Calibration for optical filter

#Different kinds of optical filters are known. Optical filters can be formed by coating a blank to form an optical filter which has different characteristics in different locations of the filter.

#Examples of such filters are found in U.S. Pat. No. 5,426,576. In these optical filters, the amount of color saturation may vary based on the distance along a gradient axis. The gradient axis can be a linear gradient axis, or a circumferential gradient axis, in this patent. Also, two filters can be used together to form a cross fader.

#Different kinds of coated optical filters are also known. In general, these coated optical filters may have characteristics that vary based on the amount of the coating.

#These and other aspects will now be described in detail, with reference to the accompanying drawings, wherein:

#FIG. 1 shows a block diagram of the luminaire system;

#FIG. 2 shows a flow diagram of forming the filters;

#FIG. 1 shows a system in which a light transmission device 99 including a lamp assembly 9, having lamp 10 and reflector 11 is caused to transmit light along an optical axis 12. A color filter assembly 13 is formed of two color filters 14 and 15 placed along the optical axis and rotatable about axis 16. Each of the color filters, such as 14, may include an alignment mark 125. The alignment mark 125 may include, for example, a physical hole in the filter. The alignment mark allows the system to determine a set point in the filter, for example the beginning of a certain color spectrum. The filters are coated with a varying amount of filtering medium, so that different areas on the filter produce a different color effect.

#The two color filters can be moved relative to one another by the motors SM1 and SM2. By moving the color filters, the degree of saturation changes, and hence the color output changes. The motors SM1 and SM2 are controlled by a controller 100. The controller 100 operates according to a prestored program which may be stored in its memory 110.

#According to the present system, each luminaire 99 should, on cue, produce the same color. This is done according to the present system by calibrating each of the filters 14, 15 in each luminaire 99 based on a reference standard. The calibration allows each luminaire to know an exact position of the filter that produces a specific color effect even if there are positional and/or color differences between the filters.