SCAN_RANGE  = [1455.0, 1475.0]
STEP_SIZE = 0.2
EXPOSURE_TIME = 1.0
SETTLING_TIME = 0.1

start = time.time()

objective = microscope.get_child("Objective")
add_device(objective, True)
objective.polling=1000


class CoefficientOfVariation(Readable):
    def read(self): 
        d = image.data
        ip = load_array(d.array, d.width, d.height)
        img_stddev = get_measurement(ip, "StdDev")
        img_mean=  get_measurement(ip, "Mean")
        try:
            return img_stddev/img_mean
        except:
            return float('nan')
        

variation = CoefficientOfVariation()
sensors = [variation]

if not get_dry_run() and str(get_setting("AUTO_SWITCH_VALVE")).lower() == "true":
    open_vg10()

init_eiger(EXPOSURE_TIME)
try:
    lscan(objective, sensors, SCAN_RANGE[0], SCAN_RANGE[1], float(STEP_SIZE), latency=SETTLING_TIME, before_read=trigger_eiger, keep=False)
finally:
    if not get_dry_run() and str(get_setting("AUTO_SWITCH_VALVE")).lower() == "true":
        close_vg10()   
    restore_eiger()
    print "Running time: " + str(time.time() - start)