An optical fiber Bragg grating (FBG) method developed at the HLD is used to measure magnetostriction in pulsed magnetic fields. The relative length change ΔL/L can be obtained from the shift of the wavelength of the reflected light in the FBG .
The structure of an optical fiber Bragg grating.
|The principle of the measurement.|
Relative length change (magnetostriction) thus is proportional to the relative wavelength change: Δλ/λ ∝ ΔL/L
Resolutions of about ΔL/L ~ 10-7 are achievable.
Standard temperature range is 1.4 – 300 K. Measurements down to ~0.6 K with a 3He system are also possible. This technique can be used in all our magnets.
The sample size should be > 1 mm.
Magnetostriction of GdSb single crystal measured in pulsed magnetic fields