CN2181700Y

CN2181700Y - Laser beam intensity distribution changing device

Info

Publication number: CN2181700Y
Application number: CN 93210840
Authority: CN
Inventors: 龙品
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-04-28
Filing date: 1993-04-28
Publication date: 1994-11-02
Anticipated expiration: 2003-04-28

Abstract

The utility model belongs to a device which can change the intensity distribution of laser beams and change the Gaussian distribution to the uniform intensity distribution. The utility model is mainly composed of a light beam expanding system and two phase elements, wherein, the surfaces of the phase elements are etched with two or more rectangular or circular ring-shaped steps with depth grade and made of material through which visible light can penetrate; the light beam expanding system comprises two lenses. Compared with prior art, the device enhances optical efficiency, reduces noise, and simplifies structure. The diffraction type light beam matrix wavefront corrector can be coaxially used.

Description

Laser beam intensity distribution changing device

The utility model belongs to the conversion equipment that the intensity distributions of laser beam is carried out conversion, particularly in the switching device that Gaussian beam is transformed to uniform beam.

As everyone knows, the intensity of the laser beam that sends from laser instrument is published as Gaussian distribution, and need the beam lighting of even light distribution at aspects such as optical information processing, optical measurement, holographs, the general now method of using is that light beam is enlarged, only get one of them fraction light beam and come illuminated objects, so just lost most beam energy; Another kind of current methods is just to realize the conversion that above-mentioned beam intensity is announced with two non-spherical lenses, but above-mentioned non-spherical lens processing and manufacturing is very difficult; Also having a kind of universal method is to adopt the computer manufacture hologram to realize the conversion of beam intensity, but the optical efficiency of computer manufacture hologram is low, and noise is big, not in coaxial use, makes the structure complicated of device.

The purpose of this utility model is exactly the shortcoming that will overcome prior aries such as above-mentioned non-spherical lens or computing mechanism hologram in Gaussian distribution being transformed to the uniform strength distribution, the conversion equipment that the utility model proposed is compared with non-spherical lens, it is fairly simple to have processing and fabricating, can produce in enormous quantities, thereby reduce cost; As comparing with the computing mechanism hologram, because device has a plurality of phase position values, can improve optical efficiency greatly, reduced noise, and can coaxially use, make simplifying the structure of system.

Another purpose of the present utility model is exactly to be worth the distance that ceases mutually between the element mutually by adjusting two multidigits, can be adapted to the requirement of different wavelength of laser beam intensity conversion, makes device have more extensive applicability.

In order to realize that the purpose of this utility model has proposed a kind of optical device that laser beam intensity is carried out conversion that is used for that laser lighting uses, and can be converted to the laser beam of Gaussian distribution the converter that light intensity is evenly divided the laser beam of face cloth.It can be used for aspects such as optical information processing, optical measurement, holograph and laser technology.

The laser beam conversion equipment that the utility model proposed, its structure mainly is worth mutually by a kind of beam expander system (or telescopic system) and two multidigits and ceases element (binary optical device) mutually and form, or be worth mutually by the multidigit that a beam expander system (telescopic system) and a slice two sides have two or more stepped profile and cease element (binary optical device) mutually and form, can restraint any needed bore to the laser beam expansion by the expansion beam ratio that changes the beam expander system, multidigit is worth no part mutually can be operated in transmission-type or reflective mode, when being operated in the transmission-type mode, the material that ceases element mutually can be used simple glass/optical glass/quartz glass/organic glass, and resin or other visible light permeable macromolecular material are made; When reflective mode is worked, can adopt metal material such as copper, aluminium, zinc, chromium or other semiconductor material, and plate the metal of one deck high reflectance on its surface, as gold.Silver, aluminium, chromium etc.What cease element mutually is configured to the parallel substrate in two sides, produce through over etching on the one or both sides therein two can a plurality of degree of depth grades rectangle step or step cutting pattern distribute, light is by the light path difference of the step surface structure back generation of the different depth on this device side, and formation diffraction, can produce any needed light wave wave front and distribute, thereby reach the purpose of the shape of the energy distribution that changes laser beam or laser beam.The element of breath mutually in this device can constitute by two, first light distribution homogenising that makes light beam wherein, and second to make outgoing beam be equality light, promptly played the effect of collimation, and two must coaxial uses.The element that ceases mutually in this device also can be made of a slice all have a step surface structure on two face device, step on its front surface structure evenly divides beam intensity, and makes the outgoing beam collimation be parallel beam at lip-deep step structure thereafter.The element that ceases mutually in this device also can be two reflective devices, also can be that a slice is a transmission-type, and another sheet is reflective device formation.

Of the present utility model that Gaussian beam is transformed to the example of the switching device of uniform beam and device thereof is shown in the drawings, and accompanying drawing has:

Fig. 1 (a) and (b) have represented that respectively the multidigit that constitutes conversion equipment of the present utility model is worth the substrate that ceases element mutually mutually, is etched with the rectangle stepped profile of a plurality of degree of depth grades on one surface;

Fig. 2 (a) and (b) have represented that respectively the multidigit that constitutes conversion equipment of the present utility model is worth the substrate that ceases element mutually mutually, and the step cutting pattern that is etched with a plurality of degree of depth grades on one surface distributes;

Fig. 3 is for constituting the structural representation of conversion equipment of the present utility model, and its working method is a transmission-type;

Fig. 4 is for constituting the structural representation of conversion equipment of the present utility model, and its working method is reflective;

Fig. 5 is for constituting the structural representation of conversion equipment of the present utility model, and its working method is reflection, transmission-type;

Fig. 6 is for constituting the work synoptic diagram of the beam expander system (telescopic system) in the converter of the present utility model.

