Comet 1K | Comet Portable Power Probes | Power Sensors - Ophir

Comet 1K

7Z02702
Description: 

The Comet 1K is a portable power puck laser sensor with a 50mm aperture. It can measure power from 20W to 1000W by sampling a 10s exposure of laser power. It has the spectrally flat broadband coating and covers the spectral range from 0.2 to 20µm.

Specification

  • N.A.
  • Ø50mm
  • 0.2-20µm
  • 20W-1000W
  • N.A.
  • N.A.
  • 295 L x 25 W x 50 D (mm)
  • N.A.
  • 4kW/cm²
  • N.A.
  • 0.3J/cm²
  • 15J/cm²
  • 1kW
  • N.A.
  • CE, China RoHS
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FAQ

How should I clean my sensor?

First, clean the absorber surface with a tissue, using Umicore #2 Substrate Cleaner, acetone or methanol. Then dry the surface with another tissue. Please note that a few absorbers (Pyro-BB, 10K-W, 15K-W, 16K-W and 30K-W) cannot be cleaned with this method. Instead, simply blow off the dust with clean air or nitrogen. Don't touch these absorbers. Also, HE sensors (such as the 30(150)A-HE-17) should not be cleaned with acetone.
 
Note: These suggestions are made without guarantee. The cleaning process may result in scratching or staining of the surface in some cases and may also change the calibration.

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What is the damage threshold of the thermal broadband coating and how does it compare with claims of other manufacturers?

We publish a nominal damage threshold for most of our thermal BB sensors as 20KW/cm2. Other manufacturers may quote higher numbers than this. In actuality, in one to one tests against competitors, our sensors show a higher damage threshold but the actual damage threshold depends on the total power as well as the power density. For very low powers such as 30W, the damage threshold can be as high as 50KW/cm2 and at high powers such as 5KW, it drops to 3KW/cm2. The Ophir sensor finder program takes account of these variations in its calculations.

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Do I need to recalibrate my instrument? How often must it be recalibrated?

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

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Can a laser measurement depend on the distance from the laser to the sensor?

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.

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Videos

FAQ: Thermal Sensors for Measuring Low, Medium & High Laser Powers FAQ: Thermal Sensors for Measuring Low, Medium & High Laser Powers
On what factors do Ophir sensor accuracy specs depend? On what factors do Ophir sensor accuracy specs depend? On what factors do Ophir sensor accuracy specs depend?

Ophir's CTO, Dr. Ephraim Greenfield discusses the various factors that contribute to uncertainties in measurement when using Ophir laser power and energy meters. He discusses the various factors and shows how they combine to give the total uncertainty.

Effects of Incidence Angle on Measurements Effects of Incidence Angle on Measurements Effects of Incidence Angle on Measurements

Are you measuring a laser beam coming at an angle correctly?
Ever wonder how your laser power measurements are affected by your beam’s angle of incidence?
In this video, you will learn to what degree a beam’s incidence angle matters, and for which sensor types this should be taken into account.

In this short “Basics” video we review the use – and selection - of thermal sensors for measuring low, medium and high laser powers.

Drawing

Tutorials

Tutorials and Articles

Laser Power Sensors introduction

As described in the general introduction, the thermopile sensor has a series of bimetallic junctions. A temperature difference between any two junctions causes a voltage to be formed between the two junctions. Since the junctions are in series and the «hot» junctions are always on the inner, hotter side, and the «cold» junctions are on the outer, cooler side, radial heat flow on the disc causes a voltage proportional to the power input. Laser power impinges on the center of the thermopile sensor disk (on the reverse side of the thermopile), flows radially and is cooled on the periphery. The array of thermocouples measures the temperature gradient, which is proportional to the incident or absorbed power. In principle, the reading is not dependent on the ambient temperature since only the temperature difference affects the voltage generated and the voltage difference depends only on the heat flow, not on the ambient temperature.

 Read more...

Common Reasons for Thermal Sensor Damage or Out of Tolerance Conditions

This document was created to assist our valued customers in the proper care and maintenance of Ophir thermal laser power sensors. The following information is for reference only. If you have any reason to believe that the sensor is no longer performing within the original specifications,we always recommend that you send it in for repair and/or recalibration by our trained technicians to bring the unit back to the proper NIST traceable standards. We believe that Ophir thermal sensors can be used for many years without any repairs when used with the proper laser optical setup. We hope that this document will enable you to also enjoy the long life and reliable results for which Ophir-Spiricon is known.

