He Jinping, Miyazaki Jun, Wang Nan, Tsurui Hiromichi, Kobayashi Takayoshi
Opt Lett. 2015 Apr 1;40(7):1141-4. doi: 10.1364/OL.40.001141.
Nonlinear photothermal microscopy, in which the intensity of the pump heating beam is modulated at f and the photothermal signal is extracted from the probe beam with a lock-in amplifier referred to 2f, is applied to the imaging of mouse melanoma without any staining. The pump and probe pulses, with central wavelengths of 488 and 632 nm, and a pulse duration of ∼100 ps, are filtered from a compact commercial supercontinuum fiber laser source. An auto-balanced detector is applied to accumulate the signal and remove the laser noise of the probe. The spatial resolution of the nonlinear photothermal imaging is enhanced by ∼18% in both theoretical calculations and experiments, compared with a linear photothermal mechanism, and the resolution enhancement is theoretically ∼42% compared with conventional optical microscopy. This imaging technique shows possibilities for the clinical evaluation of melanoma with a high contrast and spatial resolution.
非线性光热显微镜中，泵浦加热光束的强度以频率f调制，光热信号通过锁相放大器从探测光束中提取，该锁相放大器的参考频率为2f，此技术被应用于小鼠黑色素瘤的无染色成像。泵浦脉冲和探测脉冲的中心波长分别为488和632nm，脉冲持续时间约为100 ps，它们是从紧凑的商用超连续光纤激光源中滤波得到的。采用自动平衡探测器来积累信号并去除探测光的激光噪声。与线性光热机制相比，在理论计算和实验中，非线性光热成像的空间分辨率均提高了约18%，与传统光学显微镜相比，理论上分辨率提高约42%。这种成像技术显示出在黑色素瘤临床评估中具有高对比度和空间分辨率的可能性。
