CN103268016A - Homogenization method and device for a fiber-coupled semiconductor laser - Google Patents

Abstract

The invention provides an optical fiber coupling semiconductor laser unit homogenizing method for outputting light spots and a corresponding semiconductor laser unit system which can output homogenized light spots. The semiconductor laser unit system comprises a semiconductor laser unit, an optical fiber patch cord, an output connector and a homogenizing device, wherein the semiconductor laser unit, the optical fiber patch cord, the output connector and the homogenizing device are sequentially connected, the output end of the optical fiber patch cord is connected with fixed at the light receiving end of the output connector, the homogenizing device comprises a casing pipe and a homogenizer which is installed at the tail end of the casing pipe, the front end of the casing pipe is fixedly connected to a metal inserting core of the output connector in a sleeved mode, the casing pipe is a hollow type casing pipe, in a cavity of the hollow type casing pipe, the distance L between the light projecting end of the output connector and the homogenizer is not more than d/2tan (arcsinNA), d is the width of the homogenizer, and NA is a numerical aperture of the optical fiber patch cord. The optical fiber coupling semiconductor laser unit homogenizing device is simple and clear in structure, stable in operation, reliable, capable of producing the even light spots with suitable sizes and suitable luminance.

Description

Homogenization method and device for a fiber-coupled semiconductor laser

technical field

The invention belongs to the field of laser manufacturing, and relates to laser homogenization technology, in particular to a semiconductor laser homogenization method and device applicable to night vision lighting.

Background technique

At present, laser night vision devices are widely used in border defense, military, public security, cultural relics, bases, oil fields, industrial and mining, factory areas, fishing grounds, forest farms, orchards and other places and fields.

The laser is an important part of the laser night vision device. The quality of its design directly determines the performance of the entire night vision device. Traditional night vision lighting lasers generally have the disadvantages of complex structure, large volume and large loss of laser power.

Due to the defect of uneven light energy distribution in semiconductor lasers, various types of beam splitters or optical fibers are commonly used in the market to homogenize the laser beam. However, due to the high coherence of the laser itself, although all the above homogenization methods or devices will eliminate There are some light and dark stripes in the image, but all of them will produce serious laser speckle (that is, the problem of uneven light and shade in the area), which seriously affects the clarity of the captured image.

At present, there is no effective homogenization method or device that can completely eliminate laser speckle.

Contents of the invention

Aiming at the problems of uneven distribution of optical power in the output beam of fiber-coupled semiconductor lasers, the present invention proposes a method for homogenizing the output spot of fiber-coupled semiconductor lasers and a corresponding semiconductor laser system capable of outputting homogenized spots, which can solve problems caused by laser The defect of laser speckle (that is, the uneven brightness of light and dark on the light projection surface) appears in night-time video images brought about by high coherence, which makes the image clearer and completely eliminates laser speckle.

Technical scheme of the present invention is as follows:

A method for homogenizing a fiber-coupled semiconductor laser, which is to transmit the light emitted by the semiconductor laser through an optical fiber jumper, and install a homogenizer at a distance L from the light output end, so that the laser beam passes through the homogenizer and is homogenized, L Not greater than d/2tan(arcsinNA), where d is the width of the homogenizer, and NA is the numerical aperture of the optical fiber jumper.

The above-mentioned homogenizer can adopt a microlens array, a Fresnel lens, an optical waveguide or frosted glass.

The above-mentioned homogenizer is preferably frosted glass.

A semiconductor laser system capable of outputting homogenized light spots, comprising sequentially connected semiconductor lasers, optical fiber jumpers, output connectors and homogenization devices, the output end of the optical fiber jumper is connected and fixed to the light receiving end of the output connector , the homogenization device includes a sleeve and a homogenizer installed at the end of the sleeve, the front end of the sleeve is fixedly sleeved on the metal ferrule of the output connector; the sleeve is a hollow sleeve, and the hollow In the chamber of the type sleeve, the distance L between the light exit end of the output connector and the homogenizer is not greater than d/2tan(arcsinNA), where d is the width of the homogenizer, and NA is the numerical aperture of the optical fiber jumper.

The casing above is preferably a glass casing or a plastic casing, and the wall of the casing is transparent.