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How to Properly Select a Laser Power or Energy Sensor

The selection of a sensor to accurately measure the power of a laser or energy of a pulsed laser can seem like a simple and easy procedure. However, many times the selection process is limited to choosing a sensor that only meets the range of power or energy to be measured, leaving out several other essential criteria of the laser specifications; that without their consideration, can allow the wrong sensor to be selected, the laser to be measured inaccurately and likely to cause the sensor to fail prematurely.

Watch Our Laser Measurement Video

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Setting your thermal sensor up in energy mode for the best accuracy and repeatability.

Range Selection Use the lowest range that is larger than the pulse energy to be measured. For example, if you want to measure a 2.7 Joule pulse, use the 3 J range instead of the 30 J range. This will allow for maximum resolution (a 2.700 J reading versus a 2.70 J reading). Threshold Selection For most energy measurements, the default MEDIUM setting is appropriate. If taking measurements in a noisy environment or where there is a high level of background thermal radiation, the instrument may trigger spuriously on the noise or the background radiation. In this case, the user may Read more...

How Much of the Power Sensor Aperture Can My Laser Fill Up?

The entire aperture senses power, so you can use the whole head. That said, a beam in the inner 50% of the surface area (about 70% of the diameter) is specified by Ophir to be uniform within +/-2%. The sensitivity around the edges might be a little less, but generally the sensitivity doesn’t vary by more than +/-2% over the entire aperture.

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Effect of Ambient Conditions on Laser Measurements

We are often asked about the specified ranges of various ambient conditions (temperature, humidity, etc.) for Ophir instruments. In this article we will clarify the effects of these conditions on laser measurements, so you’ll be able to use your Ophir laser measurement instrument effectively.

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Ophir Power/Energy Meter Calibration Procedure and Traceability/Error Analysis

This document discusses the interpretation and basis for stated measurement accuracy of Ophir Laser Power/Energy meters.
1. General Discussion
2. Combination of Errors and Total Error
3. Analysis of Power and Energy Calibration Errors
4. Detailed Analysis of Power and Energy Calibration Errors

 Read more...

Laser Measurements in Materials Processing: How and When They Absolutely, Positively Must Be Made

19th century British physicist and engineer William Thomson, 1st Baron Kelvin, was the first to say, “If you can’t measure it, you can’t improve it.” When applying this principle to improving laser-based processes, there are a variety of parameters that must be measured. Given the continuously rising power of laser systems in material processing, the requirements for measurement systems are more challenging than ever. Which technologies are available to measure high-power lasers? How often should they be measured? What measurements should be tracked? When this data is collected, what should be done with it? Read more...

How do I know what range, or scale, to set my power/energy meter to? And what happens if I go over range?

Each given range represents one level of gain of an internal amplifier. The electronics, as always, have a limited Dynamic Range. If the measured signal is too low, in other words near the bottom of the range, then it may be lost in the noise and the reading will be inaccurate and noisy. If it’s too high – there may be saturation issues. To give an instrument a usefully wide dynamic range, multiple scales or ranges are used. Switching from range to range can be automatic (“Autorange”), or manual. Autoranging simply starts automatically at the least sensitive range and works its way down the ranges, sampling the signal as it goes, till it finds a range at which the signal is properly detected. Note, by the way, that only in POWER mode is Autoranging available. If we are working in Single Shot Energy mode, there is no Autoranging – simply because when we are measuring a single pulse, the instrument has no opportunity to work its way down the ranges as in Power mode.

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Types of power / Energy Laser Sensors General Introduction

Power and Single Shot Energy Sensors
Ophir provides two types of power sensors: Photodiode sensors and Thermal sensors. Photodiode sensors are used for low powers from picowatts up to hundreds of milliwatts and as high as 3W. Thermal sensors are for use from fractions of a milliwatt up to thousands of watts.
Thermal sensors can also measure single shot energy at pulse rates not exceeding one pulse every ~5s.

Repetitive Pulse Energy Sensors
For higher pulse rates, Ophir has pyroelectric energy sensors able to measure pulse rates up to tens of KHz. These are described in the energy sensor section, section 1.3.

 Read more...

5 Situations Where Laser Performance Measurement is Necessary

Measuring the performance of a laser has possible for a number of years and is accomplished with a variety of techniques. These electronic laser measurement solutions give the laser user more relevant, time-based data that shows trends in laser performance rather than single data points. While these solutions have provided laser users with the ability to present data in a simple and easy to understand manner, the application of the data still seems to be unclear to many laser users. Read more...