CN103676187A - High-power laser image transmission low-pass spatial filtering device - Google Patents

Abstract

The invention discloses a high-power laser image transfer low-pass spatial filtering device, which is characterized by comprising the following components: the frequency dividing lens and the restoration lens form a confocal optical system, and the filtering aperture is positioned at the focal point of the confocal optical system between the frequency dividing lens and the restoration lens. The high-power laser image transmission low-pass spatial filter device can realize image transmission by adjusting the focal lengths of the frequency division lens and the recovery lens; the substrate material of the filtering small hole only absorbs little laser power, so that the filtering small hole does not need to be water-cooled, the structure of the filtering small hole is simplified, the damage threshold value is improved, the possibility that the filtering small hole is burnt by laser is basically eliminated, and meanwhile, the high-frequency component energy of the laser beam is rapidly reduced and the low-frequency component energy is almost unchanged by utilizing the scattering effect of the roughened surface of the filtering small hole on the laser beam, so that the low-pass spatial filtering function is better realized.

Description

High-power laser image transfer low-pass spatial filter device

technical field

The invention relates to the technical field of spatial filtering devices, in particular to a high-power laser image transmission low-pass spatial filtering device.

Background technique

In high power lasers, in order to obtain high power and high beam quality at the same time, the main oscillator-amplification system is used. In the above system, in order to improve the extraction efficiency of the laser beam, it is necessary to have a good spatial overlap between the laser beam and the laser gain region, and the method of image transfer is generally used to achieve high spatial overlap efficiency. The high-frequency component in the laser amplification process is easy to be amplified due to its high power density and high extraction efficiency, which may worsen the beam quality of high-power lasers, or form "optical nails" that will cause irreversible damage to high-power lasers. destroy. The spatial filtering device can filter out the high-frequency components in the laser amplification process, improve the beam quality of the high-power laser, and effectively protect the high-power laser. For this reason, various spatial filtering devices have been proposed, for example, a plano-convex lens made of quartz crystal, A laser beam spatial shaping device composed of filter pinholes, ordinary lenses and polarizers; another volume holographic grating shaping device, which can dynamically and multi-functionally shape ultrashort pulse laser beams; and a high-power diffraction spatial filter The device meets the needs of double-pass and two-axis spatial filtering for multi-pass amplification and inter-stage isolation in high-power laser systems. The above-mentioned filter device has obtained a good filter effect to a certain extent, but there are still some problems: such as the filter pinhole that is easy to be burned under the condition of high-power laser, and the diffraction-type original is difficult to meet the needs of image transmission, and the adjustment accuracy of the device is also low. Higher requirements.

Contents of the invention

(1) Technical problems to be solved

The technical problem to be solved by the present invention is to provide a high-power laser image transfer low-pass spatial filter device, which uses a The filter hole, its matrix material only absorbs a small amount of laser power, and does not need to be water-cooled for the filter hole, which simplifies the structure of the filter hole and increases the damage threshold. The energy of the high-frequency component of the beam decreases rapidly while the energy of the low-frequency component remains almost unchanged, which better realizes the low-pass spatial filtering function of the image transfer.

(2) Technical solutions

The present invention provides a low-pass spatial filter device for high-power laser image transmission, including: a frequency-division lens, a restoration lens, and a filter pinhole, wherein the frequency-division lens and the restoration lens form a confocal optical system, and the filter pinhole An aperture is located at the focal point of the confocal optical system between the frequency dividing lens and the restoring lens.

More preferably, the frequency division lens, restoration lens, and filter pinhole are on the same optical axis as the beam propagation direction; the base material of the filter pinhole is a material with an absorption coefficient of less than 0.5%/cm for high-power laser.

Preferably, the frequency division lens is arranged at a position where the low-frequency component of the incident laser beam passing through the filter pinhole is separated at the rear focal plane of the frequency division lens, and the desired incident laser beam is restored by the restoration lens. frequency components.

