The gas jet density is determined by measuring the phase shift induced by the gas in a probe beam propagating through it. This phase shift is measured with our high resolution wavefront sensor, the SID4 HR. The measured phase or optical path difference is related to the gas jet refractive index change. The inverse Abel transform is then used to retrieve the density map. The Phasics wavefront sensor's high spatial resolution (300×400 measurement points) and high sensitivity (<2nm phase shift) ensure reliable density calculations.
As a common-path interferometer, the Phasics wavefront sensor directly measures the induced phase shift with no reference arm. Consequently, the setup is very compact and easy to align. The probe source can be a simple halogen or LED source, as well as a laser beam leakage, as the sensor is achromatic. The solution is cost-effective and versatile.