CN1740759A - Laser beam parameter measuring method based on image processing - Google Patents

Abstract

The present invention relates to a laser light beam parameter measuring method based on image processing, belonging to the field of laser parameter measuring instrument. Said invention utilizes the techniques of light intensity distribution, digital image conversion, coordinate and point-set, etc. to implement said measuring method. Said invention also provides the concrete steps of said method. Said method can be used for measuring laser light beam with high power and large diverging angle.

Description

Laser beam parameter measuring method based on Flame Image Process

Technical field

The present invention relates to a kind of laser beam parameter measuring method, relate in particular to the laser beam parameter measuring device and the measuring method of high power laser diode, belong to the laser parameter measurement instrument field based on Flame Image Process.

Background technology

Along with the semiconductor components and devices cost descends significantly, high power laser diode has obtained widespread use in fields such as range finding, guidance, processing, medical treatment.In these were used, the light beam parameters of laser diode laser beam (light field light distribution, width of light beam, the angle of divergence etc.) was the key factor that influence effect, and therefore accurately the light beam parameters of mensuration laser instrument is causing people's extensive concern in recent years.

Common measuring method is divided into scanning method and imaging method (C D method).Scanning method is divided into aperture scanning method, knife edge scanning method, slit scan method and aperture scanning method again.Scanning method needs mechanical scanning mechanism, requires mechanical positioning precision height, is unfavorable for the processing of subsequent calculations machine.And the CCD method has the mechanical scanning of need not, can realize characteristics such as synchronous triggering control, and existing laser parameter measurement mode adopts the CCD mode more.

But adopt adds the with a tight waist of a lens reconstructed light beam more in the existing C CD measuring method behind laser beam, and by the decay light intensity of laser of polaroid, the laser radiation after directly will decaying is at the photosurface of imaging components and parts.This mode is owing to be that the imaging components and parts directly are coupled with laser beam, and the imaging components and parts are satisfied easily and closed, and are subject to external interference.And because the high power laser diode angle of divergence is big, imaging components and parts photosensitive area is little, and the scope of institute's energy measurement is little, therefore can not adopt this kind mode to measure mostly.

Summary of the invention

The present invention seeks to propose a kind of laser beam parameter measuring method based on Flame Image Process, characteristics according to high power laser diode, be that the angle of divergence is big, power is big and is difficult for characteristics such as directly measurement, carry out parameter measurement based on Flame Image Process, obtain the light beam parameters of laser diode, as the angle of divergence and beam distribution etc.

The laser beam parameter measuring method based on Flame Image Process that the present invention proposes may further comprise the steps:

(1) takes up an official post in the axial direction of propagation of testing laser light beam and get a bit, convert the light distribution at this some place to two-dimensional illumination intensity distribution;

(2) convert above-mentioned two-dimensional illumination intensity distribution figure to digital picture;

(3) digital picture that obtains is obtained binary image by threshold valuesization, wherein N the point set that gray-scale value is equal constitutes the isocandela zone;

(4) the long axis direction angle α in the medium light intensity of the above-mentioned binary image of calculating zone _L, short-axis direction angle α _SAnd center point P ₀Coordinate P ₀(x ₀, y ₀), x wherein ₀And y ₀It is center point P ₀Coordinate on binary image;

(5), and utilize long axis direction angle α according to the corresponding relation of above-mentioned binary image and digital picture _L, short-axis direction angle α _SWith center point coordinate P ₀, obtain in the digital picture along the point set S on the long axis direction _LWith along the collection S on the short-axis direction _W

(6) with above-mentioned point set S _LAnd S _WRespectively with the desirable two-dimensional illumination intensity distribution of testing laser beam axis on major axis on the travel path and short-axis direction

With

Carry out match, obtain testing laser light beam parameters σ _LAnd σ _S, wherein r is point set S _LAnd S _WIn arbitrarily a bit to center point P ₀Distance;

(7) utilize the laser beam parameter σ that obtains _LAnd σ _S, the half-power angle of divergence alpha of major axis then ₁For

