PD300R

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.

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We have included this document with your recent calibration order because we have noticed an out of tolerance condition obtained from your equipment when returned for calibration. This document was created to assist our valued customers in the proper care and maintenance of Ophir photodiode 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.

Ophir photodiode sensors can be used for many years without any repairs when used with the proper laser optical setup. Many of our customers have sensors that are using their original absorber that are over ten years of age. We hope that this document will enable you to also enjoy the long life and reliable results that Ophir- Spiricon is known for.

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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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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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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

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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? Weiterlesen...

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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AbstractThis document describes the inherent problems involved with measuring average power for low frequency pulsed laser sources, and describes the new “Low Freq. Power Mode” being offered on many Ophir devices and meters to solve these problems. It describes how to use the new mode and mentions some tips for obtaining best results. Weiterlesen...

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.

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BackgroundWhen measuring average power using a photodiode detector such as PD300 or IS6-D-VIS, the maximum power or saturation power is determined by the maximal photocurrent that the photodiode can generate while still maintaining linearity. The saturation power is typically 3mW for a bare silicon photodiode. Adding attenuation in the form of a filter or through the use of an integrating sphere will naturally increase the saturation power of the sensor as a whole. Weiterlesen...

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. Weiterlesen...