Optical Inertial Reference Units (IRU's)

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An optical Inertial Reference Unit (IRU) creates a stable pseudo star in the field of view of long-range optical systems to enable precision pointing and tracking.
	All advanced aerospace laser and imaging optical control systems have three requirements in common: line-of-sight (LOS) jitter suppression, inertial attitude knowledge and precision pointing. At sub-microradian levels of pointing precision, significant disturbances to the line-of-sight originate within the optical system itself. To sample and correct for these errors requires the creation of an optical reference in inertial space, similar to a fixed star. Such an optical reference allows detection and correction of internal jitter sources along the optical train.
	ATA has developed unique MHD angular rate sensors with nano-radian resolution, 1 – 1000 Hz frequency response and low linear sensitivities to accurately detect vibrations which cause jitter in the optical system. Our IRU’s also incorporate precision displacement sensors that measure platform motions to sub-nanometer levels and high efficiency actuators to maintain platform stability in the presence of environmental disturbances in a variety of systems for airborne and space systems. ATA expertise in closed loop real-time control systems allows cancellation of the jitter to maintain precision pointing of the reference laser beam. ATA also develops adaptive optical systems and fast steering mirrors to compensate for optical system jitter in mirror sizes from 1 inch to 12 inch.
	ATA enables precision pointing of long-range optical systems and can tie the system to IMU’s or incorporate gyroscopes to provide exact inertial knowledge. Precision pointing directly relates to the ability of the optical IRU to support the far-field tracking capability of the objective system. Field of Regard is the total angular range of travel the stable platform can be externally commanded relative to the base. Peak Angular Acceleration: is the maximum angular acceleration that the stable platform can be externally commanded relative to the base. Peak Angular Rate is the maximum angular rate that the stable platform can be externally commanded relative to the base. Examples of ATA developed state-of-the-art systems are shown below.
	For details on the MIRU II and MIRU III models of Optical Inertial Reference Units, click here.