CN116047784A

CN116047784A - Precise assembly method of double-light-path coaxial optical system based on beam splitting prism refraction

Info

Publication number: CN116047784A
Application number: CN202211737462.2A
Authority: CN
Inventors: 雷昱; 康世发; 尹雅梅; 韩娟
Original assignee: XiAn Institute of Optics and Precision Mechanics of CAS
Current assignee: XiAn Institute of Optics and Precision Mechanics of CAS
Priority date: 2022-12-30
Filing date: 2022-12-30
Publication date: 2023-05-02

Abstract

The invention provides a precise assembly method of a double-light-path coaxial optical system based on beam splitting prism refraction, which aims to solve the technical problems that the existing mechanical assembly precision is low and the high-precision assembly requirement of the coaxial double-light-path optical system based on beam splitting prism refraction cannot be met. According to the precise assembly method, an optical centering processing technology and a theodolite auto-collimation imaging technology are combined, a main mirror optical axis is used as a main reference, main reference extraction and conversion are performed on the basis of auto-collimation theodolite optical axis visualization, a beam splitting prism, a reflecting mirror and an optical mirror/mirror group in a double-light-path coaxial optical system are sequentially subjected to precise adjustment, the requirement of high coaxiality of the double-light-path optical axis is guaranteed, the adjustment efficiency is effectively improved, and the high-precision adjustment of the coaxial double-light-path optical system based on beam splitting prism refraction is realized.

Description

Precise assembly method of double-light-path coaxial optical system based on beam splitting prism refraction

Technical Field

The invention relates to the technical field of precise optical mechanical assembly, in particular to a precise assembly method of a double-light-path coaxial optical system based on beam splitting prism deflection.

Background

The beam splitting prism is a typical optical structure, and is characterized in that the beam can be split into two beams with arbitrary light intensity ratio, the beam splitting prism has a function of image conversion, and the overall dimension of an optical-mechanical system is effectively reduced. Compared with a non-folding optical system, the folding optical path of the beam splitter prism has higher requirement on the assembly of the optical machine.

As shown in fig. 1, the incident light is first divided into two beams by the front primary and secondary mirror optical system and then passed through the beam splitter prism 4, and one beam is imaged on the focal plane of the receiver by the first mirror group 6; the other path of light beam is received by the receiver through the second lens group 7 after being turned back by the reflecting mirror. In order to ensure the imaging quality of the system, the optical axis of the front-end primary and secondary mirror system is split by the beam splitting prism to form two paths of light beams, the optical axes of the two paths of light beams need to ensure very high coaxiality (within 0.04 mm), and the traditional mechanical assembly precision is low, so that the assembly requirement of the system cannot be met.

Disclosure of Invention

The invention aims to solve the technical problems that the existing mechanical assembly precision is low and the high-precision assembly requirement of a coaxial double-light-path optical system based on the refraction of a beam-splitting prism cannot be met, and provides a precise assembly method of the double-light-path coaxial optical system based on the refraction of the beam-splitting prism.

In order to achieve the above purpose, the invention adopts the following technical scheme:

a precise assembly method of a double-light-path coaxial optical system based on beam splitting prism refraction, wherein the double-light-path coaxial optical system comprises a substrate, a beam splitting prism, a reflecting mirror, a primary mirror and a secondary mirror which are arranged in a primary lens barrel and a secondary lens, a first lens group arranged in a first lens barrel and a second lens group arranged in a second lens barrel; the light splitting prism is positioned on an emergent light path of the primary lens barrel and the secondary lens barrel, the first lens barrel is positioned on a transmission light path of the light splitting prism, and the reflecting mirror and the second lens barrel are sequentially positioned on a reflection light path of the light splitting prism; the beam splitting prism, the reflecting mirror, the primary and secondary lens barrels, the first lens barrel and the second lens barrel are all arranged on the substrate through a bracket;

the precise assembly method is characterized by comprising the following steps of:

step 1), centering processing is carried out on each optical lens/lens group, and in the centering processing process, the fit clearance between each optical lens/lens group and the lens cone is 0.008-0.01mm;

step 2), measuring the interval of each optical lens in the optical lens/lens group in the optical system by using a altimeter, adjusting the interval to a theoretical value, and preliminarily determining the assembly position of each optical lens/lens group;

step 3), benchmark visual extraction;

step 4) assembling a double-light-path coaxial optical system;

the pose assembly of each optical lens/lens group of the double-light-path coaxial optical system in the step 3) and the step 4) in the respective lens cone is realized by replacing the optical lens/lens group by a cross wire tool and combining an auto-collimation imaging technology; an optical glass is arranged in the cross wire tool, and the center of the optical glass is a cross wire line; the center circle of the cross wire line is a light transmission area, and the outer ring belt area is a reflecting surface.

