CN102368114A - Optical system surface shape compensation adjustment method based on wave aberration detection - Google Patents

Abstract

The invention relates to an optical system surface shape compensation adjusting method based on wave aberration detection, which comprises the following steps: 1) detecting surface wave aberration of each optical element of the optical system to be adjusted; 2) judging whether the surface shapes of the optical elements of the optical system to be adjusted are complementary or not according to an aplanatism principle, if so, directly exiting the adjusting process of the optical system to be adjusted; if not, performing step 3); 3) the spatial positions of all optical elements of the optical system to be adjusted are adjusted, so that the complementation of element surface wave aberration is realized. The invention provides the optical system surface shape compensation adjustment method based on the wave aberration detection, which has strong pertinence, rapidness in realization, simplicity and convenience in operation and strong practicability.

Description

Optical system surface shape compensation adjustment method based on wave aberration detection

technical field

The invention belongs to the field of optical engineering, and relates to an optical system installation and adjustment method, in particular to an optical system surface shape compensation installation and adjustment method based on wave aberration detection.

Background technique

The errors that affect the image quality of the optical system mainly come from two aspects: optics and mechanics. The optical error is mainly due to the limitation of the processing technology level, which causes the deviation of the radius of curvature, thickness, eccentricity and so on. These deviations cannot be changed after the component processing is completed, but the determined deviation value can be known through metrological inspection. Mechanical errors are mainly due to the fact that the coaxiality and verticality of the mechanical parts are lower than the design requirements, which reduces the surface accuracy of the assembled optical components, resulting in displacement, eccentricity, and tilt. Errors in optical machining and assembly can be summarized as component thickness deviation, displacement, eccentricity, inclination, etc. They have different effects on the image quality of the optical system. When the optical element has displacement and thickness deviation, it mainly affects the symmetrical aberration and increases the dispersion of the image point. The eccentricity and inclination of the system will lead to asymmetrical aberrations. For the on-axis point, there are central coma and vertical axis chromatic aberration, which make the diffraction ring of the image point lose symmetry and have asymmetrical color. In the case of severe decentering, two separate focal lines can also be seen in the center of the field of view, that is, central astigmatism. At the same time, astigmatism and asymmetric distortion appear in off-axis image points. The comprehensive impact of all these processing and assembly errors on the image quality of the optical system is manifested in the reduction of resolution, the increase of distortion, the increase of diffuse spot of the image point, and the decrease of transfer function. At this time, by fine-tuning the spatial relative position of each optical element, the aberration introduced by the manufacturing error can be compensated, and the imaging quality of the actual system after assembly can be improved. The classic compensation adjustment method is based on the geometric measurement and detection of optical and mechanical parts. This method is blind, requires repeated operations, and requires experienced technicians to operate. It is very inconvenient to use. At the same time , this method does not involve the wave aberration detection often performed by large-aperture optical elements and systems and the resulting possible wave surface compensation adjustment method based on the principle of equal optical path.

Contents of the invention

In order to solve the above-mentioned technical problems in the background technology, the present invention provides an optical system surface compensation and adjustment method based on wave aberration detection, which is highly targeted, quick to implement, easy to operate and highly practical.

The technical solution of the present invention is: the present invention provides an optical system surface shape compensation adjustment method based on wave aberration detection, which is special in that: the optical system surface shape compensation adjustment method based on wave aberration detection The method includes the following steps:

1) Detect the surface wave aberration of each optical element of the optical system to be adjusted;

2) According to the principle of equal optical path, judge whether the surface shape of each optical element of the optical system to be adjusted is complementary, if yes, then directly exit the adjustment process of the optical system to be adjusted; if not, proceed to step 3);

3) The spatial position of each optical element of the optical system to be adjusted is adjusted so that the surface wave aberration of the elements can be complemented.

In the above step 2), the judgment method of surface shape complementarity is:

2.1) Carry out vector superposition of the surface wave aberration of each optical element of the optical system to be adjusted which has been obtained in step 1), and obtain the surface wave aberration vector sum of each optical element after superimposition;

2.2) If the absolute value of the surface wave aberration vector sum of the superimposed optical elements decreases, the surface shapes of the optical elements of the optical system to be adjusted are complementary; if the surface wave images of the superimposed optical elements As the absolute value of the difference vector sum increases, the surface shapes of the optical elements of the optical system to be adjusted are non-complementary.

The way to adjust the spatial position of each optical element of the optical system to be adjusted in the above step 3) is: to translate, rotate or tilt each optical element of the optical system to be adjusted.

The advantages of the present invention are:

The invention provides a surface compensation and adjustment method of optical system based on wave aberration detection. The method adopts that when the geometric misalignment of each optical element in the system is zero, if only the surface error of the optical element exists, the system The principle that the wave aberration of the final image plane will be uniquely determined by the surface wave aberration of each optical element, without changing other structural relations of the optical system, through simple adjustment operations such as rotation, the surface shape of the optical parts in the optical system can be adjusted The error adjustment achieves the mutual wave aberration complementary relationship, so as to achieve the purpose of optimizing the system wave aberration and improving the system imaging quality. The installation and adjustment process is simple and controllable, the operation is simple, and the practicability is strong.

