Detection method and device of surface shape of optical aspheric surface

[0028] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following further describes the present invention in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

[0029] The embodiment of the present invention provides a method for detecting the shape of an optical aspheric surface. The method includes: irradiating the reverse compensation fringe from the projection direction onto the measured aspheric surface, and then the measured aspheric surface is reflected and imaged by the imaging system. According to the modulation fringe of the aspheric surface shape information, the surface shape deviation of the aspheric surface is obtained according to the modulation fringe, and the processing condition of the measured aspheric surface is determined according to the surface shape deviation.

[0030] The generation process of the reverse compensation fringe is: projecting one or more phase-shifted straight fringes onto an ideal aspheric surface and reflecting the image to obtain a deformed fringe modulated by the ideal aspheric surface; taking the deformed fringe as the projected straight fringe The symmetry axis is flipped to generate reverse compensation fringes.

[0031] The method also includes: when the position of the measured aspheric surface does not correspond to the position of the inverse compensation fringe projection, calibrating the modulation fringe, specifically: performing the obtained fringe according to Fourier transform or phase shift technology Phase extraction process to obtain phase data; after that, rotate the measured aspheric surface by an angle, and also perform phase extraction processing on the obtained modulation fringes to obtain phase data; finally, rotate the measured aspheric surface one week to obtain a series of modulation fringes Phase extraction processing obtains a series of phase data; in the series of phase data, the position corresponding to the modulation fringe with the smallest phase change is the position with the best calibration of the measured aspheric surface.

[0032] The obtaining the surface deviation of the aspheric surface according to the modulation fringe is specifically: performing phase extraction on the modulation fringe to obtain the phase value of the modulation fringe According to the phase value Corresponding formula with wavefront W, obtain the surface deviation W, namely

[0033] The determination of the processing condition of the measured aspheric surface according to the surface shape deviation is specifically: according to the surface shape deviation of the measured aspheric surface relative to the ideal aspheric surface, the surface shape deviation and the ideal aspheric surface are combined to finally obtain the measured aspheric surface The actual measurement surface shape of the aspheric surface.

[0034] If the measured aspheric surface is too large, the designed back projection fringe will be too dense or the fringe bends more than a fringe pitch. At this time, the processing capacity of the fringe should be properly considered, such as subtracting a light weight from the designed ideal aspheric surface. Degree aspheric surface; the modulation fringe obtained by the imaging system is a modulation deformation fringe relative to an ideal aspheric surface (or a standard aspheric surface plus a compensated mild aspheric surface), and finally the surface shape of the measured aspheric surface is determined according to the modulation deformation fringe.

[0035] Embodiment 1 of the present invention provides an optical aspheric surface shape detection device, such as figure 1 As shown, the device includes a reverse compensation fringe generating device, a beam splitting device, a standard lens, a measured aspheric surface, and an imaging system. The reverse compensation fringe generating device, beam splitting device, standard lens, and measured aspheric surface are in turn on the optical axis The top is set from left to right, the tested aspheric surface and imaging system are located on either side of the beam splitting device up and down, and the imaging optical axis thereof is perpendicular to the optical axis.

[0036] The imaging system includes an imaging lens and a CCD camera that are sequentially arranged along the optical axis.

[0037] The reverse compensation fringe generating device can adopt three structures: liquid crystal spatial light modulation method, DMD reflective spatial light modulation method, and display reflection method.

[0038] Liquid crystal spatial light modulation method: The laser beam is collimated and irradiated to the liquid crystal spatial light modulator, the modulator is controlled by a computer, and the transmission obtains the reverse compensation fringe, such as figure 2 Shown.

[0039] DMD reflective spatial light modulation method: the laser beam is collimated and irradiated on the DMD spatial light modulator, the computer controls the DMD spatial light modulator, and the reflection obtains the method of reverse compensation fringe, such as image 3 Shown.

[0040] Display reflection method: the reverse compensation fringe is generated by the computer, displayed on the display, reflected by the reflector, and collimated by the collimating mirror to obtain the reverse compensation fringe required for measurement, such as Figure 4 Shown.

[0041] Embodiment 2 of the present invention provides an optical aspheric surface shape detection device, such as Figure 5 As shown, the device includes a reverse compensation fringe generating device, a beam splitting device, a standard lens, a measured aspheric surface, a plane mirror, and an imaging system. The light beam emitted by the reverse compensation fringe generating device is projected onto the measured aspheric surface through a standard lens , The reflected light beam emitted by the tested spherical surface is reflected to the imaging system through a standard lens and a flat mirror.

[0042] The foregoing descriptions are only preferred embodiments of the present invention, and are not used to limit the protection scope of the present invention.