CN114397477A - Flexible vitreous support element, Doppler differential interferometer and preparation method - Google Patents
Flexible vitreous support element, Doppler differential interferometer and preparation method Download PDFInfo
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- CN114397477A CN114397477A CN202111374149.2A CN202111374149A CN114397477A CN 114397477 A CN114397477 A CN 114397477A CN 202111374149 A CN202111374149 A CN 202111374149A CN 114397477 A CN114397477 A CN 114397477A
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- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
- G01P5/26—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring the direct influence of the streaming fluid on the properties of a detecting optical wave
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- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
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Abstract
The invention relates to a Doppler differential interference spectrum technology, in particular to a flexible vitreous support element, a Doppler differential interferometer and a preparation method. The technical problems that the optical surface shape of the Doppler difference interferometer is changed and the basic optical path difference of two arms is changed due to the temperature change of the Doppler difference interferometer are solved. The invention comprises a beam splitter prism, a short arm view field supporting element, a short arm view field prism, a short arm grating supporting element, a short arm grating, a long arm view field supporting element, a long arm view field prism, a long arm grating supporting element and a long arm grating; the short arm view field supporting element, the short arm grating supporting element, the long arm view field supporting element and the long arm grating supporting element are all flexible vitreous supporting elements; the flexible vitreous support element is a one-piece rectangular hollow frame structure, each side of which is composed of a plurality of bonding blocks and flexible connecting blocks connecting adjacent bonding blocks. The invention also provides a preparation method of the Doppler difference interferometer.
Description
Technical Field
The invention relates to a Doppler differential interference spectrum technology, in particular to a flexible vitreous support element, a Doppler differential interferometer and a preparation method.
Background
The Doppler differential interference spectrum technology is a novel atmospheric wind field detection technology, and compared with the Michelson interference technology and the Fabry-Perot interference technology, the Doppler differential interference spectrum technology has the advantages of no moving part in a construction system, compact structure, higher spectral resolution, high flux, high stability and the like, and is particularly suitable for a satellite-borne observation platform. The Doppler difference interferometer inverts the atmospheric movement speed by observing fine spectral lines in atmospheric components and further by Doppler frequency shift, the working principle of the Doppler difference interferometer is shown in figure 1, and two diffraction gratings which are fixed in position and form a certain angle with an optical axis replace plane reflectors in two arms of a Michelson interferometer. Two arms of the Doppler difference interferometer have an asymmetric quantity, the phase sensitivity of an interferometer image is improved by introducing a basic optical path difference, light rays enter an optical system after being collimated, the light rays are divided into two beams of coherent light with equal energy by a beam splitter prism, the two beams of coherent light return after being diffracted by a grating, and finally the two beams of coherent light are scaled in an equal proportion by an imaging lens to form an interference image which is received by a detector.
The integral Doppler difference interferometer adopts a full-gluing integration method, and all optical elements are adhered into a whole through the supporting elements, and the requirements of the interferometer on gluing precision, low heat conduction among the optical elements and good adhesion strength are met. After the integral Doppler difference interferometer is optically designed, because the difference of the expansion coefficients of the materials among the optical elements is large, and the two arms of the interferometer are asymmetric, the integral Doppler difference interferometer is very sensitive to temperature change, the temperature fluctuation can cause the thermal expansion and the thermal stress of the optical elements, the optical surface shape of the interferometer is easy to be changed and the basic optical path difference of the two arms is easy to be changed, the phase of an interference pattern is easy to drift, and finally the phase inversion precision is reduced.
Disclosure of Invention
The invention aims to solve the technical problems that the optical surface profile of the interferometer is deteriorated and the basic optical path difference of two arms is changed due to the temperature change of the existing integral Doppler difference interferometer, and provides a flexible vitreous support element, a Doppler difference interferometer and a preparation method thereof. The Doppler differential interferometer can achieve good thermal stability.
The technical scheme of the invention is as follows:
a flexible vitreous support member, characterized by: the integrated rectangular hollow frame structure comprises four support frames which are connected end to end, wherein the four support frames form an integrated rectangular hollow frame structure, and each support frame consists of a plurality of bonding blocks and flexible connecting blocks for connecting adjacent bonding blocks; the thickness of the bonding block is larger than that of the flexible connecting block connected with the bonding block, and the upper end face and the lower end face of the bonding block both exceed the end faces of the flexible connecting block; the upper end surface and the lower end surface of all the bonding blocks of the four support frames respectively form an upper bonding surface and a lower bonding surface; the two bonding surfaces are parallel surfaces or non-parallel surfaces.
Further, the flexible connecting blocks are all located on the inner sides of the bonding blocks.
