New Focus Model 3501 Optical Chopper System
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New Focus Model 3501 Optical Chopper System


  • Crystal Controlled Frequency Synthesizer
  • Minimize Jitter and Drift of Chopper Head
  • Harmonic and Subharmonic Chopping
  • Chopping Frequency of 4 Hz to 6.4 kHz
  • Harmonic Chopping from 2 to 15
  • Subharmonic Chopping from 1/2 to 1/15

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This New Focus 3501 Optical Chopper Controller is used and in excellent condition. The Chopper Head and Wheels are sold separately.

Stock # 69479-1

  • Description
  • Tech Specs
  • Datasheets / Manuals 
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The New Focus Model 3501 Optical Chopper System is designed to interrupt light paths in optical experiments at frequencies from 4 Hz to 6.4 kHz. Both single and dual beam experiments can be performed across a broad range of chopping frequencies. The chopper has a crystal controlled frequency synthesizer that serves as an internal reference frequency for locking the chopper to a particular chopping frequency. Reference frequencies can also be provided through the Sync Input to allow the chopper to lock to an external source. Several measures ensure that jitter and drift of the chopping frequency is reduced to a minimum. Precision photo-etched wheels are mounted on a high quality DC motor. The motor head has a photo-sensor for monitoring the chopping frequency of the outer part of the wheel. The chopper controller then actively stabilizes the motor speed to match the desired chopping frequency. This technique minimizes phase noise at the chopping frequency and provides for long-term stable chopping with a minimum of frequency drift.

Product Family: [v]3501, [v]-3501, [v] 3501
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Manuals, Datasheets, Drivers, Links

New Focus Model 3501 Optical Chopper System Manual (pdf)  
Link to Newport / New Focus Website