CN112129775A - A uniform light rod strip light source and an optical element damage detection device based on the light source - Google Patents

Abstract

A uniform light rod strip light source and an optical element damage detection device based on the light source belong to the technical field of optical element damage detection. The problem of poor uniformity of the detection light source affecting the accuracy of the detection result in the detection of the existing large-diameter optical element is solved. The invention includes a glass rod and a laser, the glass rod is composed of a circular arc surface and a plane, the arc of the circular arc surface is greater than 180 degrees, the plane is an isosceles trapezoid, and the plane is a rough scattering surface; One end is provided with a laser, the beam of the laser is injected from one end face of the circular glass rod in the axial direction, and the end face of the other end is affixed with a reflective strip or coated with a reflective layer; the beam of the laser passes through the arc surface or The reflective strip or reflective layer attached to the other end is reflected and emitted through the rough scattering surface. The damage of the device can be detected by using camera imaging. The damage of the device can be detected by using camera imaging. Suitable for damage detection of optical components.

Description

A uniform light rod strip light source and an optical element damage detection device based on the light source

technical field

The present invention belongs to the field of optics.

Background technique

In high-energy laser devices, the damage detection of large-diameter optical components is of great significance to the safe and healthy operation of the device. In the damage detection of large-diameter optical components, the uniformity of illumination and the amount of stray light have a direct impact on the accuracy and accuracy of damage identification. However, the detection of existing optical components is usually realized by setting point light sources in parallel to form a linear light source, as shown in Figure 1 and Figure 2. However, the uniformity of the light source in this method is poor, which directly affects the measurement results and causes the problem of poor measurement accuracy.

SUMMARY OF THE INVENTION

In order to solve the problem that the uniformity of the detection light source affects the accuracy of the detection result in the existing large-diameter optical element detection, the present invention proposes a uniform light bar-shaped light source and an optical element damage detection device based on the light source.

The uniform light bar-shaped light source of the present invention includes a glass rod and a laser, the glass rod is composed of a circular arc surface and a plane, the arc of the circular arc surface is greater than 180 degrees, and the plane is an isosceles trapezoid. The plane is a rough scattering surface;

One end of the round glass rod is provided with a laser, and the beam of the laser is incident from one end face of the round glass rod in the axial direction, and the end face of the other end is attached with a reflective strip or coated with a reflective layer; the beam of the laser After being reflected by the curved surface or the reflective strip or reflective layer attached to the other end, it is emitted through the rough scattering surface.

Further, the laser is arranged on the short side of the trapezoid surface.

Further, it also includes a rectangular bottom plate, two rectangular pressing plates and a light shield;

The side of the rectangular base plate is provided with a rectangular groove along the length direction, and the rectangular groove is opened along the center line of the rectangular base plate. The rectangular groove is used to install the circular glass rod. There is a gap between the rectangular pressing plates, the gap between the two rectangular pressing plates corresponds to the center line of the rectangular groove, the scattering surface of the circular glass rod corresponds to the gap between the two rectangular pressing plates, and the laser is installed at one end of the rectangular base plate , the hood is sleeved on the outside of the laser.

Further, one end of the light shield is hermetically connected with one end of the two rectangular pressing plates.

Further, the laser adopts an LD laser.

An optical element damage detection device based on the above light source, the device includes a camera, two uniform light bar-shaped light sources are respectively arranged along the upper end surface and the lower end surface of the device to be tested, and the rough scattering surface of the uniform light bar-shaped light source is attached to the On the device to be tested, the lasers of the two uniform light bar-shaped light sources are located on both sides of the longitudinal central axis of the device to be tested; the image acquisition surface of the camera is arranged toward the device to be tested.

The invention adopts the property of total reflection after the light beam is injected inside the circular glass rod, and a scattering rough surface is provided on one side, and the uniformity of the light source is readjusted by adjusting the size of the scattering rough surface, which effectively guarantees The detection needs of aperture optics, while ensuring the uniformity of the light source. When using the light source of the present invention for device damage detection, there is no need to perform optical signal processing multiple times, and the device damage image can be collected by a camera only by attaching the light source of the present invention to both sides of the device to be tested. The accuracy and effect of device damage detection are effectively improved.

