Development of Photon Atomic Force Microscope

1)利用非接触式原子力显微镜和调频(FM)检测方法，在高真空条件下，测量了由瞬变场引起的力梯度。这种方法有两个优点。其一是作为力传感器的高灵敏度。另一种是可以在不受棱镜表面水膜毛细作用力影响的情况下估算局部力梯度。利用这种方法，我们测量了由瞬态场引起的力梯度距离曲线。我们测量了入射光强和偏置电压对由逝去场引起的力梯度的依赖关系。结果证实了表面光伏(SPV)模型。此外，利用SPV模型，我们解释了力梯度与距离和偏振的关系。2)我们提出了一种新的方法，利用非接触模式原子力显微镜结合频率调制检测方法，高分辨率地同时检测表面上的范德华力梯度和由光场引起的力梯度。通过施加偏置电压，可以增强由瞬逝电场引起的力梯度。得到直径为100 nm的聚苯乙烯乳胶球，空间分辨率优于50 nm(lambda/14)。悬臂梁的最小可检测频移为0.09 Hz，由此得到的力梯度和由瞬逝电场引起的力的最小可检测值分别小于3.8×10~(-5)N/m和0.66Pn。

1) By using the noncontact mode atomic force microscope with frequency modulation (FM) detection method in a high vacuum, the force gradient induced by the evanescent field was detected. There are two advantages of this method. One is high sensitivity as a force sensor. The other is that the local force gradient can be estimated without influence of capillary force due to water film on the prism surface. Using this method, we measured the force gradient distance curve induced by the evanescent field. We measured the incident beam intensity and bias voltage dependence of the force gradient induced by the evanescent field. As a result, we confirmed the surface photo-voltage (SPV) model. Furthermore, using the SPV model, we explained the results of the distance and polarization dependence of the force gradient.2) We demonstrated a novel method to detect the van der Waals force gradient and the force gardient induced by the optical evanescent field on the surface simultaneously with high resolution, using the noncontact mode atomic force microscopy with frequency modulation detection method. The force gradient due to the evanescent field could be enhanced by applying the bias voltage. Polystirene latex spheres with 100 nm diameter were observed with spatial resolution better than 50 nm (lambda/14). Minimum detectable frequency shift of the cantilever was 0.09 Hz, by which the minimum detectable values of the force gradient and force due to the evanescent field were estimated to be under 3.8x10^<-5> N/m and 0.66 pN,respectively.