Further, the step 1) specifically comprises:

1.1, mounting a main mirror on a main mirror frame, connecting the main mirror with a centering lathe, and adjusting the pose of the main mirror under the rotating state of a main shaft of the centering lathe to ensure that the jumping amounts of an inner hole and an end face of the main mirror are less than 0.02mm, so as to finish the superposition of the main shaft of the lathe and a mechanical rotating shaft of the main mirror;

1.2, monitoring a spherical center auto-collimation image of a main mirror by using a centering instrument, wherein the shaking amount is within 0.005mm when the spherical center auto-collimation image rotates on a main shaft of a lathe, the jumping amounts of an inner hole and an end face of the main mirror are smaller than 0.02mm, and at the moment, the main shaft of the lathe is coincident with an optical axis of the main mirror, and the main mirror optical axis is coincident with a mechanical rotation axis of a mirror frame by taking the main shaft of the lathe as traction;

1.3, processing the outer diameter of the main lens frame, and matching with the main lens barrel and the secondary lens barrel to ensure that the fit clearance between the main lens frame and the secondary lens barrel is less than 0.02mm, so as to finish the superposition of the main lens frame outer diameter circle mechanical rotary shaft and the main reference of the main lens barrel;

1.4, processing a flange of a main mirror frame to ensure that the front end face and the rear end face of the main mirror are all visible;

1.5, processing the inner diameter of the main lens frame, wherein the circular mechanical rotating shaft of the inner diameter of the main lens frame is overlapped with the reference of the main lens barrel 8 at the moment, namely, the transition of the optical axis of the main lens to the reference shaft of the inner hole of the main lens frame is considered to be completed;

1.6, sequentially completing centering processing of other optical lenses/lens groups in the double-light-path coaxial optical system based on the refraction of the beam splitter prism according to the method of 1.1-1.5, namely, considering that the transition of the optical axis of each optical lens/lens group to the corresponding lens frame inner hole reference axis is completed, and overlapping the optical axis of each optical lens/lens group with the corresponding lens frame inner hole reference axis at the moment.

Further, the step 3) specifically comprises:

3.1, preparing a first tool cross wire according to the installation inner hole of the primary lens barrel and the installation inner hole of the secondary lens barrel, wherein the matching circumferential gap between the first tool cross wire and the second tool cross wire is smaller than 0.01mm;

the first tool cross wire comprises a small central circle and an outer circular band, the small central circle is made of glass, cross scribing lines are engraved on the small central circle of the glass and the small central circle is transparent, a mechanical rotary shaft of the first tool cross wire represents an optical axis of the center of the glass, and the outer circular band is a reflecting surface;

3.2, loading the first tooling cross wire into a main lens barrel and taking the optical axis of a small glass center circle of the first tooling cross wire as a main reference for precisely adjusting the double-light-path coaxial optical system;

and 3.3, based on an optical auto-collimation imaging principle, performing visual extraction of a reference by means of an auto-collimation first theodolite.

Further, the step 4) specifically comprises:

4.1 assembling Primary and Secondary mirrors

After the step 3) is completed, the accurate positioning of the primary mirror and the secondary mirror is completed, the primary mirror and the secondary mirror are assembled on the primary lens barrel and the secondary mirror are assembled;

4.2, assembling a beam-splitting prism

4.2.1, setting a plane mirror behind the secondary mirror, keeping the position of the first theodolite motionless, taking the main reference led out by the first theodolite as a reference, and adjusting the pose of the plane mirror until the self-alignment image reflected by the plane mirror can be seen in an eyepiece of the first theodolite, and finishing the main reference led out of the system and transferred to the plane mirror;

4.2.2, installing a beam splitting prism and a reflecting mirror at the initial position determined by the double-light-path coaxial optical system, arranging a second theodolite on the reflecting optical axis of the beam splitting prism, keeping the position of the first theodolite unchanged, and adjusting the pose of the second theodolite until the first theodolite and the second theodolite are mutually aimed and oriented until the included angle of the first theodolite and the second theodolite is 90 degrees;

4.2.3, keeping the position of the second theodolite unchanged, and adjusting the pose of the beam splitter prism until the self-alignment image reflected by the beam splitter prism, the primary mirror, the secondary mirror and the plane mirror can be seen in an eyepiece of the second theodolite, so that the accurate positioning of the beam splitter prism is completed, and the assembly of the beam splitter prism is further completed;

4.3 assembling a mirror

4.3.1, dismantling the first tooling cross wire, keeping the positions of the first theodolite and the plane reflector unchanged, arranging a third theodolite on the optical axis of the second lens barrel determined by the double-optical-path coaxial optical system, and adjusting the pose of the third theodolite until the third theodolite is aligned with the plane reflector, and completing the transmission of the main reference lead-out to the third theodolite, wherein the optical axis of the third theodolite is parallel to the optical axis of the first lens barrel;

4.3.2, based on the initial position determined by the dual-light path coaxial optical system, installing a reflecting mirror on a reflecting optical axis of the beam splitting prism, and adjusting the pose of the reflecting mirror until the self-alignment image reflected by the plane reflecting mirror is seen in the ocular of the third theodolite, so as to finish the accurate positioning of the reflecting mirror and further finish the assembly of the reflecting mirror;

4.4 assembling the first lens group

4.4.1, keeping the position of the third theodolite unchanged, replacing the first theodolite with a detector at the position of the first theodolite, and finely adjusting the position of the detector until a cross cursor of the third theodolite is positioned at the center of a target surface of the detector, thereby finishing the leading-out and transmission of a main reference of the system to the detector;

4.4.2, installing a first lens cone at the initial position determined by the double-light-path coaxial optical system, and assembling a second tool cross wire into the first lens cone;

4.4.3, adjusting the pose of the first lens cone until the light emitted by the third theodolite monitored in the detector is transmitted to the target surface center of the detector through the main lens cone, the sub lens cone and the beam splitting prism, so as to finish the accurate positioning of the first lens cone, then disassembling the second tool cross wire, and assembling the first lens group on the first lens cone through tight fit, thus finishing the assembly of the first lens group;

4.5 assembling the second lens group

4.5.1, keeping the position of the third theodolite unchanged, installing a second lens cone at the initial position determined by the double-light-path coaxial optical system, and assembling a third tool cross wire into the second lens cone;

4.5.2, adjusting the pose of the second lens cone until light emitted by the third theodolite monitored in the detector is reflected by the third tool cross wire, the reflecting mirror, the beam splitting prism, the primary lens cone and the plane reflecting mirror and then transmitted by the beam splitting prism, the formed image is positioned at the center of the target surface of the detector, the accurate positioning of the second lens cone is completed, then the third tool cross wire is disassembled, the second lens group is assembled on the second lens cone through tight fit, and the assembly of the second lens group can be completed.

