Laserlabreport - 1 Measure Laser Cavity Length 62 cm Quartz window to mirror 10.5 cm Tr = roundtrip time of laser cavity = frequency at which laser

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1. Measure Laser Cavity Length – 62 cm Quartz window to mirror – 10.5 cm Tr = roundtrip time of laser cavity = frequency at which laser pulses are produced (2 62 cm ) + (2 10.5 cm ) =145 cm The round trip time for intracavity light = 145 cm 1 m 100 cm 1 3 10 8 m s 100 cm 1 m = 4.83 10 - 7 cm s In our first attempt, we first start to see light at 13000 Volts - Spontanious emmission Stimulated Emission - 14000 Volts (to get the spark across the nitrogen) Monday’s Data: Spontaneous Emission: 7 kV Stimulated Emission: 20 kV 2. Spontaneous Emission because it is not focused, not coherent. Stimulated emission on inside, focused center of the beam. Spontaneous emission on outside edges of the beam. That is when you actually get a laser. That is the voltage it takes to completely break down the Nitrogen in the laser cavity. There are many possible applications for a pulsed nitrogen laser. One possible application is using the laser to learn about properties of light and nitrogen. For example, the speed of light can be calculated from data obtained from the laser. The emission spectrum of nitrogen can also be determined since only frequencies in the emission spectrum can be produced. This laser is particularly good for making such measurements because although it is still dangerous, it is very low power and does not generate a significant amount of heat. The nitrogen laser can also be used as a power source for other lasers. The nitrogen laser can be used to pump a dye laser and in other applications where a UV pulse is needed, like UV spectroscopy. The nitrogen laser uses nitrogen as the lasing medium. The laser consists of a chamber filed with nitrogen at near atmospheric pressure. It also has two electrodes that form a spark gap inside. Unlike most lasers, no mirrors are needed due to the nitrogen's high gain as a lasing medium, but one mirror is sometimes used to increase beam intensity. When a 20kV+ electric pulse is sent over the gap, the resulting spark will give off a pulse of UV light. This light stimulates the nitrogen to send out more UV light, this forms a nanosecond pulse with UV light (peak wavelength 337nm). When the mirror is turned, it is like seeing two separate images. It changes the shape of the laser light. The shape of the cavity is circular but the shape of the image is an ellipse, longer horizontally than the vertically. There are two hacksaw blades on either side of the cavity and the electrons (spark or lightning) arcs from one side to the other, making the shortest jump as possible.
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How the laser works: There are two ways that Nitrogen can emit light; Spontanious emmission and Stimulated
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This note was uploaded on 03/03/2008 for the course A&EP 110 taught by Professor Gaeta during the Fall '05 term at Cornell University (Engineering School).

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Laserlabreport - 1 Measure Laser Cavity Length 62 cm Quartz window to mirror 10.5 cm Tr = roundtrip time of laser cavity = frequency at which laser

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