CN116678586A - Portable large-view-field focusing schlieren field display technology - Google Patents
Portable large-view-field focusing schlieren field display technology Download PDFInfo
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- CN116678586A CN116678586A CN202310637684.5A CN202310637684A CN116678586A CN 116678586 A CN116678586 A CN 116678586A CN 202310637684 A CN202310637684 A CN 202310637684A CN 116678586 A CN116678586 A CN 116678586A
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- 238000005516 engineering process Methods 0.000 title claims abstract description 18
- 238000003384 imaging method Methods 0.000 claims abstract description 38
- 238000012360 testing method Methods 0.000 claims abstract description 26
- 230000003287 optical effect Effects 0.000 claims abstract description 20
- 238000012545 processing Methods 0.000 abstract description 7
- 238000011160 research Methods 0.000 abstract description 5
- 238000004519 manufacturing process Methods 0.000 abstract description 3
- 239000000463 material Substances 0.000 abstract description 3
- 230000000694 effects Effects 0.000 abstract description 2
- 239000011521 glass Substances 0.000 abstract description 2
- 238000000034 method Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 239000007789 gas Substances 0.000 description 4
- 238000000917 particle-image velocimetry Methods 0.000 description 3
- 230000035945 sensitivity Effects 0.000 description 3
- 238000001514 detection method Methods 0.000 description 2
- 230000036541 health Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 239000003973 paint Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 239000005337 ground glass Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 238000001499 laser induced fluorescence spectroscopy Methods 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 239000005304 optical glass Substances 0.000 description 1
- 230000003071 parasitic effect Effects 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 238000000547 structure data Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 239000002341 toxic gas Substances 0.000 description 1
Classifications
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B15/00—Special procedures for taking photographs; Apparatus therefor
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M9/00—Aerodynamic testing; Arrangements in or on wind tunnels
- G01M9/06—Measuring arrangements specially adapted for aerodynamic testing
- G01M9/065—Measuring arrangements specially adapted for aerodynamic testing dealing with flow
- G01M9/067—Measuring arrangements specially adapted for aerodynamic testing dealing with flow visualisation
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B15/00—Special procedures for taking photographs; Apparatus therefor
- G03B15/02—Illuminating scene
- G03B15/06—Special arrangements of screening, diffusing, or reflecting devices, e.g. in studio
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- General Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
The invention provides a portable large-view-field focusing schlieren field display technology. Flow field displays are widely used in research involving air flow phenomena and mainly use conventional schlieren imaging techniques of "Z" type structures. The conventional schlieren imaging technology mainly adopts expensive glass to manufacture optical elements, the field of view of the optical elements is difficult to exceed phi 800mm at present, and not only the price of the optical elements is multiplied with the increase of the field of view, but also the materials and processing after the increase of the field of view have great technical risks. The volume and the key point of the conventional schlieren are large, and the conventional schlieren can be only fixed in a certain flow field phenomenon test. The flow field information obtained by the conventional schlieren technology reflects the integral effect of the light beam along the whole flow field, can not obtain certain area information of the flow field, and is not suitable for high-precision flow field display.
Description
Technical Field
The invention utilizes the focusing schlieren imaging technology principle, and the beam splitting and the synthesis of the light beams are realized by a beam splitter, a reflector and the like, so that the light source end and the imaging end share a box body mode, and the reflection and convergence ends of the large-size light beams adopt folding type retro-reflection films, thereby realizing the portability of the whole system. The size of the test field of view depends only on the size of the retroreflective film and the distance of the retroreflective surface from the test area, and large field of view flow field display is easy to achieve because larger sized retroreflective films are easy to achieve.