Further, the step 3.3 specifically includes:

a first theodolite is arranged on an optical axis of a first lens barrel of a pre-planned dual-optical-path coaxial optical system, light emitted by the first theodolite is reflected by a first tool cross wire and is received again by the first theodolite, and the angle of the first theodolite is adjusted to ensure that the center of an eyepiece of the first theodolite coincides with a self-alignment image of the first tool cross wire; and translating the first theodolite along the optical axis direction to ensure that the center of an eyepiece of the first theodolite is aligned with a cross line at the center of a cross wire of the first tool, and completing the visual extraction of the main reference.

Further, the method further comprises the following steps: step 5) calculating the optical axis coaxiality error delta of the double-light-path coaxial optical system: delta=a ² +b ² +c ² ；

Wherein a is the centering machining error of each optical lens/lens group; b is the error of the theodolite; c is the error of the detector.

Further, the second tooling cross wire and the third tooling cross wire have the same structure as the first tooling cross wire;

the fit circumferential clearance between the first tool cross wire and the main lens barrel is 0.008-0.01mm;

the circumferential fit clearance between the second tooling cross wire and the first lens cone is 0.008-0.01mm;

the circumferential fit clearance between the third tool cross wire and the second lens cone is 0.008-0.01mm.

Further, the alignment accuracy of the first theodolite, the second theodolite and the third theodolite is 3 ", and the effective distance is 1300mm.

Compared with the prior art, the invention has the following beneficial technical effects:

1. the invention provides a precise assembly method of a double-light-path coaxial optical system based on beam splitting prism refraction, which adopts an optical centering processing technology to carry out turning processing on an optical system basic unit, namely an optical lens group, and uses a centering lathe spindle as traction to coincide an optical axis of an optical element with a mechanical rotating shaft of a corresponding assembly, and simultaneously completes the coincidence of the mechanical rotating shaft of the outer diameter of a lens frame of the lens group with a reference of a lens barrel, thereby realizing the high coaxiality of the optical axis of the lens group and the corresponding mechanical shaft; in addition, based on the manufacturing cross wire tool of the optical centering processing technology, optical glass is arranged in the tool, a transmission glass is arranged in the middle of the glass, a center cross scribing line is arranged in the middle of the glass, and the rest of outer annular bands are reflecting surfaces. The optical centering processing technology is used for precisely turning the outer circle and the end face of the tool by controlling the self-alignment image and the central cross-hair image shaking amount of the glass and transiting the optical axis of the optical glass to a mechanical reference.

2. The precise assembly method adopts an auto-collimation imaging technology, realizes the extraction and transmission of the reference on the basis of using a cross wire tool to replace an optical lens group, and completes the high-precision positioning assembly of the lens cone by precisely adjusting the position of the cross wire tool imaged on the target surface of the detector at the center of the target surface by using a high-precision detector. According to the method, the cross wire tool is firstly arranged in the lens cone, then the center of the target surface of the detector is aligned with the reflection image of the tool, the optical axis reference is transited to the detector, the reference is visualized, and high-precision reference transmission is realized. By monitoring the reflected image of the cross wire tool in the detector, the high-precision positioning assembly of the lens barrel is completed.

3. Aiming at the characteristics of multi-turn light paths of the beam splitter prism, the precise assembly method of the invention combines the optical centering processing technology and the auto-collimation imaging principle to provide 2 key steps: reference extraction and reference conversion and assembly of optical mirrors/mirror groups in a dual-path coaxial optical system. According to the method, a main lens optical axis is used as a reference, and a beam splitting prism, a first lens group and a second lens group are precisely adjusted through an auto-collimation theodolite optical axis visualization method and a detector target surface monitoring method, so that the requirement of high coaxiality of double optical path optical axes of the first lens group and the second lens group is guaranteed. The angle error of the theodolite and the matching tolerance of the detector alignment error lens group are considered, and the assembly error of the method is calculated to be 0.0207mm, so that the assembly requirement of 0.04mm is completely met.

4. The invention relates to a precise assembly method, which is an interchangeability technology of high-precision matching. After the optical centering processing, the fit clearance between all the optical lens groups and the cross wire tool and the lens cone is within 0.008-0.01mm, and the reset precision is still higher after repeated disassembly. Based on the reasons, each optical lens group is removed firstly, a cross wire tool is installed for visual precise assembly, after the lens barrel positioning assembly is completed, tool cross wires are removed, each optical lens group is installed in sequence, and final optical assembly is completed through high-precision matching.

