Articles

Select any filter and click on Search to see results

Aligning an invisible laser beam with a visible pointer beam may sound simple but to do it right with everything lined up is not so obvious. Here is how it is done:

 

 

Measuring the power of scanning lasers, such bar code scanners, presents a problem. A bar code laser beam scans back and forth at a very high frequency so any ordinary photodiode power meter will not measure the power in the beam but rather the average power impinging on it, i.e. the power times the fraction of time the beam is on the detector. Therefore, when exposed to a scanned beam, the reading will be much lower than the actual power in the beam. For example, if a scanning laser delivers 2mW to a photodiode sensor and the beam is on the sensor only 1% of...

What happens when you have an application that requires a specific sensor with respect to technology and mechanical applications? You know that a standard Ophir sensor works, but you want to tweak the specification and mechanical size a little to fit your application. You call your Ophir representative and ask about OEM sensors.
 
Recently, a customer called and asked these exact questions. Knowing that Ophir has OEM prototypes available, the customer asked to evaluate the OEM thermal sensor 20C-UA. His power requirements at...

I am integrating a L100(500A) power meter head into a workstation and I would like to know how long between "readings" do I have to wait for the head to cool or what dictates how long I can shoot into the head. I realize that I can put a beam into the head at 500W for 1 min, 300W for 2 min or 75W continuously...but what determines how long I must wait if I wanted to take a 150W reading for 20 seconds, 10 times in a row (as an example)? How long would I have to wait between shots or could I take 5 readings, then wait 1 min and take 5 more etc.

The problem of irradiating...

Dr. Ephraim Greenfield CTO Ophir Optronics

  • Challenge: ever increasing demand for more accurate measurement
  • Solution: constant improvements in equipment and methods
  • How do we calibrate laser Power / Energy?
  • Basic method: stable laser and substitution
  • What is expected accuracy in simple case?

(power cal and wavelength available at NIST)

...

By Mark Slutzki , Product Manager, Power/Energy Measurement Solutions, Ophir Photonics

Confusion time…?
 
There seems to be a good deal of confusion when it comes to the terms “response time” and “integration time” of energy sensors. In this article we will clarify the meaning of these terms, as they apply to Ophir’s pyroelectric “Smart Sensors.”
 
Pyroelectric sensors use a pyroelectric crystal. When a laser pulse is absorbed,...

Julian Marsden, Hardware Team Manager, Ophir Photonics
The beauty of integrating an OEM sensor into your laser system is that you get to call the shots. What matters to you the most? Accuracy? Size? Output type? Tell us what you need and we’ll make it happen. Julian Marsden, the head of our electrical engineering department, wrote up a white paper to show you some of the OEM energy sensor options that are available...
There are two main technologies commonly used today for measuring laser beam powers:
  • Photodiode-based sensors, used for measuring low powers (from pW up to several hundred mW, typically); these are limited to spectral regions from the UV to the near IR, depending on the specific semiconductor used, and
  • Thermal sensors, used for measuring higher powers; the most sensitive thermal sensors can measure from as low as tens of microwatts, and up to 100 KW and beyond.
What if you need to measure very low power laser beams, say on the order of nanowatts, but with wavelengths in the mid or far IR region? This leaves you in a quandary...

By Mark Slutzki, Product Manager, Ophir Photonics

 

Abstract

Modern laser applications demand ever-increasing accuracy in the measurement and control of the laser beam. Various types of sensors and instruments are in use today, the choice depending on the type of measurement needed.

However, even given the correct choice of equipment, there are measurement conditions that can seriously affect the...

By Dan Ford Southwest Regional Sales Engineer, Ophir Photonics Group

In this application, our customer manufactures encoders that incorporate LED’s (light emitting diodes) that have a collimating lens attached. The LED’s produce between 850nm and 880nm at 2mW to 15mW, the beam sizes range from ¼” to ½”. Until now, a laser power meter has been used to verify the output wattage. Shining the beam on graph paper has been used to verify the beam size visually.
...

193nm excimer laser radiation needs special precautions in measurement because of its strong interaction with ordinary matter. This radiation is absorbed by ordinary air and water vapor in the air so that the intensity measured can vary by 1% per cm.

Instead of measuring power we measure total energy and the meter is fast enough to read out the energy and be ready for the next pulse 2.3s later. The accuracy of this method is better than +/-1%

When using a Fiber Adapter accessory together with one of Ophir's sensors, it is important to be aware of the power/energy density that is going to reach the sensor's surface.In most cases, the fiber adapter locates the fiber tip far enough away from the absorber surface that the spot diameter on the surface will be large, and problems of damage avoided. However, that is not always a certainty! For example, when using a sensor from the PD300 series, especially with filter IN, this distance could be quite small. A power level that is within spec limits...

