레이저를 광원으로 사용한 물결통 실험에 있어서 전구미소파의 특성 = Characteristics of Pre-wavelets in a Ripple Tank Experiment Applying a Laser Beam as a Light Source

다국어 초록 (Multilingual Abstract)

A diverging laser beam has been applied as a point light source for a ripple tank
experiment. All the image patterns appear clearly whether they are in focus or not,
and the wave natures of the ripples occurs easily and can be analyzed quantitatively.
``Pre-wavelet" were produced before and proceeded the
``main waves", even though the wave generator (point or plane) vibrated once
(1 cycle) vertically or horizontally. Depending on the pressure variation
(increasing or decreasing) caused by the generator on the water surface,
1st pre-wavelets and 2nd pre-wavelet groups or a 1st pre-warelet group only appeared.
It was confirmed that the ripples (pre-wavelets) were elastic waves of water
due to the surface tension of the water for the restoring force and their wavelengths
were within the wavelength limit of elastic waves (about 1.71 cm)
for water waves. It was also observed that when the wavelength got very small as in the pre-wavelets, the phase velocity was higher, for shorter wavelengths. Also, broadening of the wave patterns occurred because the flow velocity changed due to the water depth;
when the depth of the water go smaller (order of a wavelength),
the velocity became slower with decreasing water depth,
As a results, the wave image patterns were broadened.

국문 초록 (Abstract)

파동의 기본적인 성질을 이해하는데 있어서 중요한 실험중의 하나가 물결통 실험
(Ripple Tank Experiment.)이다. 그러나 기존의 실험장치에서 사용되고 있는
광원은 점광원이 아니어서 명확한 수면파의 상을 관찰하기가 쉽지 않다.
본 실험에서는 이것을 보완하기 위해 광원으로 레이저의 발산비임을 사용하였는데
그 결과 선명한 상과 함께 기존의 장치에서는 무시되었던 전구미소파(pre-wavelet)의
발생과 파동의 퍼짐현상(broadening)을 관찰할 수 있었고 그것의 발생특성과
전파특성을 정성적으로 조사 분석하였다.