A fast alignment method for large aperture schlieren optical path

Abstract

The present application relates to the field of optical system adjustment, in order to solve the problems of long adjustment period, low precision and poor stability of the existing schlieren optical path, a fast adjustment method for large aperture schlieren optical path is proposed, comprising the following steps: preliminary building the schlieren optical path according to the theoretical angle of system design; setting the first eight-line instrument on the optical path between the transmitting end main mirror and the imaging end main mirror; adjusting the spatial position of the transmitting end main mirror and the imaging end main mirror through the first eight-line instrument, so that the centers of the two are located on the same horizontal plane; adjusting the attitude of the transmitting end main mirror and the transmitting end secondary mirror through the second eight-line instrument, so that the image of the first eight-line instrument coincides with the image of the second eight-line instrument; adjusting the attitude of the imaging end main mirror and the imaging end secondary mirror through the third eight-line instrument, so that the image of the first eight-line instrument coincides with the image of the third eight-line instrument; finding the clearest image of the resolution plate by moving the camera to determine the spatial position of the camera, and completing the fast adjustment of the large aperture schlieren optical path.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical system adjustment, in particular to a fast adjustment method for a large-aperture schlieren light path. BACKGROUND

[0002] The schlieren imaging system is used for imaging test by using the refractive index gradient of light in the measured flow field proportional to the air flow density of the flow field, which has the characteristics of high sensitivity, good imaging quality and fast measurement speed; the imaging light path of the schlieren imaging system is usually a Z-shaped light path, and the difficulty of the adjustment of the schlieren imaging system mainly lies in the fast centering of the multi-section light path.

[0003] The current adjustment method of the schlieren imaging system is to place a crosshair reticle at the center of the light inlet of the primary mirror, to center the crosshair reticle with the primary mirror, and then to observe the image of the crosshair reticle by using the theodolite in the direction of the secondary mirror; when the theodolite is used for observation, the position and posture of the theodolite need to be initially positioned, which will cause the current schlieren light path adjustment method to waste more time and energy in the large-aperture primary mirror and the system with large adjustment space, resulting in long adjustment period, low adjustment precision, poor stability of the adjustment equipment and other problems, so that the optical index parameters in the schlieren imaging system cannot meet the system requirements. SUMMARY

[0004] In order to solve the technical problems of long adjustment period, low adjustment precision and poor stability of the adjustment equipment of the current schlieren imaging system adjustment method, the present application provides a fast adjustment method for a large-aperture schlieren light path.

[0005] To achieve the above-mentioned purpose, the technical solution provided by the present application is as follows:

[0006] A fast adjustment method for a large-aperture schlieren light path, characterized in that it comprises the following steps:

[0007] S1, initially building a large-aperture schlieren light path according to the theoretical angle of system design; setting a first octant instrument on the light path between the primary mirror at the emission end and the primary mirror at the imaging end;

[0008] S2, adjusting the spatial position of the primary mirror at the imaging end so that the centers of the primary mirror at the emission end, the first octant instrument and the primary mirror at the imaging end are located on the same horizontal optical axis;

[0009] S3, installing a second octant instrument on the optical axis between the light source and the slit, and adjusting the postures of the primary mirror at the emission end and the secondary mirror at the emission end so that the outgoing light of the second octant instrument coincides with the outgoing light of the first octant instrument after imaging through the secondary mirror at the emission end;

[0010] S4, install the third eight-line instrument on the optical axis between the imaging objective and the knife edge, adjust the poses of the imaging end primary mirror and the imaging end secondary mirror, so that the outgoing light rays of the third eight-line instrument coincide with the outgoing light rays of the first eight-line instrument after imaging through the imaging end secondary mirror;

[0011] S5, place a resolution plate on the optical path between the transmitting end and the imaging end, after turning on the light source, move the camera to find the clearest image of the received resolution plate, so as to determine the spatial position of the camera, and complete the rapid alignment of the large-aperture schlieren optical path.

