An atomic force microscope for small cantilevers

We have designed and built an atomic force microscope (AFM) with optical beam deflection detection providing a focused spot size of 1.6 mu m in diameter. This small spot size was implemented with a variable focus adjustment that allows us to re-focus on each cantilever. This design opens up the usage of a new range of small cantilevers with low-noise characteristics. We have microfabricated novel aluminum cantilevers with dimensions as small as 9 mu m in length and 2.5 mu m in width and have characterized them with this new AFM. The resonance frequency of the smallest cantilever was 2.5 MHz in air and 0.94 MHz in water. We demonstrated the imaging capabilities of the AFM head by imaging abalone nacre with a 10 mu m long cantilever using the tapping mode in liquid at a drive frequency of 442 KHz.