${\mathrm{\α}}_1=\mathrm{arcc}\tan \left(\frac{\sqrt{{\mathrm{\σ}}_L\ln 2}}{f}\frac{d2}{d1}\right)$

The half-power angle of divergence alpha of minor axis ₂For

${\mathrm{\α}}_2=\mathrm{arcc}\tan \left(\frac{\sqrt{{\mathrm{\σ}}_S\ln 2}}{f}\frac{d2}{d1}\right)$

Major axis

The power angle of divergence alpha ₃For

${\mathrm{\α}}_3=\mathrm{arcc}\tan \left(\frac{\sqrt{2{\mathrm{\σ}}_L}}{f}\frac{d2}{d1}\right)$

Minor axis

The power angle of divergence alpha ₄For

${\mathrm{\α}}_4=\mathrm{arcc}\tan \left(\frac{\sqrt{2{\mathrm{\σ}}_S}}{f}\frac{d2}{d1}\right)$

Wherein, d1 is the distance between testing laser beam light source and the two-dimensional illumination intensity distribution generation device that the light distribution of testing laser light beam is converted to two-dimensional illumination intensity distribution, d2 is the camera lens and the distance between the two-dimensional illumination intensity distribution generation device of the image acquisition device that the two-dimensional illumination intensity distribution figure of testing laser light source converted to digital picture, and f is the lens focus that the two-dimensional illumination intensity distribution figure of testing laser light source is converted to the image acquisition device of digital picture.

The laser beam parameter measuring method that the present invention proposes based on Flame Image Process, its advantage is to measure laser beam high-power, the Vernonia parishii Hook angle, and the measuring accuracy height, measuring process is simple.

Description of drawings

Fig. 1 is the structural representation that utilizes the device of the inventive method measuring laser beam parameter.

Fig. 2 is a digital picture of utilizing the inventive method to collect.

Fig. 3 carries out the binary image that obtains after the threshold values processing to the digital picture of Fig. 2.

Among Fig. 1, the 1st, camera bellows, the 2nd, testing laser light source, the 3rd, optical attenuator, the 4th, the two-dimensional illumination intensity distribution generation device is a frosted glass in this device, the 5th, and focal length is the standard lens of f, the 6th, the CCD camera, the 7th, the video connecting line, the 8th, chassis base, the 9th, the computing machine of capture card is installed.

Specific embodiments

The laser beam parameter measuring method based on Flame Image Process that the present invention proposes may further comprise the steps: at first, take up an official post in the axial direction of propagation of testing laser light beam and to get a bit, convert the light distribution at this some place to two-dimensional illumination intensity distribution; Convert above-mentioned two-dimensional illumination intensity distribution figure to digital picture; The digital picture that obtains is obtained binary image by threshold valuesization, and wherein N the point set that gray-scale value is equal constitutes the isocandela zone; Calculate the long axis direction angle α in the medium light intensity of above-mentioned binary image zone _L, short-axis direction angle α _SAnd center point P ₀Coordinate P ₀(x ₀, y ₀), x wherein ₀And y ₀It is center point P ₀Coordinate on binary image; According to the corresponding relation of above-mentioned binary image and digital picture, and utilize long axis direction angle α _L, short-axis direction angle α _SWith center point coordinate P ₀, obtain in the digital picture along the point set S on the long axis direction _LWith along the collection S on the short-axis direction _WWith above-mentioned point set S _LAnd S _WRespectively with the desirable two-dimensional illumination intensity distribution of testing laser beam axis on major axis on the travel path and short-axis direction With

Carry out match, obtain testing laser light beam parameters σ _LAnd σ _S, wherein r is point set S _LAnd S _WIn arbitrarily a bit to center point P ₀Distance; The laser beam parameter σ that utilization obtains _LAnd σ _S, the half-power angle of divergence alpha of major axis then ₁For

