CN112711029A - Area array sweep frequency measuring device and method - Google Patents
Area array sweep frequency measuring device and method Download PDFInfo
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- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
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- G01S17/06—Systems determining position data of a target
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- G—PHYSICS
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- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
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Abstract
The invention provides an area array frequency sweep measuring device and method, belonging to the technical field of laser ranging, wherein the device comprises a tunable laser, a first collimator, a first beam expander, a first beam splitter, a lens, a reflecting element, a camera and an acquisition control unit; the tunable laser is used for controlling the camera to collect interference images and provide original light beams by sending a trigger signal; the first beam splitter is used for splitting the collimated and expanded light beam into a first light beam and a second light beam, and the first light beam irradiates the object to be measured and then is reflected; the reflecting element is used for reflecting the second light beam to form reference light; the camera is used for collecting an interference image formed by interference of the first reflected light and the reference light. The invention replaces the traditional point detection acquisition mode to obtain the surface morphology, avoids the mechanical scanning error introduced during point detection, and improves the measurement accuracy under the common view field.
Description
Technical Field
The invention belongs to the technical field of laser ranging, and particularly relates to an area array frequency sweep measuring device and method.
Background
In modern industrial production, the precision degree of part processing becomes more and more the key of high-performance equipment, and it is very important to accurately and stably produce parts with required specific sizes and shapes. Therefore, accurate detection of the produced parts is an important link for ensuring high-quality production. In the prior art, the appearance of a part is required to be obtained through point-by-point scanning, and the measurement speed is limited by the scanning speed, so that the high measurement speed is difficult to obtain at the same time of high sensitivity. This is determined by the nature of the spot scan. Therefore, there is a need to develop a method for measuring the thickness and distance of an object in a large scale, with high accuracy and fast speed without scanning the sample.
The sweep frequency interference ranging is used as a new generation of non-contact precise ranging method and has multiple advantages, such as high sensitivity and high imaging speed. However, the conventional balanced detector and the high-speed data acquisition card are generally adopted to acquire interference data, and the point detection acquisition mode has certain limitation. In addition, in the conventional laser interference ranging principle, two main problems limit the practical application. Firstly, there is a fixed interference peak on the transform spectrum of the signal, when the signal peak and the interference peak are aliased, the measurement is difficult to realize, i.e. it is "immeasurable" corresponding to a certain distance range, and this immeasurable region is also called dead zone. Another problem is that there is a non-ambiguous distance to measure the distance due to the fourier transform limitations. As the measured distance becomes longer, the measurement result will oscillate repeatedly within the range of the non-fuzzy distance, so for a measurement result in a rise, the experiment cannot determine the axial moving direction of the measured point, which is the direction ambiguity caused by the non-fuzzy distance. The high-precision machining feedback can be realized only by expanding the measurement range and improving the measurement precision.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide an area array frequency sweep measuring device and method, which utilize a camera to realize high-speed measurement of an area array. The method aims to solve the problem that the conventional sweep frequency interference ranging is inaccurate in ranging under a general view field due to the fact that errors caused by mechanical scanning exist in a point detection acquisition mode.
In order to achieve the above object, in one aspect, the present invention provides an area array frequency sweep measuring device, which includes a tunable laser, a first collimator, a first beam expander, a first beam splitter, a lens, a reflecting element, a camera, and an acquisition control unit;
a first beam splitter, a lens and a camera are sequentially arranged in the direction in which the original light beam is reflected by the first beam splitter; a tunable laser, a first collimator, a first beam expander, a first beam splitter and a reflecting element are sequentially arranged in the transmission direction of an original light beam; the output end of the tunable laser is connected with the input end of the camera;
the tunable laser is used for controlling the camera to collect interference images and provide original light beams by sending a trigger signal; the first collimator and the first beam expander are respectively used for collimating and expanding the original light beam, the first beam splitter is used for splitting the collimated and expanded light beam into a first light beam and a second light beam, and the first light beam irradiates an object to be measured and then is reflected to form first reflected light; the reflecting element is used for reflecting the second light beam to form reference light; the camera is used for acquiring an interference image formed by the interference of the first reflected light and the reference light; the acquisition control unit is used for analyzing the surface appearance of the measured object according to the interference image; the lens is used for imaging the interference image on the camera.
