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White Light Interferometer | SIMTRUM Photonics Store

White Light Interferometer

White Light Interferometer

Our White Light Interferometer GOBI uses spectrally resolved interferometry to accurately measure the Group Delay Dispersion (GDD) of multi-layered ultrafast optics. The device has been developed at the MaxPlanck-Institute of Quantum Optics (Garching, Germany) to characterize and refine some of the most advanced coatings to date [1-3]. Combining spectral with temporal information and the possibility to accumulate multiple passes over the same optic ensures reliable results with unique spectral coverage of up to 250-1060 nm (UV/VIS/NIR version) and 900-2400 nm (IR version). 

Spectrally resolved detection makes reference lasers together with any related test sample restrictions on specific reflection or transmission bands obsolete. This opens the full spectral range to characterize even ultra-broadband or advanced narrowband coatings. The flexible optical setup can measure mirrors and transparent samples under angles of incidence variable between 0 and 70 degrees.


 Key Product Features:

 Ultrabroad spectral coverage • 400-1060 nm (VIS/NIR basic version) • 250-1060 nm (UV/VIS/NIR version) • 900-2400 nm (IR version)

 Direct spectrally dispersed measurement with a spectrometer

 No need for reference lasers, no requirements on specific reflectivity

 s and p polarization (separately)

 Angle of incidence: 0° and 5-70°

 Measurement of single mirrors or mirror pairs

 Laptop and userfriendly software interface included

 Footprint 45 x 45 cm2

Gobi is based on a Michelson Interferometer with an incoherent white light (WL) source. Data is acquired by scanning the delay of one arm and spectrally record the evolving interference pattern. Fully automated analysis yields the spectral phase and GDD. The spectrometer directly provides the spectrally resolved information avoiding artefacts from time-domain reconstruction. It also provides an intrinsic calibration reference for the delay scan, so that no additional reference lasers are required. This makes GOBI suitable for any optics measurements in the detection range without the need to cover a reference laser wavelength in transmission or reflectance.


In contrast to other devices GOBI is able to resolve strong GDD oscillations. Note that differences between measured and theoretical curves reflect tolerances in the manufacturing process of the coatings.

Examples of GDD measurements with our White Light Interferometer GOBI, and comparison to the theoretical design. 

(a) Ultrabroadband PC70 mirrors with our unique doubleangle design, measured at 5° and 19° angle of normal incidence, together with the average. 

(b) Pulse Compression Mirror PC1921 for the infrared.

(c) High dispersive HD73 mirror with -3000 fs2 per bounce at 1030 nm.

Specification Guide

Specifications: GOBI GOBI+ GOBIIR
 Spectral range VIS/NIR UV/VIS/NIR IR
 Wavelength range 400-1060 nm 250-1060 nm 900-2400 nm
 Spectral accuracy 1 nm 4 nm
 GDD accuracy ± 5 fs²
 Angle of incidence range 0° and 5-70°
 Polarization s and p (separately)
 Optics size 1 inch (other sizes upon request)
 Footprint 45 x 45 cm²

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GOBI 400-1060nm
White Light Interferometer
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GOBI 250-1060nm
White Light Interferometer
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GOBI 900-2040nm
White Light Interferometer
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GOBI 900-2040nm - Parameter

GOBI 250-1060nm - Parameter

GOBI 400-1060nm - Parameter

GOBI 900-2040nm - Download

GOBI 250-1060nm - Download

GOBI 400-1060nm - Download


Compare Model Drawings & Specs Availability Reference Price