A wavefront sensor is a device for measuring the aberrations of an optical wavefront

Wavefront

In physics, a wavefront is the locus of points having the same phase. Since infrared, optical, x-ray and gamma-ray frequencies are so high, the temporal component of electromagnetic waves is usually ignored at these wavelengths, and it is only the phase of the spatial oscillation that is described...

. Although an amplitude splitting interferometer such as the Michelson interferometer

Michelson interferometer

The Michelson interferometer is the most common configuration for optical interferometry and was invented by Albert Abraham Michelson. An interference pattern is produced by splitting a beam of light into two paths, bouncing the beams back and recombining them...

  could be called a wavefront sensor, the term is normally applied to instruments that do not require an unaberrated reference beam to interfere with. They are commonly used in adaptive optics

Adaptive optics

Adaptive optics is a technology used to improve the performance of optical systems by reducing the effect of wavefront distortions. It is used in astronomical telescopes and laser communication systems to remove the effects of atmospheric distortion, and in retinal imaging systems to reduce the...

 systems, lens testing and increasingly in ophthalmology

Ophthalmology

Ophthalmology is the branch of medicine that deals with the anatomy, physiology and diseases of the eye. An ophthalmologist is a specialist in medical and surgical eye problems...

.

There are several types of wavefront sensors, including:

• Shack-Hartmann Wavefront sensor
  Shack-Hartmann
  A Shack–Hartmann wavefront sensor is an optical instrument used to characterize an imaging system. It is a wavefront sensor commonly used in adaptive optics systems. It consists of an array of lenses of the same focal length. Each is focused onto a photon sensor...
  
  
• Wavefront curvature sensor
  Wavefront curvature sensor
  A wavefront curvature sensor is a device for measuring the aberrations of an optical wavefront. Like a Shack-Hartmann wavefront sensor it uses an array of small lenses to focus the wavefront into an array of spots. Unlike the Shack-Hartmann, which measures the position of the spots, the curvature...
  
  
• Pyramid wavefront sensor
• Common path interferometer
• Foucault knife-edge test
  Foucault knife-edge test
  The Foucault knife-edge test was described in 1858 by French physicist Léon Foucault to measure conic shapes of optical mirrors, with error margins measurable in fractions of wavelengths of light . It is commonly used by amateur telescope makers for figuring small astronomical mirrors...
  
  
• Multilateral shearing interferometer
• Ronchi tester
  Ronchi test
  In optical testing a Ronchi test is a method of determining the surface shape of a mirror used in telescopes and other optical devices.-Description:...
  
  
• Shearing Interferometer
  Shearing Interferometer
  The shearing interferometer is an extremely simple means to observe interference and to use this phenomenon to test the collimation of light beams, especially from laser sources which have a coherence length which is usually a lot longer than the thickness of the shear plate so that the basic...
  
  

External links

• AO Tutorial: Wave-front Sensors
• Wavefront sensing: Establishments Research groups and companies with interests in wavefront sensing and adaptive optics.