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| \begin{alignat}{2} | | \begin{alignat}{2} |
| \left( \frac{q}{k} \right)^2 | | \left( \frac{q}{k} \right)^2 |
− | & = \left( \frac{x}{ \sqrt{x^2 + d^2 + z^2 d^2 }} \right)^2 + \left( \frac{d - \sqrt{x^2 + d^2 + z^2 d^2 } }{\sqrt{x^2 + d^2 + z^2 d^2 }} \right)^2 + \left( \frac{z d }{\sqrt{x^2 + d^2 + z^2 d^2 }} \right)^2 \\ | + | & = \left( \frac{x}{ \sqrt{x^2 + d^2 + z^2 }} \right)^2 + \left( \frac{d - \sqrt{x^2 + d^2 + z^2 } }{\sqrt{x^2 + d^2 + z^2 }} \right)^2 + \left( \frac{z }{\sqrt{x^2 + d^2 + z^2 }} \right)^2 \\ |
− | & = \frac{x^2 + \left( d - \sqrt{x^2 + d^2 + z^2 d^2 }\right)^2 + z^2d^2 }{x^2 + d^2 + z^2d^2} \\ | + | & = \frac{x^2 + \left( d - \sqrt{x^2 + d^2 + z^2 }\right)^2 + z^2 }{x^2 + d^2 + z^2} \\ |
− | & = \frac{x^2 + \left( d^2 - 2d \sqrt{x^2 + d^2 + z^2 d^2} + x^2 + d^2 + z^2 d^2 \right) + z^2d^2 }{x^2 + d^2 + z^2d^2} \\ | + | & = \frac{x^2 + \left( d^2 - 2d \sqrt{x^2 + d^2 + z^2 } + x^2 + d^2 + z^2 \right) + z^2 }{x^2 + d^2 + z^2} \\ |
− | & = \frac{2 x^2 + 2 d^2 + 2 z^2d^2 - 2d \sqrt{x^2 + d^2 + z^2 d^2} }{x^2 + d^2 + z^2d^2} \\ | + | & = \frac{2 x^2 + 2 d^2 + 2 z^2 - 2d \sqrt{x^2 + d^2 + z^2 } }{x^2 + d^2 + z^2} \\ |
− | & = 2 \frac{( x^2 + d^2 + z^2d^2 ) - d \sqrt{x^2 + d^2 + z^2 d^2} }{x^2 + d^2 + z^2d^2} \\ | + | & = 2 \frac{( x^2 + d^2 + z^2 ) - d \sqrt{x^2 + d^2 + z^2 } }{x^2 + d^2 + z^2} \\ |
− | & = 2 \left( 1 - \frac{d}{\sqrt{x^2 + d^2 + z^2d^2}} \right) | + | & = 2 \left( 1 - \frac{d}{\sqrt{x^2 + d^2 + z^2}} \right) |
| \end{alignat} | | \end{alignat} |
| </math> | | </math> |
Revision as of 13:04, 13 January 2016
Working results 1
![{\displaystyle {\begin{alignedat}{2}\mathbf {q} &={\frac {2\pi }{\lambda }}{\begin{bmatrix}\sin \theta _{f}\cos \alpha _{f}\\\cos \theta _{f}\cos \alpha _{f}-1\\\sin \alpha _{f}\end{bmatrix}}\\&={\frac {2\pi }{\lambda }}{\begin{bmatrix}\sin \left(\arctan \left[{\frac {x}{d}}\right]\right)\cos \left(\arctan \left[{\frac {z}{d/\cos \theta _{f}}}\right]\right)\\\cos \left(\arctan \left[{\frac {x}{d}}\right]\right)\cos \left(\arctan \left[{\frac {z}{d/\cos \theta _{f}}}\right]\right)-1\\\sin \left(\arctan \left[{\frac {z}{d/\cos \theta _{f}}}\right]\right)\end{bmatrix}}\\&={\frac {2\pi }{\lambda }}{\begin{bmatrix}{\frac {x/d}{\sqrt {1+\left(x/d\right)^{2}}}}{\frac {d}{\sqrt {d^{2}+z^{2}\cos ^{2}\theta _{f}}}}\\{\frac {1}{\sqrt {1+\left(x/d\right)^{2}}}}{\frac {d}{\sqrt {d^{2}+z^{2}\cos ^{2}\theta _{f}}}}-1\\{\frac {z\cos \theta _{f}}{\sqrt {d^{2}+z^{2}\cos ^{2}\theta _{f}}}}\end{bmatrix}}\\&={\frac {2\pi }{\lambda }}{\begin{bmatrix}{\frac {xd}{\sqrt {d^{2}+x^{2}}}}{\frac {1}{\sqrt {d^{2}+z^{2}\cos ^{2}\theta _{f}}}}\\{\frac {d}{\sqrt {d^{2}+x^{2}}}}{\frac {d}{\sqrt {d^{2}+z^{2}\cos ^{2}\theta _{f}}}}-1\\{\frac {z\cos \theta _{f}}{\sqrt {d^{2}+z^{2}\cos ^{2}\theta _{f}}}}\end{bmatrix}}\\\end{alignedat}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/6ea671cecdf06e0446180db0c1e73d2bb4fd81a5)
