2024年3月9日发(作者：)

物理专业英语第6章翻译光波的干涉

The light intensity distribution generated when several light

waves (member waves) meet does not equal to the sum of the light

intensity distribution caused by each member wave alone, and the

phenomenon of alternating light and dark example, in

Young's double-hole interference (see Young's interference

experiment), the subwave out of each small hole H1 or H2 is a

member wave. When the hole is small, the light intensity distribution

I1 (x) caused by the member wave from the hole H1 alone is roughly

uniform in a considerable range; so is the light intensity distribution

I2 (x) caused by the member wave from the hole H2 sum

of the two is still roughly evenly the light intensity

distribution I (x) caused by the two member waves together, the

change of light and shade with position x is very significant, which

is obviously not equal to.

Each member wave alone causes a roughly uniform distribution

of light intensity, which is equivalent to requiring that each member

wave itself has no obvious diffraction, because the diffraction also

causes alternating light and dark stripes (see diffraction of

light).Therefore, when a number of member waves meet in a certain

region of space and the interference occurs, it should mean that the

diffraction of each member wave can not be considered in that

region.

Note that the aforementioned light intensity is not the

instantaneous value of the light field intensity (proportional to the

amplitude square), but the average or integral value of the light field

intensity within a certain time interval t; t depends on the

performance of the detection means or example, during

human eye observation, t is the visual retention time; while shooting

on film, t is the exposure time. The interference phenomenon usually

shows a fairly steady stripe distribution of the light field intensity in

space; sometimes, when the certain parameter of the interference

device changes with time, the light intensity received at a certain

fixed point changes alternately. The discovery of the interference

phenomenon of light has historically played an indelible role in the

evolution from the particle of light to the fluctuation of 1801,

T. Young proposed the principle of interference and first made a

double-slit interference experiment, and also explained the color of

the film 1811, the D.F.J. Arago first studied the

interference phenomenon of polarized times, light

interference has been widely used in precision measurement,

astronomical observation, photoelastic stress analysis, automatic

control in optical precision machining and many other fields.

Generate conditions Only the two columns of light waves of the

same frequency, the phase difference is constant, the vibration

direction of the same direction of the coherent light source, can

produce light light emitted by two ordinary

independent light sources can not have the same frequency, let

alone have a fixed difference, so, the interference phenomenon

cannot produce. Specific methods In order to stabilize the light

intensity distribution of the synthetic wave field over a time interval

t, the frequency of each ① member wave v (and hence the

wavelength) is the same; the initial phase difference between the

two member waves of ② remains constant within ional ②

means that several usually independent light sources meet without

interference, even if they emit light at the same

reason is that usually the light emitted by the light source is a large

number of waves distributed irregularly in the initial phase, and each

wave lasts no more than 10 seconds, that is, every 10 seconds or so,

the initial phase of the wave is a random er, the

initial phase of the wave column emitted by any two independent

light sources is again statistically can imagine that

when these independent light source wave meet, only in a very short

time to produce a certain stripe pattern, and every 10 seconds or so,

with another pattern, so far not any detection or recording device

can keep up with such sharp changes, thus observed the average

effect of the large number of patterns, namely uniform light

intensity distribution rather than light and dark r,

modern special lasers have produced tens of kilometers of waves,

even lasting on the order of 10 ore, it can be said that

if a detector with the time-resolution ability t is shorter than 10

seconds (which is possible), the interference of the light waves

emitted by two independent lasers of the same frequency can also

be addition, taking the two-wave interference as an

example also requires that: the amplitude of the ③ two waves must

not differ greatly; the polarization surface of the ④ two waves at the

superposition point must be roughly consistent. When the condition

③ is not satisfied, although the interference stripes can still arise in

principle, but the light and dark difference of the stripes is very little,

and the interference phenomenon is not ional ④ is

necessary because when the polarization surface of the two optical

waves is perpendicular to each other, the light intensity of the

synthetic field is the same value and does not show alternating light

and shade (to observe the light alternation, you must use the

polarization element). The above four points are commonly known

as coherence or more light sources or light waves

that satisfy these conditions are called coherent light sources or

coherent light waves.