Preferably, the lens is a telecentric lens.
Preferably, the reflective element is a beam splitting plate or an optical window;
preferably, the reflecting element comprises a second beam splitter, a first filter, a second filter, a first reference mirror and a second reference mirror; the first reference reflector and the first optical filter form a first reference arm, and the placing direction of the first reference arm is the direction of the original light beam reflected by the first beam splitter; the second optical filter and the second reference reflector form a second reference arm, and the placing direction of the second reference arm is the transmission direction of the original light beam; the first optical filter is positioned between the first reference reflector and the second beam splitter; the second optical filter is positioned between the second reference reflector and the second beam splitter; a second beam splitter having a fixed and non-uniform splitting ratio for splitting the second beam into the first reference beam and the second reference beam; the first reference reflector and the second reference reflector are respectively used for reflecting the first reference beam and the second reference beam to form second reflected light and third reflected light; the first reflected light, the second reflected light and the third reflected light interfere with each other to form an interference image.
Preferably, the reflective element is a tilted reflective element.
Based on the area array frequency sweep measuring device, the invention provides a corresponding area array frequency sweep measuring method, which comprises the following steps:
after the original light beam is collimated and expanded in sequence, the original light beam is divided into a first light beam and a second light beam;
the first light beam irradiates an object to be measured and then is reflected to form first reflected light; and the second light beam forms reference light after reflecting;
acquiring an interference image formed by interference of the first reflected light and the reference light by using a camera;
and analyzing the surface appearance of the measured object according to the interference image.
Preferably, the reference light is acquired by:
splitting the second beam into a first reference beam and a second reference beam;
filtering the first reference beam and the second reference beam after the first reference beam and the second reference beam are respectively reflected to obtain second reflected light and third reflected light;
wherein the reference light includes second reflected light and third reflected light.
In another aspect, the present invention provides an area array frequency sweep measuring device, including: the system comprises a tunable laser, a first collimator, a first beam expander, a first beam splitter, a lens, a camera, an acquisition control unit, a first optical fiber beam splitter and a transmission element;
the first beam splitter, the lens and the camera are sequentially arranged in the direction in which the first light beam is reflected by the first beam splitter; a first collimator, a first beam expander, a first beam splitter and a transmission element are sequentially arranged in the transmission direction of the first light beam; the output end of the tunable laser is connected with the input end of the first optical fiber beam splitter; the first output end of the first optical fiber beam splitter is connected with the first collimator, and the second output end of the first optical fiber beam splitter is connected with the transmission element;
the tunable laser is used for controlling the camera to collect interference images and provide original light beams by sending a trigger signal; the first optical fiber beam splitter is used for splitting an original light beam into a first light beam and a second light beam; the first collimator and the first beam expander are respectively used for collimating and expanding the first light beam; the first beam splitter is used for irradiating the collimated and expanded first light beam to a measured object to obtain reflected light; the transmission element is used for transmitting the second light beam to the first beam splitter to form reference light; the camera is used for collecting an interference image formed by interference of the reflected light and the reference light, and the collection control unit is used for analyzing the surface appearance of the measured object according to the interference image; the lens is used for imaging the interference image on the camera.
Preferably, the transmissive element is a slanted transmissive element.
Preferably, the lens is a telecentric lens.
Preferably, the transmission element comprises a fiber attenuator, a second collimator and a second beam expander connected in sequence;
the output end of the second beam expander is connected with the first beam expander; the second collimator and the second beam expander respectively collimate and expand the second light beam.