Furthermore, the flexible connecting block is of a U-shaped structure or an arc-shaped structure, and two end parts of the U-shaped structure or the arc-shaped structure are respectively connected with two adjacent bonding blocks.
Furthermore, the bonding blocks of the four support frames are distributed at equal intervals, and the distance between every two adjacent bonding blocks is consistent with the width of the opening of the U-shaped structure or the arc-shaped structure.
A Doppler difference interferometer comprises a beam splitter prism, a short-arm diffraction grating and a long-arm diffraction grating;
the short-arm diffraction grating comprises a short-arm view field supporting element, a short-arm view field prism, a short-arm grating supporting element and a short-arm grating which are sequentially connected to the reflecting surface of the beam splitter prism;
the long-arm diffraction grating comprises a long-arm view field supporting element, a long-arm view field prism, a long-arm grating supporting element and a long-arm grating which are sequentially connected to the transmission surface of the beam splitter prism;
it is characterized in that:
the short arm view field supporting element, the short arm grating supporting element, the long arm view field supporting element and the long arm grating supporting element are all the flexible vitreous supporting elements; the two bonding surfaces of the short-arm view field supporting element and the long-arm view field supporting element are non-parallel surfaces and are set with the same included angle; and the two bonding surfaces of the short-arm grating support element and the long-arm grating support element are parallel surfaces.
Further, the included angle of the two bonding surfaces of the short-arm view field supporting element and the included angle of the two bonding surfaces of the long-arm view field supporting element are both 4 degrees 17 ' 42 ' +/-10 '.
The preparation method of the Doppler difference interferometer is characterized by comprising the following steps:
step 1) determining optical parameters;
determining the sizes and materials of the beam splitter prism, the short-arm view field prism, the short-arm grating, the long-arm view field prism and the long-arm grating through optical design; determining the angle, distance and light transmission aperture among all optical elements;
step 2) determining the material and size of each flexible vitreous support element;
step 2.1) selecting the materials and the thicknesses of the short-arm grating support element and the long-arm grating support element according to the optical parameters in the step 1);
step 2.2) selecting the central thickness and material of the short-arm view field supporting element and the long-arm view field supporting element, wherein the selection conditions meet the following optical expression:
wherein
ΔOPD＝2(ΔD1n1+ΔD2n2)
n1Is the Littrow wave number deltaLIn vacuum refractive index n1＝1；
n2Is the Littrow wave number deltaLThe refractive index of the field prism;
α1is a long-arm view field supporting element materialThe coefficient of thermal expansion of the material;
α′1is the coefficient of thermal expansion of the short arm field support member material;
α2is the thermal expansion coefficient of the field prism material;
D1is the center thickness of the long arm field of view support element;
ΔD1the thickness of the center of the short-arm view field supporting element is increased relative to the thickness of the center of the long-arm view field supporting element;
ΔD2the thickness of the center of the long-arm view field prism is increased relative to the thickness of the center of the short-arm view field prism;
t is the temperature of the optical element;
selecting the material of the long-arm visual field supporting element according to the optical expression, and determining alpha1Value, selecting the center thickness of the long-arm view field supporting member, determining D1A value;
selecting alpha 'according to an optical expression'1And Δ D1Determining a material and center thickness of the short arm field of view support element;
step 2.3) optimizing the section size of the flexible vitreous support element;
calculating the surface type PV value of each optical working surface after thermal deformation analysis by finite element analysis when the temperature changes by 1 ℃ so that the surface type PV value of each optical surface of the Doppler difference interferometer is smaller than
(λ is Littrow wavelength of the interferometer), the cross-sectional dimensions of the resulting flexible vitreous support element are as follows:
the cross-sectional dimensions of the integrated rectangular hollow frame structures of the four flexible vitreous support elements are consistent;
the thicknesses of the short-arm grating support element and the long-arm grating support element are consistent, and the two bonding surfaces are planes vertical to the optical axis;
two bonding surfaces of the short arm view field supporting element form an included angle a, wherein one surface is vertical to the reflection optical axis;
two bonding surfaces of the long-arm view field supporting element form an included angle b, wherein one surface is vertical to the transmission optical axis;
step 3), processing to obtain a flexible vitreous support element;
step 3.1) processing the outlines of four rectangular hollow frame supporting elements according to the cross-sectional dimension of the step 2.3), wherein the outlines correspond to a short-arm view field supporting element, a short-arm grating supporting element, a long-arm view field supporting element and a long-arm grating supporting element respectively;
step 3.2) cutting the outlines of the four rectangular hollow frame flexible vitreous support elements;
cutting and processing the flexible vitreous support element into an integrated rectangular hollow frame structure, so that each side consists of a plurality of bonding blocks and flexible connecting blocks for connecting adjacent bonding blocks;
step 3.3) milling two end faces of the flexible connecting block, which are on the same side with the bonding face, down;
step 4) bonding all the optical elements into a whole through a flexible vitreous support element;
connecting a short-arm view field supporting element, a short-arm view field prism, a short-arm grating supporting element and a short-arm grating on a reflecting surface of a beam splitter prism in sequence;
and sequentially connecting the long-arm view field supporting element, the long-arm view field prism, the long-arm grating supporting element and the long-arm grating to the transmission surface of the beam splitter prism.
