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Discrete Interference Filter Monochromator

IP.com Disclosure Number: IPCOM000086927D
Original Publication Date: 1976-Nov-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 3 page(s) / 41K

Publishing Venue

IBM

Related People

Mathisen, ES: AUTHOR

Abstract

Interference filters are known devices that transmit a narrow bandwidth of light. The bandwidth is variable over a limited range for a given filter dependent upon the angle of incidence of light transmitted thereby. Shown in the drawing is a device which uses a series of interference filters 9, each of a different nominal bandwidth, to provide a monochromator for analyzing radiant energy over a relatively wide bandwidth.

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Discrete Interference Filter Monochromator

Interference filters are known devices that transmit a narrow bandwidth of light. The bandwidth is variable over a limited range for a given filter dependent upon the angle of incidence of light transmitted thereby. Shown in the drawing is a device which uses a series of interference filters 9, each of a different nominal bandwidth, to provide a monochromator for analyzing radiant energy over a relatively wide bandwidth.

As shown in the drawing, which is a partially schematic and exploded diagram, the monochromator includes a geneva mechanism 1 comprising a driver 2 that is continuously rotated by a motor 3 in the direction of the arrow. A driven member 4 is engaged with driver 2 and operates in conventional fashion to provide an intermittent motion output thereto. Connected to and driven by member 4 is a plate 8 upon which are mounted a series of interference filters 9 by a series of fixtures 10.

Each fixture 10 is free to rotate about a vertical axis and has an arm 11 connected to a stud 12. Each stud is engaged in a slot 13 of a wheel 14. A spring 15 is connected to and biases each arm so that the stud remains in the associated slot 13. Wheel 14 is driven by a gear train 16 providing, for the illustrated example, a 6-to-1 gear ratio. Wheel 14 is thus driven at a constant speed. A stationary set of fiber-optic light guides 17 and 18 are mounted above wheel 14 in line with a station at which each filter is located when the driven member 4 occupies a stationary position. Light guides 17 and 18 provide input and output channels by means of which a polychromatic light is provided as an input to produce a variable monochromatic light output. In operation, the geneva mechanism is used to position each filter 9 successively between light guides 17 and 18. As each filter is brought into position and its axis is held stationary by wheel 8 for a period of time, the continued rotation of wheel 14 pivots the filter, through arm 11, about a vert...