[0012] Further, S1.1, initially build the schlieren optical path according to the theoretical angle of the system design; the large-aperture schlieren optical path includes a light source, lenses, a slit, a transmitting end, an imaging end, a knife edge, an imaging objective and a camera arranged in sequence along the light path of the light source;

[0013] S1.2, install the first eight-line instrument on the two-dimensional lifting platform, and then place the two-dimensional lifting platform between the transmitting end primary mirror and the imaging end primary mirror, and the first eight-line instrument is located on the optical path between the transmitting end primary mirror and the imaging end primary mirror.

[0014] Further, S2.1, adjust the pose of the first eight-line instrument so that the horizontal line of the first eight-line instrument is parallel to the ground;

[0015] S2.2, adjust the height of the first eight-line instrument so that the outgoing cross beam of the first eight-line instrument coincides with the center of the transmitting end primary mirror;

[0016] S2.3, adjust the spatial position of the imaging end primary mirror so that the center of the imaging end primary mirror coincides with the outgoing light beam of the first eight-line instrument, and finally make the centers of the transmitting end primary mirror, the first eight-line instrument and the imaging end primary mirror located on the same horizontal optical axis.

[0017] Further, S3.1, adjust the installation position of the slit so that it is located at the focal point of the light source, and install the second eight-line instrument on the optical axis between the light source and the slit;

[0018] S3.2, adjust the pose of the transmitting end primary mirror so that the outgoing light rays of the first eight-line instrument are located at the center position of the transmitting end secondary mirror;

[0019] S3.3, adjust the pose of the transmitting end secondary mirror so that the outgoing light rays of the second eight-line instrument coincide with the outgoing light rays of the first eight-line instrument after imaging through the transmitting end secondary mirror, thereby completing the adjustment of the transmitting end optical path.

[0020] Further, the included angle α1 between the incident light beam of the second eight-line instrument and the outgoing light beam of the first eight-line instrument, the included angle α2 between the optical axis of the light source and the transmitting end primary mirror, and the included angle α3 between the optical axis of the imaging objective and the imaging end primary mirror satisfy the following formula:

[0021] α1=α2=α3.

[0022] Further, S4.1, the installation position of the knife edge is adjusted to be conjugated with the slit position, and a third eight-line instrument is installed on the optical axis between the imaging objective and the knife edge;

[0023] S4.2, the optical axis of the imaging end primary mirror is adjusted so that the outgoing light of the first eight-line instrument is located at the center position of the imaging end secondary mirror;

[0024] S4.3, the optical axis of the imaging end secondary mirror is adjusted so that the outgoing light of the third eight-line instrument coincides with the outgoing light of the first eight-line instrument after imaging through the imaging end secondary mirror, thereby completing the adjustment of the imaging end optical path.

[0025] Further, S5.1, the first eight-line instrument, the second eight-line instrument and the third eight-line instrument are removed;

[0026] S5.2, a resolution plate is placed on the optical path between the transmitting end and the imaging end, and the light source is turned on;

[0027] S5.3, the camera is moved forward and backward along the optical axis of the knife edge and the imaging objective, the image of the resolution plate received on the camera is observed, the clearest image received is found, and the spatial position of the camera is determined, thereby completing the rapid alignment of the large-aperture schlieren optical path.

[0028] Further, the transmitting end primary mirror, the transmitting end secondary mirror, the imaging end primary mirror, the imaging end secondary mirror, the first eight-line instrument, the second eight-line instrument and the third eight-line instrument can be adjusted in azimuth and pitch, and the adjustment of pitch, yaw and forward and backward position movement is realized.

[0029] The beneficial effects of the present application are:

[0030] [1] The operation process of the rapid alignment method for the large-aperture schlieren optical path is simple and easy to implement. The entire optical system is aligned by two eight-line instruments and a two-dimensional lifting platform, which effectively reduces the problems of poor alignment stability caused by the diversification of alignment measurement equipment, effectively shortens the alignment period, improves the alignment accuracy, makes the alignment process of the entire optical system more simple and efficient, and ensures that the optical index parameters after alignment meet the system requirements, and has high practicality and reliability.

