我們以掃描式近場光學顯微鏡(Near-Field Scanning Optical Microscope, NSOM)探討光穿透金屬奈米狹縫的行為。藉著量測在不同穿透距離下的二維穿透強度分佈，我們分析穿透光束的強度、半高寬及截面強度。我們在TM偏振入射時，光經過金屬奈米狹縫結構後，在適當距離內會形成不發散的平行光。然而，以TE偏振入射時，其出射光很明顯的有發散現象，此結果證明表面電漿扮演重要的角色。將NSOM影像與SEM影像比對分析，我們研究狹縫裡殘留的蝕刻殘餘物對於穿透光的影響。最後，我們量測了不同長度的奈米狹縫結構，來探討狹縫長度對於穿透光特性的影響。

We present transmission light behaviors from nano-metal-slits by near-field scanning optical microscope (NSOM). By measuring the contour intensity distributions at different transmission distance, we obtain the integrated intensity, full width at half maximum (FWHM) of transmitted light. When a TM-polarized light at 440nm is normally incident to the nano-metal-slits, a perfectly collimated beam without divergence can be generated at an appropriate distance after the metal-nano-slits.
In contrast, the transmission light will diverge obviously when TE-polarized light incidence. It can be demonstrated that the surface plasmon plays an important role. We also investigate the effects of etching residues existing in the slits by comparing the NSOM and SEM results. Finally, we measure the different lengths of the nano-metal-slits, and explore the impact of the slits length for the transmittance on the optical beams.

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