Abstract:
A Littrow-type spectrometer or monochromator using a folded light path to provide a compact optical instrument is disclosed. Light enters the instrument through an inlet aperture on a planar mirror. The aperture is located at the focus of a parabolic collimetor mirror. Collimated light reflected by the parabolic miror is reflected back to the planar mirror, which is positioned at an angle to the collimated light. The light reflected from the planar mirror is directed at a planar grating that produces diffracted light having all the wavelengths input into the system, including light of a selected wavelength, back towards the planar mirror. Light having the selected wavelength is thus caused to fall on the parabolic mirror. The parabolic mirror then focuses the selected wavelength of light ont a light exit aperture that is juxtaposed to the inlet light aperture. The planar grating can be rotatably mounted to scan the input light spectrum.
Abstract:
A spectroscopic system according to the present invention 10 comprises: an optical fiber bundle 12 whose emitting end 12a is arranged in a vertical direction; a slit 16 which is arranged so as to oppose the emitting end 12a of the optical fiber bundle 12; spectroscopic element arrangement means 20 which can switchably arrange either a first diffraction grating 23 in which grooves extending along the vertical direction are arranged in a horizontal direction at a predetermined groove density, or a second diffraction grating 24 in which grooves extending along the vertical direction are arranged in the horizontal direction at a groove density larger than that of the first diffraction grating 23, on an optical path of light which is emitted from the emitting end 12a of the optical fiber bundle 12 and passes through the slit 16; and a photomultiplier tube 30 in which a plurality of anodes 53 extending along the vertical direction are arranged in the horizontal direction.
Abstract:
A scanning monochromator (FIG. 12) comprises means for providing an input light beam (INPUT LIGHT BEAM); a first stage monochromator (252) including a first diffraction grating for diffracting the input light beam (INPUT LIGHT BEAM) and means for rotating the first diffraction grating, the first stage monochromator (252) providing a first stage output light beam; a second stage monochromator (254) including a second diffraction grating for diffracting the first stage output light beam and means for rotating the second diffraction grating, the second diffraction grating diffracting the first stage output light beam such that said first stage output light beam is recombined by the second diffraction grating to provide a second stage output light beam (OUTPUT LIGHT BEAM); and an output aperture (256) for passing a selected portion of the second stage output light beam (OUTPUT LIGHT BEAM) to provide increased selectivity, whereby a high close-in dynamic range is achieved.
Abstract:
A high resolution fast imaging spectrograph is disclosed which provides 400 spatial channels and 100 spectral channels of information. A collimating mirror (10) and a focusing mirror (12) face a plane diffraction grating (14), which is positioned at an acute angle to the perpendicular to the optic axis. An elongated slot (16) is cut through approximately the center of the grating allowing the light source (18) to pass through the slot and onto the collimating mirror. A turning mirror (20), which is placed at the focus of the focusing mirror and adjacent to the slot, directs radiation to a camera mirror (22), which focuses a final image outside the instrument enclosure onto a detector (24). The light source to the instrument is provided by an optical fiber ribbon. The detector will commonly be a CCD or CID 2-D detector, permitting the simultaneous measurement of spectral distribution of a spatial profile. The instrument requires no power input, has no moving parts, and is completely passive with no operating controls or adjustments. Also disclosed is a commercially significant means to utilize the high spatial resolution imaging spectrograph in earth science remote imaging applications through the utilization of a reflecting telescope connected to the spectrograph by means of an optical fiber ribbon.
Abstract:
A double-pass scanning monochromator (FIG. 1) for use in an optical spectrum analyzer (FIG. 11) includes an input optical fiber (10) for emitting an input light beam (12), a diffraction grating (16) for diffracting the input light beam (12) to produce a spatially dispersed light beam (20), a slit (24) for passing a selected portion of the dispersed light beam (20), a motor (90) for rotating the diffraction grating (16), a shaft angle encoder (92) for sensing grating position, an output optical fiber (42). The light (30) that passes through the slit (24) is directed to the diffraction grating (16) and is recombined by the diffraction grating (16) to produce an output light beam (36). The light beam (12) to be analyzed is incident on the diffraction grating (16) during first and second passes. A polarization rotation device (32) rotates the polarization components of the light beam (30) by 90° between the first and second passes so that the output of the monochromator (FIG. 1) is independent of the polarization of the input light beam (12). The output optical fiber (42) is translated by a micropositioning assembly (80) in a plane perpendicular to the output light beam (36) during rotation of the diffraction grating (16) to automatically track the output light beam (36) and to provide optical chopping.
Abstract:
Un appareil (10) de dispersion dynamique de lumière se compose d'un laser (12) optiquement couplé à un échantillon (26) de dispersion de lumière, via une première fibre (18) optique monomode et une première lentille (22). La lentille (22) produit une partie centrale du faisceau (24) dans l'échantillon (26), et de la lumière dispersée est captée par une lentille (30) de réception ainsi que par une second fibre optique (34) monomode. La seconde fibre (34) a une face d'extrémité dans le plan de Fourier (84) de la lentille de réception (30, 70), et définit une ouverture correspondant à un seul disque d'Airy (82) de la lentille (30, 70). La fibre de réception (34) reçoit de l'échantillon (26) un mode spatial individuel de lumière dispensée, ce mode correspondant à une onde de plan unique à la laquelle contribuent plusieurs diffuseurs. La fibre (34) de réception atténue également les modes spatiaux non voulus à cause de son caractère monomodal. Un photodétecteur (36) détecte de la lumière transmise par la fibre (34) de réception.
Abstract:
In an optical instrument, fiber optics are employed to receive light from a linear filament. The fiber optics are arranged into a plurality of light receiving bundle ends distributed around the linear filament and shaped into narrow rectangular slits aligned with the filament. The fibers from each of the receiving ends are equally distributed between two transmitting ends which direct the light through cylindrical lenses to opposite sides of a rotating filter wheel in a paddle wheel configuration. Light beams from the transmitting ends of the fiber optic bundles pass through filters on the filter wheel to additional fiber optic bundles which carry the received light to a probe.