Further, in the step 3.3), milling two end faces of the flexible connecting block on the same side with the bonding faces by 0.1mm to enable the two bonding faces to be higher than the two end faces of the flexible connecting block.
Further, in the step 1), the materials of the beam splitter prism, the short arm grating and the long arm grating are all JGS1, and the materials of the short arm field prism and the long arm field prism are all N-SF 57;
the thermal expansion coefficients of the JGS1 and the N-SF57 are respectively 0.5 multiplied by 10-6And 8.5X 10-6；
In the step 2.1), the short-arm grating support element and the long-arm grating support element are selected to have the same size and material, and the thickness D3All are 6mm, and the material is JGS 1;
in step 2.2), the material of the long-arm view field supporting element is selected to be JGS1, and the center thickness D1Is 5 mm;
selecting CaF as the material of the short-arm visual field supporting element2The center thickness was 13.48 mm.
Further, in step 2.3), the cross-sectional optimized dimensions for the flexible vitreous support element are as follows:
the cross section of the rectangular hollow frame is 60 mm multiplied by 50 mm;
the short-arm grating support element (4) and the long-arm grating support element (8) are consistent in thickness, the thicknesses are both 6 +/-0.01 mm, and the bonding surfaces are all planes perpendicular to the optical axis;
the included angle a of two bonding surfaces of the short-arm view field supporting element (2) is 4 degrees 17' 42 +/-10 ", wherein one surface is vertical to the reflection optical axis; the thick end of the short-arm view field prism supporting element is 7.25 +/-0.01 mm;
the included angle b of two bonding surfaces of the long-arm view field supporting element (6) is 4 degrees, 17' 42 +/-10 degrees, wherein one surface is vertical to the transmission optical axis; the thick end height of the long-arm view prism supporting element is 15.73 +/-0.01 mm.
The invention has the beneficial effects that:
1. the flexible vitreous support element of the present invention enables surface deformation between the optical elements to occur on the flexible vitreous support element, reducing deformation of the optical surfaces.
2. The Doppler differential interferometer adopts the flexible vitreous support element, and solves the technical problems that the difference of the thermal expansion coefficients of two optical element materials in the Doppler differential interferometer is large, and the optical surface shape of the interferometer is easy to change along with the temperature change and the basic optical path difference of two arms is easy to change.
3. The reasonable selection of the material and the thickness of the flexible vitreous support element can ensure that the basic optical path difference of the two arms is not changed when the interferometer is subjected to thermal expansion deformation, and provide a stable initial phase for the integral Doppler difference interferometer.
4. The flexible glass supporting element reduces the heat conduction between the optical elements, has good bonding strength and can meet the aerospace application requirements of the Doppler differential interferometer.
5. The flexible glass supporting element is integrally processed, the bonding surfaces have good flatness, the two end surfaces have good angle and thickness precision, and the requirements of the angle and distance precision between the bonded optical elements are met.
6. The Doppler differential interferometer adopts the flexible vitreous support element, so that the Doppler differential interferometer has high gluing precision and good thermal stability.
7. The preparation method has the advantages of simple process and high bonding precision, and the obtained Doppler differential interferometer has stable precision and high reliability and can be suitable for preparing Doppler differential interferometers with different detection wavelengths.
Drawings
FIG. 1 is a schematic diagram of a prior art Doppler differential interferometer;
FIG. 2 is a schematic structural diagram of an embodiment of the present invention;
FIG. 3 is a schematic structural view of the flexible vitreous support member of the embodiment of FIG. 2;
FIG. 4 is a light path trace diagram of the embodiment of FIG. 2;
FIG. 5 is a schematic structural view of the short arm field of view support element of the embodiment of FIG. 2;
FIG. 6 is a schematic structural view of the long-arm view support member of the embodiment of FIG. 2;
FIG. 7 is a schematic structural diagram of the flexible glass support element of the grating in the embodiment of FIG. 2.