Description of drawings

Figure 1 is a schematic diagram of the existing use of light source imaging to detect the damage of optical components without damage

FIG. 2 is a schematic diagram of the existing use of light source imaging to detect the damage of optical elements, and there is damage;

Figure 3 is the principle diagram of the uniform light rod on the light-emitting surface with gradual width;

4 is a schematic diagram of light energy propagation of a strip light source;

Figure 5 is a schematic diagram of light propagation on a rough scattering surface;

6 is a schematic diagram of the installation structure of a rectangular base plate and a circular glass rod;

7 is a schematic diagram of the overall structure of the strip light source;

Fig. 8 is the structure cracking diagram of strip light source;

Figure 9(a) is the distribution diagram of the total reflection light field in the homogenizing rod when h1=0.1mm, h2=0mm;

Figure 9(b) is the distribution diagram of the total reflection light field in the uniform light rod when h1=0.1mm, h2=0.0125mm;

Figure 9(c) is the distribution diagram of the total reflection light field in the uniform rod when h1=0.1mm and h2=0.025mm;

Figure 9(d) is the distribution diagram of the total reflection light field in the uniform light rod when h1=0.1mm and h2=0.0375mm;

Figure 9(e) is the distribution diagram of the total reflection light field in the uniform rod when h1=0.1mm and h2=0.05mm;

Figure 9(f) is the distribution diagram of the total reflection light field in the homogenizing rod when h1=0.1mm and h2=0.0625mm;

Figure 9(g) is the distribution diagram of the total reflection light field in the uniform light rod when h1=0.1mm and h2=0.075mm;

Figure 9(h) is the distribution diagram of the total reflection light field in the uniform rod when h1=0.1mm and h2=0.0875mm;

Figure 9(i) is the distribution diagram of the total reflection light field in the homogenizing rod when h1=0.1mm and h2=0.1mm;

Figure 10 is a graph showing the relationship between the uniformity of the light rod illumination and the grinding parameters;

Figure 11 is a three-dimensional model diagram of lighting stray light analysis;

Figure 12(a) is a simulation diagram of light propagation in the terminal optical assembly when there is no occlusion;

Figure 12(b) is a simulation diagram of light propagation in the terminal optical assembly when there is occlusion;

Figure 13(a) is a graph of the stray light illuminance distribution on the outer surface of the left optical element when there is no occlusion;

Figure 13(b) is a diagram of the stray light illuminance distribution on the outer surface of the left optical element when there is occlusion;

Figure 14(a) is a graph of the stray light illuminance distribution on the outer surface of the right optical element when there is no occlusion;

Figure 14(b) is a graph of the stray light illuminance distribution on the outer surface of the right optical element when there is no occlusion;

15 is a schematic diagram of the vertical direction of the grating etching direction and the illumination direction;

FIG. 16 is a schematic diagram showing that the grating etching direction is parallel to the illumination direction.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

It should be noted that the embodiments of the present invention and the features of the embodiments may be combined with each other under the condition of no conflict.

Embodiment 1: The present embodiment will be described below with reference to FIG. 1 . The uniform light bar-shaped light source described in this embodiment includes a glass rod 1 and a laser 2. The glass rod 1 is composed of an arc surface and a flat surface. , the arc of the arc surface is greater than 180 degrees, the plane is an isosceles trapezoid, and the plane is a rough scattering surface;

One end of the circular glass rod 1 is provided with a laser 2, and the beam of the laser 2 is axially injected from one end face of the circular glass rod 1, and the end face of the other end is affixed with a reflective strip or coated with a reflective layer; The light beam of the laser 2 is reflected by the curved surface or the reflective strip or reflective layer attached to the other end and then emitted through the rough scattering surface.

Further, the laser 2 is arranged on the short side of the trapezoid surface.