Drawings

FIG. 1 is a schematic diagram of a typical prior art dual-path coaxial optical system based on beam splitter prism refraction;

FIG. 2 is a schematic view of the appearance of a dual-path coaxial optical system based on beam splitting prism refraction;

FIG. 3 is a cross-sectional view of a dual-path coaxial optical system based on a beam splitter prism turn in accordance with an embodiment of the present invention;

FIG. 4 is a schematic diagram of a first tooling cross wire structure in the precise assembly method of the double-light-path coaxial optical system based on the refraction of the beam splitter prism;

FIG. 5 is a schematic view of the step 3) reference visualization extraction in an embodiment of the assembly method of the present invention;

FIG. 6 is a schematic view of the assembly of the beam splitting prism of step 4.2) in an embodiment of the assembly method of the present invention;

FIG. 7 is a schematic view of the assembly of the mirror at step 4.3) in an embodiment of the assembly method of the present invention;

FIG. 8 is a schematic view of the assembly of the first lens group in step 4.4) of the assembly method according to the embodiment of the present invention;

FIG. 9 is a schematic diagram of the assembly of the second lens group in step 4.5) of the assembly method embodiment of the present invention;

reference numerals:

1-base plate, 2-primary mirror, 3-secondary mirror, 4-beam splitter prism, 5-reflector, 6-first lens group, 7-second lens group, 8-primary and secondary lens barrel, 9-first lens barrel, 10-second lens barrel, 11-first theodolite, 12-first tooling cross wire, 13-second theodolite, 14-plane reflector, 15-third theodolite, 16-second tooling cross wire, 17-detector, 18-third tooling cross wire.

Detailed Description

In order to make the objects, advantages and features of the present invention more clear, the following describes in further detail a method for precisely assembling a dual-optical-path coaxial optical system based on turning of a beam splitter prism according to the present invention with reference to the accompanying drawings and specific embodiments. It should be understood by those skilled in the art that these embodiments are merely for explaining the technical principles of the present invention, and are not intended to limit the scope of the present invention. In the description of the present invention, it should be noted that the terms "first," "second," and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

As shown in fig. 2 and 3, the double-optical path coaxial optical system based on the refraction of the beam splitter prism of the present embodiment includes a substrate 1, a beam splitter prism 4, a reflecting mirror 5, and a main mirror 2 and a sub mirror 3 mounted in a main-sub lens barrel 8, a first lens group 6 mounted in a first lens barrel 9, and a second lens group 7 mounted in a second lens barrel 10. The beam splitting prism 4 is located at the rear end of the main and sub lens barrels 8, the first lens barrel 9 is located on the transmission light path of the beam splitting prism 4, the reflecting mirror 5 is located on the reflection light path of the beam splitting prism 4, and the second lens barrel 10 is located at the rear end of the reflecting mirror 5. The beam-splitting prism 4, the reflecting mirror 5, the main and sub barrels 8, the first barrel 9, and the second barrel 10 are all mounted on the substrate 1 by brackets. The optical lens/lens group is arranged in the corresponding lens frame, the lens frame is fixed in the lens barrel provided with the multi-stage step surface, and the clearance between the optical lens/lens group and the lens barrel is ensured to be within 0.01mm, so that the resetting precision is high after repeated disassembly in the assembly process.

In order to meet the requirement of high-precision adjustment of multi-optical-axis consistency of a double-optical-path coaxial optical system based on the refraction of a beam splitter prism, the position of each lens barrel needs to be accurately adjusted, the revolving body property of each lens barrel determines that the lens barrel is provided with an inner hole reference shaft, so that the optical axes of each optical lens/lens group are transited to the corresponding inner hole reference shaft by using an optical centering processing technology, the alignment of each optical lens/lens group to the reference shaft is completed, and the requirement of multi-optical-axis consistency of the optical lens/lens group can be met.

The precise coaxiality adjustment method based on the structure of the double-light-path coaxial optical system folded by the beam splitter prism in the embodiment specifically comprises the following steps:

step 1), centering each optical lens/lens group

As shown in fig. 3, the basic unit in the beam splitting prism-folded dual-optical-path optical system is a lens group, each lens group is a combination of a lens/a reflector installed in a corresponding lens frame/lens barrel, and a multi-stage step surface is arranged in the lens barrel for fixing the lens frame. The quality of the mirror frame/lens barrel revolving body determines that the mirror frame/lens barrel revolving body is provided with a mirror frame outer circle reference shaft and a lens barrel reference shaft, and a lathe rotation shaft, an optical element optical axis and a corresponding mirror frame/lens barrel mechanical revolving shaft are mutually connected by using a lathe machining technology.

Taking the main mirror 2 as an example, the centering processing steps are as follows:

1.1, mounting a main mirror 2 on a main mirror frame of the main mirror 2, connecting the main mirror 2 with a centering lathe, and adjusting the pose of the main mirror 2 in a rotating state of a main shaft of the centering lathe to ensure that the jumping amounts of an inner hole and an end face of the main mirror are smaller than 0.02mm, wherein the main shaft of the lathe is considered to coincide with a mechanical rotating shaft of the main mirror 2;

1.2, monitoring a spherical center auto-collimation image of the main mirror 2 by using a centering instrument, wherein the shaking amount is within 0.005mm when the spherical center auto-collimation image rotates on a lathe spindle, the jumping amounts of an inner hole and an end face of the main mirror 2 are both better than 0.02mm, the lathe spindle is coincident with an optical axis of the main mirror 2 at the moment, and the step 1.1) is combined, and the lathe spindle is taken as traction, so that the optical axis of the main mirror 2 is considered to be coincident with a mechanical rotary shaft of a mirror frame at the moment;

1.3, processing the outer diameter of the main lens frame, and matching with the main lens barrel 8 to ensure that the fit clearance between the main lens frame and the auxiliary lens barrel is less than 0.02mm, and considering that the round mechanical rotary shaft of the outer diameter of the main lens frame coincides with the reference of the main lens barrel 8 at the moment;

1.4, processing a flange of a mirror frame of the main mirror 2 to ensure that the front end face and the rear end face of the main mirror 2 are both visible light;

1.5, processing the inner diameter of the main mirror 2, wherein the circular mechanical rotary shaft of the inner diameter of the main mirror 2 is overlapped with the reference of the main lens barrel 8 at the moment, namely, the transition of the optical axis of the main mirror 2 to the reference shaft of the inner hole of the main mirror 2 is considered to be completed;

And 2) measuring the interval of each single lens group in the optical lens/lens group in the optical system by using the altimeter, adjusting the interval to a theoretical value, and preliminarily determining the assembly position of each optical lens/lens group.

