Differential holography

A method, comprising:

• splitting, using a first 1:3 diffractive optic splitter, an input beam into a first beam, a second beam and a third beam;
• (i) passing said first beam through a first chromatic filter to produce a first quasi-monochromatic wavelength band;
• (ii) passing said second beam through a second chromatic filter to produce a second quasi-monochromatic wavelength band;
• and (iii) passing said third beam through a third chromatic filter to produce a third quasi monochromatic wavelength band;
• splitting, using a second 1:3 diffractive optic splitter, (i) said first quasi-monochromatic wavelength band into three sub-beams referred to herein as beam 1, beam 2, and beam 3, (ii) said second quasi-monochromatic wavelength band into three sub-beams referred to herein as beam 4, beam 5 and beam 6 and (iii) said third quasi-monochromatic wavelength band into three subbeams referred to herein as beam 7, beam 8 and beam 9;
• passing each of said beams 1 to 9 through a first lens which focuses each of said beams 1 to 9 through a focal position of said first lens;
• at the focal position of said first lens, (i) passing said beam 1, said beam 4 and said beam 7 through a first filter, (ii) passing said beam 3, said beam 6 and said beam 9 through a second filter, wherein said first filter is oriented orthogonally with respect to said second filter, and (iii) passing, without filtering, said beam 2, beam 5 and beam 8 through said focal position;
• and
• collecting each of said beams 1 to 9 by a second Fourier lens which directs each of said beams 1 to 9 onto an imager sensor.

A method, comprising:

• providing an input electromagnetic radiation field;
• splitting said input field into at least a first beam and a second beam;
• optically computing a derivative of said first beam;
• optically computing a derivative of said second beam;
• detecting said derivative of said first beam as first irradiance to produce a first detected signal;
• and
• detecting said derivative of said second beam as second irradiance to produce a second detected signal;
• and
• determining a recovered wavefront phase of said input electromagnetic radiation field from said first detected signal and said second detected signal;
• wherein the step of splitting said input field further comprises splitting said input field into a third beam;
• wherein the method further comprises:
• detecting said third beam as third irradiance to produce a third detected signal;
• determining a recovered electric field amplitude from said third detected signal;
• utilizing said recovered amplitude to determine amplitude variations in said input field;
• and
• removing unwanted portions of said amplitude variations from said first and second detected signals.

An apparatus, comprising:

• an optic splitter, the optic splitter, in use, splitting an input electromagnetic radiation field into a first beam and a second beam;
• a first lens, a first filter and a second filter, wherein said first lens and said first filter optically compute a derivative of said first beam and wherein said first lens and said second filter optically compute a derivative of said second beam, wherein said second filter is orthogonal to said first filter;
• and
• at least one detector configured to (i) detect said derivative of said first beam as first irradiance to produce a first detected signal and (ii) detect said derivative of said second beam as second irradiance to produce a second detected signal;
• the apparatus further comprising means for (i)
• determining a recovered amplitude from said third detected signal, (ii) utilizing said recovered amplitude to determine amplitude variations in said input field and (iii) removing unwanted portions of said amplitude variations from said first and second detected signals.

An apparatus, comprising:

• a first 1:3 diffractive optic splitter configured for splitting a polychromatic input beam into a first beam, a second beam and a third beam;
• a first chromatic filter positioned in the path of said first beam to produce a first quasimonochromatic wavelength band;
• a second chromatic filter positioned in the path of said second beam to produce a second quasi-monochromatic wavelength band;
• a third chromatic filter positioned in the path of said third beam to produce a third quasimonochromatic wavelength band;
• a second 1:3 diffractive optic splitter configured for splitting:
• (i) said first quasi-monochromatic wavelength band into three sub-beams, referred to herein as beam 1, beam 2, and beam 3,
• (ii) said second quasi-monochromatic wavelength band into three sub-beams, referred to herein as beam 4, beam 5 and beam 6, and
• (iii) said third quasi-monochromatic wavelength band into three sub-beams referred to herein as beam 7, beam 8 and beam 9;
• a lens positioned in the path of each of said beams 1 to 9 such that said lens focuses each of said beams 1 to 9;
• a first filter and a second filter positioned at the focal position of said lens such that (i) said beam 1, said beam 4 and said beam 7 pass through said first filter, (ii) said beam 3, said beam 6 and said beam 9 pass through said second filter and (iii) wherein said beam 2, beam 5 and beam 8 pass through said focal position without filtering;
• and
• an image sensor positioned to sense each of said beams 1 to 9.