In order to realize the damage identification of optical components, the method of total reflection illumination in dark field is usually used at present, and the principle is shown in Figure 1. The illumination light source is incident on the optical element to be measured at an angle less than or equal to α, the refraction angle is β, and the incident angle of the refracted light reaching the surface of the element again is θ. Component surface exit. The camera will not image the component at this time. When there is damage on the surface of the component, the condition of total reflection on the surface of the component will no longer be satisfied, so there will be light leakage where there is damage. As shown in Figure 2, this part of the light will be imaged on the camera to achieve the purpose of damage detection. In this process, the uniformity of the illumination light source has an important influence on the experimental results. Therefore, we designed a strip light source based on a homogenizing rod. As shown in Figure 3, the homogenizing rod is made of a quartz glass round rod. A part of the shaft is ground off to make a rough diffused light-emitting surface (P2), and the diffused light-emitting surface is parallel to the central axis of the homogenizing rod. The laser light emitted by LD is injected into one end (P1) of the homogenizing rod, and the other end is pasted with a small mirror (or reflective coating). Light is incident at P1 and exits at P2. In the uniform light rod, the curved surface satisfies the condition of total internal reflection, and no light leaks out. The P2 surface is the scattering interface, and the light undergoes reflection, diffuse reflection, transmission, diffuse transmission, and interface absorption, as shown in Figures 4 and 5. The scattering surface of the homogenizing rod is close to the component to be tested.

Further, in conjunction with FIG. 6, FIG. 7 and FIG. 8, it also includes a rectangular bottom plate 3, two rectangular pressing plates 5 and a light shield 4;

The side surface of the rectangular base plate 3 is provided with a rectangular groove along the length direction, and the rectangular groove is opened along the center line of the rectangular base plate 3 . and there is a gap between the two rectangular pressing plates 5, the gap between the two rectangular pressing plates 5 corresponds to the center line of the rectangular groove, the scattering surface of the circular glass rod 1 and the gap between the two rectangular pressing plates 5 Correspondingly, the laser 2 is installed on one end of the rectangular base plate 3 , and the light shield 4 is sleeved on the outer side of the laser 2 .

Further, one end of the light shield 4 is hermetically connected to one end of the two rectangular pressing plates 5 .

In the present embodiment, the light shield 4 is used to fix the laser light source and the circular glass rod 1 , thereby reducing light leakage.

Further, the laser 2 adopts an LD laser.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 2. The optical element damage detection device described in this embodiment is implemented based on the uniform light rod strip light source described in the specific embodiment 1. The device includes a camera, two uniform light sources. The rod-shaped light source is respectively arranged along the upper end face and the lower end face of the device to be tested, and the rough scattering surface of the even-light rod-shaped light source is attached to the device to be tested, and the lasers 2 of the two even-light rod-shaped light sources are located at The two sides of the longitudinal central axis of the device under test; the image acquisition surface of the camera is set toward the device under test.

The size of the light-emitting surface of the homogenizing rod of the present invention has an important relationship with the uniformity of the illumination of the light source in the optical element and the full utilization of light energy. In order to improve the above two indicators, its parameters are optimized.

Since the rough surface close to the light injection end scatters more light energy outward, as the distance from the light injection end increases, the energy scattered by the rough surface gradually decreases. In order to make the homogenizing rod form a relatively uniform light field, the width of the light-emitting surface at the light injection end can be reduced, the width of the light-emitting surface at the other end can be increased, and a light-emitting surface with a gradual width is formed between the two ends, as shown in the figure below, at d1 A small reflector is placed at the end or coated with a reflective film, and illumination light is injected at the d2 end. Set the light scattering properties of the emitting surface as diffuse reflectance (RTS): diffuse transmittance (TTS) = 50%: 50%. The slope surface in the following three cases is simulated: the slope surface in the first case (isosceles trapezoid plane) the grinding thickness h1 = 0.1mm at the d1 end, and the grinding thickness at the d2 end is equal to 0~0.1mm. 9 data between the two; the slope surface isosceles trapezoid plane in the second case) d1 end grinding thickness h1 = 0.2mm, d2 end grinding thickness take 9 data between 0 ~ 0.2mm at equal intervals; In the three cases, the isosceles trapezoid plane of the slope surface) is the grinding thickness h1=0.4mm at the d1 end, and the grinding thickness at the d2 end takes 9 data between 0 and 0.4mm at equal intervals. In the case of double uniform light rod illumination, the corresponding internal total reflection light field distribution is obtained by simulation. r is shown in Figures 9(a) to 9(i). Figure 10 shows the relationship between the illumination uniformity of the homogenizing rod and the grinding parameters. Based on the previous analysis results, it can be seen that the grinding thickness of the d1 end is h1=0.1mm, and the grinding thickness of the d2 end is h2=0.05mm corresponding to the optimal illumination uniformity. sex.

