The optical axis refers to the center line of the light beam (light column), or the axis of symmetry of the optical system.
The beam rotates around this axis without any change in optical characteristics.However, the birefringence does not occur when the light passes through the heterogeneous gem from a special direction.This special direction is the optical axis of the gem.Optical axis can be widely used in aerospace and aviation optical systems.
Through the center of the lensLine。According to its optical properties, crystals can be divided intoHomogeneous bodyandHeterogeneous bodyOccurs when light passes through a heterogeneous bodyBirefringence, forming two mutually perpendicular polarized lights.However, the birefringence does not occur when the light passes through the heterogeneous gem from a special direction.This special direction is the optical axis of the gem.Generally,Hexagonal system、Tetragonal system、Trigonal systemThere is only one optical axis and it is parallel to the vertical crystal axis C axis, so it is calledMonoaxial crystal。One axis crystal has two optical spindles, Ne and No, respectively. When Ne is greater than No, it is one axis positive crystal, otherwise it is one axis negative crystal.Orthorhombic systemMonoclinic system and triclinic system have two optical axes calledBiaxial crystal。The biaxial crystal has three optical spindles, which are respectively Ng, Nm and Np. And the permanent Ng>Nm>Np.A uniaxial crystal has numerous sections parallel to the optical axis.The optical axis plane of the biaxial crystal is the main axis plane of NgNp.There is only one optical axis.Represented by AP or OAP.
1. Adjust the eyepiece focusing cylinder to make it perpendicular to the main lens cylinder. Install the camera tube into the eyepiece to adjustCoke drumFrom the peephole, we can see that the line from the peephole to the double crosshairs (actually the axis of the eyepiece focusing cylinder) is extended again, and it will intersect the wall of the main lens cylinder at a certain point. Mark this point, measure its position with a ruler, and then refer to the position of the eyepiece focusing cylinder in the main lens cylinder, we can judge whether the eyepiece focusing cylinder is perpendicular to the main lens cylinder.
2. Adjust the secondary mirror so that it is located on the axis of the main mirror cylinder. Remove the camera tube, install the secondary mirror, and roughly adjust the direction of the secondary mirror so that the eye can see the image of the main mirror reflected by the secondary mirror from the eyepiece focusing cylinderSecondary mirrorThe image formed after two reflections with the crosshair.From these images, we can see the relative position of the secondary mirror and the crosshair. If the center of the secondary mirror coincides with the intersection point of the crosshair, it means that the secondary mirror is located on the axis of the main mirror cylinder, otherwise it needs to be adjusted accordingly.
3. Adjust the secondary mirror to be directly below the eyepiece focusing cylinder
Seen from the direction of eyepiece focusing cylinder, it is obvious that the secondary mirror has been located below the focusing cylinder, but the accuracy cannot be guaranteed after such viewing.At this time, install the camera tube. When the eye sees through the peephole, the outermost circle is the inner wall of the camera tube (the double cross hairs do not work now and can be ignored), and the middle is the secondary mirror.If the outer circle contour of the secondary mirror and the inner wall contour of the camera tube are concentric circles, it means that the requirements are met, otherwise the secondary mirror should be adjusted in the axis direction of the primary mirror.(If the peephole is too small and the light is too dim to see clearly, a piece of white paper can be placed on the wall of the main lens barrel opposite the peephole. If the peephole is too thin to see the outer contour of the secondary lens, the peephole can be pulled out or its length can be shortened.
4. Adjust the pointing of the secondary mirror so that the optical axis of the eyepiece points to the center of the primary mirror after being reflected by the secondary mirror
On the basis of the previous step, while observing from the peephole with eyes, adjust the direction of the secondary mirror until the contour of the image formed by the primary mirror in the secondary mirror and the contour of the external circle of the secondary mirror are concentric.
5. Adjust the direction of the main mirror to make its optical axis coincide with the optical axis of the eyepiece
useFlashlightThe double crosshairs illuminate the peephole, and the eyes can see the double crosshairsPrimary mirrorThe image formed by the center point of the double cross hairs and the image formed by the double reflection.Adjust the bolts behind the main mirror to make the three concentric.So far, the optical axis of the reflector has been adjusted.The following images can be seen from the peephole for reference.