If, for example, you need to measure energy at various points along an optical setup in order to characterize each stage of your system, you can place a sensor at each location along the way and connect the sensors in parallel to, say, a multi-channel Pulsar, and log the data using the StarLab application. So long as you open all channels in a single window and log from that window, all the channels will be synchronized with the same zero point. Knowing that, you can rely on the time stamps to tell you which pulse in each channel corresponds to which pulse in...

What is the best way to measure the power of a laser that is, unfortunately, not stable, where the power is drifting upwards or downwards. I am making a measurement taking readings by hand and logging to computer?
 
The best way to measure in such a condition is to take statistics of a number of readings. In order for the sample to be truly random, you should a given intervals look at the reading and take it down as seen with no attempt to wait for it to stabilize or reach a "better" value.

Ophir pyroelectric sensors can measure energy at very low repetition rates, what is called “single shot” energy as well as at various repetition rates all the way up to the maximum in the specification for such sensors. There seems to be a misunderstanding among users that pyroelectric sensors cannot measure single shot energy. This probably comes about since thermal sensors can only measure at very low repetition rates (~0.2Hz), then it is assumed that the converse applies to pyroelectric sensors, i.e. that they only can only measure at faster...

The global medical industry incorporates thousands of lasers into its arsenal of treatment tools. Wavelengths from UV to Far-infrared are used for everything from Lasik eye surgery to cosmetic skin resurfacing. Visible wavelengths are used in dermatology and ophthalmology to target selective complementary color chromophores. Laser powers and energies are delivered through a wide range of fiber diameters, articulated arms, focusing handpieces, scanners, micromanipulators and more. With all these variables, medical laser service personnel are faced with multiple measurement obstacles. At the Laser Training Institute (lasertraining.org), with headquarters in Columbus Ohio, we offer a week-long laser service school to medical service personnel. Four times a year, a new class will learn the fundamental concepts of power and energy densities, absorption, optics and most of all how lasers work. With a nice sampling of all the major types of medical lasers, the students learn hands-on calibration, alignment and multiple service skills.

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...

An explanation of how we do this is provided below (A). In addition, a recent check of Ophir’s 5000W head by PTB in Germany shows excellent agreement between our calibration and their standards. The details of the correspondence between our sensor and their standard at powers up to 1400W is included here (B).

A. High Power Measurement Calibration Method and Estimated Accuracy of Models 5000W and 10K-W

 

  • The app does not require “state-of-the-art” phones. It works perfectly OK with 3 year-old HTC Legend (that was not top of the line phone even when it was first announced) and it works well with our test phone which is defined mid-to-low range in today’s phone standards.
  • The software does require android version of 2.3.3 and above. According to latest analysis they account for over 99% of current phones (based on Google analysis of phones accessing Google Play). Since version 2.3.3 was...
Ophir power meters use a 12 VDC power supply that supplies 500 mA. This power supply is reverse voltage to most US products, meaning the outside connection is positive (+) and the inside is negative (-). When connecting a power supply to the Ophir power meter, make sure that the power supply is a 12 VDC 500 mA power supply and that the center is positive (+). Some of the newer Ophir power meters like the Vega and Quasar are dual voltage compatible meaning it does not matter if the power supply is center positive or center negative. It still needs to be 12 VDC and 500 mA, but it can be either a center positive or center negative. It is highly recommended that the original power supply included with the equipment be used and if it is missing that Ophir be contacted for a replacement supply.

Note the settings on your meter and sensor before sending the units in for calibration. To simplify the reintegration of your Ophir measurement instruments back into your system, please record your settings and parameters before sending your devices in for calibration.

During the calibration process occasionally we change the settings on an instrument back to the default. This means that when you receive the equipment back it will likely not start up as you had it. The end-user will see a change in how the meter and/or sensor are behaving. The difference could be as simple as changing the Average function, so the readings now appear less stable.

In order for LabVIEW to work with an Ophir power meter or PC interface, you must install StarLab. LabVIEW does not communicate via the StarLab application. We created a special COM object control for integration intent. You do need to Install StarLab in order to communicate with the device. The installation process of StarLab also installs the necessary USB drivers and registers the OphirLMMeasurement COM object required for LabVIEW (or other user programs) for communication with Ophir power meters and PC interfaces.
For certain pyro sensors with a diffuser, such as the PE50BF-DIF-C P/N 7Z02941, there is a Note (b) that for 10mm beam size the damage threshold specification should be derated by 50%. To explain why the damage specification is derated for a larger beam size, please see the picture illustration below. This has to do with the smaller relative increase in spot size lowering the energy density less on a larger beam than the larger relative increase in spot size with a smaller beam lowering the energy density more

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.

Pages