Fig. 7 is worth the fundamental diagram that ceases element mutually mutually for two multidigits that constitute in the converter of the present utility model.

In Fig. 3,4,5,1 is incident beam, and 2 is the beam expander system, and 3 and 4 are respectively the transmission-type multidigit is worth mutually and ceases element mutually, and 5 is outgoing beam; 3 and 4 are respectively reflective multidigit is worth mutually and ceases element mutually;

In Fig. 6,21 is first lens in the beam-expanding system, 22 is second lens wherein, f1, f2 represent the focal length of first lens and second lens respectively, D1 and D2 represent the bore of incident beam and outgoing beam respectively, and relation: D1:D2=f1:f2 arranged, change f1 or f2 and just can obtain the ratio of incident beam and outgoing beam and bore arbitrarily.

In Fig. 7,3,4 represent that respectively first ceases element mutually and cease element mutually with second, L is two distances that cease mutually between the element, P is first radius variable that ceases element mutually, p(u) be the function of u variable, u second ceases the radius variable of element mutually, u(p) is the function of p variable, and Z is a transverse axis.If Q is first phase function that ceases element mutually, φ is second phase function that ceases element mutually, and to establish two phase functions that cease element mutually be center of circle symmetry, and then first rate of change that ceases the component position phase function mutually is:

(dQ（p）)/(dp) ＝ (2π)/(λ.L) ［u（p）－p］

And second rate of change that ceases the component position phase function mutually is:

(dQ（u）)/(du) ＝ (2π)/(λ.L) ［u－p（u）］

For different wavelength X, can make λ .L value by change L is a constant, with a tight waist at the λ irradiating light beam like this, λ irradiating light beam bore, under the fixed situation of outgoing beam bore, make the dQ(p of different wavelength)/dp and dQ(u)/du equates, reached as long as adjust two distances that cease mutually between the element, just applicable to the requirement of different wave length.

Embodiment:

When taking the master hologram of embossed hologram, the laser instrument of employing can be that nitrogen cadmium laser, wavelength are about 4416

(about 0.4416 micron), for a beam-expanding system laser beam being expanded to about 75mm for about 0.8mm from the with a tight waist of Laser Output Beam, the expansion beam ratio is 0.8:75, i.e. the ratio f1:f2=0.8:75 of the focal length of two of beam-expanding system transmissions.This moment, beam intensity still was a Gaussian distribution, adopted two 16 and was worth element mutually, and every bore is about φ 75mm.Every piece element surface etch has the annular stepped profile, first ceases element mutually and makes the beam intensity homogenising, second ceases the element standard mutually and has been worth outgoing beam, make it become directional light, two distances that cease mutually between the element are 500mm, the diameter of the light beam of output is the directional light that the uniform strength about φ 75mm distributes, and 3 as hologram shooting center reference light or thing light.

Press the above-mentioned parameter design, the element of breath mutually that Gaussian beam is converted into uniform beam of making, the Gaussian beam that can be used for the laser beam of nitrogen neon light device (wavelength is 0.6328 micron) is converted into uniform beam.As the flat 1.5mm that is with a tight waist of light of nitrogen neon laser device, the expansion beam ratio that then changes beam-expanding system is 1.5:75, makes output beam still be φ 75mm.Change two distances that cease mutually between the element simultaneously, change 0.4416X40/0.6328 into, just can make the output beam of nitrogen neon laser device be converted to even distribution, still can get very high effect from Gaussian distribution from original 500mm.Avoided redesign, making to cease element mutually, the minimizing expense has reduced cost, has improved the versatility of device.

Claims

1, a kind of equally distributed conversion equipment of laser beam intensity that makes, it is characterized in that it mainly is worth mutually by a beam expander system and two multidigits ceases element mutually and constitutes, on the described surface that ceases element mutually, be etched with the step distributed structure of two or more degree of depth grades, described two multidigits are worth mutually and cease the coaxial use of element mutually, and standoff distance (L).

2, device as claimed in claim 1, it is characterized in that described beam expander system comprises first lens, (f1), (f2) be respectively the focal length of two lens, (D1), (D2) be divided into the bore of incident and outgoing beam, and following relation: D1:D2=f1:f2 is then arranged between them.

3, device as claimed in claim 1 is characterized in that described two rate of change that cease the component position phase function mutually are respectively:

(dQ（p）)/(dp) ＝ (2π)/(λ.L) ［u（p）－p］

(dQ（u）)/(du) ＝ (2π)/(λ.L) ［u－p（u）］

In the formula: (p) (u) represents that respectively first, second ceases the radius variable of element mutually, and Q, φ represent that respectively first, second ceases the phase function of element mutually, (L) is two distances that cease mutually between the element, (λ) is wavelength.

4, device as claimed in claim 1 is characterized in that described two cease element mutually and can be transmission-type, reflective or a slice is reflective and another sheet is a transmission-type.

5, device as claimed in claim 1 is characterized in that described two cease element mutually and also can adopt a slice all to be etched with the device of step distributed structure on two surface.

6,, it is characterized in that described transmission-type ceases element mutually and can adopt visible light permeable material to make, as simple glass, optical glass, quartz glass, organic glass, resin or visible light permeable macromolecular material as claim 1,4 or 5 described devices.

7, as claim 1,4,5 described devices, it is characterized in that the described reflective element that ceases mutually can adopt the metal material manufacturing, as copper, aluminium, zinc, chromium or semiconductor material, and plate the metal of one deck high reflectance on its surface, as gold, silver, aluminium or chromium.

8,, it is characterized in that to be etched with on described one or two parallel surface that ceases element mutually the rectangle or the annular stepped profile structure of two or more degree of depth grades as claim 1,4 or 5 described devices.