Note that
, and
so:
![{\displaystyle {\begin{alignedat}{2}{\frac {1}{\sqrt {d^{2}+z^{2}\cos ^{2}\theta _{f}}}}&={\frac {1}{\sqrt {d^{2}+z^{2}\left(d^{2}/(d^{2}+x^{2})\right)}}}\\&={\frac {1}{{\sqrt {d^{2}}}{\sqrt {((d^{2}+x^{2})+z^{2})/(d^{2}+x^{2})}}}}\\&={\frac {\sqrt {d^{2}+x^{2}}}{d{\sqrt {d^{2}+x^{2}+z^{2}}}}}\\\end{alignedat}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/4916f2a7eed04ede2a97e0cd920ff9d31f311407)
And:
![{\displaystyle {\begin{alignedat}{2}\mathbf {q} &={\frac {2\pi }{\lambda }}{\begin{bmatrix}{\frac {xd}{\sqrt {d^{2}+x^{2}}}}{\frac {\sqrt {d^{2}+x^{2}}}{d{\sqrt {d^{2}+x^{2}+z^{2}}}}}\\{\frac {d}{\sqrt {d^{2}+x^{2}}}}{\frac {d{\sqrt {d^{2}+x^{2}}}}{d{\sqrt {d^{2}+x^{2}+z^{2}}}}}-1\\{\frac {z\left(d/{\sqrt {d^{2}+x^{2}}}\right){\sqrt {d^{2}+x^{2}}}}{d{\sqrt {d^{2}+x^{2}+z^{2}}}}}\end{bmatrix}}\\&={\frac {2\pi }{\lambda }}{\begin{bmatrix}{\frac {x}{\sqrt {x^{2}+d^{2}+z^{2}}}}\\{\frac {d}{\sqrt {x^{2}+d^{2}+z^{2}}}}-1\\{\frac {z}{\sqrt {x^{2}+d^{2}+z^{2}}}}\end{bmatrix}}\\\end{alignedat}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/5c94591900a0186babf354b059bd7c10cd9e96ce)
As a check:
![{\displaystyle {\begin{alignedat}{2}\left({\frac {q}{k}}\right)^{2}&=\left({\frac {x}{\sqrt {x^{2}+d^{2}+z^{2}}}}\right)^{2}+\left({\frac {d-{\sqrt {x^{2}+d^{2}+z^{2}}}}{\sqrt {x^{2}+d^{2}+z^{2}}}}\right)^{2}+\left({\frac {z}{\sqrt {x^{2}+d^{2}+z^{2}}}}\right)^{2}\\&={\frac {x^{2}+\left(d-{\sqrt {x^{2}+d^{2}+z^{2}}}\right)^{2}+z^{2}}{x^{2}+d^{2}+z^{2}}}\\&={\frac {x^{2}+\left(d^{2}-2d{\sqrt {x^{2}+d^{2}+z^{2}}}+x^{2}+d^{2}+z^{2}\right)+z^{2}}{x^{2}+d^{2}+z^{2}}}\\&={\frac {2x^{2}+2d^{2}+2z^{2}-2d{\sqrt {x^{2}+d^{2}+z^{2}}}}{x^{2}+d^{2}+z^{2}}}\\&=2{\frac {(x^{2}+d^{2}+z^{2})-d{\sqrt {x^{2}+d^{2}+z^{2}}}}{x^{2}+d^{2}+z^{2}}}\\&=2\left(1-{\frac {d}{\sqrt {x^{2}+d^{2}+z^{2}}}}\right)\end{alignedat}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/65615f038668495cd970b8c2076c1c1e0a4a5e24)
Working results 2 (contains errors)
As a check of these results, consider:
![{\displaystyle {\begin{alignedat}{2}q&={\sqrt {q_{x}^{2}+q_{y}^{2}+q_{z}^{2}}}\\&={\frac {2\pi }{\lambda }}{\sqrt {\sin ^{2}\theta _{f}\cos ^{2}\alpha _{f}+\left(\cos \theta _{f}\cos \alpha _{f}-1\right)^{2}+\sin ^{2}\alpha _{f}}}\\\left({\frac {q}{k}}\right)^{2}&=(\sin \theta _{f})^{2}(\cos \alpha _{f})^{2}+\left(\cos \theta _{f}\cos \alpha _{f}-1\right)^{2}+(\sin \alpha _{f})^{2}\\&=\left({\frac {x/d}{\sqrt {1+(x/d)^{2}}}}\right)^{2}\left(\cos \alpha _{f}\right)^{2}+\left(\cos \theta _{f}\cos \alpha _{f}-1\right)^{2}+\left({\frac {z\cos \theta _{f}/d}{\sqrt {1+(z\cos \theta _{f}/d)^{2}}}}\right)^{2}\\&=\left({\frac {x}{\sqrt {d^{2}+x^{2}}}}\right)^{2}\left(\cos \alpha _{f}\right)^{2}+\left(\cos \theta _{f}\cos \alpha _{f}-1\right)^{2}+\left({\frac {z\cos \theta _{f}}{\sqrt {d^{2}+z^{2}\cos ^{2}\theta _{f}}}}\right)^{2}\\&={\frac {x^{2}}{d^{2}+x^{2}}}\left(\cos \alpha _{f}\right)^{2}+\left(\cos \theta _{f}\cos \alpha _{f}-1\right)^{2}+{\frac {z^{2}\cos ^{2}\theta _{f}}{d^{2}+z^{2}\cos ^{2}\theta _{f}}}\\&={\frac {x^{2}}{d^{2}+x^{2}}}{\frac {d^{4}}{d^{2}+z^{2}\cos ^{2}\theta _{f}}}+\left(\cos \theta _{f}{\frac {d^{2}}{\sqrt {d^{2}+z^{2}\cos ^{2}\theta _{f}}}}-1\right)^{2}+{\frac {z^{2}\cos ^{2}\theta _{f}}{d^{2}+z^{2}\cos ^{2}\theta _{f}}}\end{alignedat}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/34fcb8ca68e2609da4a4548f56c246e044f5615f)
Where we used:
![{\displaystyle {\begin{alignedat}{2}\sin(\arctan[u])&={\frac {u}{\sqrt {1+u^{2}}}}\\\sin \theta _{f}&=\sin(\arctan[x/d])\\&={\frac {x/d}{\sqrt {1+(x/d)^{2}}}}\\&={\frac {x}{\sqrt {d^{2}+x^{2}}}}\end{alignedat}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/fc9628f0d308053600f4e02d8f80c69fc9f356d0)
And, we further note that:
![{\displaystyle {\begin{alignedat}{2}\cos(\arctan[u])&={\frac {1}{\sqrt {1+u^{2}}}}\\\cos \theta _{f}&={\frac {1}{\sqrt {1+(x/d)^{2}}}}\\&={\frac {d^{2}}{\sqrt {d^{2}+x^{2}}}}\end{alignedat}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/584da470743b7feac2b55988526dabce5b4313c4)
Continuing:
![{\displaystyle {\begin{alignedat}{2}\left({\frac {q}{k}}\right)^{2}&={\frac {x^{2}}{d^{2}+x^{2}}}{\frac {d^{4}}{d^{2}+z^{2}\cos ^{2}\theta _{f}}}+\left({\frac {d^{2}}{\sqrt {d^{2}+x^{2}}}}{\frac {d^{2}}{\sqrt {d^{2}+z^{2}\cos ^{2}\theta _{f}}}}-1\right)^{2}+{\frac {z^{2}}{d^{2}+z^{2}\cos ^{2}\theta _{f}}}{\frac {d^{4}}{d^{2}+x^{2}}}\\&=d^{4}{\frac {x^{2}+z^{2}}{(d^{2}+x^{2})(d^{2}+z^{2}\cos ^{2}\theta _{f})}}+\left({\frac {d^{4}}{\sqrt {(d^{2}+x^{2})(d^{2}+z^{2}\cos ^{2}\theta _{f})}}}-1\right)^{2}\\&={\frac {d^{4}x^{2}+d^{4}z^{2}}{d^{4}+d^{2}x^{2}+d^{4}z^{2}}}+\left({\frac {d^{4}}{\sqrt {d^{4}+d^{2}x^{2}+d^{4}z^{2}}}}-1\right)^{2}\\&={\frac {d^{2}x^{2}+d^{2}z^{2}}{d^{2}+x^{2}+d^{2}z^{2}}}+\left({\frac {d^{8}}{d^{4}+d^{2}x^{2}+d^{4}z^{2}}}-2{\frac {d^{4}}{\sqrt {d^{4}+d^{2}x^{2}+d^{4}z^{2}}}}+1\right)\\&={\frac {d^{2}x^{2}+d^{2}z^{2}}{d^{2}+x^{2}+d^{2}z^{2}}}+{\frac {d^{6}}{d^{2}+x^{2}+d^{2}z^{2}}}-2{\frac {d^{3}}{\sqrt {d^{2}+x^{2}+d^{2}z^{2}}}}+1\\&={\frac {d^{2}x^{2}+d^{2}z^{2}+d^{6}-2d^{3}{\sqrt {d^{2}+x^{2}+d^{2}z^{2}}}+d^{2}+x^{2}+d^{2}z^{2}}{d^{2}+x^{2}+d^{2}z^{2}}}\\&={\frac {d^{6}+d^{2}+d^{2}x^{2}+x^{2}+2d^{2}z^{2}-2d^{3}{\sqrt {d^{2}+x^{2}+d^{2}z^{2}}}}{d^{2}+x^{2}+d^{2}z^{2}}}\\&=?\\&=?\\&={\frac {{\sqrt {d^{2}+x^{2}+z^{2}}}-d}{2{\sqrt {d^{2}+x^{2}+z^{2}}}}}\\&={\frac {1}{2}}\left(1-{\frac {d}{\sqrt {d^{2}+x^{2}+z^{2}}}}\right)\\q&={\frac {4\pi }{\lambda }}\sin \left(\theta _{s}\right)\end{alignedat}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/a53e402ce7d56277107863fd07dc790d47e7c56b)