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.
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.
The Ophir sensors are provided with a 1.5m cable between the sensor and the smart head connector. When a longer length cable is needed it can be provided, as long as it is within operational limits. However it is not possible to add an extension to the cable, because that moves the smart head connector away from the meter or interface unit which can degrade the smart head functionality or disable it.
It is recommended that the sensor be put in a well-ventilated container instead of being put into a tool bag or in an area where other things can contact the sensor surface. The meters too should be put into a container so the screen is protected from objects that might contact and break the meter's screen.
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.
Since power and energy sensors use absorption materials that are not spectrally flat, you always need select the correct laser wavelength on the meter or in the interface software in order to achieve the specified sensor measurement accuracy. Power and energy sensors are calibrated to produce accurate measurement throughout their spectral range, however since they do not detect the wavelength in use, this is one entry that must be manually selected by the operator in order to achieve the specified accuracy.
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.
When measuring the energy of a pulsed laser setup with a pyroelectric energy sensor for the first time or after changing a setup, use the pyroelectric damage test slide provided with the sensor to insure the new energy and fluence level will not damage the sensor. The damage test slide is made of the same material as the sensor absorber and coated (if appropriate) with the same damage resistant coating.
An integrating sphere is used to measure a divergent light source. As shown in the illustration, an integrating sphere has its inner surface coated with a surface that highly reflects (typically 99%) in a scattering, nonspecular way. Thus when a divergent beam hits the walls of the integrating sphere, the light is reflected and scattered many times until the light hitting any place on the walls of the sphere has the same intensity.
The need to accurately measure laser power and energy has increased as more of these systems are used in medical procedures and industrial processes. Although a fairly simple process, this measurement is not as straightforward as an electric power measurement. With lasers, more attention must be paid to the selection of the right sensor as since different sensors perform different measurements. Selecting the wrong sensor can destroy the laser.
Ophir Photodiode sensors use silicon, germanium and InGaAs sensors together with built in and removable filters. The spectral response of these type of sensors vary widely with wavelength. When used with our smart displays or PC interfaces, the sensitivity factor for the relevant wavelength is automatically set when the user inputs the laser wavelength.
- 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)
Careful measurements are considered when testing the optical power, current, voltage, wavelength, and temperature of high output laser diodes. The test system energizes and measures the laser parameters as it will be used in the application. In some critical constant wave (CW) applications, the required output power from the laser is pushing the laser’s maximum specifications. Therefore, an accurate, stable, low drift laser power meter is required.
This document was created to assist our valued customers in the proper care and maintenance of Ophir-Spiricon pyroelectric 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 pyroelectric sensors can be used for many years without repair...
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.
The laser industry is advancing steadily with new wavelengths, higher powers and energies, and new applications all the time. As the power, energy and variety of new lasers advances, so measurement of these lasers has to advance.