Preferably, the transmissive element comprises a second fiber beam splitter, a fourth collimator, a third beam expander, a third collimator, a fourth beam expander and a third beam splitter;
the output end of the second optical fiber beam splitter is connected with a third collimator and a fourth collimator; the fourth collimator and the third beam expander form a first reference arm, the placing direction of the first reference arm is the direction of the first light beam reflected by the first beam splitter, and the third reference arm is connected to the third beam splitter through the third beam expander; the third collimator and the fourth beam expander form a second reference arm, the placing direction of the second reference arm is the transmission direction of the first light beam, and the fourth beam expander is connected to the third beam splitter; the third beam splitter is connected to the transmission direction of the first beam splitter; the second optical fiber beam splitter is used for splitting the second light beam into first reference light and second reference light; after the first reference light and the second reference light are collimated and expanded, respectively forming first transmission light and second transmission light; the first transmission light, the second transmission light and the reflected light interfere with each other to form an interference image.
Based on the area array frequency sweep measuring device, the invention provides a corresponding area array frequency sweep measuring method, which comprises the following steps:
splitting the original light beam into a first light beam and a second light beam;
after the first light beam is collimated and expanded in sequence, the first light beam irradiates an object to be measured and then is reflected to form reflected light; the second light beam passes through the first beam splitter to form reference light;
collecting an interference image formed by interference of reflected light and reference light by using a camera;
and analyzing the surface appearance of the measured object according to the interference image.
Preferably, the reference light is acquired by: and after the second light beam is collimated and expanded in sequence, the second light beam is transmitted to the first beam splitter to form reference light.
Preferably, the reference light is acquired by:
splitting the second light beam into first reference light and second reference light;
after the first reference light and the second reference light are collimated and expanded, respectively forming first transmission light and second transmission light;
the reference light includes first transmitted light and second transmitted light.
Generally, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:
the area array frequency sweep measuring device provided by the invention collects interference images by matching the lens with the camera, wherein the interference images are formed by interference of reflected light and reference light, the reflected light and the reference light are obtained by decomposing the same light beam, and the collection control unit analyzes the surface morphology of a measured object by analyzing the interference images, so that the traditional point detection collection mode is replaced to obtain the surface morphology, the mechanical scanning error introduced during point detection is avoided, and the measurement accuracy under a common view field is improved.
The design of the double reference arms adopted by the invention effectively solves the problems of non-fuzzy distance and dead zone in the traditional laser interference distance measurement, and can realize accurate distance measurement and thickness measurement.
The invention adopts the optical fiber attenuator to adjust the light intensity of the reference arm and is used for overcoming the problem that the refractive index of different measured objects is too large and the attenuator needs to be replaced so as to damage the light path.
When the reflection (transmission) element provided by the invention is an inclined reflection (transmission) element, the dead zone and the mirror image signal peak can be effectively inhibited, so that the measurement range of the area array frequency sweep can be enlarged.
Drawings
Fig. 1 is a schematic view of an area array frequency sweep measurement apparatus provided in embodiment 1 of the present invention;
fig. 2 is a schematic view of an area array frequency sweep measurement apparatus provided in embodiment 2 of the present invention;
fig. 3 is a schematic view of an area array frequency sweep measuring apparatus provided in embodiment 3 of the present invention;
FIG. 4 is a transform domain signal characteristic obtained by the measuring device when the distance between the measured point and the reference point provided by the invention is positive odd number times;
FIG. 5 shows the transform domain signal characteristics obtained by the measuring device when the distance between the measured point and the reference point provided by the present invention is a positive even number times;
the same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein,
1. a tunable laser; 3. a first collimator; 4. a first beam expander; 5. a first beam splitter; 6. an object to be measured; 7. a lens; 8. a camera; 9. a computer; 11. a reflective element; 16. a second beam splitter; 17. a first optical filter; 19. a second optical filter; 18. a first reference mirror; 10. a second reference mirror; 2. a first fiber optic splitter; 22. a second beam expander; 21. a second collimator; 20. an optical fiber attenuator; 30. a second fiber splitter; 32. a fourth collimator; 33. a fourth beam expander; 34. a third beam splitter; 35. a third collimator; 36. a third beam expander.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