[0031] [2] The transmitting end primary mirror and the imaging end primary mirror are adjusted to the same horizontal plane by the first eight-line instrument, the center of the entire system is connected in space, the accumulation of the centering error of each subsequent component causes the inclination of the entire system is reduced; at the same time, the assembly efficiency is improved, the primary mirrors of the transmitting end and the imaging end share a reference, which can effectively reduce the system error, improve the alignment accuracy, and shorten the alignment time. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1This is a schematic diagram of the optical path of an embodiment of a rapid assembly and adjustment method for large-aperture schlieren optical paths according to the present invention;

[0033] Figure 2 This is a schematic diagram showing the positions of the transmitter, the first octet, and the imaging end in step one of an embodiment of a rapid assembly and adjustment method for a large-aperture schlieren optical path according to the present invention.

[0034] Figure 3 This is a schematic diagram of the transmitter assembly structure in an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of the assembly structure of the transmitting end and the imaging end in an embodiment of the present invention;

[0036] Figure 5 This is a schematic diagram of the optical path imaging at the transmitting end and the imaging end in an embodiment of the present invention;

[0037] Figure label:

[0038] 1-Primary mirror of the transmitting end, 2-Secondary mirror of the transmitting end, 3-Two-dimensional lifting platform, 4-First octahedron, 5-Secondary octahedron, 6-Primary mirror of the imaging end, 7-Secondary mirror of the imaging end, 8-Resolution plate, 9-Light source, 10-Imaging objective lens, 11-Slit, 12-Knife edge, 13-Camera, 14-Lens, 15-Third octahedron. Detailed Implementation

[0039] like Figure 1 As shown, the large-aperture schlieren optical path includes a light source 9, a lens 14, a slit 11, an emitting end, an imaging end, a knife edge 12, an imaging objective lens 10, and a camera 13 arranged sequentially along the emitting optical path of the light source 9; wherein the emitting end includes an emitting primary mirror 1 and an emitting secondary mirror 2, and the imaging end includes an imaging primary mirror 6 and an imaging secondary mirror 7; the emitting primary mirror 1 and the imaging primary mirror 6 are arranged opposite each other on the optical axis, and the knife edge 12 is conjugate to the position of the slit 11.

[0040] A rapid assembly and adjustment method for large-aperture schlieren optical paths includes the following steps:

[0041] S1. Based on the theoretical framework of system design, a preliminary large-aperture schlieren optical path is constructed; a first octet 4 is installed on the optical path between the primary mirror 1 at the transmitting end and the primary mirror 6 at the imaging end; such as... Figure 2 As shown, the first octet 4 is installed on the two-dimensional lifting platform 3, and then the two-dimensional lifting platform 3 is placed between the transmitting end main mirror 1 and the imaging end main mirror 6, and the first octet 4 is located in the optical path between the transmitting end main mirror 1 and the imaging end main mirror 6.

[0042] S2. Determine the positions of the transmitting end primary mirror 1 and the imaging end primary mirror 6 to ensure that the heights of the transmitting end and the imaging end are on the same horizontal plane;

[0043] S2.1, adjust the posture of the first octant instrument 4 so that the horizontal line of the first octant instrument 4 is parallel to the ground;

[0044] S2.2, adjust the height of the first octant instrument 4 so that the cross light beam emitted by the first octant instrument 4 coincides with the center of the transmitting end primary mirror 1;

[0045] S2.3, adjust the spatial position of the imaging end primary mirror 6 so that the center of the imaging end primary mirror 6 coincides with the emitted light beam of the first octant instrument 4, and finally make the centers of the transmitting end primary mirror 1, the first octant instrument 4 and the imaging end primary mirror 6 located on the same horizontal optical axis.

[0046] S3, transmitting end optical path adjustment

[0047] S3.1, as shown in the figure, adjust the installation position of the slit 11 so that it is located at the focal point of the light source 9, and install the second octant instrument 5 on the optical axis between the light source 9 and the slit 11; Figure 3

[0048] S3.2, adjust the posture of the transmitting end primary mirror 1 so that the emitted light of the first octant instrument 4 is located at the center position of the transmitting end secondary mirror 2;

[0049] S3.3, adjust the posture of the transmitting end secondary mirror 2 so that the emitted light of the second octant instrument 5 coincides with the emitted light of the first octant instrument 4 after imaging through the transmitting end secondary mirror 2, thereby completing the adjustment of the transmitting end optical path.

