Imaging characteristics of an 8.8 mm long and 125 μm thick graded-index short multimode fiber probe.
Imaging characteristics of an 8.8 mm long and 125 μm thick graded-index short multimode fiber probe.
复制标题
8.8 mm 长、125 μm 渐变厚折射率短多模光纤探头的成像特性。
作者：
M. Sato;K. Shouji;D. Saito;I. Nishidate
我们证明了具有50 μm芯径、125 μm总直径和8.8 mm长度的多模光纤成像探头的可行性，这是一种典型的用于光通信的渐变折射率多模光纤。利用ABCD矩阵对成像条件和放大倍数进行了分析，得到了与测量结果吻合较好的结果。在730 nm波长下计算的横向分辨率为1.2 μm，这反映了在730 nm波长下测量的周期为4.38 μm的图像测试图案。在物镜透镜的数值孔径中，我们实验评估了放大率和耦合效率之间的折衷。在540 nm、632 nm、730 nm和852 nm四个波长下，研究对比度和信号强度对波长的关系，以表明632和730 nm下的对比度相对较高。通过使用薄的随机相位屏模型，我们解释了随着波长减小，在较高的空间频率下光学传递函数的减小越大。使用635 nm LED光源，我们对接触的鸡肌腱表面进行成像，表面粗糙度可见。
We demonstrated the feasibility of an ultrathin imaging probe with a 50-μm core diameter, a 125 μm total diameter, and an 8.8 mm length, which is a typical graded-index multimode fiber for optical communications. We used an ABCD matrix to analyze the imaging conditions and magnification, which corresponded closely to the measured results. The lateral resolution was calculated at 1.2 μm with a wavelength of 730 nm, which reflects the image test pattern where a period of 4.38 μm was measured with a wavelength of 730 nm. In the numerical aperture of the objective lens, we experimentally evaluated the tradeoff between the magnification and the coupling efficiency. At four wavelengths of 540 nm, 632 nm, 730 nm, and 852 nm, the contrast and signal intensity versus the wavelength were investigated to show that the contrast at 632 and 730 nm is relatively high. By using a thin random phase screen model, we explained that as the wavelength decreases the greater the decrease in the optical transfer function at higher spatial frequencies. Using a 635 nm LED light source, we imaged the surfaces of chicken tendons in contact and the surface roughness was visible.