This family of InGaAs and Ge detectors covers the spectal information rich 0.7 to 2.5 µm NIR measurements. These detectors are operated in the photovoltaic (unbiased) mode to provide the lowest noise for DC and low frequency operation since it avoids the shot noise associated with bias currents. One unit, model 71898 , comes with a DC bias arrangement producing 1 ns rise times. We offer amplified and unamplified, calibrated and non calibrated models, as well as TE cooled and room temperature versions. Their large areas make signal capture easy. The 1.5 Inch Series flange allows instant connectivity to other Oriel instruments, such as monochromator exit slit assemblies. Use the Ge detectors to get beyond the 1.6 µm limit of standard InGaAs.
Fig. 1 Typical Responsivity of InGaAs and Ge Detectors
Calibration
We offer calibrated and standard InGaAs and Germanium detectors. The calibrated InGaAs detectors come with NIST traceable calibrated responsivity factors for the 0.8 to 1.7 µm range. The Germanium detectors NIST traceable calibrated responsivity factors cover the 0.7 to 1.8 µm range.
Amplification
Detectors are available with and without a built-in transimpedance amplifier. Table 1 gives the gain/bandwidth information for the built-in transimpedance amplifier. The amplifier provides transimpedance gains from 104 V/A to 109 V/A. It also offers three selectable time constant settings to allow you to match the upper bandwidth limit with your experimental needs. Operating at the lowest bandwidth setting allows you to operate at the lowest noise levels. The amplified models require +/-15 V DC; the 70703 or 70709 Power Supply provides the required power.
Table 1 Bandwidth Values
|
Time Constant |
Gain |
|
104 V/A |
105 V/A |
106 V/A |
107 V/A |
108 V/A |
109 V/A |
| "MIN" |
100 kHz* |
100 kHz* |
80 kHz |
8 kHz |
800 Hz |
80 Hz |
| "MED" |
100 kHz |
10 kHz |
1 kHz |
100 Hz |
10 Hz |
1 Hz |
| "MAX" |
1 kHz |
100 Hz |
10 Hz |
1 Hz |
0.1 Hz |
0.01 Hz |
Cooled or Room Temperature?
You will do well with room temperature InGaAs and Ge devices under most measurement conditions. Both are quite stable. However, the responsivity of the diodes is sensitive to temperature changes. It can go up or down with temperature, depending on the spectral range in which you operate. Therefore, whenever you are looking for measurement reproducibility of better than ~2%, temperature stabilization becomes a necessity. Our TE cooled devices, combined with the 77055 Temperature Controller, give you excellent stability of readings. The added benefit of TE cooling is the reduction of noise levels which allows you to reach the limits of device performance.
50Ω Termination
Use a 50Ω termination when measuring ≤100 ns pulse widths or ≥10 MHz modulated signals to avoid electronic echoes generated by signal reflections at impedance mismatch locations.
Electronic Accesories
The 77055 Cooler Controller allows full function of the TE cooled devices. The 70703 or 70709 Power Supply provides the required ±15 V for the amplifiers.
Connectors and Cables
All detectors have a BNC connector for signal out. We ship these detectors with a 6 ft. (1.8 m) long BNC cable; the amplified models also include a 6 ft. (1.8 m) long cable with 3 pin banana plug, for connection to the 70703 / 70709 Power Supply.
Mounting
The flanged detectors are enclosed in aluminum housings with a 1/4-20 tapped hole in the bottom for rod mounting, and a 1.5 Inch Series female flange for direct coupling to Oriel Monochromators.
