Abstract: This invention concerns a spectroscopic method, apparatus for determining whether a component is present in a sample. In one aspect, the method includes resolving a model of the spectral data separately for candidates from a set of predetermined component reference spectra, and determining whether a component is present in the sample based upon a figure of merit quantifying an effect of including the candidate reference spectrum corresponding to that component in the model.

Abstract: In a Raman spectroscopy apparatus, exciting light is focussed on a sample (26) as a line focus 38. Spectra from points in the line focus are dispersed in rows 46 on a CCD detector 34, having a two-dimensional array of pixels. The line focus moves longitudinally in a direction Y (arrow 48) relative to the sample. Simultaneously and synchronously, charge is shifted in a parallel direction Y? (arrow 50) within the CCD, so that data from a given point in the sample continues to accumulate. This ensures that the data from each sample point arises from illumination which is integrated along the line focus, and makes it easier to stitch the data together subsequently to form an image of the sample. In order to provide averaging in the X direction during fast, low resolution scanning, the line focus is swept across the sample in a zig-zag fashion, between boundary lines 60.

Abstract: In a Raman spectroscopy apparatus, exciting light is focussed on a sample (26) as a line focus 38. Spectra from points in the line focus are dispersed in rows 46 on a CCD detector 34, having a two-dimensional array of pixels. The line focus moves longitudinally in a direction Y (arrow 48) relative to the sample. Simultaneously and synchronously, charge is shifted in a parallel direction Y? (arrow 50) within the CCD, so that data from a given point in the sample continues to accumulate. This ensures that the data from each sample point arises from illumination which is integrated along the line focus, and makes it easier to stitch the data together subsequently to form an image of the sample. In order to provide averaging in the X direction during fast, low resolution scanning, the line focus is swept across the sample in a zig-zag fashion, between boundary lines 60.

Abstract: A spectroscopic probe includes a monolithic block (10) of transparent material and GRIN lenses (20, 22, 24). Light for illuminating a sample is delivered by an optical fiber (31), and light scattered by the sample is output by an optical fiber (33). The block (10) has opposing angled faces (12A, 12B), coated with a dichroic filter coating and a reflective coating respectively. A method for making blocks (10) is also disclosed, in which the coatings are first provided on a large sheet, and blocks (10) are then cut from the sheet using angled cuts. Since the coated block reduces the number of components required, the probe can be miniaturized, e.g. for use in an endoscope.

Abstract: A spectroscopic probe includes a monolithic block (10) of transparent material and GRIN lenses (20,22,24). Light for illuminating a sample is delivered by an optical fiber (31), and light scattered by the sample is output by an optical fiber (33). The block (10) has opposing angled faces (12A, 12B), coated with a dichroic filter coating and a reflective coating respectively. A method for making blocks (10) is also disclosed in which the coatings are first provided on a large sheet, and blocks (10) are then cut from the sheet using angled cuts. Since the coated block reduces the number of components required, the probe can be miniaturized, e.g. for use in an endoscope.

Abstract: An indexing mechanism comprises a disc 2 rotatable about a central axis, suitable for holding objects such as lenses. Detents 8 are provided on the disc which interact with a pawl 14 on a fixed surface adjacent the disc 2. When the disc rotates in a first direction the pawl 14 is deflected by each passing detent 8, returning to its rest position when the detent 8 is passed. When the disc is rotated in an opposite direction, the pawl 14 abuts a detent 8 to define an index position. The disc is driven or biased in this direction to retain this position. A stop 10 may be provided on the disc 2 adjacent each detent 8 which defines the position of the pawl 14 relative to the disc 2. The disc 2 may be driven by a motor 12 and drive means. An alternative system may be used in which lever 40 interacts with a plurality of protrusions 46 on the disc to rotate the disc in a first direction or bias the disc in a second direction so that the pawl 14 abuts a detent 8.

Abstract: A mounting for optical components, e.g. in spectroscopic apparatus, has a rotatable baseplate 10, on which a plurality of quadrant-shaped mounting plates 12 can be kinematically located. Each mounting plate 12 carries respective optical components, which can be brought into and out of an optical path by rotation of the base plate 10. One or more of the mounting plates 12 carries both a housing 14 for components such as filters 20,22 and also a beam steering mirror 24 on a bracket 16. A gap is provided between the housing 14 and the mirror 24, so that the light beam 30 in the optical path can pass unhindered through the gap when this mounting plate is in an inoperative position.

Abstract: A sample placed under a microscope is illuminated by light from a laser beam. Raman scattered light is passed back via a dichroic filter to various optical components which analyse the Raman spectrum, and thence to a CCD detector. The optical components for analysing the Raman spectrum include tunable dielectric filters in a filter wheel; a Fabry-Perot etalon; and a diffraction grating. These various components may be swapped into the optical path as desired, for example using movable mirrors, enabling the apparatus to be used very flexibly for a variety of different analysis procedures. Various novel analysis methods are also described.

Abstract: A diffraction grating receives a laser beam from a semiconductor laser diode. Light is diffracted in a first order of diffraction of the grating, through an aperture which selects a desired wavelength, free from side modes of the laser diode. A minor proportion of the light is reflected back by a glass window, and is fed back into the laser diode to stabilise it, preventing mode hopping. The majority of the light of the desired wavelength passes through the window to an output. Because the output light is both free from side modes and not subject to mode hopping, it is suitable for use as the exciting light in spectroscopy, including Raman spectroscopy.

Abstract: In a Raman spectrometer having a charge-coupled device (CCD) detector (24), an incoming beam (36) containing a spectrum of Raman scattered light is dispersed by a diffraction grating (44). Different parts of the spectrum are split into separate optical paths (48A-C) by edge filters (38A, 38B) and a mirror (46). These components are tilted at different vertical angles, so that after the beams (48A-C) have been dispersed by the diffraction grating (44), they form partial spectra (50A-C), one above the other on the CCD (24). This enables several consecutive parts of a widely dispersed spectrum to be viewed simultaneously on the CCD (24) at high resolution.

Abstract: A sample (14) is illuminated by light from a laser source (16), which is reflected to it by a dichroic filter (18) and passed through a microscope objective (20). The microscope objective (20) focusses a two dimensional image of the illuminated area onto a detector (22). On the way to the detector (22), the light passes through an interference filter (26), which selects a desired line from the Raman spectrum scattered by the sample (14). The filter (26) can be tuned to any desired Raman line by rotating it through various angles of incidence (.THETA.), about an axis (28) perpendicular to the optical axis.