Description of reference numerals:
1-beam splitter prism, 2-short arm view field supporting element, 3-short arm view field prism, 4-short arm grating supporting element, 5-short arm grating, 6-long arm view field supporting element, 7-long arm view field prism, 8-long arm grating supporting element and 9-long arm grating.
Detailed Description
The invention is further described with reference to the following figures and specific embodiments.
As shown in fig. 2, the doppler difference interferometer of the present invention is a monolithic doppler difference interferometer formed by bonding optical elements by a flexible vitreous support member. The Doppler difference interferometer comprises a beam splitter prism 1, a short-arm diffraction grating and a long-arm diffraction grating; the short-arm diffraction grating comprises a short-arm view field supporting element 2, a short-arm view field prism 3, a short-arm grating supporting element 4 and a short-arm grating 5 which are sequentially connected to the reflecting surface of the beam splitter prism 1; the long-arm diffraction grating comprises a long-arm view field supporting element 6, a long-arm view field prism 7, a long-arm grating supporting element 8 and a long-arm grating 9 which are sequentially connected to the transmission surface of the beam splitter prism 1. The short-arm view field supporting element 2, the short-arm grating supporting element 4, the long-arm view field supporting element 6 and the long-arm grating supporting element 8 are all flexible vitreous supporting elements; the two bonding surfaces of the short arm view field supporting element 2 and the long arm view field supporting element 6 are non-parallel surfaces and are set with the same included angle; the two bonding surfaces of the short-arm grating support element 4 and the long-arm grating support element 8 are parallel surfaces.
As shown in fig. 3, the flexible vitreous support element includes four support frames connected end to end, the four support frames form an integral rectangular hollow frame structure with a rectangular cross section, and each support frame is composed of a plurality of bonding blocks and flexible connecting blocks connecting adjacent bonding blocks; the thickness of the bonding block is larger than that of the flexible connecting block connected with the bonding block, and the upper end face and the lower end face of the bonding block both exceed the end faces of the flexible connecting block; the upper end surface and the lower end surface of all the bonding blocks of the four support frames respectively form two bonding surfaces; the two bonding surfaces are parallel surfaces or non-parallel surfaces. The outermost round of the integrated rectangular hollow frame structure is a bonding block, and the flexible connecting blocks are located on the inner side of the bonding block. The two bonding surfaces are used for bonding the optical element. The flexible connecting block is of a U-shaped structure or an arc-shaped structure, in the embodiment, the flexible connecting block is a U-shaped block, and two end parts of the U-shaped block are respectively connected with two adjacent bonding blocks; the bonding blocks of the four support frames are distributed at equal intervals, and the distance between every two adjacent bonding blocks is consistent with the width of the opening of the U-shaped block.
It is difficult to achieve coplanarity of the upper and lower end surfaces of the independent bonding blocks, and especially when included angles exist between the bonding surfaces at the two ends of the supporting element, the flatness of the bonding surfaces formed by the position change between the spacing elements is seriously influenced. The U-shaped block connects each bonding block into a whole, so that the positions between the bonding blocks can be kept unchanged, and the flatness of the bonding surface of the flexible glass supporting element can be ensured.
The upper end face and the lower end face of the bonding block are higher than the two end faces of the flexible connecting block, so that the U-shaped block is not bonded with the optical element, the upper end face and the lower end face of the bonding block respectively form independent end faces, glue overflow on the U-shaped block when glue is dispensed on the bonding faces at the two ends of the bonding block can be avoided, a certain space is formed between the bonding faces at the two ends of the flexible glass supporting element, the dust prevention function and the air outlet function can be realized, the bonded optical surface can be kept clean, and the bonding block can be used in a vacuum environment.
The flexible vitreous support element is obtained by cutting a rectangular hollow frame support element, firstly, an integrated rectangular hollow frame support element is processed according to the angle, the distance and the light transmission caliber among optical elements, then, after the support element is cut into the outline shown in figure 3, two end faces of a U-shaped block are milled to be lower by 0.1mm, and the flexible vitreous support element is obtained by processing. The upper end and the lower end of the bonding block of the flexible vitreous support element form a bonding surface of the flexible vitreous support element, the bonding surface has good flatness, and the front bonding surface and the rear bonding surface have good angle and position accuracy.
The relative position between each independent small block bonding surface of the flexible glass supporting element can change along with the thermal expansion of the bonded optical piece, the constraint of the bonded optical surface relative to the original rectangular hollow frame supporting element is reduced, the deformation is transferred to the U-shaped block, and the surface shape change caused by the expansion of the optical surface can be obviously reduced. The optical elements bonded at the two ends of the flexible glass supporting element have large thermal expansion difference, and the flexible glass supporting element has lower rigidity than the rectangular hollow frame supporting element, so that deformation is generated on the flexible glass supporting element, and the influence of the difference of the thermal expansion coefficients of the optical element materials on the Doppler difference interferometer can be reduced.
