What is the Relative Speed of Light at an Angle?

Gear300
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Let us say that an observer, O, saw a ray of light, such as a laser light (yellow curve), pass at an angle (omega). The speed of light would be constant in all frames, but wouldn't the observer record a relative speed of light c' = c*cos(omega) -- orange line -- assuming he/she couldn't tell the intensity decrease?
 

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c' is a component of the velocity. You get the velocity vector if you add the perpendicular component (which you omitted) to it. The length of this vector is called speed.
 
Alright...Thanks for the reply.
 

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