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Line 49: − + − 11 − energies. This was accomplished by pulsing the laser at a constant rate of 50 − Hz while sweeping the diamond across the focal spot at a speed of 0.5 mm − s − . − After each completed row the diamond was shifted by 10 µm (y translation − stage) and the process was repeated until a 6.2x6.2mm2 area was rastered. − For each row, the average laser pulse energy and the row’s y-coordinate on − the diamond was calculated and recorded . The laser was run without the − gas purification system and the laser energy dropped slowly as each row − − excimer laser. The ablated surface of the diamond was measured using a − Line 72:
Line 59: − + − and accounts for the overlap between neighboring laser pulses as well as the − 12 − fluctuations in laser energy (elaser) from row to row. − R(elaser) = U(y) ∗ δx ∗ δy − V0 − (1) − U(y) is the number of microns removed (in µm) from the diamond surface − after ablation at a particular y coordinate as measured from the Zygo interferometer, − δx and δy are the distances between neighboring pulses (both − 10µm) and V0 was a normalization parameter representing the depth cut in − diamond from a single laser pulse. The data collected from Figure 9a was − used in Eq. 1 and plotted as a function of the laser energy shown in Figure − 9b. The fit of Figure 9 was made using a second order polynomial and is − shown below in Eq. 2. − R(elaser) = 245.347x − 2 + 5.440x − 2.390 (2) − During the ablation process the average laser energy was measured for − each completed row and the corresponding ablation rate was calculated using − Eq. 2. The ablation rate calculated from the last completed row was used − − adjusted by weighting a standard step size made by the y-translation stage − (y-step) by the ratio of the measured ablation rate with a desired rate of − ablation as shown in Eq. 2. − delta-y = R(measured) − R(desired) − ∗ y-step (3) − Stacking laser pulses on top of eachother increases the amount of diamond − material removed within the region of overlap. This method was used to − account for laser energy fluctuations while differentially ablating diamond to − within ±0.5µm surface variation.
Diamond Radiator Thinning Using an Excimer Laser (view source)
Revision as of 21:22, 15 December 2016
, 21:22, 15 December 2016→Ablation Rate
===Ablation Rate===
===Ablation Rate===
The ablation rate of diamond was studied over a wide range of laser
The ablation rate of diamond using 193nm light was measured under a vacuum of 650 mtorr. The laser power was gradually decreased as each row was completed so that the complete operation range could be studied. The ablated surface was then measured using a Zygo white-light interferometer and the cut depth values for each row were extracted. These values were used in the model shown below to calculate the expected cut depth of a row as a function of the average laser energy. The figures below show the Zygo image of the ablated surface and the modeled cut depth.
was completed ensuring the study covered the complete energy range of the
Zygo white-light interferometer and is shown below in Figure 9a
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The ablation rate was calculated using the model shown below in Eq. 1
The histogram above was fitted with a second order polynomial and used to correct for fluctuations in the laser energy from row to row.
to determine its overlap with the next row of laser pulses. The overlap was
==Ablation Rate==
==Ablation Rate==