Step 3), benchmark visual extraction

In the centering processing step, the outer diameters of the mirror frames of the main mirror 2 and the secondary mirror 3 are matched with the main and secondary lens barrels 8, at the moment, the mirror frames of the main mirror 2 and the secondary mirror 3 are considered to be overlapped with the mechanical rotation axes of the main and secondary lens barrels 8, the centered main mirror 2 and the centered secondary mirror 3 are assembled on the main and secondary lens barrels 8, and at the moment, the mechanical rotation axes of the main and secondary lens barrels 8 are overlapped with the optical axes of the main mirror 2 and the secondary mirror 3.

3.1, preparing a first tool cross wire 12 according to the installation inner hole of the main lens barrel 8;

as shown in fig. 4, the first tooling cross wire 12 includes a small central circle and an outer circular band, the small central circle is made of glass, and the small central circle is carved with a cross scribing line and transmits light, the mechanical rotation axis of the first tooling cross wire 12 represents the optical axis of the glass center, and the outer circular band is a reflecting surface; the outer circumferential band is precisely turned by an optical centering processing technology to obtain a first tool cross wire 12, wherein the mechanical rotating shaft of the first tool cross wire represents the optical axis of glass, and the deviation is controlled within 5 mu m. The optical axis of the small circle at the center of the glass is transited to the reference axis of the outer circular band, and the fit clearance between the glass and the main and secondary lens barrels 8 is ensured to be 0.008-0.01mm, otherwise, the first tooling cross wire 12 needs to be reprocessed.

3.2, as shown in fig. 5, the first tooling cross wire 12 is installed in the main and secondary lens barrel 8, the optical axis of the small glass center circle of the first tooling cross wire 12 is used as the main reference for precisely installing and adjusting the double-light-path coaxial optical system based on the refraction of the beam splitter prism, and the reference is visually led out by the aid of the auto-collimation first theodolite 11 based on the optical auto-collimation imaging principle.

The first theodolite 11 is arranged on the optical axis of the first lens barrel 9 of the pre-planned dual-optical-path coaxial optical system, light emitted by the first theodolite 11 is reflected by the first tool cross wire 12 and received again by the first theodolite 11, and an optical self-alignment image is formed inside the first theodolite 11, and can be observed in an eyepiece of the first theodolite 11. At the same time, the centre score line of the first tooling cross hair 12 can also be seen in the first theodolite 11. And the self-alignment image and the center line are monitored, so that the reference is visualized.

The step uses a first theodolite 11 to visually draw out a reference, and comprises the following specific operations: the angle of the first theodolite 11 is adjusted to ensure that the center of an eyepiece coincides with the self-alignment image of the first tooling cross wire 12, then the first theodolite 11 is translated along the direction of an optical axis to ensure that the center of the eyepiece coincides with a cross line at the center of the first tooling cross wire 12, at the moment, the self-alignment image seen in the eyepiece of the first theodolite 11 coincides with the self-alignment image of the first tooling cross wire 12 and the center cross wire image, namely the first theodolite 11 and the first tooling cross wire 12 mutually self-align and pass through, and the standard visual extraction is completed, so that the first theodolite 11 is kept motionless. At this time, the optical axis of the first theodolite 11 represents the optical axis of the first tooling cross wire 12, and is also the main reference in the whole precise adjustment process.

Step 4) assembling a dual-optical-path coaxial optical system

4.1 assembling primary mirror 2 and secondary mirror 3

After the step 3) is completed in the reference visualization extraction, the accurate positioning of the main mirror 2 and the secondary mirror 3 is completed simultaneously, the main mirror 2 and the secondary mirror 3 are assembled on the main and secondary lens barrels 8, and the assembly of the main mirror 2 and the secondary mirror 3 is completed.

In the centering processing step of the step 1), the outer diameters of the lens frames in the main lens 2 and the secondary lens 3 are matched with the main lens barrel 8, and the matching clearance is 0.008-0.01mm, so that the centered main lens 2 and secondary lens 3 are arranged on the main lens barrel 8, at the moment, the reference axes of the inner holes of the main lens barrel 8 are overlapped with the optical axes of the main lens 2 and the secondary lens 3 in height, and the matching clearance is 0.008-0.01mm.