Preferably, the sleeve and the metal ferrule of the output connector are interference fit.

The above-mentioned homogenizer can adopt a microlens array, a Fresnel lens, an optical waveguide or frosted glass.

The above-mentioned homogenizer adopts a multi-rib optical waveguide, the length of which is less than 10 cm (the multi-rib optical waveguide can be hollow or solid).

The above-mentioned homogenizer is preferably frosted glass (it can be single-sided wool or double-sided wool), the particle size of the frosted glass is between W5-W70, and the thickness of the frosted glass is 0.02-2.5 cm.

The present invention has the following advantages:

The invention has simple structure, stable and reliable operation, and can generate uniform light spots with proper size and brightness.

The present invention is suitable for all-weather, especially the most ideal monitoring camera system with zero light at night, and its monitoring distance ranges from a few meters to several kilometers. product.

Description of drawings

Figure 1 is a schematic diagram of the principle of the homogenization method of the present invention (also can be used as a specific embodiment).

Fig. 2 is a schematic diagram of a semiconductor laser system capable of outputting homogenized light spots of the present invention (the best embodiment).

Fig. 3 is a sectional view of a metal ferrule and an optical fiber jumper according to the present invention.

FIG. 4 is another embodiment of the semiconductor laser system capable of outputting homogenized light spots of the present invention.

Fig. 5 is an illumination effect diagram of a semiconductor laser in a conventional scheme.

FIG. 6 is an illumination effect diagram of the semiconductor laser system of the present invention.

The present invention shows significant technical effects by comparing real lighting effect diagrams, which is very intuitive and directly corresponds to application requirements, and is the easiest verification method for those skilled in the art to confirm technical effects.

Explanation of reference numbers:

1 is a semiconductor laser; 2 is an optical fiber jumper; 3 is an output connector; 4 is a sleeve; 5 is a homogenizer; 6 is a metal ferrule.

Detailed ways

Below in conjunction with accompanying drawing, describe the present invention in detail through embodiment.

The fiber-coupled semiconductor laser homogenization method of the present invention, as shown in Figure 1, after the semiconductor laser 1 is output by the fiber jumper 2 whose numerical aperture is NA, a homogenizer 5 is set at a distance from the laser output end L, wherein the homogenization The distance L between the device 5 and the light emitting end (the end of the fiber jumper 2 in FIG. 1 ) is not greater than d/2tan(arcsinNA), where d is the width of the homogenizer.

The semiconductor laser 1 can be a single-tube semiconductor laser, a bar semiconductor laser, or multiple single-tube semiconductor lasers.

The specific form of the homogenizer can be microlens array, Fresnel lens, optical waveguide, frosted glass, etc. The optical waveguide is preferably a multi-rib optical waveguide, which can be hollow or solid, and the length is less than 10 centimeters. If you choose frosted glass, the particle size of the frosted glass is preferably between W5-W70, which can be single-sided or double-sided. The thickness of the frosted glass is 0.02-2.5 cm, such as 0.02 cm, 0.05 cm, 0.3 cm, 1.0cm, 1.5cm, 2.0cm, 2.5cm.

The semiconductor laser system capable of outputting a homogenized light spot of the present invention, as shown in Figure 2, includes a semiconductor laser 1, an optical fiber jumper 2, an output connector 3, and a homogenization device; the semiconductor laser 1 outputs the laser through the optical fiber jumper 2, The output connector 3 is arranged at the output end of the optical fiber jumper 2 for fixing and connecting the optical fiber jumper 2 , and the homogenization device is arranged at the rear end of the output connector 3 . The homogenization device specifically includes a sleeve 4 and a homogenizer 5 , the sleeve 4 is sleeved on the metal ferrule 6 of the output connector 3 , and the homogenizer 5 is installed at the end of the sleeve 4 . The distance between the homogenizer 5 and the optical output end (the end of the output connector 3 in Figure 2) is L, where L is not greater than d/2tan (arcsinNA), d is the width of the homogenizer, and NA is the fiber jumper the numerical aperture.

The sleeve 4 is a transparent hollow sleeve, which can be a glass sleeve or a plastic sleeve.