[0050] Wherein, the included angle α1 between the emitted light beam of the first octant instrument 4 and the incident light beam of the second octant instrument 5 is the included angle α2 between the optical axis between the light source 9 and the transmitting end primary mirror 1 and the included angle α3 between the optical axis between the imaging objective lens 10 and the imaging end primary mirror 6.

[0051] S4, imaging end optical path adjustment

[0052] S4.1, as shown in the figure, adjust the installation position of the knife edge 12 so that it is conjugate with the position of the slit 11, and install the third octant instrument 15 on the optical axis between the imaging objective lens 10 and the knife edge 12; Figure 4

[0053] S4.2, adjust the posture of the imaging end primary mirror 6 so that the emitted light of the first octant instrument 4 is located at the center position of the imaging end secondary mirror 7;

[0054] S4.3, adjust the posture of the imaging end secondary mirror 7 so that the emitted light of the third octant instrument 15 coincides with the emitted light of the first octant instrument 4 after imaging through the imaging end secondary mirror 7, thereby completing the adjustment of the imaging end optical path.

[0055] S5, system optical path adjustment

[0056] S5.1, remove the first octant instrument 4, the second octant instrument 5 and the third octant instrument 15;​​

[0057] S5.2, a resolution plate 8 is placed in the light path between the emitting end and the imaging end, the light source 9 is turned on, and the light paths of the emitting end and the imaging end are as shown in Fig. 5; Figure 5

[0058] S5.3, the camera 13 is moved along the optical axis of the knife edge 12 and the imaging objective 10, the image of the resolution plate 8 received on the camera 13 is observed, the clearest image received is found, and the spatial position of the camera 13 is determined, thereby completing the rapid alignment of the large-aperture schlieren light path.​

Claims

1. A fast alignment method for a large aperture schlieren optical train, characterized in that, It comprises the following steps: S1, according to the theoretical angle of system design, initially build large aperture schlieren optical path; The large aperture schlieren optical path comprises a light source (9), a lens (14), a slit (11), an emitting end, an imaging end, a knife edge (12), an imaging objective (10) and a camera (13) which are arranged in sequence along the light emitting path of the light source (9); the emitting end main mirror (1) and the imaging end main mirror (6) are arranged on the same optical axis; A first eight-line instrument (4) is arranged on the optical path between the emitting end main mirror (1) and the imaging end main mirror (6); S2, adjust the spatial position of the imaging end main mirror (6), so that the centers of the emitting end main mirror (1), the first eight-line instrument (4) and the imaging end main mirror (6) are located on the same horizontal optical axis; S3, adjust the installation position of the slit (11) so that it is located at the focal point of the light source (9), install a second eight-line instrument (5) on the optical axis between the light source (9) and the slit (11), adjust the attitude of the emitting end main mirror (1) and the emitting end secondary mirror (2), so that the outgoing light of the second eight-line instrument (5) coincides with the outgoing light of the first eight-line instrument (4) after imaging through the emitting end secondary mirror (2); S4, adjust the installation position of the knife edge (12) so that it is conjugated with the slit (11), install a third eight-line instrument (15) on the optical axis between the imaging objective (10) and the knife edge (12), adjust the attitude of the imaging end main mirror (6) and the imaging end secondary mirror (7), so that the outgoing light of the third eight-line instrument (15) coincides with the outgoing light of the first eight-line instrument (4) after imaging through the imaging end secondary mirror (7); S5, place a resolution plate (8) on the optical path between the emitting end and the imaging end, turn on the light source (9), and then move the camera (13) to find the clearest image of the received resolution plate (8), thereby determining the spatial position of the camera (13), and completing the rapid assembly and adjustment of the large aperture schlieren optical path.