Preferably, the frequency division lens and the restoration lens are two convex lenses.

More preferably, the filter hole is made of a material with an absorption coefficient of less than 0.5%/cm for high-power laser light.

More preferably, the focal lengths of the frequency division lens and the restoration lens are equal, the front surface of the filter hole perpendicular to the optical axis where the laser light is incident is a textured surface, and its base material is fused silica.

Preferably, the focal length of the restoration lens is smaller than the focal length of the frequency division lens, and the rear surface of the filter hole perpendicular to the optical axis where the laser light is incident is a textured surface, and its base material is undoped yttrium aluminum garnet .

More preferably, the focal length of the restoration lens is greater than that of the frequency division lens, and the front or rear surface of the filter hole perpendicular to the optical axis where the laser light is incident is a textured surface, and its base material is sapphire.

Preferably, the aperture of the filter aperture is an adjustment aperture.

(3) Beneficial effects

The high-power laser image transmission low-pass spatial filter device of the present invention can realize different types of image transmission functions by adjusting the focal length of the frequency division lens and the restoration lens; the scattering effect of the laser beam on the textured surface can make the laser beam high-frequency The energy of the component decreases rapidly while the energy of the low-frequency component remains almost unchanged, which simply realizes the low-pass spatial filtering function. At the same time, the matrix material of the filter hole only absorbs a small amount of laser power, so there is no need for water cooling of the filter hole, which simplifies the filter The pinhole structure basically eliminates the possibility of laser burning the filter pinholes.

Description of drawings

FIG. 1 is a schematic structural diagram of a high-power laser image transfer low-pass spatial filter device in Embodiment 1 of the present invention;

2 is a schematic structural diagram of a high-power laser image transfer low-pass spatial filter device according to Embodiment 2 of the present invention;

FIG. 3 is a schematic structural diagram of a high-power laser image transfer low-pass spatial filter device according to Embodiment 3 of the present invention.

Detailed ways

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

Example 1

Fig. 1 is a schematic structural diagram of a high-power laser image transfer low-pass spatial filter device in Embodiment 1 of the present invention. As shown in Fig. Aperture 13, wherein the frequency division lens 11 and the restoration lens 12 constitute a confocal optical system, the frequency division lens 11 and the restoration lens 12 are two convex lenses; the filter aperture 13 is located in the division The focus of the confocal optical system between the frequency lens 11 and the restoration lens 12, the base material of the filter pinhole 13 is a material with an absorption coefficient of high-power laser less than 0.5%/cm, and the base material in this embodiment It is a fused silica material that can absorb high-power laser light; the front surface of the laser incident surface perpendicular to the optical axis of the filter hole 13 is a textured surface; The direction is the same as the optical axis.

Please refer to Fig. 1 again, the frequency division lens 11 is arranged so that the low frequency component 14 of the incident laser beam passing through the filter pinhole 13 is separated at the rear focal plane of the frequency division lens 11, and restored by the restoration lens 12. The frequency component of the required incident laser beam, adjust the distance between the restoration lens 12 and the frequency division lens 11, so that the focal lengths of the frequency division lens 11 and the restoration lens 12 are equal, and the incident surface 17 is formed on the exit surface 18. The image of the laser beam is formed to restore the laser beam 16, so as to realize the 1:1 image transfer function of the laser beam. The filter pinhole 3 is placed at the focal point of the confocal optical system, and its aperture can be adjusted to filter out the high-frequency component 15 of the incident laser velocity by means of the textured front surface to realize the low-pass filter function.

Example 2

Fig. 2 is a schematic structural diagram of a high-power laser image transfer low-pass spatial filter device in Embodiment 2 of the present invention. As shown in Fig. 2, the structure of this embodiment is basically the same as that of the high-power laser image transfer low-pass spatial filter device in Embodiment 1. The difference is that the focal length of the restoration lens 22 is shorter than that of the frequency division lens 21, and realizes the image transmission function of laser beam shrinkage. The base material of the filter aperture 23 is a material with an absorption coefficient of less than 0.5%/cm for high-power laser. The base material in this embodiment is undoped yttrium aluminum garnet, which is located at the focus of the confocal optical system. The rear surface of the incident laser beam perpendicular to the optical axis is a textured surface, and the high-frequency component 25 of the incident laser beam is filtered by the surface to realize the low-pass filtering function.

