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Bristol Instruments 521 Series Laser Wavelength Meter

A low-priced alternative for accurate laser wavelength measurement.

Bristol Instruments’ wavelength meters are for scientists and engineers who need to know the exact wavelength of their lasers. These systems use proven interferometer-based technology to measure absolute wavelength to an accuracy as high as ± 0.0001 nm. To achieve the reliable accuracy that is expected from Bristol Instruments, all of its wavelength meters include a built-in wavelength standard for continuous calibration. Systems are available for CW and pulsed lasers that operate at wavelengths from 350 nm to 12 µm.

Bristol Instruments 521 Series Laser Wavelength Meter

CW lasers, 400 – 1700 nm, low-priced alternative

The 521 Series Laser Wavelength Meter is for scientists and engineers who need to know the absolute wavelength of their CW laser, but do not need to know it to the highest accuracy available. The model 521 is a unique system that couples accurate wavelength measurement and affordability in a compact instrument.


  • Absolute wavelength measured to an accuracy of ± 0.005 nm
  • Continuous calibration with a built-in wavelength reference
  • Wavelength range options available from 400 to 1700 nm
  • Measurement rate of 10 Hz
  • Input power requirement as low as 5 µW
  • Displays wavelength, wavenumber, or frequency
  • Convenient pre-aligned fiber-optic input
  • Straightforward operation with PC using high-speed USB interface
  • Easy to integrate into experiment for automatic wavelength reporting and control
  • Includes software for custom or LabVIEW programming

Proven interferometer technology
The 521 Laser Wavelength Meter measures absolute wavelength of CW and quasi-CW lasers to an accuracy of ± 10 parts per million (± 0.01 nm at 1000 nm). This system uses Michelson interferometer-based technology that is similar to that used by the Bristol Instruments’ model 671, the most precise laser wavelength meter available. The primary difference is that a Moiré scale is used as its built-in reference. This high-resolution scale provides the continuous calibration that is necessary to guarantee the accuracy of the wavelength measurement. For even greater confidence, the Moiré scale can be calibrated periodically using a simple procedure with any red HeNe laser input.

Broad wavelength coverage

Two versions of the 521 Laser Wavelength Meter are available to satisfy the needs of most experiments. The 521-VIS operates over the wavelength range of 400 to 1100 nm, and the 521-NIR has an operational wavelength range of 520 to 1700 nm.

Straightforward operation

The 521 Laser Wavelength Meter operates with a PC, running under Windows, via a high-speed USB interface. Software is provided to control measurement parameters and to report data, or the system can become part of an experiment using a library of commands for custom or LabVIEW programming. Th21e laser under test enters the 521 system through a pre-aligned fiber-optic input connector to ensure optimum alignment. For free-beam lasers, the LC-1 Fiber-Optic Input Coupler is offered as a simple way to launch into fiber.





CW and quasi-CW (repetition rate >10 MHz)


400 – 1100 nm

520 – 1700 nm


± 10 ppm


± 5 ppm


Continuous with built-in Moiré scale


10 µW (400 nm)
5 µW (750 nm)
35 µW (1100 nm)

100 µW (520 nm)
5 µW (1100 nm)
20 µW (1700 nm)


10 Hz


Pre-aligned FC/UPC fiber-optic connector (9 μm core diameter)


USB interface with Windows-based display program
Library of commands for custom and LabVIEW programming