Optical axis parallelism detection method

Abstract

The application provides a light axis parallelism detection method. The detection method can quickly and accurately detect the light axis parallelism difference between two parallel light tubes by using one theodolite and one five-prism. The specific implementation steps are as follows: placing one theodolite and one five-prism in front of two parallel light tubes whose light axes are roughly adjusted; adjusting the theodolite to be level, and aiming at the corresponding parallel light tube target; recording the readings of the theodolite; rotating the theodolite, aiming at the other parallel light tube through the five-prism, and recording the corresponding azimuth and elevation readings; and detecting the parallelism error between the two parallel light tubes by processing and directly comparing the two groups of data. The method has obvious advantages in solving the light axis parallelism detection of the double parallel light tubes with long light axis spacing.

Description

Technical Field

[0001] This invention relates to the fields of optical inspection and optical assembly, specifically to a method for detecting the parallelism of optical axes, used for detecting or guiding the assembly of optical axes of dual collimators. Background Technology

[0002] In large optoelectronic devices such as astronomical telescopes and large optoelectronic theodolites, a common practice is to integrate multiple sensors with different operating wavelengths and optical fields of view into a single device in order to adapt to different environmental conditions or detect targets at different wavelengths and distances. For such optoelectronic devices, maintaining the parallelism of the optical axes of the optical systems of the various sensors is a basic assembly and adjustment requirement.

[0003] To achieve parallelism between the optical axes of different sensor optical systems, when the optical axis spacing is small, a collimator can be used to cover two sensor optical systems simultaneously. The parallelism can be confirmed by detecting whether they both image the same target at the center position. When the optical axis spacing is large, a large-diameter collimator can be used to align with both sensor optical systems simultaneously, or two collimators with adjusted parallelism can be used to align with one sensor optical system respectively, in order to confirm whether the optical axes of the two sensor optical systems are parallel.

[0004] In methods for detecting the parallelism of the optical axes of two sensor optical systems with a large optical axis spacing, a typical aperture (around 500mm) often cannot simultaneously cover both sensor optical systems, while larger aperture collimators are more difficult to manufacture and more expensive. Therefore, a more common method is to use two collimators, adjusting their positions so that their optical axes are parallel and each collimator is aligned with one sensor optical system.

[0005] To parallelize the optical axes of two collimators, the conventional approach is to simultaneously align both collimators with a large-aperture collimator mirror, and then autocollimate each collimator with a plane mirror using a Gaussian eyepiece. This ultimately achieves parallelism between the optical axes of the two collimators. Compared to the large-aperture collimator method, this method can achieve a larger optical axis spacing, but the cost of large-aperture collimators is relatively high. Furthermore, the large-aperture plane mirror often needs to be mounted at a high position, increasing the operational difficulty and risk.

[0006] Chinese Patent Application No. 201510900782.9, Publication No. CN 105423958 A, published on March 23, 2016, discloses an invention patent entitled "A Multi-Axis Parallelism Detection Device and Detection Method." This patent uses a detection platform as a reference and a moving device to translate a collimator to ensure that the target axes aligned between different sensors are parallel to each other. This method is simple in structure and low in cost. However, if an optical system with a large distance from the optical axis is required, this detection method places high demands on the travel and straightness of the moving device. Furthermore, long-focal-length collimators are generally limited by weight and size, making movement inconvenient. Moreover, this method cannot be used when the sensor optical systems are at different horizontal heights. Summary of the Invention

[0007] This invention addresses the shortcomings of existing methods in detecting the parallelism of multiple optical axes in optical systems with long optical axis distances by providing a fast, flexible, and easy-to-use detection method that can solve the problem of detecting the parallelism of multiple optical axes with almost no spatial limitations.

[0008] The technical solution adopted by this invention to solve its technical problem is:

[0009] A method for detecting optical axis parallelism, the method comprising the following steps:

[0010] Step 1) Place the optical theodolite at the light outlet of collimator one, and adjust the leveling knob so that the vertical axis of the optical theodolite is perpendicular to the earth.

[0011] Step 2) Aim the optical theodolite's azimuth mirror at collimator one, so that the target of collimator one coincides with the center of the crosshairs on the optical theodolite's dividing plate, and record the readings of the optical theodolite's azimuth angle α1 and elevation angle θ1 at this time.

[0012] Step 3) Rotate the azimuth axis and elevation axis of the optical theodolite by 180° each, so that it is aimed at the collimator one with the inverted mirror, so that the target of the collimator one coincides with the center of the crosshairs on the optical theodolite's dividing plate, and record the readings of the azimuth angle α2 and elevation angle θ2 of the optical theodolite at this time.