As shown in fig. 1, an area array frequency sweep measuring device is provided, which includes a tunable laser 1, a first collimator 3, a first beam expander 4, a first beam splitter 5, a lens 7, a reflecting element 11, a camera 8 and a computer 9;
the first beam splitter 5, the lens 7, the camera 8 and the computer 9 are sequentially arranged in the radial direction from bottom to top; the tunable laser 1, the first collimator 3, the first beam expander 4, the first beam splitter 5 and the reflecting element 11 are sequentially arranged from left to right in the transverse direction; the output end of the tunable laser 1 is connected with the input end of the camera 8;
the process of the wavelength output by the tunable laser 1 changing along with time is called optical frequency scanning, which is called frequency sweeping for short; the tunable laser 1 can send out trigger signals with equal wave number intervals, namely, each time output light of the tunable laser changes the same wave number, one trigger signal is sent out and used for controlling the camera 8 to start collecting; the computer 9 is provided with a signal collecting device such as a camera; the interference image formed between the reflected light of the object to be measured 6 and the reflected light of the reflecting element 11 is recorded by the camera 8; the computer 9 collects the interference image transmitted by the camera 8 and is used for analyzing the surface appearance of the measured object; the lens 7 is used to image the interference image on the camera 8.
Preferably, the lens 7 is a telecentric lens.
Preferably, the reflecting element 11 may be an optical element having a single reflecting surface, the reflecting surface is a reference surface of the object to be measured 6, the reflected light from the object to be measured 6 is first reflected light, the reflected light from the reflecting element 11 is reference light, and an interference image generated by the first reflected light and the reference light is recorded by the camera 8;
preferably, the reflecting element 11 may also be an optical element having two reflecting surfaces, and the optical path structure in this case may be regarded as a dual-reference-arm system. At this time, the reflected light of the object to be measured 6 is a first reflected light, the reflected light of the first reflecting surface of the reflecting element 11 is a second reflected light, the reflected light of the second reflecting surface of the reflecting element 11 is a third reflected light, the first reflected light, the second reflected light and the third reflected light interfere with each other, and the generated interference image is recorded by the camera;
further, the reflecting element 11 having two reflecting surfaces may be a beam splitter plate or an optical window, etc., an optical single element having two nearly parallel reflecting surfaces, or may be composed of a second beam splitter 16, a first optical filter 17, a second optical filter 19, a first reference mirror 18 and a second reference mirror 10, where the first reference mirror 18 and the first optical filter 17 constitute a first reference arm; the second filter 19 and the second reference mirror 10 constitute a second reference arm; the second beam splitter 16 has a fixed and non-uniform splitting ratio, e.g., a ratio of 60:40 for the first reference arm to the second reference arm, and it can be determined whether a certain interference peak originates from the first reference arm or the second reference arm by transforming the intensity of the signal.
The method comprises the following specific steps:
the first reference arm and the second reference arm have a fixed optical path difference phi between them1-φ2Wherein phi is1Is the optical path of the first reference arm, phi2For the optical path of the second reference arm, φ is assumed in this embodiment1>φ2Analysis was performed for phi1<φ2The condition of (3) is analyzed correspondingly.
In the signal transform domain as shown in fig. 4, given phi ═ phi1-φ2Interference peak P corresponding to the first reference armpInterference peak P corresponding to the second reference armsOn the left side of (A), n is determined to be an odd number, whereas, on the other hand, as shown in FIG. 5, when P is presentpAt PsOn the right side, n can be judged to be an even number.
Specifically, given a fixed optical path difference φ between the first reference arm and the second reference arm, the distance l of the object under test 6 mirrored with respect to the first reference arm is known to be at the nth non-modeThe paste distance interval satisfies the formula l is in the form of [ (n-1) lNAR,nlNAR] n∈Z+Where n is known, l is calculated according to the following formula:
wherein the content of the first and second substances,
wherein c is the speed of light,/NARIs a non-fuzzy distance, npIs the refractive index, τ, of the light-transmitting medium1And τ2Respectively representing the coordinates of the interference peak I and the interference peak II on a transform domain; when the system is a single reference arm setup, there is only one interference peak, and when it is not within the dead zone, the exact distance value is obtained. A typical dead zone range is one percent of the size of a non-ambiguity interval; z+Is a positive integer; z is an integer.