${\mathrm{\α}}_1=\mathrm{arcc}\tan \left(\frac{\sqrt{{\mathrm{\σ}}_L\ln 2}}{f}\frac{d2}{d1}\right)$

The half-power angle of divergence alpha of minor axis ₂For

${\mathrm{\α}}_2=\mathrm{arcc}\tan \left(\frac{\sqrt{{\mathrm{\σ}}_S\ln 2}}{f}\frac{d2}{d1}\right)$

Major axis The power angle of divergence alpha ₃For

${\mathrm{\α}}_3=\mathrm{arcc}\tan \left(\frac{\sqrt{2{\mathrm{\σ}}_L}}{f}\frac{d2}{d1}\right)$

Minor axis

The power angle of divergence alpha ₄For

${\mathrm{\α}}_4=\mathrm{arcc}\tan \left(\frac{\sqrt{{2\mathrm{\σ}}_S}}{f}\frac{d2}{d1}\right)$

Wherein, d1 is the distance between testing laser beam light source and the two-dimensional illumination intensity distribution generation device that the light distribution of testing laser light beam is converted to two-dimensional illumination intensity distribution, d2 is the camera lens and the distance between the two-dimensional illumination intensity distribution generation device of the image acquisition device that the two-dimensional illumination intensity distribution figure of testing laser light source converted to digital picture, and f is the lens focus that the two-dimensional illumination intensity distribution figure of testing laser light source is converted to the image acquisition device of digital picture.

The laser beam parameter measuring method based on Flame Image Process that the present invention proposes, its concrete device for carrying out said example as shown in Figure 1.In Fig. 1, the 1st, camera bellows, the 2nd, high power laser diode to be measured, the 3rd, optical attenuator, the 4th, two-dimensional illumination intensity distribution generation device, adopt frosted glass in the present embodiment, the 5th, the standard lens of focal distance f, the 6th, the CCD camera, what present embodiment adopted is the NIR300 camera of Pulnix company, the 7th, video connecting line, the 8th, chassis base.The 9th, computing machine, be installed in wherein capture card and select Picolo Pro 2 video frequency collection cards of Euresys company for use, calculating parameter in the measuring method proposed by the invention partly is written as the program that can move on computing machine 9, obtain the light beam parameters of high power laser diode to be measured after this digital picture is calculated through said procedure.So this measuring method may further comprise the steps:

(1) laser that sends of high power laser diode 2 to be measured forms the two-dimensional illumination intensity distribution image through being radiated at after the overdamping on the frosted glass 4.

(2) this two-dimensional illumination intensity distribution image images on the target surface of CCD camera 6 through camera lens 5, carries out opto-electronic conversion by CCD and forms vision signal.This vision signal is input to by video connecting line 7 on the video frequency collection card of computing machine 9, and vision signal is through obtaining digital picture as shown in Figure 2 after the AD conversion behind the video frequency collection card.This two-dimensional illumination intensity distribution figure needs to make digital picture not have full chalaza through suitable attenuation multiple.

(3) adopt the Otsu method to obtain the threshold values of digital picture, utilize this threshold values that digital picture is carried out binaryzation, obtain binary image as shown in Figure 3.Wherein N the point set that gray-scale value is equal constitutes the isocandela zone, then the white portion A in the accompanying drawing 3 has represented laser beam isocandela zone, pixel in the pixel of this binary image and the digital picture 2 is one to one, and the pixel coordinate in two images also is one to one;

(4) establish (x _i, y _i) be the more any coordinate among the A of isocandela zone, the then center P in isocandela zone ₀(x ₀, y ₀) be

$\left\{\begin{array}{c}{x}_0=\frac{1}{N}\underset{i}{\mathrm{\Σ}}{x}_i\\ y_0=\frac{1}{N}\underset{i}{\mathrm{\Σ}}{y}_i\end{array}\right.$

And following result arranged:

