Anfatec Instruments AG
Measurement Science and Technology &
Scanning Probe Microscopy

4 - quadrant photo detectors PD1 and PD2

typical applications

  • laser deflection for displacement detection
    (AFM, SNOM, micromechanics)
enlarge image of Photodetector board

Basic Data:

voltage supply: 
detector type: 
QD7-5 (R&S 652 027) 
47 kOhm 
4 x BNC

Properties of the Photo Diode:

active diameter: 
active area: 
inactive spacing: 
wave length for maximum  sensitivity: 
spectral range: 
dark current (VR = 1 V): 
3 mm 
7 mm*mm 
0,2 mm 
0,5 A/W (typ.) 
820 nm 
430 nm ... 900 nm 
0,03 nA typ., 3 nA max. 
80 pF (Vs = 0 V)

Electronic Board:

band width: 
output noise: 
current voltage converter
typical: 10 V/mA (10 kOhm)
> 300 kHz 
< 10 mVpp 
15 mm x 26 mm


The small board with soldered PD IC can be mounted into home-built AFM or SNOM set-up's. The sensitivity is optimized for 2 mW lasers at 670 nm wave length. It can be changed in dependence on the costumers requirements. The housing of the PD is on ground potential. We provide the blank board with 4 mm laboratoy connectors for the power supply and with BNC connectors for the signals. As the application can need different band width or smaller noise, we make costumer specific boards. The full data sheet is provided.

There are two types:

PD 1 PD 2
PD shape 1 pd shape 2

T = Top, B = Bottom, L = Left and R = Right, or TL = Top-Left.