Helios Plus - EtherNet/IP

The key to Helios’ ability to handle high powers with a small, uncooled body is the limit on exposure time. The specifications state a maximum accumulated energy of 10kJ, so one can hit the Helios with 12kW (max power) for up to about 0.8s.

The 2.5s response time of the Helios would indeed be problematic if it were measuring the power directly. In actuality it integrates the power received to measure the energy of the pulse. An internal photodiode is used to detect the pulse width. The power is then calculated by P = E / Δt.

Basic use with Profinet requires one power supply cable and one Profinet cable. Using RS232 or the PC application requires one power supply cable and one RS232 cable. If you want to use the Helios in a line/star topology, where it is daisy-chained with the next device in line, then you should use two power supply cables and two Profinet cables.
RS232 uses a standard DB9 RS232 cable. Profinet uses a Profinet-grade cable and RJ45 connectors. The power supply is a standard Profinet power supply from the Han PushPull series. For more information and mating connectors, see Chapter 3 of the manual.

This is limited by the temperature the Helios body reaches, that is measured by an internal sensor. The temperature shouldn’t be allowed to exceed 60° C. In our experience, this translates to about 40 kJ of accumulated exposure. Of course, the longer one waits in between pulses (allowing the body to cool), the more total energy it can take. That is why the temperature sensor should be used as the primary indicator of overheating, while 40 kJ should be treated as a rule of thumb.

After the Helios reaches the maximum temperature of 60° C (approx. 40 kJ of accumulated energy), it should take about 10 20 minutes for it to cool back down to room temperature. Therfore, use the temperature sensor as the indication of how many pulses can be measured

Whether RS232 or Profinet is used, there is a command to query the current temperature. The customer is responsible for integrating this into the measurement script and coordinating with the laser control to make sure the laser is not allowed to be measured when the temperature is over the limit. If using the PC application, one should select: Options > Log Temperature Enable. This will show the current temperature (and log it). If the temperature goes over the limit, it will turn red.

There are seven LEDs for different status/error indications. From left to right (and top to bottom), the LEDs are:

1. Power
2. COM (Green)
3. COM (Red)
4. Link (Port 1)
5. TX/RX (Port 1)
6. Link (Port 2)
7. TX/RX (Port 2)

For more detailed information, see Chapter 7 of the manual.

Use methanol and a tissue or clean air.

Unless otherwise indicated, Ophir sensors and meters should be recalibrated within 18 months after initial purchase, and then once a year after that.

In theory, if a beam is completely parallel and fits within the aperture of a sensor, then it should make no difference at all what the distance is; it will be the same number of photons (ignoring absorption by the air, which is negligible except in the UV below 250nm). If, nevertheless, you do see such a distance dependence, there could be one of the following effects happening:

• If you are using a thermal type power sensor, you might actually be measuring heat from the laser itself; when very close to the laser, the thermal sensor might be “feeling” the laser’s own heat. That would not, however, continue to have an effect at more than a few cm distance unless the light source is weak and the heat source is strong.
• Beam geometry – The beam may not be parallel and may be diverging. Often, the lower intensity wings of the beam have greater divergence rate than the main portion of the beam. These may be missing the sensor's aperture as the distance increases. To check that you'd need to use a profiler, or perhaps a BeamTrack PPS (Power/Position/Size) sensor.
• If you are measuring pulse energies with a diffuser-based pyroelectric sensor: Some users find that when they start with the sensor right up close to the laser and move it away, the readings drop sharply (typically by some 6%) over the first few cm. This is likely caused by multiple reflections between the diffuser and the laser device, which at the closest distance might be causing an incorrectly high reading. You should back off from the source by at least some 5cm, more if the beam is not too divergent.

Needless to say, it’s also important to be sure to have a steady setup; a sensor held by hand could easily be moved around involuntarily, which could cause partial or complete missing of the sensor’s aperture at increasing distance, particularly for an invisible beam.

The short answer: Yes. Now to explain: The question comes up because of the concern that the internal fast photodiode - which measures the exposure time (“pulse width”) - might get confused at sensing the end of an individual pulse within a pulsed beam, and incorrectly think that it has now measured the exposure time and needs to divide the measured energy by that time (which would of course be wrong). The Helios Plus is a bit smarter than that though; it looks simultaneously at the outputs from the fast photodiode AND from the (much slower) thermal sensor, and if it sees that the thermal sensor’s output has not “come back down”, then it knows what looked like the “end of the pulse” from the fast photodiode’s output is not really the end of the pulse.