Changes

The focal spot was studied using a gold-tungsten harp scanner in both the x and y plane. Each harp scan was comprised of an aluminum mount machined at UConn and then anodized to insulate it from the 50 micron gold-tungsten wire that was stretched across it as can be seen in the CAD drawing below.

The focal spot was studied using a gold-tungsten harp scanner in both the x and y plane. Each harp scan was comprised of an aluminum mount machined at UConn and then anodized to insulate it from the 50 micron gold-tungsten wire that was stretched across it as can be seen in the CAD drawing below.

[[Image:2wire.png|left|thumb|300px|CAD drawing of harp scan mount]]

[[Image:2wire.png|center|thumb|300px|CAD drawing of harp scan mount]]

The total current produced is dependent on the flux of UV light incident to the wire and therefore proportional to the local intensity of the beam. Passing the wire through the beam waist creates a series of pulses from the gold-tungsten wire that rise and fall in amplitude, the peak defining the coordinate of the laser pulse maxima for that particular position of L3 (which is mounted on a translation stage moving in the direction of the beam path called z). An integrating circuit was designed and constructed to measure the sum of current off the gold-tungsten wire. The scans are done in pairs of 2d projections: xz (called x-scans) and yz (called y-scans). Between the scans the wire frame is swapped out because there are separate frames for the vertical (x-scan) and horizontal (y-scan) wires. The 2d scans consist of an inner loop over the transverse coordinate, and an outer loop over z. The transverse coordinate range is 2mm and the z coordinate range is 12mm. Each pass has a single value of z, and sweeps over the full 2mm range in x or y. The output of the integrating circuit is connected to an ADC which is sampling continuously over that the whole time period the scan is taking place

The total current produced is dependent on the flux of UV light incident to the wire and therefore proportional to the local intensity of the beam. Passing the wire through the beam waist creates a series of pulses from the gold-tungsten wire that rise and fall in amplitude, the peak defining the coordinate of the laser pulse maxima for that particular position of L3 (which is mounted on a translation stage moving in the direction of the beam path called z). An integrating circuit was designed and constructed to measure the sum of current off the gold-tungsten wire. The scans are done in pairs of 2d projections: xz (called x-scans) and yz (called y-scans). Between the scans the wire frame is swapped out because there are separate frames for the vertical (x-scan) and horizontal (y-scan) wires. The 2d scans consist of an inner loop over the transverse coordinate, and an outer loop over z. The transverse coordinate range is 2mm and the z coordinate range is 12mm. Each pass has a single value of z, and sweeps over the full 2mm range in x or y. The output of the integrating circuit is connected to an ADC which is sampling continuously over that the whole time period the scan is taking place