Multiple input source technique for deriving cavity linewidth
AssigneeLitton Systems, Inc.
InventorDavid B. Hall
Life of this patent
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Abstract
A variety of techniques for deriving cavity linewidth that share the use of multiple input sources of known frequency separation is disclosed allowing the measurement of resonator cavity linewidth. Among the techniques include a double peak ratio method for measuring cavity linewidth through use of a low pass filter. The double peak ratio method allows vertical measurements which are noise immune and independent of swept frequency errors as a method of determining cavity linewidth in a straightforward and accurate manner.
Claims9
A method of measuring cavity linewidth of a passive cavity, comprising the steps of:
- periodically modulating an output coherent radiation signal from a swept frequency laser, deriving a periodically modulated output coherent radiation signal;
- separating said periodically modulated output coherent radiation signal into a series of sideband coherent radiation signals;
- injecting said sideband signals into a passive cavity;
- detecting cavity output radiation signals from said passive cavity;
- processing said detected cavity output radiation signals for analysis on a display terminal;
- whereby, the cavity linewidth may be derived.
A method of measuring cavity linewidth of a passive cavity, comprising the steps of:
- periodically modulating an output coherent radiation signal from a swept frequency laser source, deriving a modulated cavity input signal which is divided into a pair of balanced sidebands, a first sideband downshifted and a second sideband upshifted in frequency from a carrier frequency;
- eliminating said carrier frequency;
- injecting said pair of balanced sidebands into said passive cavity;
- detecting an output radiation signal from said passive cavity and presenting said output signal on a visual output display;
- and
- measuring cavity linewidth using only vertical image data present on the visual output display.
A method of measuring cavity linewidth of a passive resonator, comprising the steps of:
- injecting into said passive resonator a coherent split frequency radiation signal, said split frequency radiation signal being divided into a plurality of modes adjacent to one another and separated by a known uniform frequency splitting which is a function of resonator length;
- detecting an output radiation signal derived from the passive resonator being measured;
- processing said detected output radiation signal for analysis on a display terminal;
- whereby, the cavity linewidth of the passive resonator may be determined.
A method of measuring cavity linewidth of a passive cavity, comprising the steps of:
- periodically modulating an output coherent radiation signal from a swept frequency laser source, deriving a modulated cavity input signal which is divided into a pair of balanced sidebands, a first sideband downshifted and a second sideband upshifted in frequency from a carrier frequency;
- eliminating said carrier frequency;
- injecting said pair of balanced sidebands into said passive cavity;
- and
- detecting an output radiation signal from said passive cavity and presenting the output radiation signal on a visual output display.
Dependencies are inferred from the claim text.