CN104407435A - Large-correction-quantity low-order deformable reflector - Google Patents

Abstract

The invention discloses a large-correction-quantity low-order deformable reflector, which consists of a mirror surface, a coupling structure, a driver and a base, wherein the coupling structure comprises the following components in parts by weight: one end of each driver is fixed on a massive integral base, and the other end of each driver is connected with the mirror surface through a coupling structure. The mirror surface is made of a monocrystalline silicon material with ultra-high finish polishing, so that the high reflectivity and the low absorption coefficient of the coating film are ensured; the driver consists of a plurality of layers of piezoelectric ceramic plates or electrostrictive ceramic plates; the mount and mirror are made of the same material to match their coefficients of thermal expansion. The coupling structure acts as a flexible connection to adjust the local tilt of the mirror. When working voltage is applied, the coupling structure reduces the bending rigidity of the driver, improves the deflection capability of the mirror surface, increases the stroke of the deformable mirror, increases the interconnection value between adjacent drivers, and enhances the low-order correction capability of the deformable mirror, thereby meeting the correction requirement of a high-power laser emission system.

Description

A Low-Order Deformable Mirror with Large Correction Amount

technical field

The invention belongs to the technical field of wavefront correction of an adaptive optics system, and relates to a low-order deformable reflector with a large correction amount, which is used for an adaptive optics system for emitting laser light, and can correct atmospheric thermal halo effects, tidal current disturbances, and laser intracavity errors and errors caused by optical system errors.

Background technique

Deformable mirrors are one of the core components of adaptive optics systems. It achieves wavefront control and optical aberration correction by changing the surface shape. Deformable mirrors have important applications in laser processing, laser emission and long-distance transportation, and focusing systems. They are key technologies for adaptive control of laser beam quality and focusing characteristics.

Regardless of the gas chemical laser or the solid-state laser, there is a large thermal deformation problem in the case of high power output. David et al. in the United States once proposed the chemical Lasers have aberrations of various spatial and temporal components, among which the aberration components of low spatial frequency account for the main component. In the article "Preliminary Results of Hartmann Wavefront Sensor for COIL Laser Beam Quality Measurement" by Xu Bing in China, 1996, Yang Ping The aberrations of gas chemical lasers and solid-state lasers were measured in journals such as OPTICS EXPRESS. The measurement results showed that due to thermal deformation and other reasons, there are a large number of large-scale low-order aberrations in the output beam of the laser. These aberrations are in the Zernike aberration It manifests as low-order components such as defocus and astigmatism. These low-order and large-scale aberrations need to be eliminated by adaptive optics compensation control, and the residual error after correction is required to be as small as possible.

The traditional discrete continuous surface deformation mirror described in patent ZL2007100833867 consists of a mirror, a driver and a base. The mirror and driver are connected directly, as shown in Figure 1. The driver produces axial expansion and contraction under the action of an applied voltage, thereby pushing the mirror surface to produce local deformation. The key performance specifications for discrete continuous surface deformable mirrors are travel and cross-link values. Under the premise of guaranteeing the cross-connection value of the mirror, the stroke of the mirror is limited by the allowable stress of the mirror surface. By matching and adjusting the thickness of the mirror surface and the rigidity of the actuator, the maximum stroke of the deformable mirror composed of Ф14 actuators arranged in an equilateral triangle with a spacing of 20.5 is 6um, the cross-linking value is 9.5%, which cannot meet the correction requirements of large low-order aberrations.

New types of deformable mirrors, such as bimorph deformable mirrors, can produce a large amount of correction aberration, and have a good low-order aberration correction effect. A detailed study of this deformable mirror found that the deformed mirror with this structure can produce more than 10um of deformation. The coefficients of expansion cannot be matched, making the mirrors very sensitive to temperature changes. In a high-power laser system, the temperature rise caused by the heating of the laser beam will cause a large deformation, which is not suitable for the field of laser beam control with high power density.

The present invention proposes a new type of large-correction low-order deformable mirror, which can obtain performance similar to that of a double piezoelectric deformable mirror, can produce large-correction aberrations, and has a good low-order aberration correction effect , at the same time, it has the characteristics of insensitivity to temperature changes, overcomes the shortcomings of traditional mirrors, and successfully solves the problem of low-order aberration correction in high-power lasers.

Contents of the invention

The purpose of the present invention is to design a new type of large correction amount low-order deformable mirror, which can not only produce large correction amount aberrations, but also has a good low-order aberration correction effect, and has the characteristics of insensitivity to temperature changes, successfully It is used in high-power laser emission system.

The technical solution adopted in the present invention is: a large correction amount low-order deformed mirror, which is composed of a mirror surface, a coupling structure, a driver and a base; the driver and the mirror surface are connected through a coupling structure, and the coupling structure is used as a flexible connection to adjust the mirror surface Local tilt; one end of the driver is fixed on the rigid base, and the other end is connected to the mirror through a coupling structure; the coupling structure acts as a flexible connection to adjust the local tilt and cross-link value of the mirror: when the operating voltage is applied, the coupling structure reduces The bending stiffness of the driver improves the deflection ability of the mirror surface and increases the stroke of the deformable mirror. At the same time, the coupling structure increases the cross-connection value between adjacent drivers and enhances the low-order correction ability of the deformable mirror.

Furthermore, the mirror is made of ultra-high-gloss polished single-crystal silicon.