若干个光波（成员波）相遇时产生的光强分布不等于由各个成员波单独造成的光强分布之和，而出现明暗相间的现象。例如在杨氏双孔干涉（见杨氏干涉实验）中，由每一小孔H1或H2出来的子波就是一个成员波，当孔甚小时，由孔H1出来的成员波单独造成的光强分布 I1(x)在相当大的范围内大致是均匀的；单由从孔H2出来的成员波造成的光强分布I2(x)亦如此。二者之和仍为大致均匀的分布。而由两个成员波共同造成的

光强分布I(x)，则明暗随位置x的变化十分显著，显然不等于。

每个成员波单独造成大致均匀的光强分布，这相当于要求各成员波本身皆没有明显的衍射，因为衍射也会造成明暗相间的条纹（见光的衍射）。所以，当若干成员波在空间某一区域相遇而发生干涉时，应该是指在该区域中可以不考虑每个成员波的衍射。

应注意，前面所说的光强并不是光场强度（正比于振幅平方）的瞬时值，而是在某一段时间间隔Δt内光场强度的平均值或积分值；Δt的长短视检测手段或装置的性能而定。例如，人眼观察时，Δt就是视觉暂留时间；用胶片拍摄时，Δt则为曝光时间。

干涉现象通常表现为光场强度在空间作相当稳定的明暗相间条纹分布；有时则表现为，当干涉装置的某一参量随时间改变时，在某一固定点处接收到的光强按一定规律作强弱交替的变化。

光的干涉现象的发现在历史上对于由光的微粒说到光的波动说的演进起了不可磨灭的作用。1801年，T.杨提出了干涉原理并首先做出了双狭缝干涉实验，同时还对薄膜形成的彩色作了解释。1811年，D.F.J.阿喇戈首先研究了偏振光的干涉现象。现代，光的干涉已经广泛地用于精密计量、天文观测、光弹性应力分析、光学精密加工中的自动控制等许多领域。

产生条件

只有两列光波的频率相同，相位差恒定，振动方向一致的相干光源，

才能产生光的干涉。由两个普通独立光源发出的光，不可能具有相同的频率，更不可能存在固定的相差，因此，不能产生干涉现象。

具体方法

为使合成波场的光强分布在一段时间间隔Δt内稳定，要求：①各成员波的频率v（因而波长λ ）相同；②任两成员波的初位相之差在Δt内保持不变。条件②意味着，若干个通常独立发光的光源，即使它们发出相同频率的光，这些光相遇时也不会出现干涉现象。原因在于：通常光源发出的光是初位相作无规分布的大量波列，每一波列持续的时间不超过10秒的数量级，就是说，每隔10秒左右，波的初位相就要作一次随机的改变。而且，任何两个独立光源发出波列的初位相又是统计无关的。由此可以想象，当这些独立光源发出的波相遇时，只在极其短暂的时间内产生一幅确定的条纹图样，而每过10秒左右，就换成另一幅图样，迄今尚无任何检测或记录装置能够跟上如此急剧的变化，因而观测到的乃是上述大量图样的平均效果，即均匀的光强分布而非明暗相间的条纹。不过，近代特制的激光器已经做到发出的波列长达数十公里，亦即波列持续时间为10秒的数量级。因此，可以说，若采用时间分辨本领Δt比10秒更短的检测器（这样的装置是可以做到的），则两个同频率的独立激光器发出的光波的干涉，也是能够观察到的。另外，以双波干涉为例还要求：③两波的振幅不得相差悬殊；④在叠加点两波的偏振面须大体一致。

当条件③不满足时，原则上虽然仍能产生干涉条纹，但条纹之明暗区别甚微，干涉现象很不明显。条件④要求之所以必要是因为，当两个光波的偏振面相互垂直时，无论二者有任何值的固定位相差，合成场的光强都是同一数值，不会表现出明暗交替（欲观察明暗交替，须借助于偏振元件）。

以上四点即为通常所说的相干条件。满足这些条件的两个或多个光源或光波，称为相干光源或相干光波。