When the Doppler differential interferometer is prepared, the thickness and the material of the flexible vitreous support element are selected to meet the requirement that the basic optical path difference of the Doppler differential interferometer is not changed when the temperature is changed. The preparation method of the Doppler difference interferometer comprises the following steps:
step 1) determining optical parameters;
on-axis ray angle thetaLThe angle is incident on the grating, and the spectrum with a certain wave number is returned by the original optical path, namely the diffraction angle and the incident angle of the spectrum are equal to each other and are thetaLThe wave number delta of the spectrumLLittrow wave number, θ, of the systemLThe angle is the Littrow angle. Littrow wave number delta in Doppler differential interferometerLSpectrum of (a) in thetaLThe angle is incident to the grating and returns in the original path, the light path track is as shown in figure 4, the light on the axis passes through the light splitting surface and then is divided into two beams, the short arm light passes through D0、D1+ΔD1、D2And D3Reaches the grating and returns in the original path, and the long-arm light passes through D0、D1、D2+ΔD2And D3Reaches the grating and returns. D0The length of the main light beam passing through the splitting surface and traveling in the splitting prism is shown. D1Indicating the length that the chief ray exits from the beam splitting prism face to the long-arm field-of-view prism. D1+ΔD1The length of the main ray from the outgoing surface of the beam splitter prism to the incoming surface of the short-arm view field prism is shown, the dotted line between the beam splitter prism and the short-arm view field prism shows the position of the incoming surface of the long-arm view field prism relative to the outgoing surface of the beam splitter prism, and the length of the main ray from the outgoing surface of the beam splitter prism to the dotted line is D1Through a length Δ D1And then reaches the incidence plane of the short-arm field-of-view prism. D2Indicating the length of the chief ray that travels from the entrance face to the exit face of the short-arm field-of-view prism. D2+ΔD2The length of the main ray from the incident surface to the emergent surface of the long-arm view field prism is shown, the dotted line in the long-arm view field prism shows the position of the emergent surface of the short-arm view field prism relative to the incident surface, and the length of the main ray from the incident surface to the dotted line of the long-arm view field prism is D2Through a length Δ D2And then reaches the exit surface of the long-arm view field prism. D3The length of the main ray from the exit surface of the long and short arm field-of-view prism to the grating surface is shown, and the length of the main ray in the long arm is the same as that in the short arm.
Determining the sizes and materials of the beam splitter prism 1, the short-arm view field prism 3, the short-arm grating 5, the long-arm view field prism 7 and the long-arm grating 9 through optical design; and determining the angle, the distance and the light transmission aperture among the optical elements.
In the embodiment, the materials of the beam splitter prism 1, the short arm grating 5 and the long arm grating 9 are all JGS1, and the materials of the short arm view field prism 3 and the long arm view field prism 7 are all N-SF 57; the thermal expansion coefficients of JGS1 and N-SF57 were 0.5X 10-6And 8.5X 10-6。
Step 2) determining the material and size of each flexible vitreous support element;
step 2.1) selecting the materials and the thicknesses of the short-arm grating support element 4 and the long-arm grating support element 8 according to the optical parameters in the step 1);
in the embodiment, the sizes and the materials of the short-arm grating supporting element and the long-arm grating supporting element are determined to be consistent through optical design, and the thickness D3All 6mm, the material is JGS 1.
Step 2.2) selecting the central thickness and material of the short arm field of view support element 2 and the long arm field of view support element 6, the selection condition satisfying the following optical expression:
wherein
ΔOPD＝2(ΔD1n1+ΔD2n2)
n1Is the Littrow wave number deltaLIn vacuum refractive index n1＝1；
n2Is the Littrow wave number deltaLThe refractive index of the field prism;
α1is the coefficient of thermal expansion of the long arm field support member material;
α′1is the coefficient of thermal expansion of the short arm field support member material;
α2is the thermal expansion coefficient of the field prism material;
D1in the long-arm view-field supporting memberThe core thickness;
ΔD1the thickness of the center of the short-arm view field supporting element is increased relative to the thickness of the center of the long-arm view field supporting element;
ΔD2the thickness of the center of the long-arm view field prism is increased relative to the thickness of the center of the short-arm view field prism;
t is the temperature of the optical element;
selecting the material of the long-arm visual field supporting element 6 according to the optical expression, determining alpha1Value, selecting the center thickness of the long-arm visual field supporting member 6, determining D1A value;
selecting alpha 'according to an optical expression'1And Δ D1Values, determine the material and center thickness of the short arm field support element 2.