After analysis and experiments, after the light of the semiconductor laser 1 passes through the homogenizer 5, the diffusely reflected light generated by the homogenizer 5 will shoot to the tube wall of the casing 4. If the casing 4 is transparent, the diffusely reflected light will pass through the casing 4 After being emitted into the air, the temperature of the casing 4 will not rise; if the casing 4 is opaque, after the diffusely reflected light passes through the casing 4, the light cannot be exported in time, which will cause heat to accumulate on the casing 4, and the temperature of the casing 4 will increase. If a copper sleeve is used, the temperature will rise to about 60 degrees Celsius, which will reduce the reliability of the entire device and generate heat radiation; therefore, the sleeve 4 cannot be a metal sleeve.

Best embodiment: referring to Fig. 2, the semiconductor laser 1 selects a single-tube semiconductor laser for use, and the selected power is 5W, and the homogenization device includes a sleeve pipe and a homogenizer, the sleeve pipe is a hollow glass sleeve pipe, and the homogenizer is 0.1 cm. Thick, double-sided frosted glass with grain size W20. The light emitted by the semiconductor laser 1 is coupled into the fiber jumper 2 with a numerical aperture of NA, and output from the output connector 3. The output light is homogenized by the homogenizer 5 to obtain good uniformity and a large divergence angle (40 degrees left and right) with a large field of view.

Fig. 5 is a lighting effect diagram of the traditional solution, and Fig. 6 is a lighting effect diagram of the preferred embodiment. It can be seen that the light spot in Figure 5 is uneven, the granularity is large, the divergence angle is about 25 degrees, and the field of view is small; in Figure 6, the light spot is uniform and clear.

Another embodiment as shown in Figure 4, the semiconductor laser is a bar semiconductor laser, the homogenization device includes a sleeve and a homogenizer, the sleeve is a hollow glass sleeve, and the homogenizer 5 is a multi-edge optical waveguide. The scheme is used for night vision lighting to obtain a light spot with good uniformity and a large divergence angle, and the field of view is larger. Compared with the traditional scheme, the granularity of the illumination spot is smaller and the uniformity is better.

The invention is simple and practical, achieves good homogenization effect, clearer image and completely eliminates laser speckles.

Claims (9)

1. A fiber-coupled semiconductor laser homogenization method is characterized in that: the light that semiconductor laser is sent is transmitted by an optical fiber jumper, and a homogenizer is set at a distance from the light exit end L, so that the laser beam passes through the homogenizer and To obtain homogenization, L is not greater than d/2tan(arcsinNA), where d is the width of the homogenizer, and NA is the numerical aperture of the optical fiber jumper. 2. The homogenization method according to claim 1, characterized in that: the homogenizer adopts a microlens array, a Fresnel lens, an optical waveguide or frosted glass. 3. The homogenization method according to claim 2, characterized in that: the homogenizer is ground glass. 4. A semiconductor laser system capable of outputting a homogenized spot, characterized in that: it comprises a semiconductor laser connected in sequence, an optical fiber jumper, an output connector and a homogenizing device, and the output end of the optical fiber jumper is connected and fixed to the output The light-receiving end of the connector, the homogenization device includes a sleeve and a homogenizer installed at the end of the sleeve, and the front end of the sleeve is fixedly sleeved on the metal ferrule of the output connector; the sleeve is hollow Type sleeve, in the chamber of the hollow type sleeve, the distance L between the light exit end of the output connector and the homogenizer is not greater than d/2tan(arcsinNA), where d is the width of the homogenizer, and NA is the optical fiber The numerical aperture of the jumper. 5. The semiconductor laser system according to claim 4, characterized in that: the casing is a glass casing or a plastic casing, and the wall of the casing is transparent. 6. The semiconductor laser system according to claim 4, characterized in that: the sleeve is in interference fit with the metal ferrule of the output connector. 7. The semiconductor laser system according to any one of claims 4 to 6, wherein the homogenizer is a microlens array, a Fresnel lens, an optical waveguide or ground glass. 8. The semiconductor laser system according to claim 7, characterized in that: the homogenizer adopts a multi-edge optical waveguide with a length less than 10 cm. 9. The semiconductor laser system according to claim 7, wherein the homogenizer is ground glass, the grain size of the ground glass is between W5-W70, and the thickness of the ground glass is 0.02-2.5 cm.

Images