SU972454A1 - Optical system spherical aberration correcting method - Google Patents

Description

The invention relates to optics, and specifically to methods for correcting the spherical aberration of optical systems. A known method for correcting the spherical aberration of the optical system consists in compensating for this aberration by introducing an optical element with a spherical aberration of opposite sign into the system. An example of the implementation of this method can be a two or three glued optical system or sticking out of positive and negative. The disadvantage of this method is that the correction in this case is real. Only for one or two zones of the optical system, as well as the narrow spectral range of this correction. The closest to the proposed technical essence is a method for correcting the spherical aberration of an optical system, including determining the law of change of system parameters corresponding to the absence of spherical aberration in it, and forming zones in the system, the parameters of which are corrected by I with the specified з-кс ч cmum 2. According to a known method, from the condition that there is no spherical aberration in the system, the law of change in the shape of its surfaces is determined depending on the height of radiation incidence on the systems. y, and the formation of zones is carried out in accordance with this law by creating a stepped structure such as a Fresnel lens. In this case, it is possible to completely correct spherical aberration for several diameters of an adjustable system, which is realized, however, only under the condition of a fixed value of the wavelength of the incident radiation. In addition, the process of forming and controlling the stepped structure is rather complicated. Llejfb of the invention is the simplification of the process of forming zones in the corrected system and the expansion of the spectral range of the correction. This goal is achieved by the fact that according to the method of correcting spherical aberration of the optical system, including determining the law of change of CHCjeNbi parameters, corresponding to the absence of spherical aberration in it, and forming zones in the system, the parameters of which are monitored according to the specified law from the absence of spherical aberrations in the system determine the law of change of the wavelength of the radiation incident on it, depending on the height of its fall, and the formation of zones is carried out in accordance with m by varying their spectral transmittance,.

FIG. i presents the optical scheme of a corrected single lens with a dielectric coating applied to its surface} ;. 2, the fragmentation of the refracting surface into the concentric zones is carried out with correction; Fig. 3 is a graph of the test spherical aberration of the lens.

The essence of the proposed method we consider the example of the correction of the spherical aberration odiguyu-lenses. As is known, the magnitude of the spherical aberration of such a lens depends on its relative aperture and the refractive index of the material from which it is made. In this case, the magnitude of spherical aberration increases from the center to the periphery of the lens in the case of constant refractive index. However, the latter depends on the wavelength of radiation incident on the lens, which is explained by the dispersive properties of the lens material. Consequently, the growth of spherical aberration from the center to the periphery of the lens can be compensated for by a corresponding change in the refractive index of its material, which in turn is due to a corresponding change in the wavelength of padak to the lens of radiation depending on the height of its fall. This principle lies in

The average diameter of the zone

Example mm

ABOUT

sixteen

26

36

46

56

66

based on the proposed method. First of all, to correct spherical aberration from the condition of its absence in the lens, the law of variation of the wavelength of radiation incident on the lens is determined by calculating. depending on the height of his fall. Then, annular concentric zones are distinguished in the lens, with each of these zones corresponding to the wavelength for which the spherical aberration on the mean diameter of the zone with a finite width is zero. Finally, on one of the refracting surfaces of the lens, annular concentric zones are formed, corresponding to the selected zones, whose spectral transmittance is determined by the indicated wavelengths. This can be done, for example, by applying dielectric (Coatings that perform appropriate spectral filtering of radiation incident on the lens. Obviously, with an increase in the number of zones, the quality of the correction will improve, and the technological process of their formation will become more complicated. with that said, depending on the task.

In accordance with the proposed method, the spherical aberration of a single lens with a relative aperture of 1: 1.5 and a focal length of 100 mm was corrected. The refractive surface of this lens was divided into six annular zones (Fig. 2), for each of which the wavelength corresponding to the zero value of the spherical aberration was calculated for the average diameter of the Gtabl zone. one).

Table 1

The wavelength corresponding to zero spherical aberration at the average zone diameter (µm)

0.4046 0.4146 0.4199 0.4260 0.4490 0.4914 0.5441

The lens has the following parameters: radii 86.57; thickness 13.0 grade of glass TF 10. 86.57.

I In this case, the spherical aberration was corrected for all six selected zones (Table 2).

table 2

Claims (2)

The proposed method can be implemented using known. methods for correcting other aberrations of a single-lens optical system with spherical surfaces of the head, with a good image quality, relative aperture of up to 1: 0.5 and field of view of up to 1. Thus, the use of the invention allows to simplify the manufacturing process of the corrected optical systems and expand the spectral range of the correction. Claims of Invention A method for correcting spherical aberration of an optical system, including determining the law of change of system parameters corresponding to the absence of spherical aberration in it, and if 0f / .f --ff, o fug. 2 formation of zones in the system, whose parameters vary in accordance with this law, distinguished with the fact that, in order to simplify the process of forming zones and expand the spectral range of the correction, the law of change in the length of the incident on it is determined from the absence of spherical aberration in the system radiation depending on the height of its fall, and the formation of zones is carried out in accordance with this law by changing their spectral transmission. Sources of information taken into account during the examination 1. Slyusarev GG Methods for calculating optical systems. L., Maiin-tHocTpoe, 1969, p. 325-326. 2. USSR author's certificate for application number 2911227 / 18-10, cl. G 02 3/08, 07/14.80 (prototype). r5g- ;; F1 / g.Z. {0.5W 0.91) 0.9 G. GB 0.199 o, 0,