additional measuring channels are formed, and the second beam forming the first shifting phase interferogram is the beam reflected from the reference surface from the second channel , the periodic phase change of which is carried out in the lighting system of the interferometer, simultaneously with the first receive the second amplitude interferogram formed as a result of interference of the first beam from the first channel reflected from the reference surface and the third beam from the third channel reflected from the controlled surface, the second interferogram is projected near the first onto the recording unit, the intensity of the second interferogram is measured at the same points at which the intensity of the first interferograms, and determining the phase of the wavefront is obtained by subtracting from the intensity of the first interferogram the intensity of the second interferogram at the same points. 2. A system for interferometric measurement of the shape deviation of optical surfaces, comprising a coherent radiation source, a first filter capacitor located in the focal plane of the lens and consisting of a condenser lens, in the focal plane of which a small diameter diaphragm is installed, a beam splitter, the first and second beam splitter elements , an interferometer consisting of a controlled, mounted perpendicular to the optical axis, and reference surfaces, as well as a device for changing the optical beam travel lines; the first projection system, which, together with the lens, projects the first interference pattern onto the recording unit and the observation device, the interference pattern processing system and the self-collimating image projection system associated with the recording unit, characterized in that the beam splitting unit is located after the radiation source and forms three parallel to the optical channel axis, in two of which the second and third filter-condensers are identical to the first, and the optical change device the first beam splitter installed in the second channel between the beam splitting unit and the second filter-condenser, the beam splitting elements are located after the filter-condensers, and a dividing prism installed behind the first beam splitting element in the backward beam, the second projection system projecting the image is additionally introduced into the system the second interferogram on the registration unit, and a connecting prism installed between the projection systems and the registration unit, and the reference surface of the inter the ferrometer is tilted relatively controlled at an angle

where S ₁ is the distance between the diaphragms of the first and second filter-condensers;
f ' _about - the focal length of the lens,
and the third filter capacitor is installed at a distance S ₁ from the first.  3. The system according to claim 2, characterized in that the device for changing the optical path length of the beam is made in the form of two plane-parallel plates having the ability to synchronously tilt in opposite directions.