Further, the driver is composed of multilayer piezoelectric ceramic sheets or electrostrictive ceramic sheets.

Furthermore, the same material is used for the mirror and the base to match their thermal expansion coefficients.

Compared with the prior art, this technology has the following advantages:

1) Compared with ZL2007100833867, the novel large-correction low-order deformed mirror disclosed in the present invention has a smaller bending stiffness of the driver (3) than the mirror surface (1), and the stroke of the deformed mirror is greatly improved, which solves the problem of high-power Large-scale aberration correction problems for lasers.

2) The novel large-correction low-order deformable reflector disclosed by the present invention uses the coupling structure (2) to increase the cross-connection value of the deformable mirror, which solves the problem of low-order correction of high-power lasers.

3) Compared with the double piezoelectric deformable mirror, the novel large-correction low-order deformable mirror disclosed in the present invention has the characteristic of being insensitive to temperature changes.

Description of drawings

Fig. 1 is a schematic structural diagram of a traditional discrete deformable mirror;

Fig. 2 is a structural schematic diagram of a double piezoelectric deformable mirror;

Figure 3 is a structural schematic diagram of a low-order deformable mirror with a large correction amount;

Figure 4 is a schematic diagram of the connection of a low-order deformable mirror with a large correction amount;

Fig. 5 is a schematic diagram of the arrangement of the 85-unit low-order large-correction deformable mirror.

In the figure, 1 is a mirror surface, 2 is a coupling structure, 3 is a driver, 4 is a base, and 5 is a driving layer.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

As shown in FIG. 3 , the large correction amount low-order deformable mirror is composed of four parts: a mirror 1 , a coupling structure 2 , a driver 3 and a base 4 . One end of the driver 3 is fixed on the rigid base 4 , and the other end is connected to the mirror 1 through the coupling structure 2 .

The coupling structure 2 is used as a flexible connection to adjust the local tilt and cross-link value of the mirror 1: when the operating voltage is applied, the coupling structure 2 reduces the bending stiffness of the driver 3, improves the deflection capability of the mirror 1, and increases the At the same time, the coupling structure 2 increases the cross-connection value between adjacent drivers 3, and enhances the low-order correction capability of the deformable mirror. In some cases, the coupling structure 2 should be made into an integral structure with the mirror 1 .

The mirror surface 1 is a continuous mirror surface 1, which is made of ultra-high-gloss polished single-crystal silicon material, which ensures high reflectivity and low absorption coefficient of the coated film layer. Mirror 1 and base 4 use the same material to match their thermal expansion coefficients.

The driver 3 is composed of multilayer piezoelectric ceramic sheets or electrostrictive ceramic sheets. The control voltage of the driver 3 is supplied to the interlayer electrodes. The top of each driver 3 is connected to the mirror 1 by a coupling structure 2 .

The specific implementation manner will be described below with reference to FIG. 4 .

A low-order large-correction deformable mirror includes a mirror surface 1, a coupling structure 2, a driver 3 and a base 4. One end of the driver 3 is fixed on the base 4 , and the other end is connected to the mirror 1 through the coupling structure 2 . When a voltage is applied, the driver 3 is displaced, and the mirror 1 is driven through the coupling structure 2 to undergo controllable local deformation. The coupling structure 2 reduces the bending stiffness of the driver 3, improves the deflection capability of the mirror 1, and increases the stroke of the deformable mirror. At the same time, the coupling structure 2 increases the cross-connection value between adjacent drivers 3, enhancing the low-order correction capability of deformable mirrors.

The 85-unit low-order large-correction deformable mirror developed and successfully applied in this way is shown in Figure 5. The driver is a Φ14 driver, the pole spacing is 20.5mm, and the stroke of the deformable mirror is 12um, which is doubled compared with the stroke of the traditional discrete deformable mirror; at the same time, its cross-link value is also greatly improved to meet the large correction amount and low-order aberration correction needs.

Parts not described in detail in the present invention belong to the known techniques of those skilled in the art.

Claims (4)

1. A large correction amount low-order deformable reflector is characterized in that: it is made up of mirror surface (1), coupling structure (2), driver (3) and base (4); The driver (3) and mirror surface (1) The coupling structure (2) is used as a flexible connection to adjust the local tilt of the mirror (1); one end of the driver (3) is fixed on the rigid base (4), and the other end is connected through the coupling structure (2). Connected to the mirror (1); the coupling structure (2) is used as a flexible connection to adjust the local tilt and cross-link value of the mirror (1): when the operating voltage is applied, the coupling structure (2) reduces the driver (3) Bending rigidity improves the deflection capability of the mirror surface (1) and increases the travel of the deformable mirror. At the same time, the coupling structure (2) increases the cross-connection value between adjacent drivers (3) and enhances the deformed reflection The low-order correction capabilities of the mirror. 2. A large correction amount low-order deformable mirror according to claim 1, characterized in that: the mirror surface (1) is made of ultra-high-gloss polished single-crystal silicon. 3. A low-order deformable mirror with large correction amount according to claim 1, characterized in that the driver (3) is composed of multilayer piezoelectric ceramic sheets or electrostrictive ceramic sheets. 4. A large-correction low-order deformable mirror according to claim 1, characterized in that: the mirror surface (1) and the base (4) use the same material to match their thermal expansion coefficients.