What is DBS?
According to FEI website: "a directional backscatter (DBS) detector simplifies interpretation of various contrast mechanisms. Backscattered electrons (BSEs) carry topographic, channeling, and compositional information. BSEs exiting the sample surface at high angles, close to the beam axis, carry more sample composition information. BSEs at lower angles, closer to the sample surface plane, provide more topographic information. The DBS detector includes four annular segments concentric with the beam, allowing it to discriminate BSEs by angle and capture comprehensive information in one scan. Select any or all segments, in any combination, to create the image that best meets analytical requirements while improving time to data, minimizing sample damage, and gaining unique insights into the sample."
The lens-mounted DBS detector on the Nano NovaSEM 650
The annular, Back-Scattered (BS) detector (called the DBS - Directional Back Scatter detector) is an ultra-sensitive, Solid State (SS) detector which is sensitive to emitted electrons from 500 V onwards. Using beam deceleration (sample bias to reduce the landing energy), images with beam landing energies down to 50 V are possible. Especially when Beam Deceleration is applied in combination with immersion field, it is possible to detect all BS electrons emitted up to 90 degrees.
The lens-mounted DBS detector features four annular segments that enable separate detection of electrons emitted at different angles. All four segments may be acquired simultaneously and mixing based on adding / subtracting individual segments is possible. This way it is possible to select multiple contrasts (material and topographical) that can be optimized per application.
This detector is mounted on a bayonet mount under the final lens and allows simultaneous EDS spectra acquisition for WD greater or equal to 5 mm. Fast imaging becomes possible with this detector.