PDA520 In Stock

The PDA520 by ThorLabs is a highly sensitive, amplified Silicon photodetector that is designed to detect light in the wavelength range of 400 nm to 1100 nm. With its three-position rotary switch, the PDA520 provides the user with the flexibility to vary the gain in 10 dB steps. The device boasts a buffered output that drives a 50Ω load impedance up to 5 volts, which makes it an ideal solution for applications that require precise and accurate detection of low light levels.

The PDA520 comes with a threaded coupler that is removeable and compatible with threaded accessories with a size of 1”. This feature makes it easy to mount apertures, light filters, external optics, and other cage assembly accessories. The device housing contains a 8-32 tapped hole with a mounting depth of 0.25”, which adds to its convenient installation process. The PDA520 comes with a 120VAC 50-60Hz power supply, which makes it easy to use in a variety of settings. In order to ensure the best performance of linearity, it is suggested that a 10mW/cm maximum intensity not be exceeded when testing fiber outputs, focused beams, or beams with small diameters. When the gain on PDA520 is set to its maximum, the bandwidth tends to decrease as this behavior is universal in all amplifier systems due to a finite gain-bandwidth performance.

The gain of the PDA520 can be easily adjusted using a small slotted screwdriver to turn the internal, gain-setting rotary switch. The gain is set to 0dB when the rotary switch is set fully counterclockwise, and each clockwise click of the switch increases the gain by 10 dB. The PDA520 is switched on by the POWER toggle switch located on the rear of the optical sensor. To avoid saturation, it is recommended to modify the gain value so that the signal level measurement out of the PDA520 is under 10 volts (5 volts with a 50Ω load). If necessary, external neutral density filters can be used to reduce the input light level.

To ensure the device's longevity, the PDA520 offers output protection against short circuits, connection to output voltages, and current limiting. A 140mA resettable fuse is placed in line with the output drive supply to protect the drive circuitry from shorting or low load resistance values. Under these conditions, the fuse will ‘blow’ before damaging the unit. In order to reset the fuse, the output load will need to be removed until the fuse cools down and resets. A high-speed diode protects the output from accidental application of negative voltages and limits the output from going more than -0.6V.