A parabolic multilayer mirror as an X-ray optical device has been applied to general-purpose X-ray diffractometers since the 1990s. X-rays formed by such a device are of high brightness, of small divergence and adequately monochromated. This device enables us to use high-quality parallel X-rays even in laboratories. Also, this device makes channel-cut 2-bounce beam-conditioner optics more effective, and various measurement techniques for a variety of samples, either powder materials or thin films, are more easily performed with general-purpose X-ray diffractometers. On the other hand, the most popular optic for powder X-ray diffraction is a conventional Bragg–Brentano para-focusing optic (BB optic), due to ease of setup, high intensity, and high angular resolution. Therefore, general-purpose X-ray diffractometers can be more effectively used if both of these optics, parallel beam (PB) optic and BB optic, can be switched easily.
Rigaku has developed and patented a CBO (Cross Beam Optics) unit that can switch a BB optic and a PB optic using a parabolic multilayer mirror by simply changing the selection slit. Subsequently, the “CBO-E” unit, which has a multilayer mirror forming a convergent beam, was marketed to accommodate diverse measurement needs. In recent years, the “CBO-α” unit, which creates a divergent beam, has been also developed.
In this report, we introduce the features and applications of each member of the CBO unit series to help SmartLab users achieve effective X-ray diffraction measurements and high-quality data acquisitions for precise analyses.