Preferably, the reflective element 11 is a tilted reflective element, i.e., tilted by an angle θ with respect to the optical axis, and the dead zone can be suppressed and the range can be extended. For example, the reflective element 11 is angled at 2 ° to the x-axis; the principle of the specific oblique reflecting element for suppressing the dead zone is as follows:
assuming that (x, y) is the surface coordinates of the object to be measured, when the reflecting member 11 is not tilted, the optical path difference between the signal light and the reference light is l (x, y), and the spectrum acquired by the camera 8 is
To S1In that
After the fourier transform is performed on the domain, a pair of signal peaks which are symmetrical along a zero point and are mirror images of each other and a dead zone with a certain width near the zero point appear in the obtained first transform spectrum, the abscissa of the signal peak is ± l (x, y), and the dead zone is the fourier transform of the spectrum I (λ) of the tunable laser 1.
When the reflecting element 11 is at the point edge of (x ═ 0, y ═ 0)After the x-axis rotates by an angle theta, the optical path difference between the signal light and the reference light is l (x, y) + xsin (theta), and the spectrum acquired by the camera 8 is
To S2In that
After the Fourier transform is carried out on the domain, a pair of signal peaks symmetrical along the zero point and a dead zone with a certain width near the zero point appear in the obtained second transform spectrum, and the abscissa of the signal peak of the second transform spectrum is in direct proportion to sin (theta). Because θ is a preset fixed value, the center value of the signal peak can be estimated. The dead zone of the second transform spectrum is also the fourier transform of the spectrum I (λ) of the tunable laser 1 and does not alias with the signal peak determined by sin (θ), so that the dead zone and the signal of the negative half axis can be filtered out by using a high-pass filtering algorithm, and the filtered second transform spectrum is inverse transformed from fourier to the x domain to obtain a complex spectrum signal S3Spectral signal S3The mirror portion is also substantially suppressed, no longer including the spectrum I (λ) of the tunable laser 1, and therefore, for S3In that
The transform spectrum obtained after Fourier transform in the domain only comprises one signal peak, and both the dead zone and the image signal can be greatly inhibited. Therefore, the area array sweep frequency measurement range can be expanded from the positive half shaft to the whole positive half shaft and the whole negative half shaft, and is not interfered by dead zones.
In the present invention, both the transmissive element and the reflective element may be tilted, which is in accordance with the principle of suppressing the mirror portion and the dead zone.
Example 2
The refractive index of different testees may change greatly, and this embodiment adopts the general visual field light path that has the fiber optic splitter, and the light intensity of reference arm is adjusted to the convenient to use fiber attenuator, and need not to change the attenuator in the light path, avoids destroying the light path.
As shown in fig. 2, an area array frequency sweep measuring device is provided, which includes a tunable laser 1, a first collimator 3, a first beam expander 4, a first beam splitter 5, a lens 7, a camera 8, a computer 9, a first optical fiber beam splitter 2, a second beam expander 22, a second collimation 21, and an optical fiber attenuator 20;
the first beam splitter 5, the lens 7, the camera 8 and the computer 9 are sequentially arranged in the radial direction from bottom to top; a first collimator 3, a first beam expander 4, a first beam splitter 5, a second beam expander 22 and a second collimator 21 are sequentially arranged from left to right in the transverse direction; the output end of the tunable laser 1 is connected with the input end of the first optical fiber beam splitter 2; the first output end of the first optical fiber beam splitter 2 is connected with the first collimator 3, and the second output end of the first optical fiber beam splitter is connected with the optical fiber attenuator 20; the output end of the optical fiber attenuator 20 is connected with a second collimator 21;
a light beam output by the tunable laser 1 is divided into two beams by a first optical fiber beam splitter 2, and the first light beam is connected to a first collimator 3; the first beam expander 4 is used to expand the beam to a spot typically 30 mm; the first light beam is input from the first port of the first beam splitter 5 and output from the second port; parallel light output from the second port irradiates on a measured object 6, the optical fiber enters through the first beam splitter 5, passes through the lens 7 after being reflected by the object and irradiates on the camera 8, the second light beam is connected to the second collimator 21 through the optical fiber attenuator 20, the second beam expander 22 is used for expanding the second light beam to a light spot with a typical value of 30mm and outputting, passes through the third port of the first beam splitter 5 and irradiates on the camera 8 through the lens 7. The reflected light of the first light beam obtained by the object to be measured 6 interferes with the second light beam output by the first beam splitter 5, the obtained interference image is recorded by the camera 8, and the computer 9 performs data analysis according to the interference image; the lens 7 is used to image the interference image on the camera 8.