Background
With the development of aerospace technology, weaponry and basic disciplines in China and the higher requirements of personal health and comfortable environment, the research related to the fields of aerodynamics and the like is continuously in progress. In these research efforts, it is necessary to obtain a flow field structure around the research target using a flow field display device. For example, the flow field structure in the process of taking off and landing of an aircraft is one of important links affecting the safety of the aircraft, and the flow field structure of a scaled model of a real aircraft and a wind tunnel environment still has a certain difference, but the flow field structure in the process of taking off and landing of the real aircraft is displayed by using flow field display equipment with an ultra-large field of view. The flow field structure data of large-size bridges and surrounding high buildings in a high wind environment are important basis for designing the buildings, and the model size is expected to be larger and better in experimental research. The flow field structure of the working environment of the air conditioner, the electric fan and other electrical appliances is an important factor influencing the health and comfort of individuals, and the flow field test also hopes to directly utilize the objects for testing. The real-time monitoring of toxic gases such as gas is an important guarantee for construction safety of ground complex environments such as coal mining, and the best means for carrying out large-size long-distance real-time monitoring on the gases is to adopt a flow field display method, and many gas explosion accidents are not caused by the fact that no gas detection equipment is installed, but the accidents occur when the local detection equipment does not obtain reliable information yet. Therefore, the field study related to aerodynamics requires the use of flow field display technology.
The current flow field display technology mainly adopts schlieren imaging equipment with a Z-shaped structure, and a main device affecting the size of a field of view is optical glass processing and manufacturing, so that the flow field display technology is high in price and has technical risks of materials and processing when the size is larger than phi 800 mm. On one hand, the bubbles, stress stripes and the like in the large-size optical element material cannot meet imaging requirements, and on the other hand, the precision of the machined surface type of the surface of the large-size optical element can not meet the requirements. In addition, because the large-size optical element in the conventional schlieren has larger occupied area and larger weight, portability is not easy to realize in use, and a schlieren imaging device is usually fixed at one test point, for example, a conventional schlieren system with a test flow field area diameter of 300mm has a unilateral length of at least 3.5m. The conventional schlieren is inconvenient to carry due to large size and weight, and is usually used as conventional measuring equipment after being purchased by a user and placed on a fixed occasion for use. Therefore, in many working conditions requiring the flow field display device to obtain important flow field data, the flow field display device is expensive and has harsh use environment, so that a user only uses flow field simulation data or performs related work by virtue of empirical data.
At present, an effort is made at home and abroad to develop a portable and low-cost large-field flow field display technology, such as a recently developed background schlieren imaging technology (Background oriented schlieren, BOS) which is easy to realize a large field of view and low in cost, but the flow field structure is obtained by adopting a PIV (particle image velocimetry) data processing mode in the later stage. The imaging resolution and the sensitivity are low, and different flow field structures can be obtained by continuously changing certain boundary conditions during data processing, because the non-uniqueness, the resolution and the sensitivity of the data processing result are low and the flow field cannot be displayed in real time, the flow field becomes difficult in engineering application. Other large-field flow field display technologies, such as PIV technology, PLIF (planar laser induced fluorescence), PSP (pressure sensitive paint), TSP (temperature sensitive paint) and the like, mainly obtain parameters such as flow field speed, component concentration, pressure or temperature aiming at the structure of a certain flow field, and the technologies also obtain flow field parameters after image processing in a later stage, so that the flow field structure cannot be directly obtained in real time. Some of the techniques, such as PLIF systems, have complex structures and are difficult to apply widely in engineering.
Disclosure of Invention
Aiming at the problems of portability and large view field in flow field display, the invention develops a box type structure flow field display technology based on focused schlieren, which not only can realize portability of a flow field display system, but also can easily realize the view field size of the flow field display system to be more than meter level.
