Infrared laser beam quality measurement device and method

Abstract

The application discloses an infrared laser beam quality measuring device and method, and the infrared laser beam quality measuring method directly or focuses the infrared laser on an infrared up-conversion thick film material, converts the infrared laser spot which cannot be detected by a CMOS / CCD camera into a spot which can be detected by the CMOS / CCD camera, collects the spot on the infrared up-conversion thick film material by using the CMOS / CCD camera, quantitatively analyzes various parameters of the spot, and realizes quantitative measurement and evaluation of the infrared laser beam quality. The application converts the infrared laser spot which cannot be detected by the CMOS / CCD camera into the spot which can be detected by the CMOS / CCD camera, collects the spot by using the CMOS / CCD camera, realizes low-cost and reliable laser spot imaging, realizes measurement of the beam quality of the infrared laser which cannot be detected by the CMOS / CCD camera, and is easy to be widely popularized in industrial applications; furthermore, the reliability of the measurement is further improved, and the measurement efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to an infrared laser beam quality measurement device and method, belonging to the technical field of infrared laser beam quality measurement. BACKGROUND

[0002] Figure 1 For the light response spectrum of the commonly used CMOS camera, the cut-off wavelength in the long wave direction is slightly greater than 1000nm (the cut-off position of light response is set at 20%); the light response wavelength of the commonly used CCD camera is slightly longer than the CMOS in the long wave direction, but it only extends to slightly less than 1100nm; for laser with a wavelength greater than 1000nm (for CMOS camera) or 1080nm (for CCD camera), the commonly used silicon-based digital camera cannot detect.

[0003] As shown in Figure 2 The wavelengths of common M:YAG (M represents various types of doped metals) lasers are all greater than 1064nm, and the very active mid-infrared lasers in recent years, and even the infrared CO2 laser at a long wave of 10.6um, most of which are beyond the light response band of the silicon-based CMOS / CCD camera, and cannot obtain digitized images. Without the digitized images of the laser beam, the quality of the laser beam cannot be quantitatively measured, which is a technical problem to be solved.

[0004] In view of the above technical problems, for the acquisition of short-wave infrared laser spot images, an InGaAs-based near-infrared camera can be used, which has an intrinsic spectral response that can cover up to 1.7um band, and the extension can even cover up to 2.5um; for the acquisition of mid-infrared band laser spot images, an InSb-based or MCT-based mid-infrared camera (3um-5um) can be used to obtain the images of the laser spot; for the detection of the spot of CO2 long-wave laser at 10.6um, a silicon-based microbolometer long-wave camera can be used to acquire the images of the laser beam. However, the prices of the above-mentioned short-wave infrared, mid-wave infrared and long-wave infrared cameras are very high, and the scale and resolution of the area array are far inferior to those of the silicon-based CMOS camera, which is difficult to be widely popularized in industrial applications. SUMMARY

[0005] The present application provides an infrared laser beam quality measurement device and method, which realizes low-cost and reliable laser spot imaging and is easy to be widely popularized in industrial applications.

[0006] To solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0007] The application discloses an infrared laser beam quality measurement method, which comprises the following steps: directly or focusing the infrared laser on an infrared up-conversion thick film material, converting the infrared laser spot which cannot be detected by a CMOS / CCD camera into a spot which can be detected by the CMOS / CCD camera, collecting the spot on the infrared up-conversion thick film material by the CMOS / CCD camera, and quantitatively analyzing parameters of the spot to realize quantitative measurement and evaluation of the infrared laser beam quality.

[0008] The method realizes the collection of the infrared laser spot image by using the relatively cheap CMOS / CCD camera, has low cost and high reliability.

[0009] The parameters of the spot are one-to-one corresponding to the parameters of the laser beam, and the laser beam quality can be obtained by analyzing the spot.

[0010] The infrared laser which cannot be detected by the CMOS / CCD camera includes invisible infrared laser.

[0011] The thickness of the infrared up-conversion thick film material is not less than 0.01 mm.

