A polychromator system comprising: an optical element defining an aperture; a collimation mirror for receiving light via the aperture and reflecting substantially collimated light; at least a first dispersive optical component and a second dispersive optical component, each configured to disperse the substantially collimated light received from the collimation mirror by different amounts for different wavelengths and to provide cross-dispersed light having different wavelengths of light spaced along a first and second axis; and a focus mirror positioned to focus the cross-dispersed light onto a 2-D array detector to provide a plurality of aperture images of the aperture at a respective plurality of regions of the detector, each of the plurality of aperture images associated with a respective wavelength of the cross-dispersed light. Either one or both of the collimation mirror and the focus mirror is a freeform mirror having a reflective surface configured to mitigate effects of optical aberrations of the polychromator system over a plurality of the wavelengths of the cross-dispersed light along the first axis and the second axis and thereby optimise the resolution of the plurality of aperture images associated with the plurality of the wavelengths along the first axis and the second axis.

A compact, catadioptric and athermal imaging spectrometer is disclosed. A telecentric light (1) incident from a slit (2) is folded or refracted by an object-side prism (3) to enter a plano-convex lens (4); after being refracted by the plano-convex lens (4) and a meniscus lens (5), and refracted and reflected by a thick catadioptric lens (6), said telecentric light is incident onto a convex grating (7) in the form of a convergent beam; and after said beam is diffracted, spectral division is implemented. The divergent beam is sequentially refracted and reflected by the thick catadioptric lens (6), and refracted by the meniscus lens (5) and the plano-convex lens (4) to enter an image-side prism (8). Said beam is folded or refracted and filtered, and imaged on a focal plane (10) to realize spectral imaging.

A compact, catadioptric and athermal imaging spectrometer is disclosed. A telecentric light (1) incident from a slit (2) is folded or refracted by an object-side prism (3) to enter a plano-convex lens (4); after being refracted by the plano-convex lens (4) and a meniscus lens (5), and refracted and reflected by a thick catadioptric lens (6), said telecentric light is incident onto a convex grating (7) in the form of a convergent beam; and after said beam is diffracted, spectral division is implemented. The divergent beam is sequentially refracted and reflected by the thick catadioptric lens (6), and refracted by the meniscus lens (5) and the plano-convex lens (4) to enter an image-side prism (8). Said beam is folded or refracted and filtered, and imaged on a focal plane (10) to realize spectral imaging.

An optical arrangement for spectral decomposition of light is disclosed. In an embodiment the optical arrangement includes a reflection diffraction grating, a first medium with a refractive index n.sub.in arranged on a light incidence side of the reflection diffraction grating; and a second medium with a refractive index n.sub.G arranged on a side of the reflection diffraction grating that faces away from the light incidence side, with n.sub.in>n.sub.G, wherein the optical arrangement is configured in such a way that light impinges on the reflection diffraction grating from the first medium at an angle of incidence α, wherein a condition sin(α)>n.sub.G/n.sub.in is satisfied, wherein the reflection diffraction grating comprises a layer system with at least one unstructured layer and at least one structured layer, wherein the at least one structured layer has a periodic structure with a period p in lateral direction, and wherein the period p meets the following conditions: p<λ/[n.sub.in*sin(α)+n.sub.G] and p>λ/[n.sub.in*sin(α)+n.sub.in].

A spectral feature selection apparatus includes a dispersive optical element arranged to interact with a pulsed light beam; three or more refractive optical elements arranged in a path of the pulsed light beam between the dispersive optical element and a pulsed optical source; and one or more actuation systems, each actuation system associated with a refractive optical element and configured to rotate the associated refractive optical element to thereby adjust a spectral feature of the pulsed light beam. At least one of the actuation systems is a rapid actuation system that includes a rapid actuator configured to rotate its associated refractive optical element about a rotation axis. The rapid actuator includes a rotary stepper motor having a rotation shaft that rotates about a shaft axis that is parallel with the rotation axis of the associated refractive optical element.

A spectrometer with a Schmidt reflector is described. The spectrometer may include a Schmidt corrector and a dispersive element as separate components. Alternatively, the Schmidt corrector and dispersive element may be combined into a single optical component. The spectrometer may further include a field-flattener lens.

The invention relates to an optical arrangement, particularly for the detection beam path of a multi-spot scanning microscope, comprising a detection plane, in which a detector is positionable, comprising a dispersive device for spectrally splitting detection light. According to the invention, the optical arrangement is characterized in that a distorting optical unit is present for guiding the detection light into the detection plane, said distorting optical unit being arranged downstream of the dispersive device and upstream of a detection plane, and in that a rotating device is present for the relative rotation of a luminous field of the spectrally separated detection light and the distorting optical unit. The invention additionally relates to a multi-spot scanning microscope and a method for operating a microscope.

A downhole tool has a tool body with an outer diameter equal to a borehole diameter, at least one cavity formed in and opening to an outer surface defining the outer diameter of the tool body, a light source, a filter, and a light detector mounted in the at least one cavity, and a window disposed at the opening of the at least one cavity, wherein the window encloses the cavity.

A system for a high resolution optical spectrum analyzer (OSA) using various optical configurations to reduce polarization dependent loss (PDL) is disclosed. The system may include a birefringent element to receive an input optical beam. The birefringent element may then split the input optical beam into a first optical beam and a second optical beam. The system may also include an optical configuration, which may determine an optical beam path associated with the first optical beam and the second optical beam, transmit the first optical beam in a first direction along the optical beam path and transmit the second optical beam in a second direction along the optical beam path.

Systems and methods for measuring temperature in an environment by creating a first beam having an energy of about 50 mJ/pulse, and a pulse duration of about 100 ps. A second beam is also created, having an energy of about 2.3 mJ/pulse, and a pulse duration of about 58 ps. The first beam and the second beam are directed into a probe region, thereby expressing an optical output. Properties of the optical output are measured at a sampling rate of at least about 100 kHz, and temperature measurements are derived from the measured properties of the optical output. Such systems and methods can be used to measure temperature in environments exhibiting highly turbulent and transient flow dynamics.