The object of the invention is achieved in that: the portable large-view-field focused schlieren imaging system comprises a light beam modulation system, a light beam irradiation system, an imaging system, an image acquisition system, a retroreflection film and a box body. The light beam modulation system shapes the wide light source into uniform cone-shaped light beams with bright and dark stripe information, the cone-shaped light beams irradiate the surface of the test area and the surface of the retro-reflective film after passing through the light beam irradiation system, the retro-reflective film passes through the test area again after reflecting the light beams and enters the imaging system, the imaging objective lens in the imaging system images the test area and the source grating in the light beam modulation system, the knife edge grating is arranged at the imaging position of the source grating in the imaging system, and after the knife edge grating cuts light source images to different degrees, flow field structure display with different sensitivities of the test area can be realized. The image acquisition system records the flow field image, and if the size of the flow field image is larger than that of the CCD target surface, the flow field image is also required to be reduced by a field lens. The bright and dark stripes of the knife edge grating must be consistent with the dark and bright stripe spacing and size of the source grating image, and in order to meet the strict matching between the knife edge grating and the source grating image, the adjusting bracket of the knife edge grating must have the functions of front and back, up and down, left and right adjustment along the optical axis. In order to meet the density gradient display of different flow fields in different directions, the direction of the source grating stripes can rotate 360 degrees perpendicular to the optical axis, and the corresponding knife edge grating also has 360 degrees rotation perpendicular to the optical axis. Except for the retro-reflection film, other optical elements and supporting and adjusting structures of all the systems are arranged in the box body so as to meet the interference to external stray light and realize the integration of the whole system.
The invention relates to a portable large-view-field focusing schlieren imaging technology, which comprises the following steps:
the light beam modulation system is used for collimating the wide light source and forming a relatively uniform cone-shaped light beam, the light beam passes through the source grating to form a modulated light beam with bright and dark fringes, and the source grating is required to be placed on an adjusting frame capable of rotating along the optical axis by 360 degrees; the beam irradiation system is used for expanding the modulated beam after passing through the reflector, the imaging objective lens and the beam splitter and irradiating the modulated beam onto the test area and the counter-emission film; and the imaging system is used for enabling the light beam to pass through the testing area again after being reflected from the surface of the retro-reflective film, respectively imaging the testing area and the source grating by the focusing lens, and placing the knife-edge grating at the image position of the source grating so as to obtain a flow field image of the testing area. When the size of the flow field image is larger than the size of the CCD target surface, the flow field image needs to be reduced by a field lens; the knife edge grating needs to be provided with a precise three-dimensional adjusting bracket, has the functions of adjusting up and down, left and right and front and back along an optical axis, and simultaneously needs to rotate 360 degrees along the optical axis so as to realize complete matching with the bright and dark fringes of a source grating image; the image acquisition system is used for placing a CCD (charge coupled device) at an imaging position of the test area, and the test area image needs to be reduced through a field lens when the size of the test area image is larger than the size of a CCD target surface; usually, the cost of the field lens is high, and the simplest method is to replace the field lens by an imaging screen such as ground glass, and the imaging screen is imaged to the CCD again; a retroreflective film for forward emission of the irradiated light beam, the retroreflective film typically having a size 2 times the size of the test area; the box provides the supporting platform of series optical element to seal dustproof to optical element and adjusting device, shelter from the interference of external parasitic light to imaging simultaneously, realized the portable removal of whole imaging system through the box.
The invention has the following characteristics: 1. the light source and imaging elements in the focused schlieren system are located on the same side. 2. The primary reflection of the large-size light beam is achieved by the retro-reflective film. 3. A plurality of optical elements and support adjustment structures are located in the housing enabling portable movement of the system. 4. Increasing the size of the retro-emissive film facilitates flow field displays of larger fields of view.
Drawings
FIG. 1 is a schematic diagram of the overall structure of the present invention;
FIG. 2 is a schematic diagram of a beam modulation system according to the present invention;
FIG. 3 is a schematic diagram of the system of the present beam irradiation system;
FIG. 4 is a schematic diagram of an imaging system of the present invention;
fig. 5 is a schematic diagram of an image acquisition system according to the present invention.