1. Analysis of stray light using uniform light bar light source

It was found in the experiment that the light leakage problem of the light source will cause serious stray light. In order to control the influence of stray light of component lighting, simulation and experiment methods are used to analyze it.

(1) Simulation conditions: illumination with two uniform light rods, the light injection end of the uniform light rod is ground by 0.05mm, the reflection surface end of the uniform light rod is ground by 0.1mm, and the light injection power of the uniform light rod is P=2*1.579W=3.158W ;

(2) Simulation method: Monte Carlo Ray Tracing (MCRT), the energy decays to 1%, and the tracing is stopped.

(3) Simulation software: The simulation model of TracePro7.3.4 (Lambda Research Corporation, Littleton, America) is shown in Figure 11, and the beam tracing result is shown in Figure 12, of which Figure 12(a) is the unobstructed beam tracing As a result, Fig. 12(b) is the result of beam tracing with occlusion. It can be seen that the main light leakage occurs at the joint of the LD laser and the light rod. The simulation of light propagation in the terminal optical assembly is shown in Figs. 12(a) and 12(b). display (displays 10% of the total number of rays)

Simulation results:

a) When the light source is not blocked, the stray light power received by the outer surface of the left optical element is: Pleft=0.010W, the power ratio ηleft=(Pleft/P)×100%=0.3167%≈0.32%; the right optical element The stray light power received by the outer surface is: Pright=0.035W, the proportion ηright=(Pright/P)×100%=1.1083%≈1.11%;

b) When the light source is blocked, the stray light power received by the outer surface of the left optical element is: Pleft=0.003W, the power ratio ηleft=(Pleft/P)×100%=0.095%≈0.10%; the right optical element The stray light power received by the outer surface is: Pright=0.021W, and the proportion is ηright=(Pright/P)×100%=0.6650%≈0.67%.

Table 1 The ratio of the stray light power received by the optical elements on both sides to the total power of the light source

Table 2 The ratio of the stray light power leaked by the light source to the total power of the light source

left right superior Down forward back total leak leak ratio unobstructed 0.010 0.035 0.022 0.022 0.275 0.278 0.642 20.33% covered 0.003 0.021 0.010 0.010 0.018 0.017 0.079 2.49%

Simulation analysis conclusion: According to the light-shielding design of this scheme, the stray light can be effectively controlled by integrating the LD, the light rod and the frame of the terminal component with an integrated closed light-shielding design.

In addition to the light leakage of the light source itself, there are also some factors that introduce stray light. For example, light leakage will occur between the light emitting surface of the light source and the components, and at the boundary of the components. The leaked light will be reflected between different components, thus affecting the detection results. There are grating elements in the element, which are affected by diffraction and also bring stray light.

As shown in the figure below, since the total reflection condition is not met at the component boundary, there will be light leakage, and the leaked light will be reflected in different components, as shown in the red box on the left in the figure below. If there is damage at the strip-shaped stray light, it cannot be identified, which affects the accuracy of damage detection. Such stray light can be effectively eliminated if it is shielded at the frame of the component, as shown in the right figure below, the lower half of the frame where the light source is installed is shielded, and the lower half of the stray light in the center of the component is eliminated. When the element is a grating element, serious stray light may also exist. When the illumination direction of the illumination light source is perpendicular to the grating etching direction, the emitted light of the illumination light source irradiates the point A. At this time, the condition of total internal reflection is no longer satisfied. The illumination light will emerge from this point, and the emitted light will form stray light, which will affect the damage identification. result. A schematic diagram of the vertical direction of the grating etching direction and the illumination direction is shown in Figure 15.

