Photodiode Sensors
Ideal for measuring the power from low power CW lasers
Coherent’s LM-2 & OP-2 photodiode sensors are designed for low power measurements in the range from 1nW to 50mW (5W with optional attenuator) in the 250 – 1550nm band.
Photodiodes offer high sensitivity and low noise, enabling them to detect very low light levels. However, they saturate above approximately 1mW/cm2, so attenuating filters must be used when operating at higher powers, such as the Coherent 1000:1 accessory filter. Photodiodes also have a fast response time, so they can be convenient for tuning and peaking lasers. Photodiodes have a much more limited spectral range and lower spatial uniformity than thermal sensors. The latter can affect the measurement repeatability of non-uniform beams or of beams that wander over the detector surface between measurements. Photodiode sensors are not designed for use with pulsed lasers. Coherent photodiode sensors are calibrated using a monochromator for use over their full specified wavelength range.
The OP-2 sensors are directly compatible with the Coherent FieldMate, FieldMax II TO / TOP and LabMax TO / TOP laser power meters. The LM-2 sensors must be used in conjunction with the accessory SmartSensor adaptor.
For testing the power from optical fibres or fibre-coupled lasers, accessory fibre optic adaptors are available that screw onto the photodiode sensor heads.
|
Model |
Type |
Wavelength |
Calibration |
Power Range |
Max Power |
Detector |
||
|
Max |
Min |
Resolution |
||||||
|
OP-2 UV |
Silicon |
250-400nm |
+/- 8% |
30mW |
10nW |
1.00nW |
N/A |
6.0mm |
|
OP-2 VIS |
Silicon |
400 - 1064nm |
+/- 5% |
50mW |
10nW |
1.00nW |
5W |
7.9mm |
|
OP-2 IR |
Germanium |
800 - 1550nm |
+/- 4.5% |
10mW |
10nW |
1.00nW |
1W |
5.0mm |
|
LM-2 UV |
Silicon |
250 - 400nm |
+/- 8% |
30mW |
10nW |
1.00nW |
N/A |
6.0mm |
|
LM-2 VIS |
Silicon |
400 - 1064nm |
+/- 5% |
50mW |
10nW |
1.00nW |
5W |
7.9mm |
|
LM-2 IR |
Germanium |
800 - 1550nm |
+/- 4.5% |
10mW |
10nW |
1.00nW |
1W |
5.0mm |
Accessories for Coherent photodiode sensors are listed in the table below.
| Part No. | Description |
| 33-1298 | 1000:1 optical attenuator for photodiode sensors1 |
| 33-1413 | Fibre optic adaptor, SMA |
| 33-1421 | Fibre optic adaptor, DIN 2106 |
| 33-1439 | Fibre optic adaptor, FC/PC |
| 1056827 | SmartSensor adaptor2 |
(1) 1000:1 attenuator provides attenuation between 1100:1 and 950:1, depending upon the laser wavelength. Useful working range is 400-1800nm. Suitable for use at upto 100MW/cm2. Calibrated at 647nm with an uncertainty of +/- 5%
(2) The SmartSensor adaptor allows Coherent LM-2 series photodiode sensors to be used with FieldMax II TO, FieldMax II TOP and FieldMate power meters