diffractive lens nanopillar outlines via openCV

import numpy as np
import cv2
import math

h=1000
w=1000

scaling = 20.

fin_w = 85
fin_l = 410
fin_h = 600
focal = 10000/scaling

design_wavelength = 600/scaling

_l = int(fin_l/scaling)
_w = int(fin_w/scaling)
_x1 = _l/-2
_y1 = _w/-2
_x3 = _l/2
_y3 = _w/2
_x2 = _x3
_y2 = _y1
_x4 = _x1
_y4 = _y3

spacing = 430
img = np.zeros((h, w, 3), np.uint8)

# step along Y
for i in xrange(0, h, int(spacing/scaling)):
	# now step along X
	for j in xrange(0, w, int(spacing/scaling)):
		angle = (math.pi/design_wavelength) * (focal - math.sqrt((j-w/2)**2 + (i-h/2)**2 + focal**2))
		#angle = (math.pi/design_wavelength) * (focal - math.sqrt((j)**2 + (i)**2 + focal**2))

		angle_radians = angle #* math.pi / 180.0

		rx1 = math.cos(angle_radians) * _x1 - math.sin(angle_radians) * _y1
		ry1 = math.sin(angle_radians) * _x1 + math.cos(angle_radians) * _y1

		rx2 = math.cos(angle_radians) * _x2 - math.sin(angle_radians) * _y2
		ry2 = math.sin(angle_radians) * _x2 + math.cos(angle_radians) * _y2

		rx3 = math.cos(angle_radians) * _x3 - math.sin(angle_radians) * _y3
		ry3 = math.sin(angle_radians) * _x3 + math.cos(angle_radians) * _y3

		rx4 = math.cos(angle_radians) * _x4 - math.sin(angle_radians) * _y4
		ry4 = math.sin(angle_radians) * _x4 + math.cos(angle_radians) * _y4

		cv2.line(img, (int(rx1 + j + _x3) , int(ry1 + i + _y3)), (int(rx2 + j + _x3), int(ry2 + i + _y3)), 255, 1)
		cv2.line(img, (int(rx2 + j + _x3) , int(ry2 + i + _y3)), (int(rx3 + j + _x3), int(ry3 + i + _y3)), 255, 1)
		cv2.line(img, (int(rx3 + j + _x3) , int(ry3 + i + _y3)), (int(rx4 + j + _x3), int(ry4 + i + _y3)), 255, 1)
		cv2.line(img, (int(rx4 + j + _x3) , int(ry4 + i + _y3)), (int(rx1 + j + _x3), int(ry1 + i + _y3)), 255, 1)
cv2.imwrite('diffractive_lens.jpg', img)