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                <span style="font-family:Arial;">Dear FLASH Users,</span> 
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                <span style="font-family:Arial;">I have a question in Section 17.4.6.1 of the User's Guide, which is about the laser beam. The question is w</span><span style="font-family:Arial;">hy the local z-axis projection of s</span><sub style="font-family:Arial;">1 </sub><span style="font-family:Arial;">is </span><em style="font-family:Arial;">l₁cos(\phi)₁</em><span style="font-family:Arial;"></span><span style="font-family:Arial;"></span><em style="font-family:Arial;">cos(\theta - \pi /2)</em><span style="font-family:Arial;"> rather </span><span style="font-family:Arial;">than </span><em style="font-family:Arial;">l₁cos(\phi)₁</em><sub style="font-family:Arial;"> </sub><span style="font-family:Arial;">in equation 17.72.</span>
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                <span style="font-family:Arial;">Any possible suggestions would be great appreciated!</span> 
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<span style="font-family:Arial;">Best wishes, <br>
Chen Yunan</span><br>
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