4.2, assembly of a light-splitting prism 4

As shown in fig. 6, a plane mirror 14 is arranged behind the secondary mirror 3, a second theodolite 13 is arranged on the reflecting optical axis of the beam splitter prism 4, the position of the first theodolite 11 is kept unchanged, a main reference is led out by the first theodolite 11, and the beam splitter prism 4 and the mirror 5 are assembled in an auxiliary manner by the second theodolite 13. The method comprises the following steps:

4.2.1, setting a plane mirror 14 behind the secondary mirror 3, keeping the position of the first theodolite 11 motionless, and adjusting the pose of the plane mirror 14 by taking the main reference led out by the first theodolite 11 as a reference until the self-alignment image reflected by the plane mirror 14 can be seen in the ocular of the first theodolite 11, thus finishing the transmission of the main reference led out of the system to the plane mirror 14;

4.2.2, installing a beam splitter prism 4 and a reflecting mirror 5 at an initial position determined by a double-light-path coaxial optical system, arranging a second theodolite 13 on a reflecting optical axis of the beam splitter prism 4, keeping the position of the first theodolite 11 unchanged, and adjusting the pose of the second theodolite 13, wherein the first theodolite 11 and the second theodolite 13 are mutually aimed and oriented until the included angle between the first theodolite 11 and the second theodolite 13 is 90 degrees;

4.2.3, keeping the position of the second theodolite 13 unchanged, and adjusting the pose of the beam splitter prism 4 until the self-alignment image reflected by the beam splitter prism 4, the primary mirror 2, the secondary mirror 3 and the plane mirror 14 can be seen in the ocular of the second theodolite 13, thus finishing the accurate positioning of the beam splitter prism 4 and further finishing the assembly of the beam splitter prism 4.

4.3 assembling mirror 5

4.3.1, as shown in fig. 7, dismantling the first tooling cross wire 12, keeping the position of the first theodolite 11 and the plane mirror 14 unchanged, setting a third theodolite 15 on the optical axis of the second lens barrel 10 by the double-optical-path coaxial optical system, adjusting the pose of the third theodolite 15 to enable the third theodolite 15 to be self-aligned with the plane mirror 14, namely, seeing a self-aligned image reflected by the third theodolite 15 through the plane mirror 14 in an eyepiece of the third theodolite 15, and completing transmission of a main reference lead of the system to the third theodolite 15, wherein the optical axis of the third theodolite 15 is parallel to the optical axis of the first lens barrel 9;

4.3.2, based on the initial position determined by the dual-light path coaxial optical system, installing a reflecting mirror 5 on the reflecting optical axis of the beam splitter prism 4, and adjusting the pose of the reflecting mirror 5 until the self-alignment image reflected by the reflecting mirror 5, the beam splitter prism, the primary mirror and the secondary mirror 14 is seen in the ocular of the third theodolite 15, so as to finish the accurate positioning of the reflecting mirror 5 and further finish the assembly of the reflecting mirror 5.

4.4 assembling the first lens group 6

4.4.1, as shown in fig. 8, keeping the position of the third theodolite 15 unchanged, replacing the first theodolite 1 with the detector 17 at the position of the first theodolite 1, finely adjusting the position of the detector 17 until a cross cursor of the third theodolite 15 is positioned at the center of the target surface of the detector 17, and completing transmission of main reference lead-out of the system to the detector 17;

4.4.2, installing a first lens cone 9 at the initial position determined by the double-light-path coaxial optical system, and assembling a second tool cross wire 16 into the first lens cone 9, so as to ensure that the circumferential fit clearance between the second tool cross wire 16 and the first lens cone 9 is 0.008-0.01mm; the second tooling cross wire 16 has the same structure as the first tooling cross wire 12 and is obtained by turning through an optical centering processing technology;

4.4.3, adjusting the pose of the first lens cone 9 until the light emitted by the third theodolite 15 monitored in the detector 17 is transmitted to the second tooling cross wire 16 after passing through the main lens cone 8 and the sub lens cone 4, and the imaged image is positioned at the center of the target surface of the detector 17, so that the accurate positioning of the first lens cone 9 is completed, and then the second tooling cross wire 16 is disassembled;

because the first lens group 6 and the first lens cone 9 finish the vehicle matching in the centering process of the step 1), the matching clearance between the first lens group 6 and the first lens cone 9 is 0.008-0.01mm, after the first lens group 6 is accurately positioned, the first lens group 6 is assembled on the first lens cone 9 through tight fit, and the assembly of the first lens group 6 can be finished.

4.5 assembling a second lens group 7

4.5.1, as shown in fig. 9, keeping the position of the third theodolite 15 unchanged, installing the second lens cone 10 at the initial position determined by the dual-optical-path coaxial optical system, and assembling the third tooling cross wire 18 into the second lens cone 10, so as to ensure that the circumferential fit clearance between the third tooling cross wire 18 and the second lens cone 10 is 0.008-0.01mm; the third tooling cross wire 18 has the same structure as the first tooling cross wire 12 and is obtained by turning through an optical centering processing technology;

4.5.2, adjusting the pose of the second lens barrel 10 until the light emitted by the third theodolite 15 monitored in the detector 17 sequentially passes through the third tool cross wire 18, the reflecting mirror 5, the beam splitting prism 4, the primary and secondary lens barrels 8 and the plane reflecting mirror 14, is transmitted through the beam splitting prism 4, and the formed image is positioned at the center of the target surface of the detector 17, so that the accurate positioning of the second lens barrel 10 is completed, and then the third tool cross wire 18 is detached;

because the second lens group 7 and the second lens barrel 10 have completed the vehicle matching in the centering process of the step 1), the matching clearance between the second lens group 7 and the second lens barrel is 0.008-0.01mm, after the second lens group 7 is accurately positioned, the second lens group 7 is assembled on the second lens barrel 10 through tight fit, and the assembly of the second lens group 7 can be completed.

