Thorlabs.com - Noise Eaters / Laser Amplitude Stabilizers
https://www.thorlabs.com/newgrouppage9_pf.cfm?guide=10&category_id=95&objectgroup_id=6107[7/7/2016 8:29:39 AM]
Angle of Incidence
±2° (Max)
Input Polarization Tolerance
±3°
Wavefront Distortion
≤λ/4 at 635 nm
≤λ/2 at 635 nm
≤λ/2 at 635 nm
AR Coating
R
avg
<0.5% from 400 - 650 nm
R
avg
<0.5% from 650 -
1100 nm
R
avg
<0.5% from 1050 -
1620 nm
Modulation Performance Specs
Modulation Input
SMC Connector, 0 - 2.5 V, 10 kΩ Input Impedance
Minimum Extinction Ratio
g
512.6
7.7
6.5
Minimum Rise / Fall Time
h
0.65 ms / 7.3 ms
0.75 ms / 11.5 ms
2.8 ms / 25 ms
General Specs
Mounting Options
Two 8-32 (M4) Tapped Holes for Post Mounting
30 mm Cage System Compatible
Ø1" Lens Tube Compatible
Operating Temperature Range
15 °C to 45 °C
RMS value over 8 hours
These Noise Eaters are designed to operate down to DC frequency. However, due to external factors (e.g. ambient temperature, vibration, spatial
and/or polarization stability of the light source), the noise attenuation factor below 10 Hz is difficult to measure and quantify. Therefore our
specifications are guaranteed at 10 Hz and above.
Noise attenuation factor is the ratio of noise amplitude before and after the noise eater. It was tested at 100 mW input power with a noise amplitude
of 5% of the input power level. The nominal noise attenuation frequency range can reach up to 2.5 kHz, depending on the model. See detailed noise
attenuation plots on the
Performance
tabs for more information. The noise eater might not be able to completely eliminate high frequency noise in
certain cases, such as a laser source that contains spikes or step-like output power fluctuations.
Range of output power adjustment for a given input power level
Max input power density and laser damage threshold are wavelength-independent. Additionally, the absolute maximum input power varies with
wavelength; see the
Operation
tab for details.
Specified for a 1/e
2
beam diameter
Extinction ratio is the ratio of the signal power at minimum attenuation to the signal power at full attenuation.
Rise time is measured on the rising edge of the output intensity from 10% to 90% of full output power.
Noise Eater Performance Graphs
In the graphs below, noise attenuation was measured as one of three parameters was varied: input power level, input signal modulation (noise) amplitude, and
output signal attenuation. The graphs show that the noise eaters provide consistent performance regardless of changes in these parameters.
Graph Definitions
Noise Attenuation at Various Input Power Levels
Noise attenuation factor is the ratio of noise amplitude before and after the noise eater. In these graphs, the attenuation factor was measured for several
different input power levels, with a fixed signal modulation depth (noise amplitude). The graphs below show that the noise eaters provide consistent
performance regardless of input power level.
Noise Attenuation at Various Input Signal Modulations
In these graphs, the input signal was modulated with a sine wave to simulate noise. The attenuation factor was measured at a variety of modulation
depths (noise amplitudes). The graphs below show that the noise eater provides consistent performance even at large noise levels.
Noise Attenuation at Various Output Signal Power Levels
Since the noise eater uses a liquid crystal modulator as the optical control element, the noise attenuation is achieved by attenuating the laser beam
when noise appears. Our noise eaters are carefully designed to optimize the noise attenuation performance without needing to severely attenuate the
signal. These graphs demonstrate that the specified noise attenuation can be reached with a cost of only 5% - 10% overall attenuation of the output
power, and further increases in attenuation does not significantly improve the noise attenuation.
Modulation Performance
Noise eaters with a modulation input can also be used as EO modulators. In these graphs, a sine wave with a 2.5 V amplitude and an increasing
frequency was used to modulate a noiseless input beam. The graphs show that the maximum modulation depth decreases with increasing modulation
frequency. Further testing has demonstrated that the modulation performance is consistent for a given noise eater model, regardless of the laser beam's
input power.
P E R F O R M A N C E