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High Speed transimpedance amplifier and digital data sampler

The PLL-1701 optometer is designed for two different types of fast optical measurements with two different amplifier modes (linear or logarithmic).

The device incorporates a small integrating sphere and detector for the measurement of optical power from fibers (FC connector) in W over the wavelength range 400 nm to 1550 nm. The measurement results can be output either directly as an analogue voltage (BNC) or as digital data via USB or RS422 interface. The pure analogue measurement conversion (transimpedance) to the BNC is with a speed of 200000 Samples/s suitable for very fast measurement purposes. The digital measurement is only limited by the transmission speed of USB and RS422 (100kHz).Instead of the integrating sphere measurement, an external detector can be used with the provided BNC current-input.

The device itself can be configured by the two remote interfaces.

Flicker measurements

The fast sampling rate enables flicker evaluation of lighting products when used in conjunction with an external photometric detector such as the VL-3701-1. The standard flicker metrics Pst, SVM, Mp, Flicker frequency, Flicker index and Flicker percent are all implemented in the available software.

16 µs or 500 µs rise time linear amplifier 

The PLL-1701 linear signal amplifier offers fixed rise times of either16 µs or 500 µs for all gain ranges which can be set by remote commands. The total gain range of the current to voltage amplifier is divided in nine ranges in order to achieve an optimal signal to noise ratio.

logarithmic amplifier 

The PLL-1701 also offers a logarithmic amplifier which covers the whole dynamic range with one amplifier gain range. Hence no switching of gains is needed which would otherwise take some time and thereby limit some high speed applications.

AA, ADC and DAC mode

In addition to the traditional measurement functions of an optometer (AA - analogue to analogue (transimpedance) and ADC – analog to digital converter) the PLL-1701 incorporates a digital to analog converter able to transfer 16-bit digital data to the analogue electrical output (BNC); signal generator functionality (-5V to +5V).


Windows based software is supplied with the PLL-1701 which provides all common functions to do remote control measurements and analysis via USB and RS422. Optionally an S-SDK-PLL1701 is available to implement the meter by the user’s own software.


schematic drawing: 1 = optical fiber (user), 2 = FC connector, 3 = integrating sphere, 4 = Current in (external detector), 5 = Voltage Out, 6 = Photodiode, 7 = electronic board, 8 = Power supply, 9 = USB, 10 = I/O interface


Front View
Rear View
Short description

High-speed transimpedance amplifier, digital data sampler and function generator for versatile applications with implemented integrating sphere for radiant power (W) measurement of optical fibers. The PLL-1701 stand out with two integrated amplifiers, a linear amplifier with nine gain ranges and logarithmic amplifier with one high dynamic range without need for range switching.

Main features

Optical FC input for fast measurement of optical fibers, BNC electrical current input for external detector heads, linear and logarithmic current amplifiers

Measurement range

linear and logarithmic amplifier, radiant power measurement (W) with the integrating sphere calibrated from 400 nm to 1550 nm

typical applications

Fast measurement of optical fibers, fast measurement with detector heads, AA, ADC and DAC measurements, flicker measurements


Factory calibration. Traceable to international calibration standards

Input Interfaces

BNC-Connector (electrical)

FC-Connector (optical)

Output Interfaces

BNC-Connector, Output Voltage: ± 5V



16 bit



16 bit

Measurement range
Linear amplifier:



rise time

(10 - 90)%

rise time reduced
(10 – 90)%

± 1.17 mA

16 µs

500 µs

± 545 µA

16 µs

500 µs

± 254 µA

16 µs

500 µs

±117 µA

16 µs

500 µs

± 54 µA

16 µs

500 µs

± 25.4 µA

16 µs

500 µs

± 11.7 µA

16 µs

500 µs

± 5.45 µA

16 µs

500 µs

± 2.54 µA

16 µs

500 µs


Log amplifier:

max. current: +1 mA (analog output voltage: +4.8 V)

min. current: +100 pA (analog output voltage: -1.8 V)

spectral responsivity

PLL 1701 spectral responsivity

Calibration uncertainty
(400 - 800) nm: ± 5 %
(810 - 900) nm: ± 6 %
(910 - 1070) nm ± 6.5 %
(1080 - 1100) nm ± 7 %
(1110 - 1550) nm: ± 7.5 %


Spectral radiant intensity responsivity (400 - 1550) nm

Function generator

The PLL-1701 is able to provide electrical Signals on the BNC Output (function generator):

-5 V to +5 V, max. 10000 Values, clock speed 3 µs – 900 µs

Power Supply

(9-24) VDC

200 mA bei 12 V

sampling rate

100.000 SPS (samplings/s) with continuous data transmittance


USB V2.0 (Full Speed, HID Device)

RS422 (based on LVDS)

Limitation: Only one device can be connected by RS422.
Max. interfaces transmission speed: 100 kHz


550 g


173.3 mm x 36.2 mm x 124.4 mm


External signal: Low active, Trigger Level ca. 1V, Delay: Rise Time (16µs) + digitalization (15µs), Pre-Trigggering possible

Internal digital trigger: Delay 2µs ± 200ns.

temperature range

Storage: (-10 to 50) °C

Operation: (10 to 30) °C


<80%, non-condensing


Regular recalibration of the current calibration is recommended. Especially when very small measurement currents have to be measured. In the case of very high humidity, fault currents of the radiometer are possible at low measuring currents and should be taken into account. Temperature difference relative to the calibration temperature can increase the measurement uncertainty.

Type Description File-Type Download
Datasheet PLL-1701 PDF
Produktname Product Image Description Show product
S-SDK-PLL1701 Software Development Kit for the PLL-1701.
VL-3701 Detector head for the measurement of photopic illuminance in Lux [lx].

Features: f1 ≤ 3 %, f2 ≤ 1.5 %, 0.5 nA/lx, 20mm height, for the usage with Optometers and amplifiers, calibration certificate

Article-Nr Modell Description Request / Compare
15307746 PLL-1701

PLL-1701 Optometer

15309151 K-PLL1701

Calibration of the PLL-1701 in W in the wavelength range from 400 nm to 1550 nm including current calibration of the logarithmic and linear amplifier.

15295230 VL-3701-1

Photometric detector with –1 connector, protective cap, calibration certificate

15309839 S-PLL1701

End-user software for PLL-1701.

15309838 S-SDK-PLL1701

Software development kit for the PLL-1701

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