Auxiliary tools
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The optical axis is clearly visible
The outer diameter of the sight tube with double crosshairs is the same as the diameter of the eyepiece interface. One end of the tube is covered. The center of the cover is dug with a 2mm diameter round hole. The other end of the tube is symmetrically pulled with a white cotton thread. The distance between the two lines is 3~4mm.The tube length is determined by the following method: put the peephole (the peephole is outside) into the eyepiece focusing cylinder, one end of the peephole is flush with the outer end of the eyepiece focusing cylinder, and one end of the double cross hairs is 20~30mm away from the secondary lens.
There is no limit to the materials used to make the camera tube (if you use a 31.7mm eyepiece interface, you can consider using the black packaging box of Kodak film as the camera tube). The key is to insert the eyepiece focusing cylinder firmly and not shake too much.The double cross hairs should be pulled straight, and the small cross hairs at the intersectionsquareThe connection with the peephole should be the axis of the eyepiece focusing cylinder.
1. Positioning point of main mirror center
Cut a piece of black paper with a diameter of 5mm, and stick it to theobjective lenseThe exact center of.(Since the central area of the primary mirror does not participate in imaging, this black spot will not have a negative impact)
3. Cross line at the opening of the main mirror cylinder
Draw a cross line with a thick line at the opening of the main mirror cylinder. It is required that the two lines are perpendicular to each other and the intersection point passes through the axis of the main mirror cylinder.(Pulling the crosshair on the opening of the primary mirror may affect the operation of the secondary mirror, so it is better to mark the positions of the four intersections of the crosshair and the mirror barrel. If you feel that the crosshair is in the way, you can remove it first, and then pull it back if necessary.
Inspection method
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Optical axis spacing transformation
1. Adjust the platform and the flat plate: firstly, place the flat plate with good flatness on the platform, adjust the platform to make the plane of the flat plate horizontal, and place a prism on the flat plate;2. Adjustment platform andCollimator: Adjust the platform so that the parallel light emitted by the parallel light tube on it is reflected by the prism and self collimated, so that the optical axis of the parallel light tube is parallel to the plane of the plate;
3. Adjustment platform and collimator: removePrism, adjust the collimator on the platform, the cross line on the focal plane of the collimator is imaged on the focal plane of the collimator, so that the cross line on the focal plane of the collimator coincides with the cross line of the collimator, so that the optical axis of the collimator is parallel to the plane of the flat plate. At this time, the optical axis of the collimator is parallel to the optical axis of the collimator and the plane of the flat plate;
4. Measure the parallelism between the optical axis of the optical system to be measured and the base plane of the flat plate: place the optical system to be measured on the flat plate of the platform, align the lens of the optical system to the collimator, so that the image formed by the crosshair on the focal plane of the collimator through the optical system to be measured is displayed on the display, while the electric crosshair image of the display is displayed in the center of the display;When the optical axis of the optical system under test is parallel to the base plane of the plate, the two crosshair images are completely coincident;When the optical axis of the optical system to be measured is not parallel to the base plane of the flat plate, the two crosshair images are not coincident. Adjust the platform to make the optical axis of the collimator parallel to the optical axis of the optical system to be measured, and the image formed by the crosshair on the focal plane of the collimator displayed on the display through the optical system to be measured coincides with the image of the electric crosshair;Then take down the measured optical system. At this time, the optical axis of the collimator is not parallel to the optical axis of the collimator. Observe that the cross line of the collimator is no longer coincident with the cross image of the collimator imaging on its focal plane. Use the reading drum of the collimator to measure the angle of deviation between the two optical axes of the collimator and the collimator,The parallelism inspection between the optical axis of the optical system and its mounting base plane is completed.