In this embodiment, the long-arm view supporting element is made of JGS1 with a center thickness D1Is 5 mm; the material of the short-arm view field supporting element is CaF2The center thickness was 13.48 mm.
The size and material of the field prism are determined during the optical design, so
Is a known item, the long-arm view supporting element is selected to be in accordance with the material of the beam splitter prism, i.e. alpha1Are known. Selecting a center thickness D of the long arm field of view support member1Selecting suitable alpha 'according to optical expression as 5 mm'1And Δ D1Finally determining the material of the short-arm view field supporting element as CaF2The center thickness was 13.48 mm.
Step 2.3) optimizing the section size of the flexible vitreous support element;
after the thickness and the material of the flexible glass supporting element are determined, the section size is optimized, so that the flexible glass supporting element not only reduces the surface shape change of the optical element and the heat conduction between the optical elements, but also can meet the requirement of bonding strength under certain mechanical conditions.
Calculating the surface type PV value of each optical working surface after thermal deformation analysis by finite element analysis when the temperature changes by 1 DEG CThe surface type PV value of each optical surface of the Doppler difference interferometer is less than
(lambda is Littrow wavelength of the interferometer), the number of the cutting blocks of the long side and the short side of the flexible glass supporting element obtained by optimization is increased to 7 multiplied by 6, the surface type requirement can be met, and the obtained bonding surface is reduced to 40% of that of the rectangular hollow frame. 7G calculated by finite element analysis2Under the random vibration load of/Hz, the stress of the bonding surface of the flexible vitreous support element is less than 0.5MPa and much less than the tensile strength and the shear strength of the bonding glue, and the accurate section dimension of the flexible vitreous support element is obtained after optimization. The cross-sectional dimensions in this example are as follows:
the cross-sectional dimensions of the one-piece rectangular hollow frame structure of the four flexible vitreous support elements are all 60 x 50 mm. The short-arm grating supporting element 4 and the long-arm grating supporting element 8 are consistent in thickness, the thicknesses of the short-arm grating supporting element and the long-arm grating supporting element are both 6 +/-0.01 mm, and the two bonding surfaces are both planes perpendicular to the optical axis. The two bonding surfaces of the short-arm view field supporting element 2 have an included angle a of 4 degrees 17 ' 42 ' +/-10 ', wherein one surface is vertical to the reflection optical axis, and the thick end height of the short-arm view field prism supporting element is 7.25 +/-0.01 mm. The two bonding surfaces of the long-arm view field supporting element 6 have an included angle b of 4 degrees 17' 42 +/-10 ", wherein one surface is vertical to the transmission optical axis, and the height of the thick end of the long-arm view field prism supporting element is 15.73 +/-0.01 mm.
Step 3), processing to obtain a flexible vitreous support element;
and 3.1) processing the outlines of four rectangular hollow frame supporting elements according to the cross section size obtained in the step 2.3), wherein the outlines correspond to the short-arm view field supporting element 2, the short-arm grating supporting element 4, the long-arm view field supporting element 6 and the long-arm grating supporting element 8 respectively.
Step 3.2) cutting the outlines of the four rectangular hollow frame flexible vitreous support elements;
the flexible vitreous support element is cut and processed into an integrated rectangular hollow frame structure, and each side of the integrated rectangular hollow frame structure is composed of a plurality of rectangular bonding blocks and flexible connecting blocks for connecting adjacent bonding blocks. The flexible connecting block is a U-shaped block, and the U-shaped blocks are all positioned on the inner side of the integrated rectangular hollow frame; the bonding blocks are all positioned on the outer side of the integrated rectangular hollow frame; the bonding block is connected with a lug of the U-shaped block; the bonding blocks at the edge of the integrated rectangular hollow frame are distributed at equal intervals, and the distance between every two adjacent bonding blocks is consistent with the width of the opening of the U-shaped block; the width of a cutting seam of the U-shaped block is 2mm, the width of a lug is 2mm, and the width of an opening is 2 mm; the width of the bonding block is 3mm, and the length is more than 6 mm.
Step 3.3) milling two end faces of the U-shaped block, which are on the same side with the connecting surface, down;
milling two end surfaces of the U-shaped block cut and processed in the step 3.2) and on the same side with the bonding surface by 0.1mm, so that the upper end surface and the lower end surface of the bonding block are higher than the two end surfaces of the U-shaped block and on the same side with the bonding surface.