[0012] Under the general low laser power density, the nonlinear effect can be ignored, the brightness of any point of the spot on the infrared up-conversion thick film material can be considered to be proportional to the light intensity of the infrared laser, and the spot on the infrared up-conversion thick film material can reflect the light intensity distribution of the infrared laser without distortion.

[0013] The application discloses an infrared laser beam quality measurement device, which comprises a CMOS / CCD camera, an imaging lens, a beam splitter and an infrared up-conversion thick film material.

[0014] Alternatively, the infrared laser beam quality measurement device comprises a focusing lens, a CMOS / CCD camera, an imaging lens, a beam splitter and an infrared up-conversion thick film material.

[0015] The application discloses an infrared laser beam quality measurement method, which comprises the following steps: directly or focusing the infrared laser on an infrared up-conversion thick film material, converting the infrared laser spot which cannot be detected by a CMOS / CCD camera into a spot which can be detected by the CMOS / CCD camera, collecting the spot on the infrared up-conversion thick film material by the CMOS / CCD camera, and quantitatively analyzing parameters of the spot to realize quantitative measurement and evaluation of the infrared laser beam quality.

[0016] 1) The infrared laser beam emitted by an infrared laser is directly or focused by the focusing lens, and then is reflected by the beam splitter to the infrared up-conversion thick film material to form a spot.

[0017] 2) the light spot on the infrared up-conversion thick film material is reflected, sequentially passes through the beam splitter and the imaging lens, and is imaged onto the photosensitive sensor surface of the CMOS / CCD camera to obtain a digital image (image of the light spot), and quantitative analysis of various parameters of the obtained image is performed to realize quantitative measurement and evaluation of the quality of the infrared laser beam.

[0018] Since the infrared up-conversion thick film material is an opaque material, the infrared laser and the camera need to be arranged on the same side of the up-conversion thick film material to collect the image of the laser light spot.

[0019] In order to facilitate detection arrangement, preferably, the CMOS / CCD camera, the imaging lens, the beam splitter and the infrared up-conversion thick film material are sequentially arranged from top to bottom. At this time, in the above step 1), the infrared laser beam emitted by the infrared laser is directly or focused after passing through the focusing lens, passes through the beam splitter, reverses the direction of the light, and images the infrared laser light spot on the horizontally placed infrared up-conversion thick film material; in step 2), the light spot on the infrared up-conversion thick film material is reflected upward, sequentially passes through the beam splitter and the imaging lens, and is imaged onto the photosensitive sensor surface of the CMOS / CCD camera to obtain a digital image, and quantitative analysis of various parameters of the obtained image is performed to realize quantitative measurement and evaluation of the quality of the infrared laser beam.

[0020] In order to ensure that the camera can vertically shoot the pattern of the laser light spot, thereby recording the shape and intensity distribution of the laser light spot without distortion, the beam splitter is a 45-degree beam splitter.

[0021] The 45-degree beam splitter, that is, when placed horizontally, the included angle between the beam splitting surface and the horizontal plane is 45 degrees, can be a cubic beam splitter composed of two 45° right-angle prisms, or can be a single 45-degree beam splitter.

[0022] In order to ensure the fidelity of the light spot recording, the optical axis of the focusing lens and the optical axis of the imaging lens are perpendicular to each other, and the included angles between the optical axis of the focusing lens and the beam splitting surface of the beam splitter and the optical axis of the imaging lens and the beam splitting surface of the beam splitter are both 45 degrees.

[0023] In step 1), due to the complexity of the energy level structure of the infrared up-conversion material, especially the longer energy level lifetime, the inventors found in experiments that: a, from the moment when the infrared laser hits the infrared up-conversion thick film material to the appearance of a stable visible light spot on the infrared up-conversion material, it takes about 1-2 seconds according to different infrared up-conversion thick film materials; b, under continuous infrared laser irradiation, the optical conversion efficiency of the infrared up-conversion material seriously decays after about 5 seconds, and the visible light spot on the infrared up-conversion material gradually disappears, which will seriously affect the accuracy of the measurement results; c, if the second infrared laser irradiation is performed immediately after the first infrared laser irradiation, the same light spot as the previous experiment cannot be repeated on the infrared up-conversion thick film material immediately, that is, the infrared up-conversion material needs sufficient time to recover to the initial state, usually about 5 minutes.