Preferably, the lens 7 is a telecentric lens.
Example 3
A general view field light path with the optical fiber beam splitter can solve the problems of distance blurring and dead zones by adopting a double-reference-arm structure. The principle is the same as in example 1, except that the reference light is derived from transmitted light in this example, and the reference light is derived from reflected light in example 1.
As shown in fig. 3, an area array frequency sweep measuring device is provided, which includes a tunable laser 1, a first collimator 3, a first beam expander 4, a first beam splitter 5, a lens 7, a camera 8, a computer 9, a first optical fiber beam splitter 2, a second optical fiber beam splitter 30, a fourth collimator 32, a third collimator 35, a third beam expander 36, a fourth beam expander 33, and a third beam splitter 34;
the first beam splitter 5, the lens 7, the camera 8 and the computer 9 are sequentially arranged in the radial direction from bottom to top; a first collimator 3, a first beam expander 4 and a first beam splitter 5 are sequentially arranged from left to right in the transverse direction;
the output end of the tunable laser 1 is connected with a first optical fiber beam splitter 2, one end of the first optical fiber beam splitter 2 is connected with a first collimator 3, the other end of the first optical fiber beam splitter 2 is connected with a second optical fiber beam splitter 30, the second optical fiber beam splitter 30 divides two reference arms, the first reference arm is composed of a fourth collimator 32 and a third beam expander 36, the third beam expander 36 is connected to the radial direction of a third beam splitter 34, the second reference arm is composed of a third collimator 35 and a fourth beam expander 33, and the fourth beam expander 33 is connected to the transverse direction of the third beam splitter 34; the third beam splitter 34 is connected in the transmission direction of the first beam splitter 5;
the tunable laser 1 is divided into two beams of light by a first optical fiber beam splitter 2, the first beam of light is connected to a first collimator 3 through an optical fiber and enters a measuring arm, and the detailed process is as described above; the second beam of light is connected to a second optical fiber beam splitter 30 through an optical fiber, and the second optical fiber beam splitter 30 splits the second beam of light into first reference light and second reference light; the first reference light is connected to the fourth collimator 32 through an optical fiber, is input from a third port of the third beam splitter 34 through the third beam expander 36, is output from a fourth port of the third beam splitter 34, and is irradiated onto the camera 8 through the first beam splitter 5; the second reference light is connected to the third collimator 35 through an optical fiber, is input from the second port of the third beam splitter 34 through the fourth beam expander 33, is output from the fourth port of the third beam splitter 34, and is irradiated onto the camera 8 through the first beam splitter 5, reflected light of the object to be measured 6, the first reference light and the second reference light interfere with each other, and a generated interference image is recorded by the camera 8 and transmitted to the computer 9 for analyzing the surface topography of the object to be measured 6; the lens 7 is used to image the interference image on the camera 8.
Preferably, the lens 7 is a telecentric lens.
