Spectrally-encoded labeling and reading

1. A spectrally-encoded label, comprising a spectrally-selective optical element having a label spectral signature, wherein:

the label spectral signature is determined according to a spectral-encoding scheme so as to represent predetermined label information within the spectral encoding scheme;

the label emits output light in response to input light selected by the label spectral signature of the optical element;

the spectrally-selective optical element has at least one spatially-varying optical property;

the spectrally-elective element includes at least two distinct areal segments each having a corresponding distinct areal spectral signature substantially spatially uniform over the corresponding areal segment; and

the areal spectral signatures of an active fraction of the areal segments contribute to the label spectral signature, and the areal spectral signatures of a remaining deactivated fraction of the areal segments do not contribute to the label spectral signature.

2. The label of claim 1 , wherein the deactivated areal segments are masked by a static mask.

3. The label of claim 1 , wherein the deactivated areal segments are masked by a controllable dynamic mask, thereby enabling controlled alteration of the label information.

4. The label of claim 1 , wherein the deactivated areal segments are deactivated by structural alteration of the spectrally-selective optical element.

5. The label of claim 1 , wherein:

the label spectral signature comprises a plurality of spectral bands, each spectral band having a nominal center wavelength and a spectral bandwidth;

each spectral band that may be used to contribute to the label spectral profile within the spectral encoding scheme corresponds to an areal spectral signature of at least one of the areal segments of the optical element; and

each spectral band that contributes to the label spectral profile corresponds to an areal spectral signature of at least one of the active areal segments.

6. A spectrally-encoded label, comprising a spectrally-selective optical element having a label spectral signature, wherein:

the label spectral signature is determined according to a spectral-encoding scheme so as to represent predetermined label information within the spectral encoding scheme;

the label emits output light in response to input light selected by the label spectral signature of the optical element;

the spectrally-selective optical element has at least one spatially-varying optical property;

the spatially-varying optical property of the spectrally-selective optical element varies substantially continuously over an area of the optical element;

the continuously-varying area of the optical element comprises at least two distinct areal segments each having a corresponding areal spectral signature;

the areal spectral signatures of an active fraction of the areal segments contribute to the label spectral signature; and

the areal spectral signatures of a remaining deactivated fraction of the areal segments do not contribute to the label spectral signature.

7. The label of claim 6 , wherein the deactivated areal segments are masked by a static mask.

8. The label of claim 7 , wherein the static mask comprises a spatial barcode formed on a substantially transparent label and applied over the optical element.

9. The label of claim 6 , wherein the deactivated areal segment are masked by a controllable dynamic mask, thereby enabling controlled alteration of the label information.

10. The label of claim 6 , wherein the deactivated areal segments are deactivated by structural alteration of the spectrally-selective optical element.

11. The label of claim 6 , wherein:

the label spectral signature comprises a plurality of spectral bands, each spectral band having a nominal center wavelength and a spectral bandwidth;

each spectral band that may be used to contribute to the label spectral profile within the spectral encoding scheme corresponds to an areal spectral signature of at least one of the areal segments of the optical element; and

each spectral band that contributes to the label spectral profile corresponds to an areal spectral signature of at least one of the active areal segments.

12. A spectrally-encoded label, comprising a spectrally-selective optical element having a label spectral signature, wherein:

the label spectral signature is determined according to a spectral-encoding scheme so as to represent predetermined label information within the spectral encoding scheme;

the label emits output light in response to input light selected by the label spectral signature of the optical element;

the spectrally-selective optical element comprises a diffraction grating; and

diffractive elements of the grating are circular.

13. A spectrally-encoded label, comprising a spectrally-selective optical element having a label spectral signature, wherein:

the label spectral signature is determined according to a spectral-encoding scheme so as to represent predetermined label information within the spectral encoding scheme;

the label emits output light in response to input light selected by the label spectral signature of the optical element;

the spectrally-selective optical element comprises a diffraction grating; and

the grating surface is curved.

14. A spectrally-encoded label, comprising a spectrally-selective optical element having a label spectral signature, wherein:

the label spectral signature is determined according to a spectral-encoding scheme so as to represent predetermined label information within the spectral encoding scheme;

the label emits output light in response to input light selected by the label spectral signature of the optical element;

the spectrally-selective optical element comprises a diffraction grating; and

the grating is a chirped grating.