POWER DETECTORS

Well established in this field for over 30 years Gentec Electro-Optics has been a leader in the field of laser power and energy measurement. The average power density damage threshold of 100 kW/cm2 that we introduced with the WB series in the mid 1990s is still unsurpassed. Gentec-EO also offers you broadband spectrally flat power detectors for general use in the PS 310 & 330 series, high peak power pulse damage resistance for specific UV and IR bands with the PSV series, and high average power detectors in the air and water cooled High Power PS series for the big jobs. We also have 2 lines of OEM detectors in our LT-50 and LT-200 series and the SD thermopile disks as well.

How they work

The basic laser power detector is essentially a thermopile. The more familiar application for thermopiles, in fact where the common name "thermo electric cooler" comes from, is when a voltage is applied to cool one side of the thermopile and whatever it is bonded to. Thermopiles for laser power measurement are however used in the opposite fashion. That is, a temperature difference is used to create a voltage. On one side is material heated by the laser and on the other is a heat sink. The laser energy absorbed by that material is converted to heat. With the hot absorber on one surface and the cold heat sink on the other, there is a temperature difference across the thermo electric device and the heat flows through it. This temperature difference causes the thermopile to generate a voltage. That voltage is proportional to the temperature difference which in turn is proportional to the laser power. The monitor measures this voltage to provide the laser power reading in watts.

ENERGY DETECTORS

Gentec Electro-Optics provides a full range of products to meet your pulse energy measurement needs. They range from the tiny and sensitive ED-100A+, to our large world-class custom calorimeters. All of our plus series detectors are the toughest in the world at 2J/cm2. Having introduced the first pyroelectric joulemeter over 30 year ago, Gentec-EO is well established as an experienced source of energy measurementexpertise.

How they work

In simple terms, a pulse of light is absorbed by the surface of the detector and heats it up. That in turn changes the temperature in a pyroelectric material underneath. This separates electrical charges in the pyroelectric which creates a voltage as the pulse of heat energy passes through it to a heat sink. The heat sink removes the heat energy to allow the pyroelectric to be ready for another pulse and to prevent it from overheating. The monitor reads the electrical voltage which is the signal proportional to the pulse energy.

The absorber

The business end of the detector is the absorber that coats the side of the pyroelectric material exposed to the laser. That material absorbs most of the light energy from the laser and converts it to heat. A small fraction is reflected. How much is shown by the spectral response curve for the material. The thermal mass of the absorber and its thickness determine how quickly the heat can flow to the pyroelectric detector and hence its response time. Lowering the thermal impedance by using an absorber with a lower thermal mass or reducing the thickness of the absorber will increase the detector's speed.

High Energy Spectral
Absorption (ED+ Series)

Attenuator Transmission
(ED-200LA+)

Mid-IR Spectral Absorption
(ED-500LIR)

TPM-300CE

TPM-300CE

This is our rugged, portable and easy-to-use workhorse for power measurement. It comes equipped with two large displays. The 3.5 inch analog meter is great for tuning while the convenient 4 digit LCD lets you read your measurement with precision. You can also take the data from the RS-232 interface or the analog output which is ideal for chart recorders. This meter auto-calibrates using the data in the smart interface connector on our power detectors. It features a zero-adjust potentiometer, 12 power scales and a low battery LED indicator. The rechargeable battery is good for 8 hours on the road. You will also like the unique 360¢ªpivoting stand that can be locked into any position.

SOLO

SOLO

This new family of single channel monitors will give you the utmost capability for your handheld power and energy measurements. The Windows CETM operating system gives you an easy to use interface and the ability to upgrade over the internet. They will support RS-232 interface and offer a very readable high resolution display. They will also be compatible with Gentec-EO power and energy detectors, old and new. You will  get the same great functionality as the DUO, including auto-calibration and Personal wavelength correctionTM based on data measured uniquely from each detector.

     SOLO-P
     For single channel power measurement.
     SOLO-E
     For single channel energy measurement.
     SOLO-PE
     For single channel power and energy measurement.

DUO

Specifications :
2-WATT BROADBAND POWER/ENERGY METER

Measurement Specifications

Calibrated Range :

200nm-20§­(400nm-2§­ with filter)

Power(energy) Range :

10¥ìW-2W(10¥ìJ-2J) with 10-¥ìW(10-¥ìJ) resolution

Range Selection :

7-position switch, 3-3000mW(mJ)

Offset :

±25mW(mJ) with 10-turn potentiometer

Pulse Repetition Rate(energy mode) :

Single pulse or 1Hz maximum

Maximum Pulse Width(energy mode) :

100 msec

Noise Equivalent Power/Energy :

10¥ìW(¥ìJ) rms

Drift :

Less than 15¥ìW over 60 min

Response Time :

<0.5sec

Calibration :

±5% NIST traceable

Detector

Type :

10mm-diameter large-area thermopile, high-density graphite disc

Uniformity :

±1% over central 8mm

Maximum Power Dissipation :

3W

Maximum Energy Density :

~1J/cm2 for pulse width(¥ó)¡Ã10-7sec
~(¥ó/10-7)J/cm2 for pulse width(¥ó)¡Â10-7sec
e.g., ~10-5J/cm2 for pulse width(¥ó)=10-12sec

Maximum Irradiance
(subject to 3W total power limitation):

200 W/cm2 average, 100MW/cm2 short pulse (tested with excimer and YAG laser pulses from 1nsec to 10sec)

Displays

Digital :

3-1/2 digit LED display

Analog :

Precision backlit mirror scale

External Analog Output :

Rear-panel BNC (1Vdc full scale)

Power Requirements

Voltage :

115Vac+10%, -20%, 230Vac±10%, rear-panel selector switch

Frequency :

50-60Hz

Power :

<10W

Dimensions

Control/Display Unit(W x H x D):

185mm x 130mm x 125mm(7.3in. x 5.1in. x 4.9in.)

Sensor Head :

48mm(1.9 in.) in diameter, 60mm(2.4 in.)long

Cable :

1.6m(5.2ft)

Combined Weight :

2.4kg(5.3lb)

Temperature :

+15¢ªto +35¡É(operating), -20¢ªto +55¡É(storage)

Safety

CE compliant

Fig. 2.

Fig. 2. The PowerMonitor
- the pneumatic shutter is at the top
- bores with close tolerances
can be used to fix the FocusMonito
directly on the PowerMonitor

One of the basics of laser material processing is the exact knowledge of the laser power available at the workpiece. Even in complex processing systems significant differences between the power at the laser's output window and the power at the workpiece often occur.

Moreover the user gets information about the laser power independent of the display at the laser source.

The following criteria are met by this device:
- Long-term stability
- Reproducibility
- Precision
- Short Measuring Time

All parts in the device which get in contact with the cooling water are made of copper or brass, so that any corrosion in the coolant circuit because of different chemical potentials is avoided. A pneumatic shutter is used to close the beam input aperture and to protect the entrance mirror of the PowerMonitor againstdust.

Accuracy and operation conditions :

Power Range :

0-8 kW(up to 25kW with 100mm aperture is optional)

Reproducibility :

better than 1%

Time constant :

15 seconds up to 99% of the final value

Flow rate :

minimum is 5 litres water per minute

Absolute accuracy :

better than 2%

Power density :

up to 15kW/cm2

Free aperture :

48mm or customer specific solutions

Dimensions :

Dimensions :

Height : 125mm, Length : 242mm, Depth : 400mm

Compact Laser Power Meter

- fast and convenient
- easy handling
- practical design

PocketMonitor (Model 30p)