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.

Integration of a high-speed repetitively pulsed laser with a high-speed CCD camera

Abstract: An integrated, high-speed photographic system combining a high-repetition rate, pulsed ruby laser and a high-framing rate CCD camera has been demonstrated. Individually, the laser and camera have been discussed previously and each was developed under the Small Business Innovative Research (SBIR) sponsorship through the Air Force Research Lab (AFRL). This paper presents for the first time digital images captured at 333 kHz using the two elements integrated as a high-speed photographic system. The laser is capable of generating a train of 65 pulses at 500 kHz operation with micropulse energy of∼350 mJ each (>25 J for the macropulse). The test reported herein required only about 10% of this capability or ∼40 mJ per pulse. The laser was selected as the master time control because the laser pulse could be located in time with high precision (<1 ns jitter) relative to a secondary laser output trigger. The laser pulse occured at the end of the Q-switch open time, as previously shown by the authors (PSI). Synchronization of the camera and the laser Q-switch driver in this way required different repetition rates for the laser and the camera due to the state triggering requirements of the two components. The illuminated object for this test case was an Air Force 3-bar resolution chart. A f=-100 mm negative lens expanded the laser beam to fill the target area while a sheet of ground glass placed after the lens diffused the beam to remove coherent laser speckle from the image. A 17 nm wide ruby filter with 75% transmission centered at 694 nm (Andover Corporation) was used to remove stray light. The CCD array imaged the 3-bar chart through a f/4, 100 mm lens. The Silicon Mountain Design camera used here had the capability to capture 16 frames at a framing rate up to 1 MHz (SMD 64klM). This test was configured at 1/3 of the maximum framing rate. In order to achieve the high framing rate, only one out of sixteen sub-pixels was active per frame comprising a 256x256 array for each frame. This effected the resolution of an image and the sequential frame to frame resolution. The observed resolution was 0.25 line pairs per mm using 256 2 pixels on a 2 cm 2 array. The effective camera open shutter time for this test case equals the laser pulse width of ∼10 ns (FWHM laser pulse). This paper details the fluence requirements for the test case, the synchronization of laser pulses to camera open shutter time (integration time) and the resolution of the image versus the expected resolution. It has been demonstrated that 10 ns wide high-speed laser pulses can be captured digitally at a high frame rate. Integration of these two elements into a high-speed photographic system expands image capture capabilities and facilitates near real time data analysis.

Numerical study of the Cr:YSO Q-switched ruby laser

Abstract: The passive Q-switching performance of the Cr:YSO Q-switched ruby laser for different polarization orientations is numerically studied in detail with the Runge-Kutta method. The simulation results show that the Cr:YSO Q-switched ruby laser system has a better passive Q-switching performance when the polarization orientation is along the n1 axis of the Cr:YSO, when compared to the n2 and n3 axes. With a typical laser configuration, aQ-switched laser pulse of 19.8 mJ in 22.3 ns can be obtained. © 2001 Society of Photo-Optical Instrumentation Engineers.

A mode controlled q-switched tuneable ruby laser.

Abstract: The application of a pulsed ruby laser to the spectroscopic measurement of the profile of atmospheric water vapor has been demonstrated. The measurements needed for studies of water vapor are those of the time history of the backscattered optical radar return at a wavelength corresponding to a water vapor line center (6943.8 A) and the similar return in the line wing. The usefulness of this method has been limited because existing laser systems lack the combination of monochromaticity and tuneability necessary in such work. The half-width of the water vapor line at surface conditions is approximately 0.04 A. Calculations have shown that a wavelength shift of 0.1 A from the center of the line is required for these studies. Due to the rapid temporal variations in the atmospheric backscatter cross section, it is necessary that this pair of measurements be made within a time interval of the order of 1 sec. Techniques have been developed which provide many of the features required in this work. For example, the laser wavelength may be shifted over a 10-Å interval by varying the temperature of the ruby rod. The sensitivity of this control is 0.065 Å/ °C . The difficulty with such an approach is that it has not proved feasible to maintain the rod at constant temperature at high pulse repetition rates. Further, it does not appear possible to shift the temperature of the rod and the cooling bath accurately in a one second period. Considerable work has been done on the problem of the control of the width of the laser line. Normally the Q-switched ruby laser has a line width of the order of 0.1 A due to the excitation of many axial and transverse modes of the laser cavity. However, the width of the line may be reduced to tha t of a single axial mode by including a Fabry-Perot resonant reflector in the cavity and by performing the Q switching by means of a saturable cell (Stoicheff, McClung and Weiner, Hercher). In these systems the temperature of the ruby red rod is adjusted so Fig. 1. Computed reflectivity as a function of wavelength for the Hercher resonant reflector.