In summary, compared with the prior art, the invention has the following advantages:
the area array sweep frequency measuring device provided by the invention has the advantages that the interference image is acquired by the camera, the interference image is formed by interference of reflected light and reference light, the reflected light and the reference light are acquired by decomposing the same light beam, the acquisition control unit analyzes the surface appearance of the measured object by analyzing the interference image, the traditional point detection acquisition mode is replaced to acquire the surface appearance, the mechanical scanning error introduced during point detection is avoided, and the measurement accuracy under a common view field is improved.
The design of the double reference arms adopted by the invention effectively solves the problems of non-fuzzy distance and dead zone in the traditional laser interference distance measurement, and can realize accurate distance measurement and thickness measurement.
The invention adopts the optical fiber attenuator to adjust the light intensity of the reference arm and is used for overcoming the problem that the refractive index of different measured objects is too large and the attenuator needs to be replaced so as to damage the light path.
When the reflection (transmission) element provided by the invention is an inclined reflection (transmission) element, the dead zone and the mirror image signal peak can be effectively inhibited, so that the measurement range of the area array frequency sweep can be enlarged.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (12)
1. An area array sweep frequency measuring device is characterized by comprising a tunable laser (1), a first collimator (3), a first beam expander (4), a first beam splitter (5), a lens (7), a reflecting element (11), a camera (8) and an acquisition control unit;
the first beam splitter (5), the lens (7) and the camera (8) are sequentially arranged in the direction in which the original light beam is reflected by the first beam splitter (5); the first collimator (3), the first beam expander (4), the first beam splitter (5) and the reflecting element (11) are sequentially arranged in the transmission direction of the original light beam; the output end of the tunable laser (1) is connected with the input end of the camera (8);
the tunable laser (1) is used for controlling a camera to collect interference images by sending a trigger signal and providing original light beams; the first beam splitter (5) is used for splitting the collimated and expanded light beam into a first light beam and a second light beam, and the first light beam irradiates the object to be measured and then is reflected to form first reflected light; the reflecting element (11) is used for reflecting the second light beam to form reference light; the camera (8) is used for acquiring an interference image formed by the interference of the first reflected light and the reference light; the acquisition control unit is used for analyzing the surface appearance of the measured object according to the interference image; the lens (7) is used for imaging the interference image on the camera (8).
2. A swept frequency measuring device according to claim 1, characterised in that the reflecting elements (11) comprise a second beam splitter (16), a first filter (17), a second filter (19), a first reference mirror (18) and a second reference mirror (10);
the first reference mirror (18) and the first filter (17) form a first reference arm, and the placement direction of the first reference arm is the direction in which the original light beam is reflected by the first beam splitter (5); the second optical filter (19) and the second reference reflector (10) form a second reference arm, and the placement direction of the second reference arm is the transmission direction of the original light beam; the first filter (17) is located between the first reference mirror (18) and the second beam splitter (16); the second filter is located between the second reference mirror (10) and the second beam splitter (16);
the second beam splitter (16) having a fixed and non-uniform splitting ratio for splitting the second light beam into a first reference beam and a second reference beam; the first reference mirror (18) and the second reference mirror (10) are respectively used for reflecting the first reference beam and the second reference beam to form second reflected light and third reflected light; the first reflected light, the second reflected light and the third reflected light interfere with each other to form an interference image.
3. An amplified area array swept frequency measurement device as claimed in claim 1, wherein the reflective element (11) is a tilted reflective element.
4. An area array frequency sweep measuring method based on the area array frequency sweep measuring device of claim 1 is characterized by comprising the following steps:
after the original light beam is collimated and expanded in sequence, the original light beam is divided into a first light beam and a second light beam;
the first light beam irradiates an object to be measured and then is reflected to form first reflected light; and the second light beam forms reference light after reflecting;
acquiring an interference image formed by interference of the first reflected light and the reference light by using a camera;
and analyzing the surface appearance of the measured object according to the interference image.
5. A scanning frequency measuring method according to claim 4, characterized in that the reference light is obtained by:
splitting the second beam into a first reference beam and a second reference beam;
filtering the first reference beam and the second reference beam after the first reference beam and the second reference beam are respectively reflected to obtain second reflected light and third reflected light;
wherein the reference light includes second reflected light and third reflected light.
