In an is-TPG method in which lasers having two different wavelengths are used to generate a wavelength-variable far-infrared light, a far-infrared light (TPG light) having an unstable output at a broad wavelength is also slightly generated at the same time with only one laser light. The generated is-TPG and the TPG light are converted, after passing through a specimen, to near-infrared light inside a nonlinear optical crystal for detection and are observed by a detector. The signal light output of the is-TPG light becomes unstable due to the TPG light. According to the present invention, the TPG light is removed by means of a slit and the like (filter) immediately before the specimen and is not introduced into the nonlinear optical crystal for detection. At this time, by using a change in the emission direction when the frequency of the is TPG light is changed, the filter is moved in accordance with the frequency so that only the is-TPG light passes therethrough.

Embodiments of a terahertz (THz) sensor module are disclosed for spectroscopy and imaging in a dynamic environment. In an embodiment, a terahertz (THz) sensor module comprises: a THz emitter configured to emit a THz beam into an environment; one or more movable micro-electromechanical system (MEMS) micromirrors; and one or more MEMS motors or actuators coupled to the one or more MEMS micromirrors. The one or more MEMS motors or actuators are configured to move the one or more MEMS micromirrors to change a direction of the THz beam in the environment. A THz receiver is configured to receive a reflection of the THz beam from a reflective object in the environment.

Embodiments are disclosed for terahertz spectroscopy and imaging in dynamic environments. In an embodiment, a transmitter of an electronic device emits a continuous electromagnetic (EM) wave in the terahertz (THz) frequency band into a dynamic environment that includes a transmission medium that changes over time. A receiver of the electronic device, receives an EM wave reflected off an object in the environment and determines a spectral response of the reflected EM wave. The spectral response includes absorption spectra at a frequency in the THz frequency band that is indicative of a known target transmission medium. The absorption spectra of the target transmission medium and a path length of the reflected EM wave signal are used to obtain the concentration level of the target transmission medium from a reference library of known concentration levels.

Embodiments are disclosed for terahertz spectroscopy and imaging in dynamic environments. In an embodiment, a method comprises emitting a continuous electromagnetic (EM) wave in a terahertz (THz) frequency band into a dynamic environment. The EM THz wave is reflected off an object in the environment. A spectral response of a received signal indicative of the reflected EM wave is determined that includes absorption spectra at a frequency in the THz frequency band. The absorption spectra is indicative of a transmission medium in the environment. The spectral response of the received signal is compensated for fixed and frequency-specific losses. The compensated absorption spectra is compared with known absorption spectra of target transmission mediums. Based on results of the comparing, a particular target transmission medium is identified as being the transmission medium in the environment. The absorption spectra loss is used to determine a concentration level of the target transmission medium.

A gas analyzer includes an optical emitter that irradiates measurement light into a measurement region including a gas to be measured; a reflector that reflects the measurement light irradiated from the optical emitter; an optical receiver that receives the measurement light reflected by the reflector; and an aligner that expands a beam diameter of the measurement light at the reflector.

A spectral detector includes a light source, a sample cell in which a sample flows therein, an optical sensor, an optical system that guides light from the light source to the sample cell and guides light from the sample cell to the optical sensor, the optical system has a spectroscope for dispersing light and the spectroscope is arranged between the light source and the sample cell or between the sample cell and the optical sensor, and a housing integrally including a lamp house part for housing the light source and an optical system housing part for housing at least the sample cell and the optical system. Since the lamp house part and the optical system housing part are integrated to constitute the housing, heat is easily transmitted from the lamp house part to the optical system housing part, and the time until the entire detector reaches thermal equilibrium is shortened.

A spectrometer includes a light source that emits a beam into a sample volume comprising an absorbing medium. Thereafter, at least one detector detects at least a portion of the beam emitted by the light source. It is later determined, based on the detected at least a portion of the beam and by a controller, that a position and/or an angle of the beam should be changed. The beam emitted by the light source is then actively steered by an actuation element under control of the controller. In addition, a concentration of the absorbing media can be quantified or otherwise calculated (using the controller or optionally a different processor that can be local or remote). The actuation element(s) can be coupled to one or more of the light source, a detector or detectors, and a reflector or reflectors intermediate the light source and the detector(s).

An optical detecting apparatus includes a light source, a receiving unit and a first optical element. The light source is configured to emit first light. The receiving unit includes a light splitting portion and a sensing portion, wherein the light splitting portion is configured to separate second light with a predetermined bandwidth from the first light, the sensing portion is configured to receive the second light with the predetermined bandwidth, and the light splitting portion and the sensing portion are connected. The first optical element is disposed between the light source and the receiving unit and is configured to converge or collimate the first light.

A gas measurement system as disclosed can include a coherent light source, which emits a light beam; a detector; a beam path formed between the light source) and the detector; and a gas cell arranged in the beam path such that the detector receives light transmitted through the gas cell. The gas cell can include a porous ceramic and have an optical path length which is a multiple of the actual layer thickness of the gas cell. A optical element can be arranged in the beam path between the light source and the gas cell with the light beam emitted by the light being widened and unfocussed as the light beam enters the gas cell.

A gas analyzer includes an optical emitter that irradiates measurement light into a measurement region including a gas to be measured; a reflector that reflects the measurement light irradiated from the optical emitter; an optical receiver that receives the measurement light reflected by the reflector; and an aligner that expands a beam diameter of the measurement light at the reflector.