Step 4) bonding all the optical elements into a whole through a flexible vitreous support element;
connecting a short-arm view field supporting element 2, a short-arm view field prism 3, a short-arm grating supporting element 4 and a short-arm grating 5 on the reflecting surface of the beam splitter prism 1 in sequence; the long-arm view field supporting element 6, the long-arm view field prism 7, the long-arm grating supporting element 8, and the long-arm grating 9 are connected in this order on the transmission surface of the beam splitter prism 1.
The short arm field of view support element 2 is designed as shown in fig. 5, the long arm field of view support element 6 is designed as shown in fig. 6, and the long arm and short arm grating flexible vitreous support element is designed as shown in fig. 7. The distance and angle between the optical elements are ensured by the thickness of the flexible vitreous support element and the included angle of the front and back faces.
Claims (10)
1. A flexible vitreous support member, characterized by: the integrated rectangular hollow frame structure comprises four support frames which are connected end to end, wherein the four support frames form an integrated rectangular hollow frame structure, and each support frame consists of a plurality of bonding blocks and flexible connecting blocks for connecting adjacent bonding blocks; the thickness of the bonding block is larger than that of the flexible connecting block connected with the bonding block, and the upper end face and the lower end face of the bonding block both exceed the end faces of the flexible connecting block; the upper end surface and the lower end surface of all the bonding blocks of the four support frames respectively form an upper bonding surface and a lower bonding surface; the two bonding surfaces are parallel surfaces or non-parallel surfaces.
2. A flexible vitreous support member according to claim 1, wherein: the flexible connecting blocks are all positioned on the inner sides of the bonding blocks.
3. A flexible vitreous support element according to claim 1 or 2, characterized in that: the flexible connecting block is of a U-shaped structure or an arc-shaped structure, and two end parts of the U-shaped structure or the arc-shaped structure are respectively connected with two adjacent bonding blocks.
4. A flexible vitreous support element according to claim 3, wherein:
the bonding blocks of the four support frames are distributed at equal intervals, and the distance between every two adjacent bonding blocks is consistent with the width of the opening of the U-shaped structure or the arc-shaped structure.
5. A Doppler difference interferometer comprises a beam splitter prism (1), a short-arm diffraction grating and a long-arm diffraction grating;
the short-arm diffraction grating comprises a short-arm view field supporting element (2), a short-arm view field prism (3), a short-arm grating supporting element (4) and a short-arm grating (5) which are sequentially connected to the reflecting surface of the beam splitter prism (1);
the long-arm diffraction grating comprises a long-arm view field supporting element (6), a long-arm view field prism (7), a long-arm grating supporting element (8) and a long-arm grating (9) which are sequentially connected to the transmission surface of the beam splitter prism (1);
the method is characterized in that:
the short-arm view field supporting element (2), the short-arm grating supporting element (4), the long-arm view field supporting element (6) and the long-arm grating supporting element (8) adopt the flexible vitreous supporting element of any one of claims 1 to 4; the two bonding surfaces of the short-arm view field supporting element (2) and the long-arm view field supporting element (6) are non-parallel surfaces and are set with the same included angle; and the two bonding surfaces of the short-arm grating support element (4) and the long-arm grating support element (8) are parallel surfaces.
6. A Doppler differential interferometer according to claim 5, characterised in that:
the included angle of the two bonding surfaces of the short-arm view field supporting element (2) and the included angle of the two bonding surfaces of the long-arm view field supporting element (6) are both 4 degrees, 17' 42 +/-10 ".
