Missing measurements

[Henttinen]

Hi,
I am trying to use the PM100USB¹ with a ES120C² sensor, running on a Python script that is recording the data received from the sensor.

The problem is, that sometimes we don't get any data, from a 1Hz pulsing rate.

The code we are using for the measuring

import time
from datetime import datetime
from ctypes import cdll, c_long, c_ulong, c_uint16, c_uint32, c_float, byref, create_string_buffer, c_bool, c_char_p, c_int, c_int16, c_double, sizeof
from TLPMX import TLPMX
from TLPMX import TLPM_DEFAULT_CHANNEL
import os


class energy:
    def __init__(self, measureTime: int = 30) -> None:
        self.measureTime = measureTime
        self.tlpm = TLPMX()
        deviceCount = c_uint32(0)
        self.tlpm.findRsrc(byref(deviceCount))

        resourceName = create_string_buffer(1024)
        i: int = 0

        for i in range(0, deviceCount.value):
            self.tlpm.getRsrcName(c_int(i), resourceName)

        self.tlpm.open(resourceName, c_bool(True), c_bool(True))

        self.tlpm.setAttenuation(c_double(0), TLPM_DEFAULT_CHANNEL)
        self.tlpm.setWavelength(c_double(1574), TLPM_DEFAULT_CHANNEL)
        self.tlpm.setBeamDia(c_double(20), TLPM_DEFAULT_CHANNEL)
        self.tlpm.setPeakThreshold(c_double(0), TLPM_DEFAULT_CHANNEL)
        self.tlpm.setCurrentRange(c_double(1/1000), TLPM_DEFAULT_CHANNEL)
        self.tlpm.setEnergyRange(c_double(1/1000), TLPM_DEFAULT_CHANNEL)

        minEnergyRange = c_double()
        self.tlpm.getEnergyRange(
            1, byref(minEnergyRange), TLPM_DEFAULT_CHANNEL)
        print(f'Min energy range in J: {minEnergyRange.value}')

        self.measurementList = []
        start_time = time.perf_counter()
        while (time.perf_counter()-start_time) < self.measureTime:
            energy = c_double()
            self.tlpm.measEnergy((byref(energy)), TLPM_DEFAULT_CHANNEL)
            epoch = time.time()
            self.measurementList.append((epoch, energy.value))
        cwd: str = os.getcwd()

        fileFolder: str = f'{cwd}/enegytest/'
        os.makedirs(fileFolder, exist_ok=True)
        dtFormat: str = datetime.now().strftime('%Y-%m-%d-%H.%M.%S')
        fileName: str = f'{fileFolder}/{dtFormat}.csv'
        f = open(fileName, 'w+')
        f.write('index,epoch,energy_J\n')
        for i, (epoch, energy) in enumerate(self.measurementList, 1):
            f.write(f'{i},{epoch},{energy}\n')
        f.close()


if __name__ == '__main__':
    em = energy()

Footnotes

1. https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=4037&pn=PM100USB ↩

2. https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=3337&pn=ES120C ↩

[gboedecker]

Make sure to select a suitable threshold and energy range. It is easier to test this in the Optical Power Meter GUI.