Integrated reading and writing of a hologram with a rotated reference beam polarization
AssigneeInPhase Technologies, Inc.
InventorKenneth E. Anderson
Life of this patent
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Abstract
A method for monitoring diffraction while reading a hologram includes: illuminating a holographic medium with a reference beam to generate a data beam for a hologram that has been recorded at a set diffraction efficiency with a first polarization, the reference beam having a second polarization; and measuring an offset component in an output arm of the data beam.
Claims22
A method for monitoring diffraction while reading a hologram, comprising:
- illuminating a holographic medium with a reference beam to generate a data beam for a hologram that has been recorded at a set diffraction efficiency with a first polarization, the reference beam having a second polarization, and
- measuring an offset component in an output arm of the data beam.
A method as claimed in 4, further comprising:
- adjusting the reference beam based on the positioning condition.
A method as claimed in 4, further comprising:
- adjusting the holographic medium based on the positioning condition.
A method as claimed in 7, further comprising:
- calibrating the input power based on the hologram type.
A method as claimed in 7, further comprising:
- calibrating the output power based on the hologram type.
A method as claimed in clam 1, wherein measuring the offset component in the output arm of the data bean includes:
- splitting the offset component from the output arm of the data beam to form an offset beam;
- and
- detecting the offset bean.
An apparatus for reading a hologram, comprising:
- a holographic medium including a hologram that has been recorded at a set diffraction efficiency with a first polarization,
- reference-beam source for illuminating the holographic medium with a reference beam to generate a data beam corresponding to the hologram, the reference beam having a second polarization;
- a polarizing beam splitter for separating an offset component from an output arm of the data beam;
- and
- a detector for measuring the offset component.
An apparatus as claimed in 12, further comprising a monitoring unit for:
- determining an output power from the offset component;
- determining an input power corresponding to an input arm of the reference beam;
- and
- determining a diffraction efficiency from the output power and the input power.
An apparatus as claimed in 13, wherein the monitoring unit further includes operations for monitoring the diffraction efficiency to determine a validation condition for reading the hologram based on the set diffraction efficiency.
An apparatus as claimed in 12, further comprising a monitoring unit for:
- determining an output power from the offset component;
- determining an input power corresponding to an input arm of the reference beam;
- determining an estimated output power from the set diffraction efficiency and the input power;
- and
- monitoring the output power from the offset component to determine a positioning condition fur reading the hologram based on to estimated output power.
An apparatus as claimed in 15, further comprising:
- an adjustment unit for adjusting the reference beam based on the positioning condition.
An apparatus as claimed in 15, further comprising:
- an adjustment unit for adjusting the holographic medium based on the positioning condition.
An apparatus as claimed in 12, further comprising a monitoring unit for:
- determining an output power from the offset component;
- determining an input power corresponding to an input arm of the reference beam;
- determining an estimated output power from the set diffraction efficiency and the input power;
- and
- monitoring the output power from the offset component to determine a hologram type based on the estimated output power.
An apparatus as claimed in 12, further comprising:
- a lens for focusing the offset component onto the detector.
An apparatus as claimed in 12, wherein the second polarization differs from the first polarization by a small rotation.
Dependencies are inferred from the claim text.