7. A method for preparing a Doppler differential interferometer according to claim 5 or 6, comprising the steps of:
step 1) determining optical parameters;
determining the sizes and materials of the beam splitter prism (1), the short-arm view field prism (3), the short-arm grating (5), the long-arm view field prism (7) and the long-arm grating (9) through optical design; determining the angle, distance and light transmission aperture among all optical elements;
step 2) determining the material and size of each flexible vitreous support element;
step 2.1) selecting the materials and the thicknesses of the short-arm grating support element (4) and the long-arm grating support element (8) according to the optical parameters in the step 1);
step 2.2) selecting the central thickness and material of the short-arm view field supporting element (2) and the long-arm view field supporting element (6), wherein the selection condition meets the following optical expression:
wherein
ΔOPD＝2(ΔD1n1+ΔD2n2)
n1Is the Littrow wave number deltaLIn vacuum refractive index n1＝1；
n2Is the Littrow wave number deltaLThe refractive index of the field prism;
α1is the coefficient of thermal expansion of the long arm field support member material;
α′1is the coefficient of thermal expansion of the short arm field support member material;
α2is the thermal expansion coefficient of the field prism material;
D1is the center thickness of the long arm field of view support element;
ΔD1the thickness of the center of the short-arm view field supporting element is increased relative to the thickness of the center of the long-arm view field supporting element;
ΔD2the thickness of the center of the long-arm view field prism is increased relative to the thickness of the center of the short-arm view field prism;
t is the temperature of the optical element;
selecting the material of the long-arm visual field supporting element (6) according to the optical expression, determining alpha1Value, selecting the center thickness of the long-arm view supporting member (6), determining D1A value;
selecting alpha 'according to an optical expression'1And Δ D1-values determining the material and the central thickness of the short arm field support element (2);
step 2.3) optimizing the section size of the flexible vitreous support element;
calculating the surface type PV value of each optical working surface after thermal deformation analysis by finite element analysis when the temperature changes by 1 ℃ so that the surface type PV value of each optical surface of the Doppler difference interferometer is smaller than
(λ is Littrow wavelength of the interferometer), the cross-sectional dimensions of the resulting flexible vitreous support element are as follows:
the cross-sectional dimensions of the integrated rectangular hollow frame structures of the four flexible vitreous support elements are consistent;
the thicknesses of the short-arm grating support element (4) and the long-arm grating support element (8) are consistent, and the two bonding surfaces are planes vertical to the optical axis;
two bonding surfaces of the short arm view field supporting element (2) form an included angle a, wherein one surface is vertical to the reflection optical axis;
two bonding surfaces of the long-arm view field supporting element (6) form an included angle b, and one surface is vertical to the transmission optical axis;
step 3), processing to obtain a flexible vitreous support element;
step 3.1) processing the outlines of four rectangular hollow frame supporting elements according to the cross-sectional dimension of the step 2.3), wherein the outlines correspond to the short-arm view field supporting element (2), the short-arm grating supporting element (4), the long-arm view field supporting element (6) and the long-arm grating supporting element (8) respectively;
step 3.2) cutting the outlines of the four rectangular hollow frame flexible vitreous support elements;
cutting and processing the flexible vitreous support element into an integrated rectangular hollow frame structure, so that each side consists of a plurality of bonding blocks and flexible connecting blocks for connecting adjacent bonding blocks;
step 3.3) milling two end faces of the flexible connecting block, which are on the same side with the bonding face, down;
step 4) bonding all the optical elements into a whole through a flexible vitreous support element;
connecting a short-arm view field supporting element (2), a short-arm view field prism (3), a short-arm grating supporting element (4) and a short-arm grating (5) on a reflecting surface of a beam splitter prism (1) in sequence;
the long-arm view field supporting element (6), the long-arm view field prism (7), the long-arm grating supporting element (8) and the long-arm grating (9) are sequentially connected to the transmission surface of the beam splitter prism (1).
8. The method for manufacturing a doppler difference interferometer according to claim 7, wherein: and 3.3), milling two end faces of the flexible connecting block on the same side with the bonding faces by 0.1mm, so that the two bonding faces are higher than the two end faces of the flexible connecting block.
9. The method for manufacturing a doppler difference interferometer according to claim 7, wherein: in the step 1), the materials of the beam splitter prism, the short arm grating and the long arm grating are all JGS1, and the materials of the short arm view field prism and the long arm view field prism are all N-SF 57;
the thermal expansion coefficients of the JGS1 and the N-SF57 are respectively 0.5 multiplied by 10-6And 8.5X 10-6；
In step 2.1), the short-arm grating support is selectedThe support element and the long-arm grating support element have the same size and material, and the thickness D3All are 6mm, and the material is JGS 1;
in step 2.2), the material of the long-arm view field supporting element is selected to be JGS1, and the center thickness D1Is 5 mm;
selecting CaF as the material of the short-arm visual field supporting element2The center thickness was 13.48 mm.
10. The method for manufacturing a doppler difference interferometer according to claim 7, wherein:
in step 2.3), the cross-sectional optimized dimensions for the flexible vitreous support element are as follows:
the cross section of the rectangular hollow frame is 60 mm multiplied by 50 mm;
the short-arm grating support element (4) and the long-arm grating support element (8) are consistent in thickness, the thicknesses are both 6 +/-0.01 mm, and the bonding surfaces are all planes perpendicular to the optical axis;
the included angle a of two bonding surfaces of the short-arm view field supporting element (2) is 4 degrees 17' 42 +/-10 ", wherein one surface is vertical to the reflection optical axis; the thick end of the short-arm view field prism supporting element is 7.25 +/-0.01 mm;
the included angle b of two bonding surfaces of the long-arm view field supporting element (6) is 4 degrees, 17' 42 +/-10 degrees, wherein one surface is vertical to the transmission optical axis; the thick end height of the long-arm view prism supporting element is 15.73 +/-0.01 mm.
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