Ruby laser

About: Ruby laser is a research topic. Over the lifetime, 2474 publications have been published within this topic receiving 38933 citations. The topic is also known as: corundum laser & ruby rod.

Laser-induced damage to semiconductors

Abstract: An experimental study has been made of the damage to p-type silicon caused by a normal and a Q-switched ruby laser. For the normal laser irradiation, the crack-line formation was due to thermal stress. For the Q-switched laser irradiation, cracks extending into the volume of the crystal were produced at a high power density of about 350 MW cm-2. The damage threshold was almost independent of the mechanical damage depth and the ratio of the damage threshold for a mechanically lapped sample to that for a chemically polished one (IK/ID) was only about 1/2 approximately 1/3. The damage induced in GaP whose forbidden-band width is greater than the photon energy was also investigated.

High-speed laser speckle photography. Part 1: repetitively Q-switched ruby laser light source

Abstract: A system to record laser speckle photographs at framing rates in the range of 105 to 106 frames/s has been developed, based on a repetitively Q-switched ruby laser and rotating mirror high-speed camera. The laser and electro-optic modulator are described. The circuit diagram for an inexpensive high-voltage amplifier, capable of switching 2.5 kV at up to 1 MHz with fall and rise times of 100 and 200 ns, respectively, is given. The resulting optical pulse trains have pulse energy fluctuations at half the driving frequency. We show how these may be suppressed by reducing the time the Q-switch is left open. Both the subharmonic component and its suppression are explained from limiting cases of the laser rate equations. Representative pulse trains over a range of repetition rates are given; pulse energies greater than 20 mJ with pulse energy fluctuations of less than plus or minus one-half of a stop are obtained at rates of up to 500 kHz.

Color Centers and Ruby‐Laser Output‐Energy Degradation

Abstract: The use of lasers in rangefinding and other applications requires that the laser be capable of being fired many times without its output characteristics changing substantially. A gradual reduction in ruby (Cr3+ in Al2O3) laser output energy has been observed during repeated firing of the laser. This degradation is found to occur with varying degrees of severity in all ruby rods tested. We have traced this to the formation of color centers within or on the surface of the ruby rod: defects, impurities, etc., present before exposure can be converted into color centers by the blue and ultraviolet content of the pumplight. Conversion of Cr3+ to other valence states is very small, amounting to less than 1% of the total Cr3+ density (the sensitivity of the measurement) for most samples and to 3% for one vintage of ruby. The radiation induced absorption which was found agrees well with x‐ray induced color‐center absorption in undoped α‐Al2O3 rather than absorption by Cr2+ or Cr4+. We have shown that the subsequent pump light absorption by these color centers, which serves to deplete the pumping energy internally in the rod and to cause bulk absorption loss at 6943 A, fully explains the degradation observed to within the limits of experimental error. A reliable indicator of color center formation is the orange‐brown appearance which develops in the ruby; only a partial restoration of output energy can be achieved by heating the rods at 900°C for 24 h; the use of pyrex to filter the ultraviolet from the pump light can reduce but not eliminate the rate of energy decay. The contribution of this work is that we have determined the principal mechanisms out of several possible ones which explains the energy decay observed in U.S. grown ruby samples. The complete solution to this problem will be known when it is understood how to prevent color center formation in Al2O3 upon ultraviolet irradiation.

Triggering of a pressurized spark gap by a laser beam

Abstract: A delay line was discharged into a terminating resistor by a spark gap of coaxial design. The spark gap was triggered by a focused laser beam, introduced along the axis; a Q-switched ruby laser giving pulses of 20 ns duration and up to 50 MW power was used. The range of operation of the gap, formative time of the breakdown and jitter were investigated for different gases at pressures above atmospheric, gap widths of 4-10 mm and voltages of up to 120 kv. Mixtures of argon and nitrogen were found to have certain advantages, such as a low threshold for ionization by the laser beam, sufficient dielectric strength, low values of the formative-time jitter and chemical inertness. Formative times of down to about 1 ns and jitters below 1 ns were found. The laser power can be relatively low (0·5-5 MW). An explanation for the breakdown mechanism is proposed.