In the figure: 1. a beam modulation system; 2. a cone beam; 3. a beam irradiation system; 4. a test area; 5. a retroreflective film; 6. an imaging system; 7. an image acquisition system; 8. a box body.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1 to 5, in the present embodiment: referring to fig. 1, main optical components of the whole portable large-field focusing schlieren imaging system are placed in a box (8), and a light beam modulation system (1), a light beam irradiation system (3), an imaging system (6) and an image acquisition system (7) are arranged according to fig. 1. According to the position where the box body (8) is placed when the light beam at the outlet of the box body (8) fills the test area (4), the distance between the retroreflective film (5) and the test area (4) is the same as the distance between the light beam outlet of the box body (8) and the test area (4), and the light beam passing through the test area can be completely irradiated on the retroreflective film (5);
referring to fig. 2, a wide light source (101) is selected according to test requirements, and can be an LED light source or other light sources, but when a laser light source is selected, a certain flexible light screen needs to be placed between the wide light source (101) and a collecting lens (102), a conical light beam (2) can be filled or not filled with a source grating (104), when the conical light beam (2) is filled with the source grating (104), a knife edge grating (602) can be placed in a positioning mode by using bright and dark stripes on a boundary, when the conical light beam (2) is not filled with the source grating (104), positioning points need to be arranged on the source grating (104), and the knife edge grating (602) is placed according to the positioning point image of the source grating (104);
referring to fig. 4, in order to receive a large-sized light beam and obtain a good imaging effect, the objective lens (605) generally adopts a lens with better aberration correction and a larger caliber, and the lens such as a copier or a projector can meet the use requirements. The manufacturing method of the knife edge grating (603) is preferably realized by adopting photographic reproduction, or a large-picture film is placed at the position of the imaging surface 2 (604), the image of the source grating (104) is directly sensitized, the bright and dark stripes on the film are just opposite to the image of the source grating (104), and the knife edge grating (602) manufactured by adopting the method can cut the image of the source grating (104) more accurately. The field lens (601) with low requirements on imaging quality can be a Fresnel lens, and the field lens (601) with high requirements on distortion and the like is manufactured by glass;
referring to fig. 5, the camera (702) is selected according to the duration of the flow field, for example, a common camera or a camera with a lower frame rate can be used for a low-speed flow field, and an ultra-high-speed camera or a light source (101) with a shorter pulse width is needed for an over-speed flow field.
Finally, it should be noted that: the foregoing description is only a preferred embodiment of the present invention, and the present invention is not limited thereto, but it is to be understood that modifications and equivalents of some of the technical features described in the foregoing embodiments may be made by those skilled in the art, although the present invention has been described in detail with reference to the foregoing embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. A portable large-view-field focusing schlieren imaging technology is characterized in that: the light source comprises a light source in a light source end, a condensing lens, a Fresnel lens, a source grating, a condensing lens in an imaging end, a knife edge grating, a field lens and the like, wherein reflected light is converged by adopting a large-size foldable retroreflective film.
2. A light source end as claimed in claim 1, characterized in that: the optical element and the supporting structure in the light source end are positioned on one side of the box body, and modulated light beams are output in a beam splitter mode.
3. The imaging terminal as claimed in claim 1, wherein: the imaging end is provided with a plurality of optical elements and a supporting structure, and the optical elements and the supporting structure are positioned on the other side of the box body and are used for receiving the converging light beams in a beam splitting lens mode.
4. The reflective light collection format of claim 1, wherein: the large-size light beam is converged by the retro-reflective film.
5. The imaging modality of claim 1 wherein the primary optics are located in a housing, and the large size retroreflective film is foldable to enable portable, mobile testing of the system and provide large field display and focusing features.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310637684.5A CN116678586A (en) | 2023-05-31 | 2023-05-31 | Portable large-view-field focusing schlieren field display technology |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310637684.5A CN116678586A (en) | 2023-05-31 | 2023-05-31 | Portable large-view-field focusing schlieren field display technology |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116678586A true CN116678586A (en) | 2023-09-01 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310637684.5A Pending CN116678586A (en) | 2023-05-31 | 2023-05-31 | Portable large-view-field focusing schlieren field display technology |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116678586A (en) |
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2023
- 2023-05-31 CN CN202310637684.5A patent/CN116678586A/en active Pending
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