Optical axis classification
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Astigmatic axis
The astigmatic axis represents that the axial direction of the lens is determined according to the direction where your cornea has the largest curvature and the weakest refractive power.The line in a certain direction seen by the astigmatic eye is clear or fuzzy, depending on the axis and degree of astigmatism.In general, the direction of blurred lines on the astigmatic eye's watch is the direction of the negative lens axis worn by the eye.For example, a 1. ODC × 180 astigmatic eye, its astigmatic force is in the vertical meridian, and the horizontal meridian is in the front view.In other words, the astigmatic eye has stronger vertical meridian refraction than horizontal meridian refraction.I. When looking at the astigmatism meter with ODC × 180 degree astigmatism eyes, the vertical lines are clear and the horizontal lines are fuzzy, which is the reason why the astigmatism meter is used to determine the astigmatism axis.
Secondary optical axis
abbreviationCountershaft, viaMonosphereSpecularcurvatureCenter, but any straight line that does not pass through the center (vertex) of spherical light passing aperture.yesThin lensWhen the refractive index of the space where the incident ray is located is the same as that of the space where the outgoing ray is located, any straight line passing through the optical center but not passing through the curvature center of the refractive sphere is the secondary optical axis.
Main optical axis
The main shaft is also called 'main optical shaft'.The straight line passing through the center of two spherical surfaces of the lens is called.The optical axis of a single spherical mirror is a straight line passing through the center of the spherical surface and perpendicular to the mirror surface;The optical axis of the lens or coaxial optical device group is the line connecting the spherical center of each lens.It should be noted that any straight line passing through the optical center can be called the optical axis of the lens, and they are generally called the secondary optical axis.
LM Shaft
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LM Shaft Its types include ordinary linear optical axis, chrome plated linear optical axis, chrome plated linear flexible axis, stainless steel linear axis and chrome plated hollow axis.1. Ordinary linear optical axis (sf): because the ordinary linear optical axis andLinear bearingPoint to face contact requires high surface hardness of ordinary straight optical axis, so materials and heat treatment methods are very important.Material: suj2 (equivalent) national standard gcr15. Hardness: hrc602 Hardened layer depth: 0.8-3mmSurface roughness: ra0.10m-ra0.35m Straightness: shaft outer diameter tolerance below 70m/1000mm g62, chrome plated straight optical axis (sfc): chrome plated straight optical axis is a layer of hard chrome plated on the basis of ordinary straight optical axis, which can be applied to environments prone to rust or bad environments. This axis is widely used in industrial machinery and the moving parts of automatic sliding system devices.Material: suj2 (equivalent) national standard gcr15. Hardness: hrc602 Hardened layer depth: 0.8-3mm Surface roughness: ra0.10m-ra0.35m Straightness: 70m/1000mm below chrome coating thickness: 3m-5m Shaft outer diameter tolerance g63, chrome plated linear flexible shaft (rsfc)Self lubricating bearingThe cooperation of.Because of its moderate hardness, it has been applied in many fields.Material: 45 # or 40cr or 2cr13 Hardness: hb220-260 Hardened layer depth: 0.8-3mm Straightness: 0.15mm/below 1000mm Chromium plating layer thickness: 0.02-0.05mm4, stainless steel linear shaft: stainless steel linear shaft has high corrosion resistance, high strength and wear resistance to maintain its efficient operation performance.Therefore, it can be used in places prone to oxidation, such as water, chemicals, steam, seawater, etc.Material: sus404c,Sus304 Hardness: hrc602 Hardened layer depth: 0.8-3mm Surface roughness: ra0.10m-ra0.35m Straightness: 70m/1000mm below Chromium plating layer thickness: 3m-5m Shaft outer diameter tolerance g65, Chrome plated hollow shaft: Due to the characteristics of its hollow structure, the hollow shaft has greatly reduced its weight and simplified its structure, and its interior is suitable for penetrating measuring wires, compressed air,Add lubricating oil or use it on robot arm.
Application of optical axis
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Industrial applications
Solid shaft, generally applicable to industrial robots, is used as a professional measuring instrument, medical equipment, precision machine tool, aircraft shaft, and pneumatic ejector movement part.
The hollow shaft, with its advantages of reducing the weight of equipment and simplifying the structure, can be used to thread measuring wires, compressed air, or add lubricating oil and hydraulic oil inside.
Stainless steel shaft is generally used as a part of measurement in corrosive environment with chemicals, seawater and other substances.
Special processing shaft, which is completed after heat treatment and hard chromium plating, is used for various automatic equipment.