Step 5), calculating the coaxiality error of the optical axis of the double-light-path coaxial optical system

After the assembly steps are completed, the unification of the optical axes of the refraction light path and the reflection light path of the beam splitting prism 4 is realized, and the coaxiality of the system is ensured. Since the angular error of each theodolite is 3 ", the effective distance is 1300mm, and the theodolite produces an error of 1300mm tan 3" =0.018 mm. The detector alignment error is 1 pixel (0.002 mm), and the maximum reset error of each optical mirror/mirror group is 0.01mm, so the total error delta is calculated as follows:

Δ＝0.01 ² +0.018 ² +0.002 ² ＝0.0207mm

therefore, the coaxiality of the optical axes at the front end and the rear end of the double-optical-path coaxial optical system is 0.0207mm, and the assembly requirement is met by 0.04mm.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced with equivalents; such modifications and substitutions do not depart from the spirit of the invention.

Claims

1. A precise assembly method of a double-light-path coaxial optical system based on beam splitting prism refraction, wherein the double-light-path coaxial optical system comprises a substrate (1), a beam splitting prism (4), a reflecting mirror (5), a main mirror (2) and a secondary mirror (3) which are arranged in a main lens barrel (8), a first lens group (6) arranged in a first lens barrel (9) and a second lens group (7) arranged in a second lens barrel (10); the beam splitting prism (4) is positioned on an emergent light path of the primary lens barrel (8), the first lens barrel (9) is positioned on a transmission light path of the beam splitting prism (4), and the reflecting mirror (5) and the second lens barrel (10) are sequentially positioned on a reflection light path of the beam splitting prism (4); the beam splitting prism (4), the reflecting mirror (5), the primary and secondary lens barrels (8), the first lens barrel (9) and the second lens barrel (10) are all arranged on the substrate (1) through brackets;

step 3), benchmark visual extraction;

step 4) assembling a double-light-path coaxial optical system;

2. The precise assembly method of the double-light-path coaxial optical system based on the refraction of the beam splitter prism as claimed in claim 1, wherein the step 1) is specifically as follows:

1.1, mounting a main mirror (2) on a main mirror frame and then connecting the main mirror with a centering lathe, and adjusting the pose of the main mirror (2) under the rotating state of a main shaft of the centering lathe to ensure that the jumping amounts of an inner hole and an end face of the main mirror are less than 0.02mm, thereby finishing the superposition of the main shaft of the lathe and a mechanical rotating shaft of the main mirror (2);

1.2, monitoring a spherical center auto-collimation image of a main mirror (2) by using a centering instrument, wherein the spherical center auto-collimation image is in 0.005mm when a lathe spindle rotates, the jumping amount of an inner hole and an end face of the main mirror (2) is smaller than 0.02mm, and at the moment, the lathe spindle is overlapped with an optical axis of the main mirror (2), and the optical axis of the main mirror (2) is overlapped with a mechanical rotating shaft of a mirror frame by taking the lathe spindle as traction;

1.3, machining the outer diameter of a lens frame of a main lens (2), and matching the lens frame with a main lens barrel (8), wherein the fit clearance between the lens frame and the main lens barrel is less than 0.02mm, and the superposition of a circular mechanical rotary shaft of the outer diameter of the lens frame of the main lens and a main reference of the main lens barrel (8) is completed;

1.4, processing a flange of a mirror frame of the main mirror (2) to ensure that the front end face and the rear end face of the main mirror (2) are all visible;

1.5, processing the inner diameter of the main mirror (2), wherein the circular mechanical rotary shaft of the inner diameter of the main mirror (2) coincides with the reference of the main and secondary lens barrels (8), namely the transition of the optical axis of the main mirror (2) to the reference shaft of the inner hole of the main mirror (2) is considered to be completed;

3. The precise assembly method of the double-light-path coaxial optical system based on the refraction of the beam splitter prism as claimed in claim 2, wherein the step 3) is specifically as follows:

3.1, according to the installation inner hole of the primary and secondary lens cone (8), a first tool cross wire (12) is matched, and the matching circumferential gap between the two is smaller than 0.01mm;

the first tool cross wire (12) comprises a small central circle and an outer circular band, the small central circle is made of glass, a cross scribing line is carved on the small central circle of the glass and the small central circle is transparent, a mechanical rotary shaft of the first tool cross wire (12) represents an optical axis of the center of the glass, and the outer circular band is a reflecting surface;

3.2, loading the first tooling cross wire (12) into the main and secondary lens barrels (8), and taking the optical axis of the small glass center circle of the first tooling cross wire (12) as a main reference for precisely adjusting the double-light-path coaxial optical system;

and 3.3, based on the optical auto-collimation imaging principle, carrying out visual extraction of the reference by means of an auto-collimation first theodolite (11).

4. The precise assembly method of the double-light-path coaxial optical system based on the refraction of the beam splitter prism according to claim 3, wherein the step 4) is specifically as follows:

4.1 assembling a primary mirror (2) and a secondary mirror (3)

After the step 3) is completed in the visual extraction of the reference, the main mirror (2) and the secondary mirror (3) are positioned accurately, the main mirror (2) and the secondary mirror (3) are assembled on the main and secondary lens barrels (8), and the assembly of the main mirror (2) and the secondary mirror (3) is completed;

4.2, assembly light splitting prism (4)

4.2.1, setting a plane reflecting mirror (14) behind the secondary mirror (3), keeping the position of the first theodolite (11) motionless, taking the leading-out main reference of the first theodolite (11) as a reference, and adjusting the pose of the plane reflecting mirror (14) until the self-alignment image reflected by the plane reflecting mirror (14) can be seen in an eyepiece of the first theodolite (11), and finishing the leading-out and transmission of the main reference of the system to the plane reflecting mirror (14);