[0024] Therefore, in engineering practice, measures need to be taken to make the obtained light spot image consistent in all possible variables. To this end, the present application installs an electrically controlled shutter in the laser light path for controlling the start time, closing time and gap time of the light beam hitting the infrared up-conversion thick film material. The structure and principle of the electrically controlled shutter can be directly referred to the prior art, and the present application does not have special improvements, so it will not be described again.

[0025] The above-mentioned electrically controlled shutter is installed at the light inlet end of the infrared laser beam quality measurement device (the end where the laser first enters during measurement).

[0026] If the electrically controlled shutter is also provided in the device, the method for measuring the quality of the infrared laser beam includes the following steps:

[0027] 1) Open the electrically controlled shutter and close the CMOS / CCD camera. The infrared laser beam emitted by the infrared laser passes through the focusing mirror and then the beam splitter, and is reflected to the infrared up-conversion thick film material to form a light spot. After a time td, a relatively stable and complete visible laser light spot is established, and this light spot can be maintained for a time tso.

[0028] 2) At the time td after the electrically controlled shutter is opened, open the CMOS / CCD camera. After the CMOS / CCD camera is exposed for a time tc, close the CMOS / CCD camera and save the image.

[0029] 3) After a time tsc, repeat steps 1-2) to continue the measurement.

[0030] In the above-mentioned step 2), td is 1-2 seconds, and td+tc is not more than 5 seconds. In step 3), tsc is 4-7 minutes.

[0031] In the above step 2), after the photographing is completed, the laser shutter can be closed to stop the irradiation of the infrared laser on the infrared up-conversion thick film, so that the infrared up-conversion thick film has a time tsc to recover to the original state. After the infrared up-conversion thick film recovers to the original state, the above image acquisition process can be repeated.

[0032] Since the infrared up-conversion thick film material needs to wait for a time tsc after the previous measurement, and the second measurement cannot be started until the infrared up-conversion thick film recovers to the original state, the efficiency of the device is relatively low. Therefore, the inventors further install the infrared up-conversion thick film material on a moving platform. After the above step 2) is completed, the moving platform drives the infrared up-conversion thick film material to move, so that the position of the light spot for the next imaging is different from the position of the light spot for the previous imaging (the imaging just completed). In step 3), without waiting for the time tsc, the steps 1-2) are directly repeated for continuous measurement. That is, after the previous measurement is completed, as long as the moving platform moves the infrared up-conversion thick film material to a new position, the second measurement can be started at any time, which greatly improves the feasibility of the device.

[0033] In order to facilitate control and assembly, the above moving platform is an XY moving platform, or a rotating platform, or a combination of an XY moving platform and a rotating platform.

[0034] When the moving platform is an XY moving platform, after the above step 2) is completed, the XY moving platform drives the infrared up-conversion thick film material to move in the X or Y direction, so that the position of the light spot for the next imaging is different from the position of the light spot for the previous imaging.

[0035] When the moving platform is a rotating platform, after the above step 2) is completed, the rotating platform drives the infrared up-conversion thick film material to rotate, so that the position of the light spot for the next imaging is different from the position of the light spot for the previous imaging.

[0036] In order to more uniformly use the infrared up-conversion thick film, the moving platform is a combination of an XY moving platform and a rotating platform. The infrared up-conversion thick film material is first installed on the rotating platform, and then the rotating platform is installed on the XY moving platform. In this way, the working point on the infrared up-conversion thick film can move along the radial direction or along the circular arc, so that more efficient measurement work can be achieved.

[0037] The CMOS / CCD camera of the present application is a CMOS camera or a CCD camera.

