| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2003: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2002: ¥1,600,000 (Direct Cost: ¥1,600,000)
|
|---|
| Research Abstract |
A measurement method for displacement of micrometer-order using ultrasonic wave of 40kHz in air is newly proposed and evaluated experimentally. The displacement of an reflector is measured from the phase difference φ between the transmitting and received ultrasonic wave signals using a single transducer by reflection method. For detection of displacement under a thousandth of wavelength ~of ultrasonic wave, a novel measurement method of the phase difference φ between the transmitting and received signals is described. The reference signals, of which the number is N, are introduced in this method. The reference signals are locked in the transmitting signal to constant phase differences θ_i(i=0,1,2,...,N) within the range of 0 to 2π. The phase differences ψ_i(i=0,1,2,...,N) between the received signal from the transducer and the reference signals are obtained by phase detection. The displacement is calculated from the phase difference φ which is estimated by the least squares method with the phase differences ψ_i. The displacement measurements based on our method were carried out using ultrasonic wave of 40kHz in air with piezoelectric ceramic transducer. The displacement of 1μm steps of the reflector, which can be translated with 10nm-order accuracy by mechanical translation stage, is measured. The relation ship between the displacement of the reflector and the measured displacement shows good linearity. The displacement measurements have resolution 40nm with the reference signals(N=12). Without a transducer in MHz range, our method having the resolution of 1μm on the displacement measurement with air-coupled ultrasonic transducer of 40kHz is useful
|
