With the custom-made low-energy electron point projection microscope (PPM) and the single atom emitters which have the characteristics of high brightness and coherence, interference fringes have been investigated, and diffraction patterns could also be observed without any lens. In the first part, carbon nanotubes is used as the sample for the observation of the interference fringes induced by the biprism effect. When the tip-sample distance fixed, the fringe spacing decrease, and the region with regularly-spaced fringes increases as the tip bias increases. Combining with the simulation results, the induced charge density also increases as the tip bias rises up. This result reveals that the biprism effect will gradually dominate the formation of interference fringes as the tip-sample distance decreases below a certain value.
In the second part, we redesign the instruments for diffraction experiments. A piece of suspended graphene replaces carbon nanotubes as the sample. With the thin enough graphene, the diffraction patterns can be obtained easily in our lensless instrument by adjusting the position of detector (retractable MCP). The symmetrical hexagonal diffraction spots are clearly observed on the detector, which can be acquired with a CCD camera using a short exposure time about a few seconds.

本論文是利用自製低能量電子點投影顯微儀搭配具有高亮度及高同調性之單原子針觀察由電子束引起的干涉條紋，及在沒有任何透鏡的情況下 取得繞射圖形。首先，我們利用奈米碳管當做樣品以觀察由感應電荷引起的干涉條紋。固定針和樣品之間的距離，藉由增大加在針上的偏壓，不只干涉條紋的間距會受到影響而變小，具有等寬條紋的區域也會因而擴大。搭配理論模擬可得知奈米碳管上的感應電荷密度也隨著加在針上的偏壓增加而增加。由此可知當真和樣品之間的距離逐漸減少時，電荷感應效應會逐漸主導且成為干涉條紋的形成主要原因。
在第二個部分，我們改變部分的儀器架構以利於進行繞射實驗。在繞射實驗中，我們選擇利用懸掛在樣品支架中的單層石墨烯當做繞射實驗的樣品。藉由調整伸縮式的光電倍增板至適當的位置，即可觀察到單層石墨烯的繞射圖形。不需藉助任何透鏡的調整，只需曝光數秒鐘就可以得到六角型對稱的繞射圖形。

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