[0038] The technologies not mentioned in the present application refer to the prior art.

[0039] The infrared laser beam quality measurement method can convert the infrared laser spot that cannot be detected by the CMOS / CCD camera into a spot that can be detected by the CMOS / CCD camera, and realizes low-cost and reliable laser spot imaging by using the CMOS / CCD camera to collect the spot, realizes the measurement of the beam quality of the infrared laser that cannot be detected by the CMOS / CCD camera, and is easy to be widely popularized in industrial applications; further, the reliability of the measurement is further improved, and the measurement efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 The spectrum response spectrum of the common CMOS / CCD camera;

[0041] Figure 2 The wavelength distribution diagram of the common laser light source;

[0042] Figure 3 The effect diagram of the 1550nm laser beam hitting the infrared up-conversion thick film material in the embodiment 1 of the present application;

[0043] Figure 4 The structure schematic diagram of the infrared laser beam quality measurement device in the embodiment 2 of the present application;

[0044] Figure 5 The structure schematic diagram of the infrared laser beam quality measurement device in the embodiment 3 of the present application;

[0045] Figure 6 The timing sequence logic of the shutter and image acquisition in the embodiment 3 of the present application;

[0046] Figure 7 The structure schematic diagram of the infrared laser beam quality measurement device in the embodiment 4 of the present application;

[0047] Figure 8 The structure schematic diagram of the infrared laser beam quality measurement device in the embodiment 5 of the present application;

[0048] In the figure, 1 is a focusing mirror, 2 is a CMOS / CCD camera, 3 is an imaging lens, 4 is a beam splitter, 5 is an infrared up-conversion thick film material, 6 is an infrared laser, 7 is an electrically controlled shutter, 8 is an XY moving platform, 9 is a rotating platform, and 10 is a spot. DETAILED DESCRIPTION

[0049] In order to better understand the present application, the content of the present application will be further illustrated below in combination with the embodiments, but the content of the present application is not limited to the following embodiments.

[0050] The orientation words such as “up”, “down”, “top”, “bottom” and the like in the present application are based on the relative orientation or position relationship shown in the drawings, and cannot be understood as a limitation on the present application.

[0051] Embodiment 1

[0052] The method for measuring the quality of an infrared laser beam comprises the following steps: directing or focusing infrared laser light onto an infrared up-conversion thick film material, converting the spot of the infrared laser light that cannot be detected by a CMOS / CCD camera into a spot that can be detected by the CMOS / CCD camera, collecting the spot on the infrared up-conversion thick film material by using the CMOS / CCD camera, and quantitatively analyzing various parameters of the spot to realize quantitative measurement and evaluation of the quality of the infrared laser beam.

[0053] The brightness of any point on the spot on the infrared up-conversion thick film material is proportional to the light intensity of the laser light, and the spot on the infrared up-conversion thick film material can reflect the light intensity distribution of the infrared laser light without distortion.

[0054] The method uses a relatively inexpensive CMOS / CCD camera to collect the image of the infrared laser light spot, has low cost and high reliability.

[0055] For example, a silicon-based CMOS / CCD camera cannot directly obtain a digital image of a 1550nm infrared laser beam, as shown in FIG. Figure 3 The 1550nm laser beam is directed onto an infrared up-conversion thick film material, the infrared up-conversion thick film material can convert the 1550nm laser light spot that cannot be detected by the CMOS / CCD camera into a visible light spot that can be detected, and then the spot on the infrared up-conversion thick film material is collected by using the CMOS / CCD camera, various parameters of the spot are quantitatively analyzed, and quantitative measurement and evaluation of the quality of the infrared laser beam are realized.

