knife_polygon

lenstest.lenstest.knife_polygon(s, phi, ds)

Create a polygon for a rotated knife edge.

The polygon is a vertical 1:2 rectangle that is shifted and then rotated counter clockwise.

When the shift is zero, then the edge of the knife edge is at the origin. Specifing a shift translates the knife edge across the origin. Then the knife is rotated about the origin by an angle phi.

Parameters:

• s – short side of the rectangle [mm]

• phi – CCW rotation from vertical [radians]

• ds – shift of knife edge [mm]

Returns:

x, y – coordinates of knife polygon