581
edits
Changes
Jump to navigation
Jump to search
Line 77:
Line 77: − *A FORTRAN program has been written which simulates rays exiting the laser aperture and then focused through a fused silica lens. We are able to determine the smallest spot size attainable as a function of the distance away from the lens.+ − + − + − + − + + + + + + + + + + + + + + + − + + + +
Diamond Radiator Thinning Using an Excimer Laser (view source)
Revision as of 18:03, 23 April 2010
, 18:03, 23 April 2010→Updates for April 2010
*A fluorine resistant regulator will be purchased by the first week in April.
*A fluorine resistant regulator will be purchased by the first week in April.
==Updates for April 2010==
==Updates for April 2010==
[[Image:r0(2)r0(1).jpg|right|thumb|117px|Original Beam Profile]] [[Image:r2.png|right|thumb|117px|Focused Beam Profile]]
[[File:r0(2)r0(1).jpg|right|thumb|Original Beam Profile]]
*A FORTRAN program has been written which simulates rays exiting the laser aperture and then propagating through a fused silica plano-convex lens. Using this program we can observe the geometry of the beam as it passes through the focusing lens onto a target. We have seen that the beam leaving the laser aperture has a flat top distribution in the X plane and a Gaussian in the Y. As the beam is focused projections close to the waist show both the X and Y projections going Gaussian.
[[File:r2.png|right|thumb|Focused Beam Profile]]
*Taking the X and Y projections of the focused beam and fitting them with a Gaussian distribution, we are able to attain the <math>\sigma_{X}\,</math> and the <math>\sigma_{Y} \,</math>.
*Taking the X and Y projections of the focused beam and fitting them with a Gaussian distribution,
*Assuming a Gaussian distribution at the waist of the beam, we now find the FWHM (full width at half maximum) by the following relation, <math>\mathrm{FWHM} = 2 \sqrt{2 \ln 2}\ \sigma. </math>
{| cellpadding="3" style="text-align: margin: 1em auto 1em auto"
|-
| [[Image:g_r1X.png|right|thumb|117px|X-axis Projection of Focused Beam]] || ||
[[Image:g_r1Y.png|right|thumb|117px|Y-axis Projection of Focused Beam]]
|-
|}
we are able to attain <math>\sigma_{X}\,</math> and <math>\sigma_{Y} \,</math>.
*Assuming a Gaussian distribution at the waist of the beam, we now find the FWHM (full width at half maximum) by the following relation,
:<math>\mathrm{FWHM} = 2 \sqrt{2 \ln 2}\ \sigma. </math>
*The smallest value of <math>\mathrm{FWHM_{X}}</math> and <math>\mathrm{FWHM_{Y}}</math> were 1.49mm and 0.552mm respectively.
*The smallest value of <math>\mathrm{FWHM_{X}}</math> and <math>\mathrm{FWHM_{Y}}</math> were 1.49mm and 0.552mm respectively.
*The Rayleigh Length,<math>\mathrm{Z_{R}}</math> is defined as the distance from the beam waist along the axis of propagation to the point where its cross section is doubled. Taking <math>\mathrm\omega_{0}</math> as the beam waist, and using the <math>\mathrm{FWHM}</math> as its value we are looking for the point where <math>\mathrm{FWHM} = 2 \sqrt{2 \ln 2}\ \omega_{0}. </math>
*The Rayleigh Length, <math>\mathrm{Z_{R}}</math> is defined as the distance from the beam waist along the axis of propagation to the point where its cross section is doubled, <math>\mathrm\omega_{R}</math>. Taking <math>\mathrm\omega_{0}</math> as the beam waist, and using the <math>\mathrm{FWHM}</math> as its value we are looking for the point where
:<math>\omega_{R} = \sqrt{2}\ \omega_{0}. </math>
*Plotting <math>\mathrm\omega_{R}</math> as a function of distance away from the beam waist center, we find an average Rayleigh Length,
:<math>\mathrm{Z_{RX}} =11.8mm</math> and <math>\mathrm{Z_{RY}} =10.5mm</math>