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全息技术是测振的很有效的方法。通常用时间平均法测量振动物体的振幅要比其它方法精确,但是要确定振动相位则较困难。本文采用了参考光相位调制法来确定相位,用此法可较方便地确定振型。如果一个物体处于共振状态,参考光亦利用与物体同步振动的反射镜而振动。首先,用调制器调节振动反射镜的振动相位,使之等于物体上某点的振动相位。然后再以被调制的参考光作为基础,利用到达干板的参考光和物光来记录物体的全息图。在再现物体的干涉条纹中,物体上与参考光同相位、同振幅处就显出最亮条纹。这些最亮条纹是同一方向振动的等值线。如果在物体的表面上有若干个振动方向相互相反的区域,那么与最亮条纹同方向振动的区域就都存在最亮条纹;与此相反,另外那些没有最亮条纹的区域,其振动方向就相反。按照这个方法,可以计算出物体上任何一点的振幅,还可以获得在各个固有频率下的振型。全息干涉技术作为一种新的光学技术,目前在许多部门正被用于计测方面,由于它能把计测对象粗糙表面的微小动态、静态变形特征用非接触方式进行全埸记录和再现,并可根据记录的干板再现干涉条纹,定性地了解所研究对象的变形状态和定量地计算其变形大小,因而在机械设计中日益广泛地成为一个重要的手段。特别是在模型动态试验中用来检验模型的动态变形更为优越。但是常用的时间平均法对于某些复杂的振型的相位状态往往不易判断,因而在判断其模态方面有困难。我室利用对参考光进行正弦波调制的全息干涉技术,成功地获得了被测对象明确的振动模态。
Holography is a very effective method of vibration measurement. It is usually more accurate than the other methods to measure the amplitude of a vibrating object using the time-average method, but it is more difficult to determine the phase of the vibrations. In this paper, the reference phase modulation method to determine the phase, this method can be more easily determine the mode shape. If an object is in resonance, the reference beam also vibrates with a mirror that vibrates in synchronization with the object. First, use the modulator to adjust the vibration phase of the vibrating mirror so that it equals the vibration phase of a point on the object. Then, based on the modulated reference light, the hologram of the object is recorded by using the reference light and the object light reaching the dry plate. In an interference fringe of an object of reproduction, the object is in phase with the reference light and shows the brightest fringes at the same amplitude. These brightest stripes are contours of vibration in the same direction. If there are several regions on the surface of the object that are opposite in direction of vibration, the brightest stripes exist in the region that vibrates in the same direction as the brightest stripes; on the other hand, the regions other than the brightest stripes vibrate in the same direction in contrast. According to this method, the amplitude of any point on the object can be calculated and the mode shapes at each natural frequency can be obtained. As a new optical technology, holographic interferometry is currently being used in many sectors for measurement. Because it can record and reproduce all the small dynamic and static deformation characteristics of the rough surface of the measurement object in a non-contact manner, And according to the recorded interference fringes reproduced by the dry plate, it can qualitatively understand the deformation state of the studied object and calculate its deformation quantitatively. Therefore, it has become an increasingly important means in mechanical design. Especially in the model dynamic test to test the dynamic deformation of the model is more superior. However, the commonly used time-average method is not easy to judge the phase state of some complex vibration modes, so it is difficult to judge the modal state. I use the room for the reference light sine wave holographic interferometry technology successfully obtained the measured object vibration mode.