2. The method for fast alignment of large aperture schlieren optical train according to claim 1, wherein, Step S1 is specifically: S1.1, according to the theoretical angle of system design, initially build the schlieren optical path; the large aperture schlieren optical path comprises a light source (9), a lens (14), a slit (11), an emitting end, an imaging end, a knife edge (12), an imaging objective (10) and a camera (13) which are arranged in sequence along the light emitting path of the light source (9); S1.2, install the first eight-line instrument (4) on the two-dimensional lifting platform (3), and then place the two-dimensional lifting platform (3) between the emitting end main mirror (1) and the imaging end main mirror (6), and the first eight-line instrument (4) is located on the optical path between the emitting end main mirror (1) and the imaging end main mirror (6).

3. The method for fast alignment of large aperture schlieren optical train as claimed in claim 2, wherein, Step S2 is specifically: S2.1, adjust the attitude of the first eight-line instrument (4), so that the horizontal line of the first eight-line instrument (4) is parallel to the ground; S2.2, adjust the height of the first eight-line instrument (4), so that the cross beam emitted by the first eight-line instrument (4) coincides with the center of the emitting end main mirror (1); S2.3, adjust the spatial position of the imaging end main mirror (6), so that the center of the imaging end main mirror (6) coincides with the outgoing light beam of the first eight-line instrument (4), and finally the centers of the emitting end main mirror (1), the first eight-line instrument (4) and the imaging end main mirror (6) are located on the same horizontal optical axis.

4. The method for fast alignment of large aperture schlieren optical train as claimed in claim 3 wherein, Step S3 is specifically: S3.1, adjust the installation position of the slit (11) to be at the focal point of the light source (9), and install the second octupole instrument (5) on the optical axis between the light source (9) and the slit (11); S3.2, adjust the attitude of the transmitting end primary mirror (1) so that the outgoing light of the first octupole instrument (4) is at the center position of the transmitting end secondary mirror (2); S3.3, adjust the attitude of the transmitting end secondary mirror (2) so that the outgoing light of the second octupole instrument (5) coincides with the outgoing light of the first octupole instrument (4) after imaging through the transmitting end secondary mirror (2), thereby completing the adjustment of the transmitting end optical path.

5. The method according to claim 3, wherein in step S3, the angle α1 between the incident light beam of the second octupole instrument (5) and the outgoing light beam of the first octupole instrument (4), the angle α2 between the optical axis between the light source (9) and the transmitting end primary mirror (1), and the angle α3 between the optical axis between the imaging objective (10) and the imaging end primary mirror (6) satisfy the following formula: Step S4 is specifically: α1＝α2＝α3。 6. The method for fast alignment of large aperture schlieren optical train as claimed in claim 3 wherein, S4.1, adjust the installation position of the knife edge (12) to be conjugate with the slit (11), and install the third octupole instrument (15) on the optical axis between the imaging objective (10) and the knife edge (12); S4.2, adjust the attitude of the imaging end primary mirror (6) so that the outgoing light of the first octupole instrument (4) is at the center position of the imaging end secondary mirror (7); S4.3, adjust the attitude of the imaging end secondary mirror (7) so that the outgoing light of the third octupole instrument (15) coincides with the outgoing light of the first octupole instrument (4) after imaging through the imaging end secondary mirror (7), thereby completing the adjustment of the imaging end optical path. Step S5 is specifically:

7. The method for fast alignment of large aperture shadowgraph optical train according to claim 6, wherein, S5.1, remove the first octupole instrument (4), the second octupole instrument (5) and the third octupole instrument (15); S5.2, place the resolution plate (8) on the optical path between the transmitting end and the imaging end, and turn on the light source; S5.3, move the camera (13) along the optical axis of the knife edge (12) and the imaging objective (10), observe the image of the resolution plate (8) received on the camera (13), find the clearest image received, and determine the spatial position of the camera (13), thereby completing the fast alignment of the large-aperture schlieren optical path. The transmitting end primary mirror (1), the transmitting end secondary mirror (2), the imaging end primary mirror (6), the imaging end secondary mirror (7), the first octupole instrument (4), the second octupole instrument (5) and the third octupole instrument (15) can be adjusted in azimuth and pitch.

8. The method for fast alignment of large aperture shadowgraph optical train according to claim 7, wherein: ​

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