Example 3

Fig. 3 is a schematic structural diagram of a high-power laser image transfer low-pass spatial filter device in Embodiment 3 of the present invention. As shown in Fig. 3, the high-power laser image transfer low-pass spatial filter device of this embodiment and embodiment 1 and embodiment 2 The structures are basically the same, the difference is that the focal length of the restoration lens 32 is greater than that of the frequency division lens 31, and realizes the image transmission function of laser beam expansion. The base material of the described filter aperture 33 is a material with an absorption coefficient of high-power laser less than 0.5%/cm. The base material in this embodiment is sapphire, which is located at the focal point of the confocal optical system. The front or rear surface where the laser is incident is a textured surface, and the high-frequency component 35 of the incident laser beam is filtered out by the textured surface to realize the low-pass filtering function.

In summary, the high-power laser image transfer low-pass spatial filter device of the present invention uses the confocal frequency-division lens and the restoration lens combined with different focal lengths, the filtering holes of the low-absorption matrix material and the scattering effect of the textured surface, The image transfer and low-pass spatial filtering of high-power laser beams can be realized, so it has broad application prospects in national security, advanced manufacturing and other fields.

The above embodiments are only used to illustrate the present invention, but not to limit the present invention. Those of ordinary skill in the relevant technical field can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all Equivalent technical solutions also belong to the category of the present invention, and the scope of patent protection of the present invention should be defined by the claims.

Claims (8)

1. a high power laser light picture transmits low pass spatial filter arrangement, it is characterized in that, comprise: step lens, recovery lens and filtering aperture, wherein said step lens and described recovery lens form confocal optical system, the focus place of the confocal optical system of described filtering aperture between described step lens and described recovery lens.

2. high power laser light picture as claimed in claim 1 transmits low pass spatial filter arrangement, it is characterized in that described step lens, recovery lens and filtering aperture and the same optical axis of direction of beam propagation; The base material of described filtering aperture is for being less than the material of 0.5%/cm to high power laser light absorption coefficient.

3. high power laser light picture as claimed in claim 1 or 2 transmits low pass spatial filter arrangement, it is characterized in that, described step lens is arranged at the position that the low frequency component that makes the incoming laser beam of aperture is after filtering separated at the back focal plane of described step lens, restores the frequency component of required incoming laser beam by described recovery lens.

4. high power laser light picture as claimed in claim 3 transmits low pass spatial filter arrangement, it is characterized in that, described step lens and described recovery lens are two convex lens.

5. high power laser light picture as claimed in claim 4 transmits low pass spatial filter arrangement, it is characterized in that, the focal length of described step lens and described recovery lens is equal, and described filtering aperture is texturing surface perpendicular to the front surface of the laser incident of optical axis, and its base material matter is fused quartz.

6. high power laser light as claimed in claim 4 passes picture and passs low pass spatial filter arrangement, it is characterized in that, the focal length of described recovery lens is less than the focal length of described step lens, described filtering aperture is texturing surface perpendicular to the rear surface of the laser incident of optical axis, and its base material matter is doped yttrium aluminum garnet not.

7. high power laser light picture as claimed in claim 4 transmits low pass spatial filter arrangement, it is characterized in that, the focal length of described recovery lens is greater than the focal length of described step lens, and described filtering aperture is texturing surface perpendicular to the front or rear surface of the laser incident of optical axis, and its base material matter is sapphire.

8. high power laser light picture as claimed in claim 4 transmits low pass spatial filter arrangement, it is characterized in that, the aperture of described filtering aperture is adjustment aperture.

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