1.怎样清理photdiode的表面呢？可参考这里： Although photodiodes in packages or in chip form are reasonably rugged, avoid touching the cell or package window with bare fingers. To clean a detector, any dust or loose particles should first be blown away using dry compressed gas. The detector surface or window can then be cleaned by using a lint free swab […]
1.在Optical Coherence Tomography – Technology and Applications的第27页中，提到： OCT imaging is performed with low numerical aperture focusing in order to have a large depth of field. 通常情况下，成像的焦深大于相干长度，这样就能保证在一定的深度下，系统能够实现相干成像。 2.在Optical Coherence Tomography – Technology and Applications的第29页中，提到： OCM images can be obtained at different depths by adjusting the focus depth while matching the reference arm path delay to the […]
1.在Optical Coherence Tomography – Technology and Applications的第10页中，提到： Using low-coherence length light, interference only occurs when the path lengths are matched to within the coherence length。 为什么要在OCT系统中使用弱相干光，就是为了获得较小的相干长度，而理论的轴向分辨率是相干长度的2倍。因此，这样就可以得到更小的轴向分辨率。补充一下相关内容： Low-coherence light can be characterized as having statistical phase discontinuities over a distance known as the coherence length, which is inversely proportional to the frequency bandwidth of the light. […]
1. ROLL AVG When a trace is set to ROLL AVG mode, each time measurement is performed the sweep average is taken of the current and past measured data, and the measurement data are updated. {W_j}(i) = {W_{j - 1}}(i) \cdot (n - 1)/n + W(i) \cdot 1/n i = 1,2, \cdots ,N. {W_j}(i): Newly […]
The user manual for AQ6370D Optical Spectrum Analyzer can be found here. I will list some notes or confusions I met during reading this manual. Fig.1. AQ6370D Optical Spectrum Analyzer. 1. The wavelength range of input light that can be auto-measured is 840–1670 nm. This is the auto-measured wavelength range. During the measurement, span width […]
1. What is FC/APC? “FC” means “fiber channel”, and “APC” stands for “angled physical contact”. Below is a FC/APC connector product from Thorlabs. These connectors allow the surfaces of two connected fibers to be in direct contact with each other and because the fiber end is polished at an angle to prevent reflected light from […]