Development of photomechanical sensor for measurement of deposition thickness using optical fiber

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(1)Fundamental experiments on Au or Ag deposition・・・The resonance frequencies were measured as a function of the deposition thickness of Au and Ag using a quartz core microcantilever fabricated from an optical fiber in an ion sputtering apparatus. The resonance frequencies monotonously decreased with increase in deposition thickness in both Au deposition and Ag deposition. The rates of decrease were about 0.015% / nm in Au deposition and about 0.009%/nm in Ag deposition. Overall tendencies of experimental values and calculated values applying the theory related to the flexural vibration of a cylindrical composite beam were similar.(2)Effects of cantilever size・・・Effects of cantilever size were discussed. Deposition thickness dependence of resonance frequency was measured on three cantilevers with different length and almost the same diameter. Relative rates of resonance frequency shifts of them didn't depend on the length of their cantilevers. Since measurement accuracy for deposition … More thickness is determined by a product of resonance frequency and its relative rate, the length of the cantilever should be shorter in order to obtain a better accuracy.(3)Automatic measurement of resonance frequency of the cantilever・・・Automatic measurement of resonance frequency of the cantilever was tried using personal computer which controled the frequency for excitation the cantilever and input vibrating signal. The scattering of resonance frequencies became about 80%. and time required for measurement became shorter compared with former way.(4)Measurement of deposition thickness by thin glass vibrator installed with micro-ball lens in FC connector・・Thin glass vibrator deposited Cr and Au was fixed at the tip of PC connector with micro-ball lensin. The resonance frequency as a function of depositon thickness could measured without optical adjustments. Resonance frequency of the glass vibrator with 5mm in length, 2mm in width and 135 mu m in thickness decreased 37Hz from 3.28kHz during deposition of Au 5OOnm. The average rate of resonance frequency shifts was 0.0741Hz/nm in the region.(5)Deposition thickness measurements for some deposition materialsResonance frequencies of quartz core cantilevers with almost same size (30mu m in diameter and 2.2mm in length, resonance frequency before deposition was about 5kHz) were measured with deposition thickness of Au, Ag, Mo and Cr. Bigger resonance frequency shift was obtained in case of deposition material with higher density. Resonance frequency shifts were almost caused by only increace in additional mass of the cantilever not the elasticity of deposition materials. Less