Surface of analyzing software
Long-term measurement	WS-7 with enlarged 40 mm interferometer: The side mode of a diode laser is easy to observe

The optical unit and associated electronics are housed in a compact, thermal casing. The connection to a computer or notebook is via a USB port or PCI-card, which allows a high data read-out rate. The analyzing software displays all the interferometer information and is compatible with Windows or, on request, Linux. Standard features of the basic meters are:

• Measurement of wavelength & frequency: The measurement is displayed on the computer via the supplied user-friendly software. Installation and setup is straight forward. The displayed result may be switched between wavelength, frequency or wavenumber to suit the test requirements. The displayed interferometer pattern provides information regarding the spectral profile of pulsed or continuous wave laser sources.
• Long-term measurement: This operation mode records the measured wavelength against time. The data is displayed on the screen or may be exported for further analysis.
• Record- and Replay Mode: This operation mode records all interferometer data and allows for a subsequent play-back. In combination with the Resolver Option (see Options), a detailed line profile analysis of the data can be performed.
• Average: Two different arithmetic averaging techniques may be applied on 0 to 999 measurement points.
• Data-Control: The software “DataDemo” provides an interface to different software for controlling the WLM. Source code is included.

• Grating Option (D): The Grating Option allows the analysis of the spectrum to an accuracy of 0.2 nm. This is applicable to laser sources with broad emission.
• Linewidth Option (L): Linewidth measurement of a single mode laser source isis performed by a special algorithm which eliminates interferometer apparatus function. The algorithm enables the measurement of the linewidth several times better than the interferometer resolution. With multimode lasers or lasers with sidebands, the value is interpreted as FWHM of their envelope function. The longitudinal mode splitting needs to be less than 300 MHz, otherwise the linewidth of one mode will be measured.
• Resolver Option (R): The resolver option is based on a special optical design. It enables observation of the complex multimode laser spectrum in a range of up to 10nm and see qualitatively (with specified resolution) the profile of every spectral line. Additionally, the FWHM of this profile approximation is displayed. 
• Laser-Control Option:

Frequency stability of a diode laser controlled by a WS/Ultimate	Deviation Signal Control

The Laser-Control Option allows an active high speed wavelength stabilisation of laser sources. The measured signal is compared to a reference value providing an error signal for regulation. The reference wavelength and the dimension of the error signal can be selected on the software interface. The Laser-Control Option finds applications eg. in LIDAR systems in which the laser frequency has to be detuned from absorption lines in a controlled way.  

• Mode Separation Option (S): The frequency distance between different laser beams is measured and displayed.

WS-7R, measuring the spectra of a laser pointer, oszillating on different modes in a range of 4 nm



• Double-Pulse Option:

Simultaneous measurement of two laser wavelengths

The Double-Pulse Option allows the measurement of two almost simultaneous laser pulses. Timing gates of at least 400 ns are applied and the emission of the two lasers is monitored. The Double-Pulse Option has applications in pump and probe experiments.

• Saturation spectroscopy
  The diagram shows a measurement with the WS/Ultimate on a rubidium saturation spectrum.
  Three transition lines are shown.
  Blue line: literature value.
  Red line: measurement and mean deviation.

• Stability of temperature
  Measurement of a WLM in a climate chamber. The thermal isolation casing contributes to the high stability of wavelength measurements.The internal temperature sensor compensates for thermal drifts.

• Spectral sensitivity
  The diagram shows the extreme sensitivity of the WS-series. In the visible range a power of 30 nW is sufficient for full operation.

• Spectral Analyser
  The Spectral Analyser performs spectral analysis of multimode laser emission in a range of about 600 nm and a resolution of 1 GHz.
• Absolute Frequency
  The Absolute Frequency Standard (DFB-Laser) provides a reference wavelength for absolute calibration and up to 50 mW external output power as a reference Laser. The wavelength is controlled by the Doppler free spectra of a well known atomic transition.

• WS/5-Compact
  Turns your PC into a full wavelength meter, offering all advantages of the WS-Series! The integrated unit of the size of a CD-Rom-Drive can be easily plugged into a free 5 1/4" bay on a PC.
• Stand-Alone Device
  With the stand-alone device data can be read out and analyzed without an extra computer or notebook. Several standard ports are installed.