Fukuma Takeshi
Frontier Science Organization, Kanazawa University, Kakuma-machi, 920-1192 Kanazawa, Japan.
Rev Sci Instrum. 2009 Feb;80(2):023707. doi: 10.1063/1.3086418.
I developed a wideband low-noise optical beam deflection sensor with a photothermal cantilever excitation system for liquid-environment atomic force microscopy. The developed sensor has a 10 MHz bandwidth and 4.7 fm/sq.rt.Hz deflection noise density in water. The theoretically limited noise performance (i.e., the noise level limited only by the photodiode shot noise) has been achieved in liquid for the first time. Owing to the wide bandwidth and the replaceable focus lens design, the sensor is applicable to cantilevers with various dimensions. The deflection noise densities of less than 7.8 fm/sq.rt.Hz have been achieved in water for cantilevers with lengths from 35 to 125 microm. The ideal amplitude and phase versus frequency curves without distortion are obtained with the developed photothermal excitation system. The excitation system is applicable to relatively stiff cantilevers (>20 N/m) in liquid, making it possible to obtain true atomic-resolution images in liquid. True atomic-resolution imaging of mica in water is demonstrated using the developed deflection sensor and the photothermal excitation system.
我开发了一种宽带低噪声光束偏转传感器，它带有用于液体环境原子力显微镜的光热悬臂激发系统。所开发的传感器在水中具有10 MHz的带宽和4.7 fm/√Hz的偏转噪声密度。首次在液体中实现了理论上有限的噪声性能（即仅受光电二极管散粒噪声限制的噪声水平）。由于带宽宽且聚焦透镜设计可更换，该传感器适用于各种尺寸的悬臂。对于长度为35至125微米的悬臂，在水中已实现小于7.8 fm/√Hz的偏转噪声密度。使用所开发的光热激发系统获得了无失真的理想幅度和相位与频率曲线。该激发系统适用于液体中相对较硬的悬臂（>20 N/m），从而有可能在液体中获得真正的原子分辨率图像。使用所开发的偏转传感器和光热激发系统展示了在水中云母的真正原子分辨率成像。
