Abstract: An optical head for a Raman spectroscopy system includes a housing an input configured to allow input radiation of a selected wavelength into the housing, a first lens disposed in an end of the housing to allow the input radiation to emit from the housing through the first lens and to receive reflected radiation including specular reflection and diffuse reflection, and a second lens disposed in the housing and configured to receive reflected radiation from the first lens. The optical head includes an output configured to receive the reflected radiation from the second lens. The optical head includes a blocking mirror disposed in the housing between the first lens and the second lens. The blocking mirror is configured and positioned to direct the radiation from the input to the first lens. The blocking mirror blocks at least a portion of specular reflection from reaching the second lens but allows diffuse reflection to the reach the second lens.

Abstract: An optical head for a Raman spectroscopy system includes a housing an input configured to allow input radiation of a selected wavelength into the housing, a first lens disposed in an end of the housing to allow the input radiation to emit from the housing through the first lens and to receive reflected radiation including specular reflection and diffuse reflection, and a second lens disposed in the housing and configured to receive reflected radiation from the first lens. The optical head includes an output configured to receive the reflected radiation from the second lens. The optical head includes a blocking mirror disposed in the housing between the first lens and the second lens. The blocking mirror is configured and positioned to direct the radiation from the input to the first lens. The blocking mirror blocks at least a portion of specular reflection from reaching the second lens but allows diffuse reflection to the reach the second lens.

Abstract: A system for suppressing noise by frequency dither includes a transmitter, receiver and a frequency dither circuit, as well as a cavity along a propagation path of the electromagnetic signal between the transmitter and the receiver. The transmitter is configured to transmit an electromagnetic signal to the receiver at each of one or more selectable frequencies. The frequency dither circuit is configured to apply a frequency dither to the electromagnetic signal transmitted from the transmitter to the receiver at each of the selectable frequencies. In this regard, the applied frequency dither has a span having been selected as a function of a minimum frequency period of an expected standing wave in the system, and a rate having been selected as a function of a signal processing bandwidth for sampling a frequency spectrum including the selectable frequencies.

Abstract: A system for suppressing noise by frequency dither includes a transmitter, receiver and a frequency dither circuit, as well as a cavity along a propagation path of the electromagnetic signal between the transmitter and the receiver. The transmitter is configured to transmit an electromagnetic signal to the receiver at each of one or more selectable frequencies. The frequency dither circuit is configured to apply a frequency dither to the electromagnetic signal transmitted from the transmitter to the receiver at each of the selectable frequencies. In this regard, the applied frequency dither has a span having been selected as a function of a minimum frequency period of an expected standing wave in the system, and a rate having been selected as a function of a signal processing bandwidth for sampling a frequency spectrum including the selectable frequencies.

Abstract: A system for processing signals includes a receiver assembly for receiving a signal. The signal has a sample component with a sample electric field and a sample polarization, and has a reference component with a reference electric field and a reference polarization. The receiver assembly includes an analyzer for polarimetrically processing the signal, including differencing the signal to generate a difference electric field proportional to the difference of the sample and reference electric fields. By polarimetrically differencing the signal, the analyzer reduces the magnitude of the common-mode signal at the difference signal receiver. The receiver assembly includes an electric-field detector for measuring the difference electric field such that the reduction in common-mode amplitude decreases the noise equivalent power of the electric-field detector.