Add Keck Lyot stop that was originally in #155

hcipy/aperture/realistic.py

@@ -1519,3 +1519,76 @@ def func(grid):
 		segments = [segment_with_strut(segment) for segment in segments]
 
 	return func, segments
+
+def make_keck_lyot_stop(normalized=True, gap_padding=10, segment_transmissions=1):
+	"""Make the Keck L-band Lyot stop.
+
+	Create the L-band Lyot stop used with the vortex charge 2 coronagraph that is installed on Keck 2
+	that is available for science with NIRC2. The values were extracted from drawings of the mask
+	and represent that mask installed around 2018 that is currently available in 2022.
+
+	Parameters
+	----------
+	normalized : boolean
+		If this is True, the outer diameter will be scaled to 1. Otherwise, the
+		diameter of the pupil will be 10.95 meters.
+	gap_padding : scalar
+		Arbitrary padding of gap size to represent gaps on smaller arrays - this effectively
+		makes the gaps larger and the segments smaller to preserve the same segment pitch.
+	segment_transmissions : scalar or array_like
+		The transmission for each of the segments. If this is a scalar, this transmission
+		will be used for all segments.
+
+	Returns
+	-------
+	lyot_stop : Field generator
+		A field generator for the Lyot stop.
+	"""
+	conversion = 10.95 / (2 * 12.05 / 1000)  # based on drawing
+	pupil_diameter = 10.95  # m actual circumscribed diameter
+	actual_segment_flat_diameter = np.sqrt(3) / 2 * 0.00337 * conversion  # m actual segment flat-to-flat diameter
+	central_obscuration_diameter = 0.00698 * conversion
+	actual_segment_gap = 0#0.003  # m actual gap size between segments
+	spider_width = 0.0005 * conversion  # m actual strut size
+	num_rings = 3  # number of full rings of hexagons around central segment
+
+	if normalized:
+		actual_segment_flat_diameter /= pupil_diameter
+		actual_segment_gap /= pupil_diameter
+		spider_width /= pupil_diameter
+		central_obscuration_diameter /= pupil_diameter
+		pupil_diameter = 1.0
+
+	# padding out the segmentation gaps so they are visible and not sub-pixel
+	segment_gap = actual_segment_gap * gap_padding
+
+	segment_flat_diameter = actual_segment_flat_diameter - (segment_gap - actual_segment_gap)
+	segment_circum_diameter = 2 / np.sqrt(3) * segment_flat_diameter  # segment circumscribed diameter
+
+	segment_positions = make_hexagonal_grid(actual_segment_flat_diameter + actual_segment_gap, num_rings)
+	segment_positions = segment_positions.subset(lambda grid: ~(make_circular_aperture(segment_circum_diameter)(grid) > 0))
+
+	segment = make_hexagonal_aperture(segment_circum_diameter, np.pi / 2)
+
+	spider1 = make_spider_infinite([0, 0], 0, spider_width)
+	spider2 = make_spider_infinite([0, 0], 60, spider_width)
+	spider3 = make_spider_infinite([0, 0], 120, spider_width)
+	spider4 = make_spider_infinite([0, 0], 180, spider_width)
+	spider5 = make_spider_infinite([0, 0], 240, spider_width)
+	spider6 = make_spider_infinite([0, 0], 300, spider_width)
+
+	segmented_aperture = make_segmented_aperture(segment, segment_positions, segment_transmissions, return_segments=True)
+	segmentation, segments = segmented_aperture
+
+	def segment_with_spider(segment):
+		return lambda grid: segment(grid) * spider1(grid) * spider2(grid) * spider3(grid) * spider4(grid) * spider5(grid) * spider6(grid)
+
+	segments = [segment_with_spider(s) for s in segments]
+	contour = make_segmented_aperture(segment, segment_positions)
+
+	def func(grid):
+		res = contour(grid)
+		res *= make_circular_aperture(central_obscuration_diameter)(grid)
+		return Field(res, grid)
+
+	return func