Laser Power and Position
Laser position and power

Laser Power and Position Sensors for OEM Applications


This page presents greenTEG’s Laser Power and Position Sensors for OEM Applications.


Introduction to Laser Power and Position technology


Laser position and power

Measure your laser’s power and position with gRAY sensors. gRAY Laser Power and Position Sensors enable wavelength independent measurements with highest precision. The sensors are available as bare-die components, PCB-mounted, mounted, or housed. With a small footprint they are ideal for OEM system integration.

gRAY Sensors are integrated in medical laser systems, laser sources, power meters, and beam positioning systems.

Since July 2017 we are Thorlabs’ exclusive partner for thermal sensors. Contact us for more information! or consult the product data sheet available here.


Comparison of detection technologies


The three main characteristics and differentiators of laser power detectors are 1. wavelength, 2. rise time and 3. power threshold.


1. Wavelength


The most common detectors for low powers are photodiodes due to their good power resolution and fast response time. Light is absorbed in the material and converted into an electrical current proportional to the radiation power. Depending on the material composition, each wavelength results in a different signal and only a narrow bandwidth of wavelengths lead to an electric signal at all, as can be seen in the chart on the right.

Laser position and power

Besides the widely available Si, Ge and InGaAs are also used as photodetectors. The absorption characteristics of those two materials extend into the NIR spectrum, up to 1800 nm. When electrically biased appropriately, InGaAs can even absorb at higher wavelengths. All available photodiodes together cover a total range of UV, VIS, and NIR.

The working principle of thermopile sensors is fundamentally different from that of photodiodes (to learn more about this, click here). In an absorption layer on the sensor surface, the incident radiation is transformed into heat energy. This heat energy is measured by thermopile sensors. Thermopile sensors are therefore sensitive to radiation of all wavelengths, as long as the absorptive coating is efficient. Broad band absorbers are typically used and hence the spectrum from DUV to MIR lies within the detection range.

2. Rise Time


Due to their working principles, photodiodes and thermopile detectors have different signal response times. Photodiodes are very fast and react from 1 ns to incoming radiation. When read out with commercially available power meters, the speed is lowered due to the electronics and results in a rise time of 0.1 – 0.2 s. Therefore, photodetectors are suitable for fast measurements and a good choice, if the wavelength range and the power range (see below) are appropriate. Thermopile sensors are slower in their signal response. Since the sensors are based on thermal transport, the rise time is related to the thermal mass that needs to be heated. Therefore, larger or thicker thermopiles have longer response times than thinner or smaller ones. Peltier elements respond to incoming radiation with a minimum rise time of 1.8s due to their large thermal mass. Conventional disk-type sensors have minimum response times of 1s. greenTEG’s Thermal Laser Power Detectors are considerably thinner and are able to achieve response times of 0.1 s.


Laser position and power

3. Power Threshold



Laser position and power


Both detector types, photodiodes and thermopile sensors, cover a large dynamic range of powers,  and are therefore applied in different settings.


Applications


Our laser power detectors measure in real time and provide you with accurate data. By delivering information about the laser power, the gRAY detectors allow you to monitor and control your laser system. gRAY detectors are used in various applications ranging from industry to academic research. A few of them are listed in the following.

  • Industrial Laser Systems
  • Medical Laser Systems
  • Laser Sources
  • Power Meters
  • Beam Positioning

In industrial laser systems, it is crucial to monitor the laser power to avoid waste production. The results of laser marking, welding, cutting etc. are affected by too high or too low power. To allow continuous monitoring, the sensor is typically integrated behind a beam splitter where it measures only part of the beam. The main part of the beam is used for the process.

Laser position and power

Working Principle


Step 1

The laser irradiates the sensor surface. The light gets converted into heat when being absorbed by the coating.

Step 2

This heat impact causes a temperature difference between the exposed top surface and the non exposed bottom side.

Step 3

The T-difference produces a voltage based on the Seebeck effect. It is directly proportional to the input power and can be used to calculate the power of laser.


Laser position and power
Step 1
Laser position and power
Step 2
Laser position and power
Step 3

Overview of Laser Power and Position Products


Overview of the various items available

Mounted Detector

Build the mounted detector module into your monitoring unit to record laser powers – even if space is limited.
Absolute power sensing of laser beams up to 100 W
300 ms rise time
Compact design for versatile system integration
Optional: Amplification circuit board for electrical integration

Laser position and power

Laser position and power

PCB MOUNTED DETECTOR

Measure µW laser powers with highest accuracy with the thermally compensated detector module.
Two detectors mounted on a metal-core PCB; no thermal integration needed
10 µW to 5 W power range
Thermal background compensation
Integrated NTC
Simple, compact and robust mounting
Available with NIST/PTB traceable calibration


PCB SINGLE MOUNTED DETECTOR

Measure low laser powers in your laser system without worrying about electrical, mechanical and thermal integration.
Single detector mounted on a metal-core PCB
100 µW to 5 W power range
Integrated NTC
Simple, compact and robust mounting
Available with NIST/PTB traceable calibration

Laser position and power

Laser position and power

BARE DIE COMPONENT

Avoid wavelength or angle dependence of your detector signal by integrating gRAY sensor components into your laser sources
100 µW to 5 W power range
Linear power response
Signal independent of illumination angle
Ultra-thin design
Simple integration on PCBs
Attractive OEM pricing
Various sizes available (2×2 to 10×10 mm²)


MINIATURE THERMOPILE DETECTOR

Determine laser power at all wavelengths without loosing much space in your laser source.
Most compact thermal detector
Sensitive to all wavelengths
Powers of up to 500 mW
Integration like an SMD-component
Attractive OEM pricing at high volumes

Laser position and power

Laser position and power

POSITION DETECTOR

Align your laser beam efficiently with micro meter accuracy – even if it is not visible.
Position sensing and power measurement
Lateral resolution on the micro meter scale
µW to W power range
Compact design for versatile system integration
Sensitive to all wavelengths from UV to MIR


All the products datasheets are available in the download section, here, in English [EN] and Chinese [CN]. Contact us for any additional questions!