Optical spectrometer and method
An optical apparatus and associated method(s) that utilize zeroth-order feedback to provide precise positional information about optical components comprising the optical apparatus.
1 . In an optical device having at least one movable element, a method of operating the optical device comprising the steps of:
receiving an optical signal from an optical input aperture;
diffracting the optical signal into one or more chromatically dispersed non-zeroth-order components and a non-chromatically dispersed zeroth-order component; and
directing one of the non-zeroth-order components to an optical output;
CHARACTERIZED IN THAT:
positional feedback information about the movable element is determined. from the zeroth-order optical signal.
2 . The method according to claim 1 further comprising the step of:
directing the zeroth-order component to a position detector.
3 . The method according to claim 2 further comprising the step of:
directing the optical signal to the movable element.
4 . The method according to claim 3 wherein the optical-signal directing, the zeroth-order-component directing, and the non-zeroth-order-component directing is performed by a common optical element.
5 . The method according to claim 4 wherein the common optical element is a lens.
6 . The method according to claim 1 wherein the diffracting step is performed by the action of the movable element and that movable element is a diffraction grating.
7 . The method according to claim 1 further comprising the step of:
positioning the movable element based upon the positional feedback information.
8 . The method according to claim 1 wherein the movable element is a mirror.
9 . The method according to claim 1 wherein the optical input aperture comprises a plurality of input apertures.
10 . The method according to claim 1 wherein the optical output comprises a tapered slit.
11 . The method according to claim 1 further comprising the step of:
chopping the non-zeroth order components such that desirable signal/noise characteristics are realized.
12 . An optical device comprising:
an input for receiving an optical signal;
a diffractor, for diffracting the optical signal into a one or more chromatically dispersed non-zeroth-order components and a non-chromatically-dispersed zeroth-order component;
a movable reflector, for selectively directing one of the non-zeroth order components to an output; and
a position detector; responsive to the zeroth-order component; for providing positional feedback information about the movable reflector.
13 . The optical device according to claim 7 wherein the movable reflector is responsive to control signals determined from the positional feedback information.
14 . The optical device according to claim 7 wherein the diffractor is a diffraction grating.
15 . The optical device according to claim 7 wherein the diffractor and the movable reflector are the same optical element and that same optical element comprises a grating.
16 . The optical device according to claim 8 further comprising an optical element for directing the input optical signal to the diffractor.
17 . The optical device according to claim 8 further comprising an optical element for directing the input optical signal to the diffractor and a non-zeroth-order component to the output.
18 . The optical device according to claim 12 further comprising an optical element for directing the zeroth-order component to the position detector.
19 . The optical device according to claim 13 wherein the input optical signal director element, the non-zeroth-order directing element and the zeroth-order directing element are a common optical element.
20 . The optical device according to claim 14 wherein the common optical element comprises a lens.
21 . The optical device according to claim 12 wherein the input comprises one or more apertures.
22 . The optical device according to claim 12 wherein the output comprises a tapered slit.
23 . An optical device comprising:
means for inputting an optical signal;
means for diffracting the optical signal into one or more chromatically dispersed non-zeroth-order components and a non-chromatically dispersed zeroth-order component;
means for directing, one of the non-zeroth components to an output; and
means for determining, a position of the directing means from information derived from the zeroth-order component.
24 . The optical device according to claim 16 further comprising a means for directing the zeroth-order component to the position determining means.
25 . The optical device according to claim 17 wherein the zeroth-order component directing means and the non-zeroth order directing means are lenses.
26 . The optical device according to claim 17 wherein the zeroth-order component directing means and the non-zeroth order directing means comprise a common lens.
27 . The optical device according to claim 23 further comprising:
means for chopping the output directed components.