def find_beam_trajectory(self,
start_point=None,
scan_direction_x=1,
scan_direction_z=1,
z_samples=5,
measure_power=False):
"""Find trajectory of single beam.
The optional arguments are:
scan_direction_x (1): Integers +1 (-1) indicate to scan in the
positive (negative) x direction.
scan_direction_z (1): Integers +1 (-1) indicate to scan in the
positive (negative) z direction.
z_samples (5): Number of points to sample the beam.
measure_power (False): Include power with beam data.
"""
beam = Beam()
# Find the beam at the first z extreme.
if start_point is None:
start_point = Vector([
self.axes[0].limits.direction(-scan_direction_x),
self.axes[1].limits.middle(),
self.axes[2].limits.direction(-scan_direction_z)])
delta_z = -scan_direction_z * self.axes[2].limits.length() / z_samples
sample_positions = list(arange(
self.axes[2].limits.direction(scan_direction_z),
self.axes[2].limits.direction(-scan_direction_z),
delta_z))
sample_positions.reverse()
intercept = self.find_beam_center(start_point, scan_direction_x)
if intercept is None:
print "Trajectory cannot be established."
return None
# Calculate rough trajectory of the beam.
beam.add_sample(intercept)
self.change_grouping(1, fast=True)
small_step = intercept + (scan_direction_z * array([0, 0, 10]))
if abs(delta_z) > 10:
self.position(small_step, wait=True)
else:
self.position(intercept + (
scan_direction_z * array([0, 0, abs(delta_z)])), wait=True)
intercept = self.center_beam()
while intercept is None:
small_step = small_step - (scan_direction_z * array([0, 0, 2]))
self.position(small_step, wait=True)
intercept = self.center_beam()
beam.add_sample(intercept)
if sample_positions[0] == intercept[2]:
sample_positions.pop(0)
try:
for z_sample in sample_positions:
self.position(beam.position(z_sample), wait=True)
intercept = self.center_beam()
if intercept is not None:
beam.add_sample(intercept)
else:
# Cross this bridge when we get there.
pass
except TrackerError:
if len(beam.samples) < 2:
raise
beam.power = (0, 0)
if measure_power:
beam_angle = sys_math.degrees(sys_math.asin(beam.azimuth().value))
stage_angle = self.devices['r_stage'].position()
self.position(beam.intercept, wait=True)
self.rotate(stage_angle - beam_angle, wait=True)
self.center_beam()
ccd_power = self.devices['profiler'].average_power()
beam.distortions = self.devices['profiler'].profile()
self.devices['driver'].shutter_state(0, 0)
self.devices['driver'].shutter_state(1, 0)
sleep(0.1)
monitor_powers = []
for _ in range(10):
monitor_powers.append(self.devices['monitor'].read())
beam.power = (ccd_power, mean(monitor_powers))
self.rotate(stage_angle, wait=True)
self.position(intercept, wait=True)
return beam
def find_beam_center(self, start_point=None, scan_direction_x=1):
"""Scans in X for a single beam and centers it on the CCD.
The optional arguments are:
scan_direction_x (1): Integers +1 (-1) indicate to scan in the
positive (negative) x direction.
"""
if start_point is None:
start_point = [
self.axes[0].limits.lower,
self.axes[1].limits.lower,
self.axes[2].limits.lower]
x_axis = self.axes[0]
beam_position = self.get_beam_position()
if beam_position is not None:
# Beam is already in view.
if beam_position[2] != start_point[2]:
# Capture trajectory and move to correct z position.
beam = Beam()
beam.add_sample(self.center_beam())
delta_z_sign = ((start_point[2] - beam_position[2]) /
abs(start_point[2] - beam_position[2]))
self.change_grouping(1, fast=True)
self.position(beam_position +
delta_z_sign * array([0, 0, 10]), wait=True)
beam.add_sample(self.center_beam())
beam_position = self.position(
beam.position(start_point[2]), wait=True)
else:
# Beam not in view. Move camera into full starting point.
self.change_grouping(1, fast=True)
self.position(start_point, wait=True)
self.change_grouping(1, fast=False)
number_of_scans = 0
while beam_position is None:
# Scan for beam crossing.
x_axis.position(self.axes[0].limits.direction(scan_direction_x))
beam_position = self._scan_until_beam_visible(x_axis)
if number_of_scans * 3.0 > self.axes[1].limits.length():
print "Beam cannot be found. Check beam height and power."
return None
number_of_scans += 1
scan_direction_x = -scan_direction_x
if beam_position is None:
if self.axes[1].position() == self.axes[1].limits.upper:
self.axes[1].position(0, wait=True)
else:
self.axes[1].position(self.axes[1].position() + 3.0, wait=True)
# Move back to beam position.
self.change_grouping(1, fast=True)
self.position(beam_position, wait=True)
# The beam should now be in view.
self.change_grouping(3, fast=True)
beam_position = self.center_beam()
if beam_position is None:
# If it's not in view do a short scan to refind it.
self.change_grouping(1, fast=False)
self.position(
self.position() + [
self._z_cosine * scan_direction_x * 18.0, 0, 0],
wait=False)
beam_position = self._scan_until_beam_visible(x_axis)
if beam_position is None:
self.position(
self.position() + [
self._z_cosine * scan_direction_x * -36.0, 0, 0],
wait=False)
beam_position = self._scan_until_beam_visible(x_axis)
beam_position = self.center_beam()
# Return position or None, whatever it may be.
return beam_position
