### 目前分類：雷射光學 Laser Optics (5)

• Apr 08 Sun 2012 10:39

# 波板

## 運作

• Jun 25 Sat 2011 23:44
• ## Wiki：DPSS Laser － 我剛翻譯的

DPSS Laser(Diode-pumped Solid-State Laser)

Diode-pumped Solid-State (DPSS) laser 是一種透過 pump 一固態增益材料的方式產生的固態雷射。例如，以紅寶石、釹雅鉻晶體作為增益材料，透過雷射二極體而成的 Ruby Laser(紅寶石雷射)、Nd-Yag Laser(釹雅鉻雷射)。

## 耦合(Coupling)

1. fast axis 由一預先校正準直過的柱狀微透鏡去調整其準直性。

2. 此時經由校準過、進入晶體中的光束，可由晶體縱向的前後兩端、或晶體橫向的三面以上的方向，將晶體激發出雷射。

### 常見的 DPSS 雷射的流程

Green DPSS 雷射的轉換效率大約為 20%，有些雷射的轉換效率可高達 35%。也就是說，若以 2.5W 的 Laser Diode 能量去 pump KTP 倍頻器，理想上，我們預期能產生出 500~900 mW 、波長為 532nm 雷射。

• May 26 Tue 2009 13:07
• ## 準分子雷射與眼科雷射

「重塑角膜」的手術，為什麼要用上準分子雷射呢？

• Dec 11 Thu 2008 11:39
• ## Wiki：Q-switch－我剛翻譯的

Q-switch (Q switch,Q-switching)

Q-switching，以具有「大能量的脈衝」聞名，是一項能產生脈衝式雷射的科技。這項科技能讓雷射釋出相當高（Giga Watt）能量峰值的脈衝光。以 Q-switch 觸發的雷射，具有遠比以 CW（連續波）觸發的方式還要高的能量。相較於另一項脈衝雷射的新科技（mode locking）比較，Q-switch 型的雷射為頻率較低、單脈衝能量較高的特性，脈衝長度也較長。這兩項科技，有時候會同時被應用在某些用途上。

Q-switching 技術於 1958 年，由 Gordon Gould 首度提出，並由 R.W. Hellwarth F.J. McClung 1961 年（或 1962 年）建立，並在 Ruby 雷射中，以electrically switched Kerr cell shutters （電子式切換 Kerr cell 快門？）證實。

Q-switching的原理：

Q-switching 的效果可由放入可變衰減器到雷射共振腔中達成。當衰減器被啟用時，由增益材料（可被激發並釋出光線的材料）被激發出來的光線並不會被反射回去（故雷射此時尚無法開始擊發）。在共振腔中放入衰減器，等同於降低 Q-factorquality factor of the optical resonator）數值的效果。當 Q-factor 值越高時，代表光線在共振腔中每次來回共振的損失越低，反之則是損失增加。而用於這個用途的「可變衰減器」，正是我們常聽到的「Q-switch」。

Q-switching主要有兩種類型：

• Aug 28 Thu 2008 08:32
• ## Q-Switch Laser

Q-switching

Q-switching, sometimes known as giant pulse formation, is a technique by which a laser can be made to produce a pulsed output beam. The technique allows the production of light pulses with extremely high (gigawatt) peak power, much higher than would be produced by the same laser if it were operating in a continuous wave (constant output) mode. Compared to modelocking, another technique for pulse generation with lasers, Q-switching leads to much lower pulse repetition rates, much higher pulse energies, and much longer pulse durations. Both techniques are sometimes applied at once .

Q-switching was first proposed in 1958 by Gordon Gould, and independently discovered and demonstrated in 1961 or 1962 by R.W. Hellwarth and F.J. McClung using electrically switched Kerr cell shutters in a ruby laser.

Principle of Q-switching

Q-switching is achieved by putting some type of variable attenuator inside the laser's optical resonator. When the attenuator is functioning, light which leaves the gain medium does not return, and lasing cannot begin. This attenuation inside the cavity corresponds to a decrease in the Q factor or quality factor of the optical resonator. A high Q factor corresponds to low resonator losses per roundtrip, and vice versa. The variable attenuator is commonly called a "Q-switch", when used for this purpose.

Initially the laser medium is pumped while the Q-switch is set to prevent feedback of light into the gain medium (producing an optical resonator with low Q). This produces a population inversion, but laser operation cannot yet occur since there is no feedback from the resonator. Since the rate of stimulated emission is dependent on the amount of light entering the medium, the amount of energy stored in the gain medium increases as the medium is pumped. Due to losses from spontaneous emission and other processes, after a certain time the stored energy will reach some maximum level; the medium is said to be gain saturated. At this point, the Q-switch device is quickly changed from low to high Q, allowing feedback and the process of optical amplification by stimulated emission to begin. Because of the large amount of energy already stored in the gain medium, the intensity of light in the laser resonator builds up very quickly; this also causes the energy stored in the medium to be depleted almost as quickly. The net result is a short pulse of light output from the laser, known as a giant pulse, which may have a very high peak intensity.