聲光效應實驗組

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This set has been designed for some sophisticated experiments, which deal with the interactions between a mechanical wave and light – the acousto-optical effects (AOM, acousto-optical modulation). The experiments promote a knowledge and understanding of the propagation characteristics of mechanical as well as electromagnetic waves.
It is shown that the changes in density that occur due to the compression and dilatation of an ultrasound wave cause a change in the diffraction index of the medium. The grating created causes the diffraction of laser light. In addition, the intensity modulation and wavelength alteration of laser light are demonstrated.
In different experiments, the diffraction characteristics of light at standing and travelling ultrasonic waves are investigated and measured. The sound velocity of different liquids is determined by means of the variation of the interference maxima of the laser light at different ultrasound frequencies (resonance cell).
The amplitude modulation and phase shifting of laser light at a standing wave can be represented with a photodiode and recorded with an oscilloscope. The frequency change of the sound wave influences the amplitude modulation and makes it possible to calculate the sound velocity of the medium.
The difference of the diffraction at standing and travelling waves is demonstrated by means of an acoustic absorber, which prevents the formation of standing ultrasound waves in the sample reservoir.
At the travelling ultrasonic wave, a frequency shift of the laser light, caused by the Doppler effect, can be measured. Buy using a beam splitter and reflectors, differently diffracted portions of light can be turned into interference. The resulting beats are displayed and measured with the oscilloscope.
This experimental set is suitable both for the demonstration of the acousto-optical effects and their application in technology and for carrying out interesting experiments in advanced practical training for students in higher education of all natural scientific and technical fields.

• 研究機械波與光波之間的相互作用
• 由超音波壓縮與膨脹引起的介質折射率變化產聲光柵導致光的繞射
• 可演示雷射光的強度調控與波長變化
• 研究不同超音波頻率下雷射光干涉最大值的變化
• 利用光電二極管可用示波器顯示並記錄駐波上雷射光的震幅調控與相位差
• 證明駐波與連續波的差異性