[0056] Embodiment 2

[0057] As shown in FIG. Figure 4 An infrared laser beam quality measurement device comprises a focusing mirror, a CMOS / CCD camera, an imaging lens, a beam splitter, and an infrared up-conversion thick film material. The CMOS / CCD camera, the imaging lens, the beam splitter, and the infrared up-conversion thick film material are arranged in sequence from top to bottom. The focusing mirror is arranged on one side of the beam splitter. In order to ensure that the camera can vertically shoot the pattern of the laser light spot and thus record the shape and intensity distribution of the laser light spot without distortion, the beam splitter is a 45-degree beam splitter, and the beam splitter shown in the figure is a cubic beam splitter composed of two 45° right-angle triangular prisms. In order to ensure the fidelity of the spot recording, the optical axis of the focusing mirror and the optical axis of the imaging lens are perpendicular to each other, and the included angle between the optical axis of the focusing mirror and the imaging lens and the splitting surface of the beam splitter is 45 degrees.

[0058] The method for measuring the quality of an infrared laser beam by using the above-mentioned infrared laser beam quality measurement device comprises the following steps:

[0059] 1) as shown in FIG. Figure 4As shown, the infrared laser beam emitted by the infrared laser is focused directly or after passing through a focusing lens, and then passes through a 45-degree beam splitter to reverse the light direction and image the infrared laser spot onto a horizontally placed infrared upconversion thick film material.

[0060] 2) The light spot on the infrared upconversion thick film material is reflected and sequentially passes through a beam splitter and an imaging lens, and is imaged onto the photosensitive sensor surface of a CMOS / CCD camera to obtain a digital image. The parameters of the obtained image are quantitatively analyzed to realize the quantitative measurement and evaluation of the quality of the infrared laser beam.

[0061] Example 3

[0062] Based on Example 2, the following improvements were made: an electronically controlled shutter was installed on the laser optical path to control the start time, closing time, and interval time of the beam hitting the infrared upconversion thick film material. For example... Figure 5 As shown, the electronically controlled shutter is installed at the light inlet of the infrared laser beam quality measurement device.

[0063] The method for measuring the quality of an infrared laser beam using the aforementioned infrared laser beam quality measuring device includes the following steps:

[0064] 1) With the electronic shutter open and the CMOS / CCD camera closed, the infrared laser beam emitted by the infrared laser, either directly or after being focused by a focusing lens, passes through a beam splitter, causing the light to be refracted onto the infrared upconversion thick film material, forming a light spot, such as... Figure 6 As shown, after time td, a relatively stable and complete visible laser spot is established, and this spot can be maintained for time tso.

[0065] 2) such as Figure 6 As shown, at time td after the electronic shutter opens, the CMOS / CCD camera is turned on. After the CMOS / CCD camera has been exposed for time tc, the CMOS / CCD camera is turned off and the image is saved. td is 1 to 2 seconds, and td + tc does not exceed 5 seconds.

[0066] 3) After the time tsc is reached, repeat steps 1-2) to continue the measurement. The tsc is approximately 5 minutes.

[0067] Example 4

[0068] Based on Example 3, the following improvements were made: Figure 7 As shown, the infrared laser beam quality measurement device also includes an XY moving platform, on which the infrared upconversion thick film material is mounted.

[0069] The method for measuring the quality of the infrared laser beam using the above infrared laser beam quality measuring device is different from that of Embodiment 3 in that: in Embodiment 3, after the infrared up-conversion thick film undergoes the previous measurement, it needs to wait for the time tsc, and the second measurement can be started only when the infrared up-conversion thick film returns to the original state. The efficiency of the device is relatively low. In this example, the infrared up-conversion thick film material is installed on a moving platform. After the end of step 2), the XY moving platform drives the infrared up-conversion thick film material to move in the X or Y direction, so that the position of the reimaging light spot is away from the position of the last imaging light spot. In step 3), there is no need to wait for the time tsc, and the steps 1-2) are directly repeated for continuous measurement.

[0070] Embodiment 5

[0071] On the basis of Embodiment 3, the following improvements are further made: as shown in Figure 8 The infrared laser beam quality measuring device further comprises a rotating platform, and the infrared up-conversion thick film material is installed on the rotating platform.

