The noiseproof wavefront testing method in both time- and spatial-domain mentioned, which neither equal step-length
phase-shifting nor accurate step-length calibration is necessary in this method. Active phase-shifting works associated
with passive phase-shifting caused by the environmental vibration and air turbulences. Large amount of sequentially
acquired interferograms are analyzed for the phase distributions corresponding to each interferogram, and then all the
phase distributions are averaged to produce a wavefront free from various random noises in time- and spatial-domain.
The problems in most available anti-vibration phase-shifting interferometry can be avoid. Large-aperture optical
elements testing with high accuracy can be achieved with this method. In this paper an experimental system is set up
comprising a minitype interferometer made by ourselves. Surface profile measurement of a standard plane is done with
this method and the result is compared with that obtained with a Zygo interferometer. The two results coincide well with
each other, which demonstrate further that this method is insensitive to the environmental vibration and air turbulence
and it can help improve the noiseproof feature of the interferometer. High-accuracy testing of large-aperture optical
elements and systems can be achieved with this method.
The proposed wavefront testing method in time- and spatial-domain takes advantage of both active and passive phaseshifting.
It obtains stable wavefront with random noises removed after processing of large amount of serially collected
interforograms. Since the environmental vibration and air turbulence are adopted as the passive phase-shifting source,
this method performs well in normal laboratory environment without special vibration isolation or air flow control. This
method has application prospect in large-aperture optical surface test because it can help simplify the system and reduce
the cost and difficulty in fabrication. In order to quantitatively evaluate the anti-vibration capability of this method, the
influence of vibration on the measurement accuracy is simulated and analyzed. It is confirmed that corresponding to
certain accuracy tolerance, the product of maximum tolerant vibration amplitude and frequency is invariable. This very
product is adopted as the threshold indicating anti-vibration capability. More conclusions can be drawn after analysis
about the influence of active phase-shifting velocity, sampling frame frequency and relative sampling frame number on
the measurement accuracy: when the relative sampling frame number is fixed, the anti-vibration capability of the method
is increased with active phase-sifting velocity.
The wavefront time-domain detection algorithm is a simple, practical and low-cost interferometry method, which can be
adapted to all kinds of outside noise and achieve high accuracy in interferometric measurement on optical components
and systems. For further understanding the wavefront time-domain measurement of anti-jamming capability and
accuracy of interferometry, the simulation is presented of time-domain sampling frequency of interferograms, external
vibration frequency and amplitude, and harmonic effect, etc. in this paper. This algorithm makes the measurement
controlled by means of using the environment vibration and air turbulence as phase shifters, simply with assistance of
active phase shifting. Acquiring adequate interferograms to calculate the phase value of each point, we can obtain the
stable wave surface wiping off random vibration and air turbulence by the unwrapping and average calculation. In this
process, by changing the time-domain sampling frequency, external vibration frequency and amplitude in the simulation,
the relationships among them can be obtained. The appropriate sampling frequency could be chosen according to the
conditions of actual measurement to ensure the accuracy and stability of measurement. According to statistical analysis,
this algorithm enhance its ability of anti-jamming, and improve the adaptability and especially for the real-time detection
of large aperture mirror.