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给出了3种多波长测量技术的应用实例.采用多波长二极管激光器干涉仪测量表面轮廓.3个二极管激光器分别发射780nm、823nm和825nm3种近红外光波,可以得到2个近似15μm和29μm的合成波长.激光二极管的注入电流用1MHz左右的3种不同频率调制,以获得干涉仪的相位调制.这3个干涉信号用1个光电检测器和锁相放大器检测.采用同样的干涉仪,仅用2种波长进行了圆度偏差测量.论述了相移干涉测量技术,其试件的长度表示为光源波长的倍数.如果只使用1种波长,则要求确切知道整数干涉级;而使用多种波长,如532nm、633 nm和780nm时,可得到几个独立的长度,此时整数衍射级不同,可以通过“精确小数法”计算得到.PTB精密干涉仪长度测量不确定度很小,其单值性范围约0.6mm,因此其近似的长度估算足以满足超精密长度测量的要求.
The application examples of three multiwavelength measurement techniques are given.The multi-wavelength diode laser interferometer is used to measure the surface profile.The three diode lasers emit three kinds of near-infrared light waves of 780nm, 823nm and 825nm, respectively, so that two synthetic approaches of approximately 15μm and 29μm can be obtained Wavelength. The injection current of the laser diode is modulated with three different frequencies around 1 MHz to obtain the phase modulation of the interferometer. The three interference signals are detected by a photodetector and a lock-in amplifier. Using the same interferometer, 2 kinds of wavelength were measured roundness deviation.The phase shift interferometry technology was discussed, the length of the specimen is expressed as a multiple of the wavelength of the light source.If only one wavelength is used, it is required to know exactly the integer interference level; the use of multiple wavelengths , Such as 532nm, 633nm and 780nm, you can get several independent lengths, this time different integer diffraction orders, can be calculated by the “exact fraction method.” PTB precision interferometer length measurement uncertainty is small, the single value The approximate range of sexuality is about 0.6 mm, so the approximate length estimate is sufficient to meet the requirements of ultra-precision length measurement.