[0072] The method for measuring the quality of the infrared laser beam using the above infrared laser beam quality measuring device is different from that of Embodiment 3 in that: after the end of step 2), the rotating platform drives the infrared up-conversion thick film material to rotate, so that the position of the reimaging light spot is away from the position of the last imaging light spot. In step 3), there is no need to wait for the time tsc, and the steps 1-2) are directly repeated for continuous measurement.

[0073] Embodiment 6

[0074] On the basis of Embodiment 3, the following improvements are further made: the infrared laser beam quality measuring device further comprises an XY moving platform and a rotating platform. The infrared up-conversion thick film material is first installed on the rotating platform, and then the rotating platform is installed on the XY moving platform. In this way, the working point on the infrared up-conversion thick film can move along the radial direction or along the circular arc, and higher efficiency of measurement can be achieved.

[0075] The method for measuring the quality of the infrared laser beam using the above infrared laser beam quality measuring device is different from that of Embodiment 3 in that: after the end of step 2), the XY moving platform and the rotating platform drive the infrared up-conversion thick film material to move, so that the position of the reimaging light spot is away from the position of the last imaging light spot. In step 3), there is no need to wait for the time tsc, and the steps 1-2) are directly repeated for continuous measurement.

Claims

1. An infrared laser beam quality measurement method, characterized in that: an infrared laser beam quality measurement device comprises a focusing mirror, a CMOS / CCD camera, an imaging lens, a beam splitter and an infrared up-conversion thick film material; the CMOS / CCD camera, the imaging lens, the beam splitter and the infrared up-conversion thick film material are sequentially arranged; the focusing mirror is arranged on one side of the beam splitter; an electrically controlled shutter is arranged on a laser light path for controlling a starting time, a closing time and a gap time of a light beam hitting the infrared up-conversion thick film material; the electrically controlled shutter is arranged at an entrance of the infrared laser beam quality measurement device; a moving platform is further arranged, and the infrared up-conversion thick film material is arranged on the moving platform; the moving platform is a combination of an XY moving platform and a rotating platform, the infrared up-conversion thick film material is first arranged on the rotating platform, and then the rotating platform is arranged on the XY moving platform; the thickness of the infrared up-conversion thick film material is not less than 0.01 mm; the infrared laser and the CMOS / CCD camera are arranged on the same side of the up-conversion thick film material to collect an image of a laser spot; the infrared laser beam quality measurement method comprises the following steps: 1) opening the electrically controlled shutter and closing the CMOS / CCD camera, and the infrared laser beam emitted by the infrared laser is focused by the focusing mirror and then reflected by the beam splitter to form a spot on the infrared up-conversion thick film material; 2) at a time td after the electrically controlled shutter is opened, the CMOS / CCD camera is opened, the spot on the infrared up-conversion thick film material is reflected upward, sequentially passes through the beam splitter and the imaging lens, and is imaged on a photosensitive sensor surface of the CMOS / CCD camera to obtain a digital image; after the CMOS / CCD camera is exposed for a time tc, the CMOS / CCD camera is closed, the image is saved, and each parameter of the image is quantitatively analyzed to realize quantitative measurement and evaluation of the infrared laser beam quality; the moving platform drives the infrared up-conversion thick film material to move, so that a position of a newly imaged spot is different from a position of a previously imaged spot; td is 1-2 s, and td+tc is not more than 5 s; and 3) without waiting for a time tsc, steps 1-2) are repeated to continue measurement. The brightness of any point of the spot on the infrared up-conversion thick film material is proportional to the light intensity of the laser, and the distribution of the brightness of the spot on the infrared up-conversion thick film material reflects the light intensity distribution of the infrared laser. The beam splitter is a 45-degree beam splitter; the optical axis of the focusing mirror and the optical axis of the imaging lens are perpendicular to each other, and the included angle between the optical axis of the focusing mirror and the imaging lens and the beam splitting surface of the beam splitter is 45 degrees. ​ ​ ​ ​ ​ ​ ​ ​ ​ 2. The method of claim 1, wherein: ​ 3. The method of claim 1 or 2, wherein: ​

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