[0013] Step 4) Place a pentagonal prism at the two light outlets of the collimator, and make its center height the same horizontal line as the horizontal axis of the optical theodolite;

[0014] Step 5) Rotate the optical theodolite and aim at the target of collimator 2 in the upright state using the pentagonal prism, so that the target of collimator 2 coincides with the center of the crosshairs on the optical theodolite's dividing plate, and record the azimuth reading β1 of the optical theodolite at this time; rotate the azimuth axis and elevation axis of the optical theodolite 180° each, so that it aims at collimator 2 in the inverted state, so that the target of collimator 2 coincides with the center of the crosshairs on the optical theodolite's dividing plate, and record the azimuth reading β2 of the optical theodolite at this time.

[0015] Step 6) Replace the pentagonal prism at the light outlet of the collimator with an optical theodolite, and adjust the leveling knob of the optical theodolite so that the vertical axis of the optical theodolite is perpendicular to the earth.

[0016] Step 7) Aim the crosshair center of the optical theodolite's dividing plate at the target center of collimator II in both the upright and inverted mirror states to obtain the corresponding pitch angle data δ1 and δ2.

[0017] Step 8) Based on the above data α1, α2, β1, β2, θ1, θ2, δ1 and δ2, obtain the parallelism error between collimator one and collimator two.

[0018] Furthermore, step 8) includes:

[0019] Step 8-1) Based on the azimuth angle readings α1 and α2 of the optical theodolite, calculate the average value of the upright and reverse mirrors α = (α1 + α2 ± 180°) / 2 as the azimuth angle position of the target in the collimator;

[0020] Step 8-2) Based on the azimuth angle readings β1 and β2 of the optical theodolite, calculate the average value of the upright and reverse mirrors β = (β1 + β2 ± 180°) / 2 as the azimuth angle position of the two targets in the collimator;

[0021] Step 8-3) Based on the elevation angle readings θ1 and θ2 of the optical theodolite, calculate the average value of the upright and reverse mirrors θ = (θ1-θ2+360°) / 2 as the elevation angle position of the target in the collimator;

[0022] Step 8-4) Based on the elevation angle readings δ1 and δ2 of the optical theodolite, calculate the average value of the upright and reverse mirrors δ = (δ1 - δ2 + 360°) / 2 as the elevation angle position of the two targets in the collimator;

[0023] Step 8-5) The parallelism deviation between collimator 1 and collimator 2 in the azimuth direction is calculated as: 90° - |α - β|;

[0024] Step 8-6) The parallelism deviation between collimator 1 and collimator 2 in the pitch direction is calculated as: |θ-δ|.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] (1) It has a wide range of applications and is not limited by space. This detection method is not only applicable to various scenarios with different optical axis spacing lengths, but also completely applicable when the two optical systems are at different heights.

[0027] (2) The device is simple and low-cost. Optical theodolites are commonly used tools for manufacturing, assembling, and testing optical equipment, and high-precision pentagonal prisms are not expensive. Using this method, there is no need to spend extra money to purchase special testing equipment, thus achieving low cost.

[0028] (3) Simple and easy to operate. Only those with conventional optical theodolite operation skills are required to complete the measurement process. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the principle of the testing method provided by the present invention. Figure 1 ;

[0030] Figure 2 This is a schematic diagram of the principle of the testing method provided by the present invention. Figure 2 .

[0031] Among them: 1-Columnar tube one; 2-Columnar tube two; 3-Optical theodolite; 4-Pentagonal prism. Detailed Implementation

[0032] See Figure 1 The present invention uses an optical theodolite 3 and a pentagonal prism 4 to measure the parallelism of the optical axes of collimator 1 and collimator 2.

[0033] Place collimator 1 and collimator 2 approximately horizontally to the optical axis, ensuring their light output directions are aligned. Place the pentaprism 4 and the optical theodolite 3 at the light outlets of collimator 2 and collimator 1, respectively. The center of the pentaprism 4 should be at the same horizontal height as the horizontal axis of the optical theodolite 3. After measuring the horizontal and pitch angles of collimator 1 and collimator 2, as well as the horizontal angle of collimator 2, ... Figure 2 Remove the pentagonal prism 4 and replace it with an optical theodolite 3.