$I_x=\frac{1}{N}\underset{i}{\mathrm{\Σ}}{(y_i-y_0)}^2$

$I_y=\frac{1}{N}\underset{i}{\mathrm{\Σ}}{(x_i-x_0)}^2$

$I_{\mathrm{xy}}=\frac{1}{N}\underset{i}{\mathrm{\Σ}}(x_i-x_0)(y_i-y_0)$

$I_a=\frac{I_x+I_y}{2}+\sqrt{{\left(\frac{I_x+I_y}{2}\right)}^2+I_{\mathrm{<figure-callout\; id="2"\; label="xy"\; filenames="A20051010329100081.png"\; state="\{\{state\}\}">xy</figure-callout>}}^2+I_x{I}_y}$

$I_b=\frac{I_x+I_y}{2}-\sqrt{{\left(\frac{I_x+I_y}{2}\right)}^2+I_{\mathrm{<figure-callout\; id="2"\; label="xy"\; filenames="A20051010329100081.png"\; state="\{\{state\}\}">xy</figure-callout>}}^2+I_x{I}_y}$

(5) angle [alpha] of major axis _LFor

${\mathrm{\&alpha;}}_L=\mathrm{arcc}\tan \left(\frac{I_x-I_a}{I_{\mathrm{xy}}}\right)$

Short-axis direction angle α _S

α _S＝90+α _L

(6) long axis direction angle α _L, short-axis direction angle α _SWith center point coordinate P ₀, the point set of establishing on the long axis direction is S _L, S _LIn point be (x _Li, y _Li), its coordinate can be tried to achieve by following relational expression

y _li＝y ₀+tgn(α _L)(x _li-x ₀)

Point set on the short-axis direction is S _W, S _WIn point be (x _Si, y _Si), its coordinate can be tried to achieve by following relational expression

y _si＝y ₀+tgn(α _S)(x _si-x ₀)

(7) because coordinate and the coordinate on the digital picture on the binary image are one to one, so point set is S on the long axis direction on the digital picture _L[r _Li, g _Li], the point set on the short-axis direction is S _W[r _Si, g _Si], wherein, $r_{\mathrm{li}}=\sqrt{{(x_{\mathrm{li}}-x_0)}^2+{(y_{\mathrm{li}}-y_0)}^2},$ $r_{\mathrm{si}}=\sqrt{{(x_{\mathrm{si}}-x_0)}^2+{(y_{\mathrm{si}}-y_0)}^2},$ g _LiBe (x _Li, y _Li) point gray scale, g _SiBe (x _Si, y _Si).

(8) with above-mentioned point set S _LAnd S _WRespectively with the desirable two-dimensional illumination intensity distribution of testing laser beam axis on major axis on the travel path and short-axis direction $g_l=A_L\mathrm{Exp}(<figure-callout\; id="2"\; label="-\; r\; l"\; filenames="A20051010329100081.png"\; state="\{\{state\}\}">-</figure-callout>\frac{{r_l}^{}}{}\frac{{{}_{}}^2}{{\mathrm{\&sigma;}}_L})$ With $g_s=A_S\mathrm{Exp}(-\frac{{r_s}^2}{{\mathrm{\&sigma;}}_S})$ Carry out match and obtain σ _LAnd σ _WValue obtains testing laser light beam parameters σ _LAnd σ _S

(9)) utilize the laser beam parameter σ that obtains _LAnd σ _S, the half-power angle of divergence alpha of major axis then ₁For

${\mathrm{\&alpha;}}_1=\mathrm{arcc}\tan \left(\frac{\sqrt{{\mathrm{\&sigma;}}_L\ln 2}}{f}\frac{d2}{d1}\right)$

The half-power angle of divergence alpha of minor axis ₂For

${\mathrm{\&alpha;}}_2=\mathrm{arcc}\tan \left(\frac{\sqrt{{\mathrm{\&sigma;}}_S\ln 2}}{f}\frac{d2}{d1}\right)$

Major axis

The power angle of divergence alpha ₃For

${\mathrm{\&alpha;}}_3=\mathrm{arcc}\tan \left(\frac{\sqrt{{2\mathrm{\&sigma;}}_L}}{f}\frac{d2}{d1}\right)$

