Optical Power Meter OPM500

Artifex Optical power meter OPM500 for the precise measurement of power, from pW to mW. The output is a voltage linearly proportional to the input power.

The OPM500 is very flexible with USB and hard-wire interface control of gain, bandwidth and polarity. A graphical user interface is delivered with the amplifier.

Characteristics

Interfaces: USB and hard-wire (DB25)
Rise time: 45µs
Noise equivalent current: 30 pW(RMS)
Gain, bandwidth and polarity control:
6 gain ranges; 4 bandwidths; polarity inversion
Auto-null function: up to 10V offset nulling

Description

PRINCIPLES OF OPERATION

The OPM500 measures optical power via a photodiode. Photodiodes are useful for power measurement in the visible and near infra-red due to their inherent sensitivity and speed of measurement. Photodiodes produce a current which is proportional to the incident light power over a wide dynamic range. The disadvantage when compared to calorimetric devices is the wavelength dependance. However, for use with monochromatic sources, the detector can be calibrated and the measured current corrected accordingly. The current from the photodiode is converted to a voltage through a precise transimpedance amplifier. This amplifier is very linear over the full measurement range of the device. The OPM500 has 6 gain ranges. The switch is a semiconductor device, free from degradation. A unique feature of the OPM500 is the auto-null function. Further functions include signal inversion and bandwidth reduction. The analogue output signal is available at the BNC connector on the front panel an on the appropriate line on the interface port on the back panel. The voltage generated is then converted to a digital value via a 12 bit A/D converter. This process and all calculations and communication with the PC are controlled by a microcontroller. The measurement process is started via a command over the USB interface (software trigger). Alternatively, a continuous measurement stream can be started which samples at 1.5 kS/s. The measured photocurrent may also be read out from the USB port. In addition, the calibration value for a given wavelength may be read out. Using these two values, the optical power can then be calculated.

FIELDS OF APPLICATION

This optical power monitor is particularly useful for the measurement of fibre coupled sources. The output is a voltage linearly proportional to input power. The fast response time at high signal-noise ratio makes this OPM series particularly useful in systems control feedback loops. The high sensitivity and large dynamic range allow measurement of a wide range of optical sources such as lasers and LEDs alike. The OPM500 series is insensitive to electromagnetic interference by design, an important factor when working in “dirty” industrial environments. The proprietary auto-nulling function allows up to 10V of offset nulling. This is particularly useful for nulling dark current or for eliminating a DC signal component to concentrate on signal changes, such as in component burn-in and life-time testing.

Specifications

Parameter	Conditions	Si, InGaAs	Ge	Units
Input
Wavelength range	extended InGaAs	950 – 2100	800 – 1500	dBm
	InGaAs	800 – 1650		dBm
	visible enhanced InGaAs	400 – 1600		dBm
	UV-Si	190 – 950		dBm
Power ranges (full scale)		+ 5¹ 0 – 10 – 20 – 30 – 40	+ 15 + 10 0 – 10 – 20 – 30	dBm
Noise equivalent power (NEP_RMS )	Range 1 – 5 Range 6	full scale – 45 (max) – 75 (max)	full scale – 32 (max) – 62 (max)	dB dBm
Polarization Dependant Loss (PDL)		0.02 – 0.1	0.02 – 0.1	dB
Fibre type		single mode, multi-mode (core Φ ≤ 62.5 μm; NA ≤ 0.275)	single mode, multi-mode (core Φ ≤ 62.5 μm; NA ≤ 0.275)
Receptacles		FC, SMA, free beam	FC, SMA, free beam
Output
Function		Linear analogue : V_out = scale factor x P_in	Linear analogue : V_out = scale factor x P_in
Output scale	Range 1 Range 2 Range 3 Range 4 Range 5 Range 6	1¹10 100 1 10 100	0,1 1 10 0,1 1 10	V/mW V/mW V/mW V/µW V/µW V/µW
Output range (full scale)		10 (max)	10 (max)	V
Connectors		BNC and DB25 (Adapters for other connector systems available)	BNC and DB25 (Adapters for other connector systems available)
Rise / Fall time (10% – 90%)	Small signal (-1 → +1V) Large signal (-10 → +10V)	45 (max) 65 (max)	45 (max) 65 (max)	µs
Accuracy		± 5 (min)	± 5 (min)	%
Reproducibility		± 0.5 (min)	± 0.5 (min)	%
Linearity		± 0.1 (typ) ± 0.2 (max)	± 0.1 (typ) ± 0.2 (max)	dB
Output impedance	BNC-Output DB25-Output	50 0	50 0	Ω
Logic
Current required for switching		– 10 (min) 0.01 (typ) 10 (max)	– 10 (min) 0.01 (typ) 10 (max)	µA
Switching time		150² (max)	150² (max)	µs
Power supply
Type		Wall plug (supplied)	Wall plug (supplied)
Dimensions		30 x 50 x 60	30 x 50 x 60	mm
Dimensions
		105³ x 45 x 116 (B x H x L)	105³ x 45 x 116 (B x H x L)	mm

¹ Linearity guaranteed to 0dBm (1 mW).
² Logic switching < 1µs. Effective switching time limited by setting time.
³130 mm including case wings.

Options

Detector: UV-Si, Ge, V-InGaAs, x-InGaAs
Input receptacle: FC-receptacle, SMA-receptacle, free beam
Case: gull wing, lab style

Accessories

Attenuators: FC-PC, FC-APC

Artifex Software Development Kit

The SDK is a fixed, free component when purchasing a device.

It comes with the source code of the application program (in VB.net) and a LabView VI with the basic functions of the instrument. A description of the communication with the devices and a list of the commands used is also included.

For some devices (currently LDD100, LIV120 in preparation) there is a dll file (library file) with documentation and exemplary applications in VB.net and LabView.