[0034] The specific implementation steps of the method described in this invention are as follows:

[0035] 1) Level the optical theodolite 3 so that its vertical axis is perpendicular to the earth;

[0036] 2) Use the 3rd positive mirror of the optical theodolite to aim at the target of the collimator-1, and record the azimuth and elevation angle values ​​at this point;

[0037] 3) Use the inverted mirror of the optical theodolite 3 to aim at the target of the collimator 1, and record the azimuth and elevation angle values ​​at this point;

[0038] 4) Rotate the optical theodolite 3, aim at the target 2 through the pentagonal prism 4, and record the azimuth angle value at this point;

[0039] 5) Use the inverted mirror of the optical theodolite 3 to aim at the target 2 of the collimator and record the azimuth angle value at this location;

[0040] 6) Remove the pentagonal prism 4 and place the optical theodolite 3 here;

[0041] 7) Level the optical theodolite 3, ensuring its vertical axis is perpendicular to the ground. Use both the upright and inverted sights to aim at the target in collimator 2, and record the corresponding pitch angle values.

[0042] 8) Data processing yields the parallelism error of the two parallel light tubes.

[0043] In summary, the method of the present invention can quickly and accurately detect the difference in optical axis parallelism between two collimators using a theodolite and a pentaprism.

Claims

1. A method for detecting optical axis parallelism, characterized in that, The method includes the following steps: Step 1) Place the optical theodolite at the light outlet of collimator one, and adjust the leveling knob so that the vertical axis of the optical theodolite is perpendicular to the earth. Step 2) Aim the optical theodolite's azimuth mirror at collimator one, so that the target of collimator one coincides with the center of the crosshairs on the optical theodolite's dividing plate, and record the readings of the optical theodolite's azimuth angle α1 and elevation angle θ1 at this time. Step 3) Rotate the azimuth axis and elevation axis of the optical theodolite by 180° each, so that it is aimed at the collimator one with the inverted mirror, so that the target of the collimator one coincides with the center of the crosshairs on the optical theodolite's dividing plate, and record the readings of the azimuth angle α2 and elevation angle θ2 of the optical theodolite at this time. Step 4) Place a pentagonal prism at the two light outlets of the collimator, and make its center height the same horizontal line as the horizontal axis of the optical theodolite; Step 5) Rotate the optical theodolite and aim at the target of collimator 2 in the upright state using the pentagonal prism, so that the target of collimator 2 coincides with the center of the crosshairs on the optical theodolite's dividing plate, and record the azimuth reading β1 of the optical theodolite at this time; rotate the azimuth axis and elevation axis of the optical theodolite 180° each, so that it aims at collimator 2 in the inverted state, so that the target of collimator 2 coincides with the center of the crosshairs on the optical theodolite's dividing plate, and record the azimuth reading β2 of the optical theodolite at this time. Step 6) Replace the pentagonal prism at the light outlet of the collimator with an optical theodolite, and adjust the leveling knob of the optical theodolite so that the vertical axis of the optical theodolite is perpendicular to the earth. Step 7) Aim the crosshair center of the optical theodolite's dividing plate at the target center of collimator 2 in both the upright and inverted mirror states to obtain the corresponding pitch angle data δ1 and δ2. Step 8) Based on the above data α1, α2, β1, β2, θ1, θ2, δ1 and δ2, obtain the parallelism error between collimator one and collimator two.

2. The method for detecting optical axis parallelism according to claim 1, characterized in that, Step 8) includes: Step 8-1) Based on the azimuth angle readings α1 and α2 of the optical theodolite, calculate the average value of the upright and reverse mirrors α = (α1 + α2 ± 180°) / 2 as the azimuth angle position of the target in the collimator; Step 8-2) Based on the azimuth angle readings β1 and β2 of the optical theodolite, calculate the average value of the upright and reverse mirrors β = (β1 + β2 ± 180°) / 2 as the azimuth angle position of the two targets in the collimator; Step 8-3) Based on the elevation angle readings θ1 and θ2 of the optical theodolite, calculate the average value of the upright and reverse mirrors θ = (θ1-θ2+360°) / 2 as the elevation angle position of the target in the collimator; Step 8-4) Based on the elevation angle readings δ1 and δ2 of the optical theodolite, calculate the average value of the upright and reverse mirrors δ = (δ1 - δ2 + 360°) / 2 as the elevation angle position of the two targets in the collimator; Step 8-5) The parallelism deviation between collimator 1 and collimator 2 in the azimuth direction is calculated as: 90° - |α - β|; Step 8-6) The parallelism deviation between collimator 1 and collimator 2 in the pitch direction is calculated as: |θ-δ|.

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