research on white light reconstruction holography and its application to thermal flow diagnosis

• Main Authors: lin, kuo-wei, 林國偉
• Other Authors: Sheng-Mao Tieng
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/93543499788914742745

碩士 === 國立成功大學 === 航空太空工程學系 === 85 === The purpose of this research is to apply the white light reconstruction technique on the double-exposure holographic interferometry of phase objects. Here are two white light reconstruction techniques.They are the one-step rainbow technique and the volume reflection technique. Where the method to make white light reconstruction of one-step rainbow hologram is using the property of spatial filtering. The method to make white light reconstruction of volume reflection hologram is using the Bragg effect of three-dimensional gratings to filter light of different wavelengths. I choose volume reflection hologram as the white light reconstruction technique to apply on double-exposure holographic interferometry of phase object according to the light amplitude where the hologram displays. In double-exposure holographic interferometry ,interference takes place between the wave fronts reconstructed by two holograms of the object recorded on the same photographic plate. In this experiments ,the first exposure is made with the phase object in its initial state ,and the second is made when the phase object was heated. In this research using the He-Ne laser as the recording light source. White light as the reconstruction light source. Agfa 8E75 as the recording material. The phase object(test section) of the holographic interferometry is the air which light pass through in dark room. The phase difference at any point in the interference pattern is due to the variation of the refraction index of the two exposures.The case which can be analytic treated is that the refractive index distribution which is radial symmetric about an axis normal to the line of sight. Here I use a three-order function to map the radial symmetric refraction index of air . Under a simple calculation process compared with the numerical analysis ,I got a similar temperature distribution with the data measured directly by thermocouple.