Abstract: An optical measurement method in which a series of light pulses are generated using a pulsed laser having a set of different mode hop sequences (e.g., an external-cavity quantum cascade laser (EC-QCL)), the light pulses are detected with the detector to generate a respective pulse data set for each of the light pulses, and the pulse data sets are sorted into classes based on correlation coefficients. Sorting the pulse data sets into classes allows the pulse data sets originating from each of the mode hop sequences of the pulsed laser to be treated independently of the pulse data sets originating from others of the mode hop sequences in subsequent processing.

Abstract: A method and apparatus for obtaining reference samples during the generation of a mid-infrared (MW) image without requiring that the sample being imaged be removed is disclosed. A tunable MIR laser generates a light beam that is focused onto a specimen on a specimen stage that moves the specimen in a first direction. An optical assembly includes a scanning assembly having a focusing lens and a mirror that moves in a second direction, different from the first direction, relative to the stage such that the focusing lens maintains a fixed distance between the focusing lens and the specimen stage. A light detector measures an intensity of light leaving the point on the specimen. A controller forms an image from the measured intensity. A reference stage is positioned such that the mirror moves over the reference stage in response to a command so that the controller can also make a reference measurement.

Abstract: A light source having first and second wire-grid polarizers and a laser that emits a beam of linearly polarized light that is characterized by a propagation direction is disclosed. The first wire-grid polarization filter is characterized by a first linear polarization pass direction and a first actuator for causing the first linear polarization pass direction to rotate relative to the beam of linearly polarized light. The second wire-grid polarization filter is characterized by a second linear polarization pass direction and a second actuator for causing the second linear polarization pass direction to rotate relative to the beam of linearly polarized light. A controller sets the first and second linear polarization pass directions to provide linearly polarized light having a specified polarization direction.

Abstract: A method and apparatus for measuring diffuse and specularly reflected light from a sample to provide a reflection spectrum as a function of wavelength and as a function of position on a sample is disclosed. The apparatus includes a MIR light source that generates an illumination beam of linearly polarized light. An illumination system illuminates a location on a specimen with part of the illumination beam. A linear polarization filter characterized by a polarization axis that defines a direction of polarization of linearly polarized light that is reflected by the linear polarization filter, a first detector that measures an intensity of light leaving the linear polarization filter and a light collection system collects light reflected from the location on the specimen and directs that light to the linear polarization filter. A controller measures an output from the first detector for each of a plurality of different polarization axis positions.

Abstract: A light source having first and second wire-grid polarizers and a laser that emits a beam of linearly polarized light that is characterized by a propagation direction is disclosed. The first wire-grid polarization filter is characterized by a first linear polarization pass direction and a first actuator for causing the first linear polarization pass direction to rotate relative to the beam of linearly polarized light. The second wire-grid polarization filter is characterized by a second linear polarization pass direction and a second actuator for causing the second linear polarization pass direction to rotate relative to the beam of linearly polarized light. A controller sets the first and second linear polarization pass directions to provide linearly polarized light having a specified polarization direction.

Abstract: A method and apparatus for obtaining reference samples during the generation of a mid-infrared (MW) image without requiring that the sample being imaged be removed is disclosed. A tunable MIR laser generates a light beam that is focused onto a specimen on a specimen stage that moves the specimen in a first direction. An optical assembly includes a scanning assembly having a focusing lens and a mirror that moves in a second direction, different from the first direction, relative to the stage such that the focusing lens maintains a fixed distance between the focusing lens and the specimen stage. A light detector measures an intensity of light leaving the point on the specimen. A controller forms an image from the measured intensity. A reference stage is positioned such that the mirror moves over the reference stage in response to a command so that the controller can also make a reference measurement.

Abstract: An apparatus having a variable angle light source characterized by a pivot point, a variable response optical receiver, and a first optical system is disclosed. The variable response optical receiver receives light generated by the light source on a receiving surface, the receiver generating a signal indicative of an intensity of light that impinges on a receiving surface. The first optical system images the pivot point to a fixed point relative to the receiver surface. In one aspect of the invention the first optical system is chosen such that light from the variable angle light source covers more& than half the receiving surface. The variable angle light source can include a gain chip in a semiconductor laser having a pivot point located substantially on a facet of the gain chip.

Abstract: A system for performing optical spectroscopy measurements includes a light source for generating an input optical beam and an interferometer. The interferometer includes a beam splitter that splits the input optical beam into first and second light beams; a first light path that directs the first light beam through a sample containing an analyte to a first output port; and a second light path that directs the second light beam to the first output port. At least one of the first and second light paths adjusts a relative phase of a corresponding one of the first and second light beams, so that the first and second light beams are out of phase at the first output port, substantially canceling background light and outputting sample light corresponding to a portion of the first light signal absorbed by the sample in the sample cell. A detection system detects the output sample light.

Abstract: An apparatus having a variable angle light source characterized by a pivot point, a variable response optical receiver, and a first optical system is disclosed. The variable response optical receiver receives light generated by the light source on a receiving surface, the receiver generating a signal indicative of an intensity of light that impinges on a receiving surface. The first optical system images the pivot point to a fixed point relative to the receiver surface. In one aspect of the invention the first optical system is chosen such that light from the variable angle light source covers mores than half the receiving surface. The variable angle light source can include a gain chip in a semiconductor laser having a pivot point located substantially on a facet of the gain chip.

Abstract: A system for performing optical spectroscopy measurements includes a light source for generating an input optical beam and an interferometer. The interferometer includes a beam splitter that splits the input optical beam into first and second light beams; a first light path that directs the first light beam through a sample containing an analyte to a first output port; and a second light path that directs the second light beam to the first output port. At least one of the first and second light paths adjusts a relative phase of a corresponding one of the first and second light beams, so that the first and second light beams are out of phase at the first output port, substantially canceling background light and outputting sample light corresponding to a portion of the first light signal absorbed by the sample in the sample cell. A detection system detects the output sample light.