| 摘要 |
Methods and apparatus for providing an optical analog quantity proportional to <IMAGE> Input light (a4) of intensity proportional to an is directed (21,31) to the input end of an nth optical module comprising a modulator (22) whose output light intensity is responsive to an electrical potential difference across it and a beam combiner (23). While the light is passing through the modulator (22), a potential difference (24) is applied across it such that the intensity of the output light from the modulator (22) is proportional to anx, and this light (a4x) is directed, through the beam combiner (23), to the output end of the optical module. Input light (a3) of intensity proportional to an-1 is directed (25), via the beam combiner (23), to the output end of the optical module, to combine with the light from the modulator (22) so that the intensity of the output light (32) from the nth optical module is proportional to anx+an-1; this light is directed to the input end of an (n-1)th optical module essentially similar to the nth; and so on in the same manner; and finally to the first module, so that its output light has an intensity proportional to p(x).
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