PDA55 In Stock

The ThorLabs PDA55 is a powerful and precise silicon detector with exceptional sensitivity that has been specifically designed to accurately detect light signals from DC to 10MHz. The PDA55 is equipped with a rotary switch that boasts five positions offers users the ability to vary the gain in steps of 10 dB, providing precise control over signal detection. The PDA55 also features a buffered output that can drive a 50Ω load impedance up to 5 volts.

The PDA55 housing includes a threaded, removeable coupler which is compatible with a variety of 1” threaded accessories. This feature enables the mounting of external optics, cage assembly accessories, light filters, and apertures, making it an ideal choice for use in elaborate 3D optical assemblies. Compatible accessories include FC fiber adapters, SMA fiber adapters, ST fiber adapters, stackable lens tubes, and cage assemblies. To make use of the PDA55, simply use a tiny slotted screwdriver to rotate the gain-adjustment rotary switch. The gain is set to 0dB when the slot is aligned counterclockwise as far as it will go. Turning the switch clockwise boosts the gain by 10 dB with each click. The PDA55 is switched on at the rear of the optical sensor by using a POWER toggle switch.

The output maximum of the PDA55 is 5 volts for loads that are 50Ω loads and 10 volts for loads with high impedance. To avoid saturation, adjust the gain so that the measured signal level out of the PDA55 is under 10 volts. Neutral density filters that are external can be used to reduce the input light level when necessary. When measuring small diameter beams, fiber outputs, or focused beams, it is essential to not exceed a 10mW/cm intensity maximum to ensure the PDA55 performs with maximum linearity. Furthermore, the gain settings of the PDA55 will have an effect on its bandwidth since all amplifier circuitry has a limited capability to manage gain and bandwidth. As the gain settings are increased, the bandwidth decreases.

To ensure the photodetector's maximum accessibility, the diode’s front surface is extended outside of the PDA housing. It is important to make sure that the fiber ferrule does not come into contact with the detector when using fiber adapters. If it does, damage can occur to either the fiber or the diode. To prevent this, a 1” threaded coupler can have a compatible retaining ring installed inside prior to installing the fiber adapter. The PDA55 features a 8-32 mounting hole that is tapped and has a mounting depth of 0.25” mounting depth and comes equipped with a 120VAC power AC/DC supply.