Minor axis

The power angle of divergence alpha ₄For

${\mathrm{\&alpha;}}_4=\mathrm{arcc}\tan \left(\frac{\sqrt{{2\mathrm{\&sigma;}}_S}}{f}\frac{d2}{d1}\right)$

Wherein, d1 is the distance between testing laser beam light source and the two-dimensional illumination intensity distribution generation device that the light distribution of testing laser light beam is converted to two-dimensional illumination intensity distribution, d2 is the camera lens and the distance between the two-dimensional illumination intensity distribution generation device of the image acquisition device that the two-dimensional illumination intensity distribution figure of testing laser light source converted to digital picture, and f is the lens focus that the two-dimensional illumination intensity distribution figure of testing laser light source is converted to the image acquisition device of digital picture.

Claims (1)

1, a kind of laser beam parameter measuring method based on Flame Image Process is characterized in that this method may further comprise the steps:

(1) takes up an official post in the axial direction of propagation of testing laser light beam and get a bit, convert the light distribution at this some place to two-dimensional illumination intensity distribution;

(2) convert above-mentioned two-dimensional illumination intensity distribution figure to digital picture;

(3) digital picture that obtains is obtained binary image by threshold valuesization, wherein N the point set that gray-scale value is equal constitutes the isocandela zone;

(4) the long axis direction angle α in the medium light intensity of the above-mentioned binary image of calculating zone _L, short-axis direction angle α _SAnd center point P ₀Coordinate P ₀(x ₀, y ₀), x wherein ₀And y ₀It is center point P ₀Coordinate on binary image;

(5), and utilize long axis direction angle α according to the corresponding relation of above-mentioned binary image and digital picture _L, short-axis direction angle α _SWith center point coordinate P ₀, obtain in the digital picture along the point set S on the long axis direction _LWith along the collection S on the short-axis direction _W

(6) with above-mentioned point set S _LAnd S _WRespectively with the desirable two-dimensional illumination intensity distribution of testing laser beam axis on major axis on the travel path and short-axis direction

With

Carry out match, obtain testing laser light beam parameters σ _LAnd σ _S, wherein r is point set S _LAnd S _WIn arbitrarily a bit to center point P ₀Distance;

(7) utilize the laser beam parameter σ that obtains _LAnd σ _S, the half-power angle of divergence alpha of major axis then ₁For

${\mathrm{\&alpha;}}_1=\mathrm{arcc}\tan \left(\frac{\sqrt{{\mathrm{\&sigma;}}_L\ln 2}}{f}\frac{d2}{d1}\right)$

The half-power angle of divergence alpha of minor axis ₂For

${\mathrm{\&alpha;}}_2=\mathrm{arcc}\tan \left(\frac{\sqrt{{\mathrm{\&sigma;}}_S\ln 2}}{f}\frac{d2}{d1}\right)$

Major axis

The power angle of divergence alpha ₃For

${\mathrm{\&alpha;}}_3=\mathrm{arcc}\tan \left(\frac{\sqrt{2{\mathrm{\&sigma;}}_L}}{f}\frac{d2}{d1}\right)$

Minor axis

The power angle of divergence alpha ₄For

${\mathrm{\&alpha;}}_4=\mathrm{arcc}\tan \left(\frac{\sqrt{2{\mathrm{\&sigma;}}_S}}{f}\frac{d2}{d1}\right)$

Wherein, d1 is the distance between testing laser beam light source and the two-dimensional illumination intensity distribution generation device that the light distribution of testing laser light beam is converted to two-dimensional illumination intensity distribution, d2 is the camera lens and the distance between the two-dimensional illumination intensity distribution generation device of the image acquisition device that the two-dimensional illumination intensity distribution figure of testing laser light source converted to digital picture, and f is the lens focus that the two-dimensional illumination intensity distribution figure of testing laser light source is converted to the image acquisition device of digital picture.

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