详细信息

Phase Locked Optical Choppers

◆Stable and reliable phase locking

◆Chopping is phase-locked to an internal frequency synthesizer

◆Frequencies from 4 Hz to 10.65 kHz

◆Lock to external references for harmonic or sub-harmonic chopping

The 3502 optical chopper provides rock-solid stability and flexibility because its chopping frequency is phase-locked to its own internal frequency synthesizer. It can chop from 4 Hz to 10.65 kHz, using either the internal frequency synthesizer or an external source as the reference. You can chop at the fundamental, a harmonic (2 to 15), or even a sub-harmonic (1/2 to 1/15) of the reference.

主要特点：

Complete Chopper System

 

 

The 3502 optical chopper comes complete with six chopper wheels, a wheel cover, and a controller with A USB interface.

Stable and Reliable Phase Locking

For stable chopping with minimum jitter and drift, the Model 3502 optical chopper uses precision photo-etched wheels mounted on a high-quality DC motor. In addition, the chopper controller has its own internal crystal-controlled frequency synthesizer and phase-locked loop for precisely locking the chopping frequency. A photo-interrupter on the chopper head monitors the chopping frequency, and the chopper controller actively stabilizes the motor speed to ensure stable chopping with a minimum of frequency drift.
In internal-reference mode, the chopper controller uses its internal frequency synthesizer as the reference. When the Model 3502 is operated in external-reference mode, the chopping rate is locked to the user-provided reference from another chopper or signal source. The chopper may also be run asynchronously with the rear-panel analog-control-voltage input. In all cases, the frequency-synthesizer output is available on the front panel for use in your measurement setup. The reference signal can be divided and multiplied by the sub-harmonic and harmonic generators before being processed by the phase shifter.

Unique Chopper Features

Unique features of the Model 3502 include outputs at the sum and difference of the inner and outer wheels’ chopping frequencies for nonlinear-optics experiments, and a high-stability phase shifter that can lock two choppers together for long fluorescence-decay measurements. The chopping frequency, as well as a number of other operating parameters, can be viewed on the front panel display. Easy-to-use cursor keys provide easy adjustment of operating parameters.

Six Broadbａnd Absorber Coated Chopper Wheels Included

 

 

Six chopper wheels are included with the 3502 optical chopper system allowing for chopping frequencies from 4 Hz to 10.65 kHz. Shown in the top row are 2-slot and 60-slot wheels. The middle row shows 7/5-slot and 42/30-slot wheels, and the bottom row shows 60/2-slot and 100-slot wheels. All chopper wheels are 4.50 inch (114.3 mm) diameter.

Advanced Optical Chopper Controller

 

 

The front panel display of the controller allows monitoring of the chopping frequency, as well as a number of other operating parameters. Easy-to-use cursor keys provide easy adjustment of operating parameters. The chopping rate may be set from 4 Hz to 2.00 kHz, using either the internal frequency synthesizer or an external source as the reference. Chopping mode options are selectable at the fundamental, a harmonic (2 to 15), or even a sub-harmonic (1/2 to 1/15) of the reference.

Optical Chopper Setup Instructions

Optical Chopper Initial Diagnostic Instructions

 

INTERNAL SYNTHESIZER
Stability	100 ppm after one hour warm-up
Drift	Less than 10 ppm/°C
Accuracy	< 1/5 of least significant digit
Resolution	3 significant digits
Range limits (EXT)	4 Hz to 2.00 kHz
REFERENCE INPUT
Input Type	Sync InTTL-level pulse
Frequency Limit	Same as internal oscillator
Pulse width	≥ 1 µs
REFERENCE OUTPUT
Sync Out	TTL level square wave May be used as free-running oscillator when using EXT+, EXT- or Vext Sync setting
Fouter	TTL-level square wave at the chopping frequency
OUT 1	TTL level pulse:  5*Fouter in NORMAL mode  (H/S)*Fouter in H/S mode
OUT 2	TTL level pulse:  [H/(7*S)]*Fsync in H/S mode
PHASE SHIFTER
Range	-180.0° to +179.0°
Resolution	0.1°, increasing to 0.25° at 2.0 kHz
HARMONIC LOCKING
Harmonic (H)	1 to 15
Subharmonic (S)	1 to 15
EXTERNAL VOLTAGE CONTROL
Voltage	0 to 10.0 VDC
Control Range	0 to of maximum chopping frequency
GENERAL
Net Weight	2.59 kg [5.7 lbs], including chopper head
Electrical Ratings	100 to 240 VAC, 50 to 60 Hz 25 Watts
Operating Environment	10°C to 40°C [50°F to 104°F] ≤ 90% humidity, non-condensing
Storage Environment	0°C to 50°C [32°F to 122°F] ≤ 90% humidity, non-condensing
Altitude	< 3000 meters [10000 feet]
Pollution Degree	2

 

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