4.2.2, installing a beam splitting prism (4) and a reflecting mirror (5) at an initial position determined by a double-light-path coaxial optical system, arranging a second theodolite (13) on a reflecting optical axis of the beam splitting prism (4), keeping the position of the first theodolite (11) unchanged, adjusting the pose of the second theodolite (13), and mutually aiming and orienting the first theodolite (11) and the second theodolite (13) until the included angle between the first theodolite (11) and the second theodolite (13) is 90 degrees;

4.2.3, keeping the position of the second theodolite (13) unchanged, and adjusting the pose of the beam splitting prism (4) until the self-alignment image reflected by the beam splitting prism (4), the primary mirror (2), the secondary mirror (3) and the plane reflecting mirror (14) can be seen in an eyepiece of the second theodolite (13), so that the beam splitting prism (4) is accurately positioned, and further the beam splitting prism (4) is assembled;

4.3, fitting mirror (5)

4.3.1, dismantling the first tooling cross wire (12), keeping the position of the first theodolite (11) and the plane reflector (14) unchanged, setting a third theodolite (15) on the optical axis of the second lens barrel (10) determined by the double-optical-path coaxial optical system, and adjusting the pose of the third theodolite (15) until the third theodolite (15) is self-aligned with the plane reflector (14), so as to finish the transmission of the main reference extraction to the third theodolite (15), wherein the optical axis of the third theodolite (15) is parallel to the optical axis of the first lens barrel (9);

4.3.2, based on the initial position determined by the dual-light path coaxial optical system, installing a reflecting mirror (5) on a reflecting optical axis of the beam splitting prism (4), and adjusting the pose of the reflecting mirror (5) until a self-alignment image reflected by a plane reflecting mirror (14) is seen in an eyepiece of a third theodolite (15), so as to finish the accurate positioning of the reflecting mirror (5) and further finish the assembly of the reflecting mirror (5);

4.4 assembling a first mirror group (6)

4.4.1, keeping the position of the third theodolite (15) unchanged, replacing the first theodolite (11) with a detector (17) at the position of the first theodolite (11), and finely adjusting the position of the detector (17) until a cross cursor of the third theodolite (15) is positioned at the center of a target surface of the detector (17), so as to finish the transmission of the main reference extraction of the system to the detector (17);

4.4.2, installing a first lens cone (9) at the initial position determined by the double-light-path coaxial optical system, and assembling a second tool cross wire (16) into the first lens cone (9);

4.4.3, adjusting the pose of the first lens cone (9) until the light emitted by the third theodolite (15) monitored in the detector (17) is transmitted to the second tooling cross wire (16) after passing through the main lens cone (8) and the sub lens cone (4), the image formed by the second tooling cross wire (16) is positioned at the center of the target surface of the detector (17), the accurate positioning of the first lens cone (9) is completed, then the second tooling cross wire (16) is disassembled, and the first lens group (6) is assembled on the first lens cone (9) through tight fit, so that the assembly of the first lens group (6) can be completed;

4.5, second mirror group (7) is assembled

4.5.1, keeping the position of the third theodolite (15) unchanged, installing a second lens cone (10) at the initial position determined by the double-light-path coaxial optical system, and assembling a third tooling cross wire (18) into the second lens cone (10);

4.5.2, adjusting the pose of the second lens cone (10) until the light emitted by the third theodolite (15) monitored in the detector (17) sequentially passes through the third tool cross wire (18), the reflecting mirror (5), the beam splitting prism (4), the main lens cone (8) and the plane reflecting mirror (14) and then is transmitted through the beam splitting prism (4), the formed image is positioned at the center of the target surface of the detector (17), the accurate positioning of the second lens cone (10) is completed, then the third tool cross wire (18) is disassembled, the second lens group (7) is assembled on the second lens cone (10) through tight fit, and then the assembly of the second lens group (7) can be completed.

5. The precise assembly method of the double-light-path coaxial optical system based on the refraction of the beam splitter prism according to claim 4, wherein the step 3.3 is specifically:

a first theodolite (11) is arranged on an optical axis of a first lens barrel (9) of a pre-planned dual-optical-path coaxial optical system, light emitted by the first theodolite (11) is reflected by a first tooling cross wire (12) and is received again by the first theodolite (11), and the angle of the first theodolite (11) is adjusted to ensure that the center of an eyepiece of the first theodolite coincides with a self-alignment image of the first tooling cross wire (12); and translating the first theodolite (11) along the optical axis direction to ensure that the center of an eyepiece of the first theodolite is aligned with a cross line at the center of a first tool cross wire (12), so as to complete the main reference visual extraction.

6. The method for precisely assembling a double-light-path coaxial optical system based on beam-splitting prism refraction according to any one of claims 1 to 5, further comprising:

step 5) calculating the optical axis coaxiality error delta of the double-light-path coaxial optical system:

7. The precise assembly method of the double-light-path coaxial optical system based on the refraction of the beam splitter prism according to claim 6, wherein the precise assembly method comprises the following steps:

the second tooling cross wire (16) and the third tooling cross wire (18) have the same structure as the first tooling cross wire (12);

the fit circumferential clearance between the first tooling cross wire (12) and the main and secondary lens barrels (8) is 0.008-0.01mm;

the circumferential fit clearance between the second tooling cross wire (16) and the first lens cone (9) is 0.008-0.01mm;

the circumferential fit clearance between the third tool cross wire (18) and the second lens cone (10) is 0.008-0.01mm.

8. The precise assembly method of the double-light-path coaxial optical system based on the refraction of the beam splitter prism according to claim 7, wherein the precise assembly method comprises the following steps:

the alignment accuracy of the first theodolite (11), the second theodolite (13) and the third theodolite (15) is 3', and the effective distance is 1300mm.