Description of drawings

Fig. 1 is a schematic diagram of the assembly and adjustment process of the assembly and adjustment method provided by the present invention.

Detailed ways

The principle of the present invention is: when light propagates from one point to another in any medium, it propagates along the path with the shortest required time. This principle is also called the principle of minimum time or the principle of extremely short optical path. Pierre de Fermat first proposed Fermat's Principle in 1657. Fermat's principle is an important principle in geometric optics, which can prove the law of straight line propagation, the law of reflection and refraction that light obeys when propagating in a homogeneous medium, and the equal optical path length of optical systems under paraxial conditions. Therefore, the design process of all imaging optical systems follows the principle of equal optical path length.

According to the above principles, the present invention provides a method for adjusting and adjusting the surface shape of an optical system based on wave aberration detection. The method includes the following steps:

1) Detect the surface wave aberration of each optical element of the optical system to be adjusted;

2) According to the principle of equal optical path, judge whether the surface shape of each optical element of the optical system to be adjusted is complementary, if yes, directly exit the adjustment process of the optical system to be adjusted; if not, proceed to step 3):

The complementary judgment process is:

2.1) Superimpose the surface wave aberrations of the optical elements of the optical system to be adjusted that have been obtained in step 1), and obtain the surface wave aberration vector sum of the superimposed optical elements;

2.2) If the absolute value of the surface wave aberration vector sum of the superimposed optical elements decreases, the surface shapes of the optical elements of the optical system to be adjusted are complementary; if the surface wave images of the superimposed optical elements When the absolute value of the difference vector sum increases, the surface shape of each optical element of the optical system to be adjusted is non-complementary.

3) The spatial position of each optical element of the optical system to be adjusted is adjusted by translation, rotation and/or tilt, etc., so that the surface shape of each optical element of the optical system to be adjusted is complementary.

Referring to FIG. 1 , the present invention takes the optical system shown in FIG. 1 as an example to describe in detail the surface shape compensation and adjustment method of the optical system based on wave aberration detection provided by the present invention. In Fig. 1, the optical system includes a primary mirror, a secondary mirror, an object point O, and an image point I, wherein the solid line represents a schematic diagram of the surface structure of each optical element in an ideal state; the dotted line represents the actual measurement of each optical element obtained in practice. Schematic diagram of the surface structure; when the surface wave aberration of the primary mirror is W _main (that is, the surface wave aberration represented by the dotted line), the surface wave aberration of the secondary mirror is W _sec (that is, the surface wave aberration represented by the dotted line difference), the spherical wave W O emitted by the object point _O and the wave aberration W _I at the image point I can be expressed as:

W _I ＝W _O +k _m W _main +k _s W _sec

Among them, k _m is the pupil magnification from the primary mirror to the secondary mirror, and k _s is the pupil magnification from the secondary mirror to the image plane, both of which are determined by the system structure parameters. According to the principle of equal optical path design, the primary mirror and secondary mirror There is a complementary relationship between surface shape errors. That is to say, assuming that the geometric misalignment of each optical element in the system is zero, if only the surface error of the optical element exists, the wave aberration of the final image plane of the system will be uniquely determined by the surface wave aberration of each optical element .

Claims (3)

1. an optical system surface shape compensation that detects based on wave aberration is debug method, it is characterized in that: the said optical system surface shape compensation that detects based on wave aberration is debug method and may further comprise the steps:

1) the face shape wave aberration of each optical element of detection light modulation to be installed system;

2), judge whether the face shape of each optical element of light modulation to be installed system exists complementation, if then directly withdraw from the process of debuging of light modulation to be installed system according to the aplanatism principle; If not, then carry out step 3);

3) treating the locus of debuging each optical element of optical system adjusts.

2. the optical system surface shape compensation that detects based on wave aberration according to claim 1 is debug method, it is characterized in that: the judgment mode that face shape is complementary said step 2) is:

2.1) the face shape wave aberration of each optical element of light modulation to be installed system that has obtained in the step 1) is superposeed, and the face shape wave aberration vector of each optical element after obtaining superposeing with;

2.2) if the face shape wave aberration vector of each optical element after the stack and absolute value reduce, the face shape of each optical element of light modulation then to be installed system is complementation; If the face shape wave aberration vector of each optical element after the stack and absolute value increase, the face shape of each optical element of light modulation then to be installed system is non-complementary.

3. the optical system surface shape compensation that detects based on wave aberration according to claim 1 and 2 is debug method, it is characterized in that: treating the mode of the locus of debuging each optical element of optical system adjusting in the said step 3) is: treat and debug each optical element of optical system and carry out translation, rotation or inclination.

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