Bilingual edition: English is preserved and Chinese follows each unit. Terminology uses the confirmed v20260916 glossary; automated semantic review remains traceable.
中英双语版：英文原文完整保留，中文紧随对应单元；术语采用 v20260916 确认表，自动语义审校结果可追溯。

Cylindrical Lens for Positioning

用于定位的圆柱形透镜

A clever use of a cylindrical lens generates a correction signal to position the main focusing lens for the detector in a compact disc player. The combination of a symmetric lens and a cylindrical lens produces a circular beam at only one distance past the cylindrical lens. A segmented photodiode arrangement can detect whether the beam is circular and generate an error voltage to reposition the main lens so that it is. The error voltage drives a coil which can rapidly reposition the lens in response to changes in distance to the CD as it rotates.

利用一个圆柱形透镜巧妙地产生一个校正信号，以将主聚焦透镜定位到探测器，用于紧凑型光盘播放机。对称透镜与圆柱形透镜的组合在距离圆柱形透镜仅一距离处产生圆形光束。分段光电二极管排列可以检测光束是否为圆形，并生成一个误差电压以重新定位主透镜，使其保持圆形。该误差电压驱动一个线圈，可以迅速响应到光盘旋转时与光盘距离的变化而重新定位透镜。
 Index

CD concepts

Sound reproduction concepts

Reference
Rossing
Physics Teacher, Dec. 87
索引 CD 概念 声音重放概念 参考文献：Rossing，Physics Teacher，Dec. 87
 
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Cylindrical lens
圆柱形透镜
Photodiode
光二极管
Difference amplifier
差分放大器
 Index

CD concepts

Sound reproduction concepts

Reference
Rossing
Physics Teacher, Dec. 87
索引 CD 概念 声音重放概念 参考文献：Rossing，Physics Teacher，Dec. 87
 
HyperPhysics***** Sound ***** Optics
HyperPhysics ***** 声学 ***** 光学
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 Go Back
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CD Storage Capacity

CD存储容量

A compact disc can store more than 6 billion bits of binary data. This is equivalent to 782 megabytes, and at 2000 characters per page this is equivalent to about 275,000 pages of text (Rossing). Because the analog-to-digital conversion for making CD's involves 16-bit sampling of sound waveforms at 44.1 kHz, the amount of data involved in the recording of high-fidelity sound is very large. The 12 cm diameter compact disc can hold 74 minutes of digital audio which has a frequencies over the full audible range of 20-20,000 Hz. The signal-to-noise ratio and the dynamic range can exceed 90 decibels.

一张紧凑盘可以存储超过60亿位二进制数据。这相当于782兆字节，按每页2000个字符计算，相当于约275,000页的文本（Rossing）。由于制作CD的模拟-数字转换涉及以44.1 kHz对声音波形进行16位采样，因此高质量声音的录音所涉及的数据量非常大。直径12厘米的紧凑盘可以存储74分钟的数字音频，其频率覆盖全 audible 范围20-20,000 Hz。信噪比和动态范围可以超过90分贝。
 Index

CD concepts

Sound reproduction concepts

Reference
Rossing
Physics Teacher, Dec. 87
索引 CD 概念 声音重放概念 参考文献：Rossing，Physics Teacher，Dec. 87
 
HyperPhysics***** Sound ***** Optics
HyperPhysics ***** 声学 ***** 光学
R Nave
 Go Back
返回