Application of Optical Tables

With the development of advanced equipment and processes, nanometer-scale measurements are possible. For example, phase-change optical interferometers measure the surface roughness of objects and can currently achieve a resolution of 1 nanometer. In the field of semiconductors, integrated circuits with line widths in the sub-micron order have been produced, and the precision requirement of measurement accuracy of less than 50 nanometers has been proposed.

Such applications place extremely high demands on the relative accuracy and stability of the different components in the system. For example, in an imaging system that uses a microscope to perform highly magnified images, the microscope and photographic objective together determine the image of each point on the photographic paper. If every part of the optical system (illumination system, sample, microscope optics, imaging optics, and paper plane) moves precisely together during exposure, there is no relative displacement, and the image will be sharp. If the sample moves relative to the objective, the image will be blurred. Controlling relative motion is important in optical interferometry, holography, and the application of similar motions.

Inside an ideal rigid body (which exists only in theory), the relative positions of any two points are constant. That is, the size and shape of any entity remain constant in the presence of vibrations, static moments, or temperature changes. If all the elements are firmly connected to form an ideal rigid body, with no relative displacement between the different elements, the performance of the system will also be stable. The ideal rigid body does not exist, and the real system can only be regarded as rigid approximately. Therefore, its stability is affected by many factors. For example, the external vibration source, the weight of the system, the structure of the optical table and so on.
In order to improve the stability of the system, we can start from the following aspects.

1. Isolate the system from the vibration source.
There are many sources of external vibration sources, such as the natural vibration of the ground, various sounds and so on. But the most influential are the various low-frequency vibration sources, mainly concentrated in the frequency of 10 ~ 100Hz. Isolating the system from these vibration sources can effectively improve the stability of the system. The air spring support with large damping can better isolate the system from the vibration source.

2. Control the effect of vibration.
Assembling the system into a dynamic rigid structure can ensure the relative stability inside the system, and can reduce the probability of resonance under the influence of the outside world, and improve the stability of the system.

3. Controls the effect of static torque.
The hard-to-weight ratio of an optical table has an important effect on its resonant frequency. A higher stiffness-to-weight ratio can increase the resonant frequency of the platform, thereby reducing its vibration under external influences. Moreover, under the action of external force, the platform with a higher stiffness-to-weight ratio can produce the least deformation under the smallest weight, increasing the rigidity inside the system. The optical table with the honeycomb support structure inside can fully improve the ratio of hard to weight and achieve the purpose of improving the performance of the system.

4. Control temperature changes.
Over time, irregular temperature changes cause gradual structural bending. The key to reducing temperature effects is to control the environment to reduce temperature changes. For example, avoid placing heat dissipation equipment under the platform, and isolate heat source equipment and hardware, such as light sources, flames, etc.

5. Design tables as insensitive to temperature as possible.
Good thermal conductivity can play a role, however, in extremely special applications, special materials that do not change their dimensions with temperature are necessary. For example, super-inflexible steel has a very small coefficient of thermal expansion. A meter of super-inflexible steel expands to a length of about 0.2 microns when the temperature changes by 1K. The optical table we provide adopts the surface ferromagnetic stainless steel and the structure is supported by the core honeycomb structure. This structure not only gives full play to the advantages of ferromagnetic stainless steel material with good rigidity, small thermal expansion coefficient and corrosion resistance, but also improves the hard-to-weight ratio of the platform, increases the rigidity, reduces the amount of deformation, and improves the ability to resist a static moment. . Moreover, the ferromagnetic stainless steel is corrosion-resistant and can absorb the magnetic base, which can easily build various optical systems. It is suitable for systems with large loads and high requirements for vibration resistance.

The optical plates we offer are made of high-quality aluminum. Compared with steel, aluminum has a large hardness-to-weight ratio, has certain vibration resistance, good temperature conductivity, small temperature deformation in adverse environments, beautiful appearance after anodizing, and wear-resistant, but aluminum has poor rigidity and cannot bear large loads.  Therefore, it is generally used in systems with smaller loads. And it should not be suspended using.