The core principle of a laser interferometer is to utilize the interference of light. By measuring the change in the distance difference between two coherent light beams, it achieves high-precision measurement of physical quantities such as displacement, angle, and flatness. Specifically, it divides a laser beam into two: one follows a fixed reference light path, and the other follows the measurement light path of the moving object under test. When two beams of light meet again, interference fringes will be produced due to the path difference. Then, by calculating the changes in the fringes, the displacement, angle difference and surface flatness of the object being measured can be calculated.

Interference fringe

(Note: Image from online resources)

The accuracy of a laser interferometer cannot be achieved without the coordination of four core components:

1.Laser: The laser emission device is the foundation of the interferometer, used to provide a light source with extremely strong monochromaticity and coherence. Only when the light is stable can the accuracy of the measurement be guaranteed.

2.Main part of the interferometer: Responsible for beam splitting and combining, such as the Michelson interference structure, which determines the generation mode of interference fringes.

3.Detector: It captures the changes in interference fringes, converts optical signals into electrical signals, and serves as a monitor for reading measured values.

4. Positioning and adjustment system: Controls the minute postures of the reference mirror and the measuring mirror, such as angles and positions, as well as drives the movement of the object under test.

Among them, the role of the positioning adjustment system is extremely crucial, as the measurement accuracy of the laser interferometer can be significantly affected by even minor vibrations, optical path offsets, and environmental disturbances. For instance, even if the reference mirror is offset by 0.01 microns, the interference fringes will be distorted and the measurement result will be directly invalidated. This is like when observing cells under a microscope, if the objective lens suddenly moves or the stage shakes, the field of vision will become blurred. The laser interferometer measures nanoscale displacements, and the requirements for the positioning system are extremely strict.

CoreMorrow piezo nano-positioning technology provides a key solution for meeting the high-precision phase shifting requirements of laser interferometers. The measurement of a laser interferometer utilizes phase-shifting interferometry, which requires extremely precise, linear, and known phase steps. The piezo nano-positioning stage (PZT) precisely meets the requirements for displacement control with nanoscale precision within the micrometer range.

The piezo nano-positioning stage can be controlled by a piezo controller to easily achieve multiple (such as 4, 5, 7 times, etc.) equal-step phase shifts, quickly collect multiple interference patterns, and then calculate the precise phase distribution on the surface of the object under test through algorithms (such as phase shift algorithms), thereby obtaining its flatness information.

The Core Capabilities of CoreMorrow Piezo Technology Perfectly Meet the Requirements of Laser Interferometers:

1.Nanometer positioning accuracy

It features high positioning accuracy, meeting the minor adjustment requirements during the measurement process, and can perform sub-nanometer-level step phase shifting.

2.Millisecond response speed

The response time of the piezo nano-positioning stage can reach the millisecond level, and it can perform rapid equal-length step operations.

3.Ultra-high stability

The integrated structural design offers high rigidity and high load capacity, with a load capacity of up to over 25kg. It is suitable for phase shift adjustment of both small and large lenses.