闪烁计数是最灵敏和最有效的辐射检测方法之一。它使用与闪烁体耦合的光电倍增管,闪烁体在受到辐射时会产生光。在辐射测量中,应测量两个参数:单个辐射粒子的能量和辐射量。当辐射粒子进入闪烁体时,闪烁体会产生可见光以响应每个粒子。光量极低,但与入射粒子的能量成正比。由于光电倍增管可检测到单个闪光,因此从光电倍增管获得的输出脉冲包含有关脉冲能量和数量的信息。使用多通道分析仪 (MCA) 分析这些输出脉冲,可获得脉波振幅分布 (PHD) 或能量谱,并且可以准确测量各种能量水平的入射粒子量。
暴露于辐射(如 X 射线)下时会发光的材料。闪烁体分为无机闪烁体和有机闪烁体。众所周知的无机闪烁体是掺有少量活化剂(如 TI(铊))以提高发射效率的 CsI(碘化铯)晶体或粉末。有机闪烁体包括萘、蒽、塑料、液体闪烁体和 lumogen。lumogen 是一种响应紫外线而发光的材料,因此有时被涂覆在没有紫外线灵敏度的前照式 CCD 上。
这是负载电阻为零时在光电二极管中流动的输出电流。这称为“白光灵敏度”,以区别于光谱灵敏度特性,是使用在 2856K 分布温度(色温)下工作的标准钨灯的光测量的。我们的产品目录列出了在 100 lx 照度下测量的短路电流。
这是在 0 V 附近工作的光电二极管的电压/电流比。在我们的产品目录中,分流电阻通过以下公式指定,其中暗电流 (ID) 是在 10 mV 反向电压下测量的值。$$ Rsh[ohms]=\frac{0.01 [V]}{ID[A]} $$ 在没有向光电二极管施加反向电压的应用中,分流电阻产生的噪声成为主导。
设计为以单横模(电磁场分布)传输光的光纤。单模光纤的传输损耗低,不受模态色散的影响,因此适用于长距离传输。但是,当连接到光发射器时,需要精确的纤芯对准,因为其芯径较小。
在图像传感器中,弥散现象是指强输入光产生的信号电荷泄漏到相邻像素或 CCD 传输区域,并导致原始信号变得弥散(模糊)。与饱和后发生的“光晕”相反,弥散甚至在饱和前就会发生。弥散往往发生自波长较长的光,而不是波长较短的光。
一种使用半导体的光学放大器。其结构与法布里-珀罗激光二极管非常相似,但设计成不会在边缘导致反射。SOA 能够在宽光谱范围内进行放大,并且所需组件比 EDFA 少,这使得放大器器件更小并降低了功耗。
这是使用光纤的高速数字通信方法的国际标准。SONET(同步光网络)是由 ANSI(美国国家标准协会)根据 Bellcore Technologies(现为 Telcordia Technologies)开发的技术制定的北美标准规范。SDH(同步数字体系)是 ITU(国际电信联盟)基于 SONET 制定的国际标准化接口。虽然在一些次要方面有所不同,但 SONET 和 SDH 可以被视为几乎相同的标准,并允许彼此互连。SONET 在北美广为人知,而 SDH 主要在欧洲使用。
当入射到光电传感器上的光被阻挡时,耗尽层中的载流子分布会受到干扰。载流子随后被拉到电极,并在耗尽层中产生一个与施加的偏压方向相反的电场。这种现象被称为空间电荷效应,当入射光量较高时,可能会降低响应特性(下降时间)。
图像传感器忠实捕捉物体细节的能力。MTF(调制传递函数)通常用于评估图像传感器的分辨率。当对具有正弦波辉度分布的物体成像时,MTF 指示正弦波辉度对比度如何随空间频率变化。空间频率是每单位长度重复正弦波的次数。由于 CCD 的感光面由离散像素组成,因此它表现出由基于离散采样定理的奈奎斯特极限决定的极限分辨率。例如,当使用 CCD 查看黑白图案时,黑白信号电平之间的差异会随着图案的精细而减小,最终达到无法再解析图案的程度。理想的 MTF 表示如下:sinc* {(π x f ) / (2 x fn)}(f:空间频率,fn:空间奈奎斯特频率)。然而,由于难以产生光正弦波,因此通常改用矩形波响应测试图。在这种情况下,空间频率特性称为 CTF(对比度传递函数)。
* sinc:理想矩形函数的傅里叶变换
光源发射能量的波长范围。波长范围根据输入能量、气压、光源类型(连续模式与闪光模式)和窗材的透射率而变化。
发射光谱输出最大值一半处的全宽,以波长 (nm) 表示。
由给定入射光量产生的光电流随波长变化。光电转换灵敏度和波长之间的这种关系称为光谱响应特性,以感光灵敏度或量子效率与波长的关系来表示。
Stealth DicingTM 工艺是滨松开发的一种新型切割方法。它使用激光光束在晶圆内部形成改性层,并将晶圆高质量地切割成芯片。由于使用的是透射到材料中的光,所以在晶圆表面不会发生热损伤。Stealth DicingTM 工艺不会产生任何切割损失,因此每个晶圆的芯片产量可以提高到最大。绝对没有污染物,例如传统切割技术中无法避免的飞溅碎屑,而且 Stealth DicingTM 工艺是一种完全干燥的工艺,因为不需要清洗用水。
当电子或正电子加速到接近光速并在磁场中弯曲时产生的强光。同步辐射覆盖从红外光到 X 射线的广泛光谱范围。这种光比普通 X 射线发生器发出的光亮一亿多倍。人们正在研究同步辐射在更广泛领域(包括医学、物理和化学)中的应用。
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