The Application of PZT & Piezo Tilt Mirrors in Light Field Control
Update time:2021-11-08 09:29:39Clicks:1287second
The light field is a vector function that describes the amount of light flowing through each point in space in various directions. Michael Faraday was the first to propose that light should be interpreted as a field, just like the magnetic field he has been studying for years. The term "light field" was coined by André Gershun in a classic paper on the radiation characteristics of light in three-dimensional space.
The ray represents the straight line of the propagation path and direction of the light. From science perspective, the ray is described by a five-dimensional plenoptic function: each ray is defined by three coordinates and two angles in 3D space to specify the direction that they are in 3D space.
Two Kinds of Light Field Control: Coherent Synthesis and Adaptive Optics
The light field control of coherent synthesis is generally completed by a polygonal plane mirror, while the light field control in adaptive optics is generally completed by a continuous, deformable mirror.
01
Coherent Combining-Light Field Control
Regardless of multiple factors, in simple terms, coherent combining is to output the laser array in the same phase to improve the brightness of the combined laser.
Coherent combination is to divide the beam into multiple sub-aperture beams and then perform coherent combination. However, in the process of light transmission, due to various reasons, such as thermal effects and other factors, the phase and direction of the light will change. The simplest, direct and quick way to solve this problem is to use a piezo tilt mirror, and control the tilt angle of the piezo tilt mirror by adding a piezo control signal to control the piezo tilt mirror.
The coordinated use of multiple piezo tilt mirrors increases the surface shape of the reflector, thereby increasing the light intensity.
Piezo Tilt Mirror: High Speed Piston Plus TiltThe piezo tilting mirror is driven by PZT piezo ceramics, which has the characteristics of fast response speed and high resolution. With the flexible hinge mechanism, it also has the features of no friction, no wear, small space size, high motion sensitivity, and easy control, stable operation and other advantages.
The inner part of CoreMorrow P32 fast steering mirror (piezo tilting mirror) is driven by three PZT piezo ceramics, which can produce high-speed millisecond-level Z-direction piston movement and θX, θY tilting movements.
The linear piston movement can quickly adjust the phase, optical path, etc. of the light, while the θX and θY tilt movements can quickly change the transmission direction of the outgoing light reflected by the reflective lens.
02
Adaptive Optics-Light Field Control
Adaptive optics is a technology that uses a deformable mirror to correct the distortion of the wavefront of light caused by atmospheric jitter, thereby improving the performance of the optical system. It also phase-locks the laser sub-beams to increase the brightness.
The more commonly used deformable mirrors in adaptive optics are generally piezo deformable mirrors, which are driven by piezo ceramic arrays. Among them, piezo ceramic arrays are divided into multilayer piezo ceramic arrays and single-layer piezo ceramic arrays. The most significant differences between the two driving methods are the driving voltage, output displacement and external dimensions.
Piezo Ceramic Array: High-Speed Piston MotionMulti-layer piezo ceramic arrays are widely used in piezo deformable mirrors because of their greater displacement and lower driving voltage.
The piezo deformable mirrors in different system structures have different requirements for the size and displacement of the piezo ceramic array, and the selected piezo ceramics have different parameters.
CoreMorrow has a variety of piezo ceramics, the external size can be as small as 1.22×1.3×1.7mm3.
Piezo Deformable Mirror Drive Power SupplyThe piezo ceramic units in the piezo deformable mirror range from dozens of units to hundreds of units, and driving so many capacitive ceramic units has strict requirements on power, voltage, number of channels, and external dimensions. This requires customizing a suitable deformable mirror drive power supply.
To meet the needs of piezo deformable mirror drive power supply, CoreMorrow has developed and designed a variety of piezo drive power supplies, with the number of channels up to several hundred channels. E82.A64K series piezo ceramic drive power is one of them.
Driven by the piezo deformable mirror drive power supply, each unit of the piezo ceramic array generates a corresponding displacement, so as to control the surface shape of the adaptive mirror surface.