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Adjustment Mechanisms
Published in Anees Ahmad, Handbook of Optomechanical Engineering, 2018
Hydrostatic bearings, which include both gas and oil bearings, are virtually free of friction and wear and have a negligible cross-axis runout. In optical systems, oil bearings are not commonly used because these are messy and present the risk of contaminating the optics. An optical system that requires an adjustment mechanism with a long travel range and high accuracy and load capacity can use a gas bearing. The pressurized gas is generally very clean and dehumidified air, but in some applications dry nitrogen or helium may be required. The main disadvantages of gas bearings are their cost and complexity. A remote and elaborate pumping and filtration system is required to supply clean and dry air. The design and fabrication of gas bearings is complex and expensive. The number and size of air jets, size of the air relief pockets, surface area of the bearing, and supply pressure of the air must all be taken into account when designing the air bearing for an application.
Adjustment Mechanisms
Published in Anees Ahmad, Handbook of Optomechanical Engineering, 2017
Hydrostatic bearings, which include both gas and oil bearings, are virtually free of friction and wear and have a negligible cross axis runout. In optical systems, oil bearings are not commonly used because these are messy and present the risk of contaminating the optics. An optical system that requires an adjustment mechanism with a long travel range and high accuracy, stiffness, and load capacity can use a gas bearing. The pressurized gas is generally very clean and dehumidified air, but in some applications, dry nitrogen or helium may be used. The main disadvantages of gas bearings are their cost, size, and design complexity. A remote and elaborate pumping and filtration system is required to supply clean and dry air or nitrogen. The design and fabrication of gas bearings is complex and expensive. The number and size of air jets, size of the air relief pockets, surface area of the bearing, and supply pressure of the air must all be taken into account when designing the air bearing for an application.
Polygonal Scanners: Components, Performance, and Design
Published in Gerald F. Marshall, Glenn E. Stutz, Handbook of Optical and Laser Scanning, 2018
The polygonal mirror requires a bearing system and a drive mechanism to turn it into a functional scanner. Drive mechanisms include pneumatic, AC hysteresis synchronous, and brushless DC. Bearing systems used in most applications are ball bearing, aerostatic air bearings, or aerodynamic air bearings.
An effective approach to identify the mass properties of a satellite attitude dynamics simulator
Published in Australian Journal of Mechanical Engineering, 2020
Ghasem Sharifi, Ehsan Zabihian
The satellite simulators commonly use air bearing to simulate frictionless and microgravity space environments. In the air bearing, compressed air passes through the pores on the bearing surface and creates a thin layer of air that endures the weight of movable parts as will not cause any shear stress on the bearing. Generally, these bearings are classified in two types of planar and spherical. The planar air bearing systems are capable of providing one rotational and two translational degrees of freedom and they are often used for simulation of formation flying, rendezvous and docking. Due to the capability of providing three-degree-of-freedom (3DOF) rotational motion, spherical air bearing systems are used for satellite attitude control simulations (Kim and Agrawal 2009).