Finding the “Right” Sensor for Your Application

Mark Slutzki, Product Manager, Ophir Optronics

Ophir provides a convenient Laser Sensor Finder utility that makes it easy to input laser parameters and, in return, receive a list of sensor options. The list of sensors is arranged in order, starting with the sensors most suitable to your laser parameters. When applicable, less expensive options are shown first.

Below are some of the features provided through the Sensor Finder:

The sensors are selected in terms of cost effectiveness and ease of use, i.e. photodiode sensors and thermopiles are selected first and then pyroelectric sensors. If you want to measure only power, pyro sensors will not be selected even if they could operate within all other given laser parameters.

Since it is not practical to allow the beam to fill the entire aperture, the sensors are selected so that the sensor aperture is reasonably larger than the beam. For a circular flat top beam, the aperture must be at least 3mm or 10% larger than the beam whichever is smaller. If the beam is rectangular its corners can touch the aperture. For a Gaussian beam, the aperture must be at least 1.5 times the 1/e² beam diameter to insure that 99% of the beam is inside the aperture.

When entering the size and power or energy of the laser, the power or energy density is computed and displayed. Some sensors are closer to the laser damage threshold than others. Since the damage threshold can vary somewhat from case to case and also is cumulative, the Sensor Finder Program mentions how close a particular sensor is to the damage threshold. The displayed percent of damage threshold is the highest of either the power or the energy threshold. It is recommended to select a sensor that is less than 50% of the damage threshold if possible.

In order to find power/energy meters or PC interfaces that are compatible with various sensors, try our Meter Finder. Note that some of the sensors are not compatible with all meters or PC interfaces and in that case there will be a note to that effect at the bottom of the list of sensors.

The Sensor Finder Program now includes Ophir sensors that can be used in Pulsed Power mode. For example, when measuring up to 10 kW, besides the expected sensors (e.g. 10K-W, 15K-W), the Sensor Finder will also suggest the L40(150)A-LP2 with the description “Up to 10 kW for short exposures.”