If the illumination direction is changed so that the illumination direction is parallel to the grating etching direction, as shown in the figure below, at this time, the illumination light irradiates the part where the grating is engraved, and the incident angle remains unchanged, so the condition of total internal reflection is still satisfied, and there will be no light. leakage. Schematic diagram of grating etching direction parallel to illumination direction, as shown in Figure 16

Considering the above factors, we designed the following internal total reflection illumination method to achieve uniform illumination:

1. The strip light source based on the homogenizing rod is designed. The light source structure is shown in the figure below. The LD laser 2 emits laser light, and the light outlet is aligned with the homogenizing rod. The uniform light rod is made of a quartz glass round rod, and a part of it is ground along the axial direction to make a rough scattered light-emitting surface. The scattered light-emitting surface is parallel to the central axis of the uniform light rod. The laser light from LD is injected into one end of the homogenizing rod, and the other end is pasted with a small reflector (or coated with reflector). Both the LD laser 2 and the homogenizing rod are fixed on the base plate, and the pressing plate is used to fix the homogenizing rod. The light-shielding cover 4 covers the LD laser 2 and the connection with the homogenizing rod, so as to reduce the light leakage of the light source.

Although the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and other arrangements can be devised without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that the features described in the various dependent claims and herein may be combined in different ways than are described in the original claims. It will also be appreciated that features described in connection with a single embodiment may be used in other described embodiments.

Claims (6)

1. The light homogenizing rod-shaped light source is characterized by comprising a glass rod (1) and a laser (2), wherein the glass rod (1) consists of an arc surface and a plane, the radian of the arc surface is greater than 180 degrees, the plane is in an isosceles trapezoid shape, and the plane is a rough scattering surface;

a laser (2) is arranged at one end of the round glass rod (1), a light beam of the laser (2) is emitted from one end face of the round glass rod (1) along the axial direction, and a reflective strip or a reflective layer is adhered to the end face of the other end of the round glass rod; and the light beam of the laser (2) is reflected by the arc-shaped surface or a reflecting strip or a reflecting layer attached to the other end and then is emitted out through the rough scattering surface.

2. An dodging stick light source according to claim 1, wherein the laser (2) is arranged on the short side of the trapezoidal face.

3. A light homogenizing bar light source according to claim 1 or 2, characterized by further comprising a rectangular base plate (3), two rectangular press plates (5) and a light shield (4);

the side of rectangle bottom plate (3) is opened along length direction has the rectangular channel, the central line along rectangle bottom plate (3) is seted up to the rectangular channel, the rectangular channel is used for installing circular glass stick (1), and two parallel buckles of rectangle clamp plate (5) are established on rectangle bottom plate (3), and leaves the gap between two rectangle clamp plates (5), gap and rectangular channel central line between two rectangle clamp plates (5) correspond, and the scattering surface of circular glass stick (1) corresponds with the gap between two rectangle clamp plates (5), and the one end at rectangle bottom plate (3) is installed in laser instrument (2), and the outside at laser instrument (2) is established to lens hood (4) cover.

4. A light homogenizing bar light source according to claim 3, characterized in that one end of the light shield (4) is hermetically connected with one end of the two rectangular pressing plates (5).

5. A light homogenizing bar light source according to claim 3, characterized in that the laser (2) is LD laser.

6. The optical element damage detection device based on the light homogenizing bar-shaped light source of any one of claims 1 to 5, characterized in that the device comprises a camera, two light homogenizing bar-shaped light sources are respectively arranged along the upper end surface and the lower end surface of the device to be detected, the rough scattering surface of the light homogenizing bar-shaped light source is attached to the device to be detected, and the lasers (2) of the two light homogenizing bar-shaped light sources are positioned on two sides of the longitudinal central axis of the device to be detected; the image acquisition surface of the camera is arranged towards the element to be measured.

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