6. An area array frequency sweep measuring device, characterized by comprising: the device comprises a tunable laser (1), a first collimator (3), a first beam expander (4), a first beam splitter (5), a lens (7), a camera (8), an acquisition control unit, a first optical fiber beam splitter (2) and a transmission element;
the first beam splitter (5), the lens (7) and the camera (8) are sequentially arranged in the direction in which the first light beam is reflected by the first beam splitter (5); the first collimator (3), the first beam expander (4), the first beam splitter (5) and the transmission element are arranged in sequence in the transmission direction of the first light beam; the output end of the tunable laser (1) is connected with the input end of the first optical fiber beam splitter (2); the first output end of the first optical fiber beam splitter (2) is connected with the first collimator (3), and the second output end of the first optical fiber beam splitter is connected with a transmission element;
the tunable laser (1) is used for controlling a camera to collect interference images by sending a trigger signal and providing original light beams; the first optical fiber beam splitter (2) is used for splitting an original light beam into a first light beam and a second light beam; the first beam splitter (5) is used for irradiating the collimated and expanded first light beam to a measured object to obtain reflected light; the transmission element is used for transmitting the second light beam to the first beam splitter to form reference light; the camera (8) is used for collecting an interference image formed by interference of the reflected light and the reference light, and the collection control unit is used for analyzing the surface appearance of the measured object according to the interference image; the lens (7) is used for imaging the interference image on the camera (8).
7. A swept array measurement apparatus as claimed in claim 6, wherein the transmissive element comprises a fibre attenuator (20), a second collimator (21) and a second beam expander (22) connected in series;
the output end of the second beam expander (22) is connected with the first beam splitter (5); the second collimator (21) and the second beam expander (22) collimate and expand the second light beam, respectively.
8. A swept frequency measurement device according to claim 6, wherein the transmissive element comprises a second fiber beam splitter (30), a fourth collimator (32), a third beam expander (36), a third collimator (35), a fourth beam expander (33) and a third beam splitter (34);
the output end of the second optical fiber beam splitter (30) is connected with the third collimator (35) and the fourth collimator (32); the fourth collimator (32) and the third beam expander (36) form a first reference arm, which is placed in the direction in which the first beam is reflected by the first beam splitter (5), and the third beam expander (36) is connected to the third beam splitter (34); the third collimator (35) and the fourth beam expander (33) form a second reference arm, the second reference arm is placed in the transmission direction of the first light beam, and the fourth beam expander (33) is connected to the third beam splitter (34); the third beam splitter (34) is connected to the transmission direction of the first beam splitter (5); the second optical fiber beam splitter (30) is used for splitting the second light beam into first reference light and second reference light; after the first reference light and the second reference light are collimated and expanded, respectively forming first transmission light and second transmission light; the first transmission light, the second transmission light and the reflected light interfere with each other to form an interference image.
9. An amplified area array swept frequency measurement device as claimed in claim 6, wherein the transmission element is a tilted transmission element.
10. An area array frequency sweep measuring method based on the area array frequency sweep measuring device of claim 6 is characterized by comprising the following steps:
splitting the original light beam into a first light beam and a second light beam;
after the first light beam is collimated and expanded in sequence, the first light beam irradiates an object to be measured and then is reflected to form reflected light; the second light beam passes through the first beam splitter to form reference light;
collecting an interference image formed by interference of reflected light and reference light by using a camera;
and analyzing the surface appearance of the measured object according to the interference image.
11. A method for area array frequency sweep measurement as claimed in claim 10, wherein the method for acquiring the reference light is: and after the second light beam is collimated and expanded in sequence, the second light beam is transmitted to the first beam splitter to form reference light.
12. A method for area array frequency sweep measurement as claimed in claim 10, wherein the method for acquiring the reference light is:
splitting the second light beam into first reference light and second reference light;
after the first reference light and the second reference light are collimated and expanded, respectively forming first transmission light and second transmission light;
the reference light includes first transmitted light and second transmitted light.
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