Browse Prior Art Database

Spectrum Analyzer

IP.com Disclosure Number: IPCOM000085009D
Original Publication Date: 1976-Feb-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 15K

Publishing Venue

IBM

Related People

Kern, RW: AUTHOR

Abstract

The diffraction grating 15 in a spectrum analyzer is continuously rotated to provide a data synchronizing signal.

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Spectrum Analyzer

The diffraction grating 15 in a spectrum analyzer is continuously rotated to provide a data synchronizing signal.

The spectrum analyzer employs two different selectable light sources 1, 2. For example, a deuterium lamp 1 is used for the lower wavelength region, e.g., 2000 Angstroms to about 4500 Angstroms, and a quartzline lamp 2, e.g., tungsten, is used for a longer wavelength region, e.g., 4000 Angstroms to 10,000 Angstroms.

The light beam from the selected one of the lamps 1, 2 is reflected from an associated one of the fixed mirrors 3 toward a three-position concave spherical first surface reflector 4. Depending on which lamp 1, 2 is being used, reflector 4 is previously rotated to one of its three discrete angular positions about an axis 5 that passes through the vertex of its spherical surface.

In one operational mode, for two of the positions, reflector 4 directs the light beam of the selected lamp directly toward flow cell 6, which contains a liquid sample to be analyzed, the light beam passing through collimating lens 7 before reaching flow cell 6. For this mode, transmission or absorption measurements are conducted with the light beam directed through windows 6a, 6b of flow cell 6 via lens 7.

In another operational mode, fluorescence measurements are made. In this mode, flow cell 6 is illuminated using lamp 1 and with reflector 4 positioned to its third angular position. As a result, lamp 1's light beam, which is reflected from lower mirror 3, is directed by reflector to a fixed mirror 8 and is focused onto adjustable entrance slit 9 of the fluorescence excitation mode monochromator. After passing through slit 9, the beam is dispersed by multipositionable plane diffraction grating 10 toward spherical concave first surface reflector 11 and from there is directed toward flow cell 6.

Mask 12 in front of flow cell 6 passes a narrow wavelength band of light through flow cell window 6c and illuminates and excites the sample for fluorescence measurements. The spectral bandwidth is controlled by the width of entrance slit 9 and the width of mask 12. The central wavelength passing through mask 12 is determined by the angular position of grating 10.

It will be assumed for purposes of explanation, that grating 10 is in a position which produces a selected central wavelength when fluorescence measurements are being conducted. For example, grating 10 may be positionable in 15 discrete angular positions by a drive system, not shown, controlled by a potentiometer or ratchet type system, not shown, to cover a total wavelength range from 2000 Angstroms to 4500 Angstroms. Adjustable entrance slit 9 and mask 12 are set, for example, to a 150 Angstrom bandwidth illumination of the sample. Flow cell 6 has SUPERSIL* or equivalent type windows for transmission of ultraviolet light. Wall 6d of cell 6 is opposite to excitation window 6c and is reflective to enhance the fluorescence e...