4-quadrant photodetector
Koheron PD4Q is a 4-quadrant photodetector with 100 kV/A transimpedance gain and 250 kHz bandwidth. The PD4Q outputs three voltages: X = (A+D)-(B+C), Y = (A+B)-(C+D) and SUM = (A+B+C+D)/4. Thanks to its low noise and high dynamic range, the PD4Q can measure laser beam position with a resolution below 20 nm in a 10 kHz bandwidth.
| Quantity | Price |
|---|
Resources
Specifications
| PD4Q-10k | PD4Q-100k | |
|---|---|---|
| Detector | ||
| Wavelength range | 400 nm to 1050 nm | 400 nm to 1050 nm |
| Active area per quadrant | 12.3 mm² | 12.3 mm² |
| Photodiode peak responsivity(900 nm) | 0.64 A/W | 0.64 A/W |
| Maximum photocurrent per quadrant | 1 mA | 100 µA |
| Electronics | ||
| 3 dB bandwidth | 500 kHz | 250 kHz |
| Transimpedance gain | 10 kV/A | 100 kV/A |
| Noise Equivalent Power(at 10 kHz) | 8.3 pW/√Hz | 1.6 pW/√Hz |
| Output impedance | 1 kΩ | 1 kΩ |
| Output voltage range | -10 V to 10 V | -10 V to 10 V |
| Output | SMA female connector | SMA female connector |
| Power supplies | ||
| Positive supply voltage | 11.5 V to 13 V, nom. 12 V | 11.5 V to 13 V, nom. 12 V |
| Negative supply voltage | -13 V to -11.5 V, nom. -12 V | -13 V to -11.5 V, nom. -12 V |
| Quiescent current per rail | 20 mA | 20 mA |
| Maximum current per rail | 75 mA | 75 mA |
| Other | ||
| Outside dimensions | 60 mm x 49 mm x 18 mm | 60 mm x 49 mm x 18 mm |
| Operating temperature | 0 °C to 50 °C | 0 °C to 50 °C |
| Weight | 43 g | 43 g |
More Photodetectors
Functional diagram
Characterization
Output noise
The figure below shows the X output (X = (A+D)-(B+C)) power spectral density, with and without light. The optical source is a 810 nm LED driven by a Koheron DRV110-A-375 laser driver.
Frequency response
The figure below shows the frequency response of the PD4Q photodetector.
Noise Equivalent Power
The figure below shows the Noise Equivalent Power of the PD4Q photodetector measured at 810 nm.
Position noise
The Noise Equivalent Power (NEP) of the detector can be converted into a position noise spectral density:
where $D$ is the beam diameter, $P_{\rm opt}$ is the total input optical power and $S$ is the photodiode responsivity. Below is the position noise over a $\Delta f$ = 10 kHz bandwidth for a 800 nm laser with 4 mm beam diameter:
