Spectrophotometer with photodiode array

• US 4,054,389 A
• Filed: 09/23/1976
• Issued: 10/18/1977
• Est. Priority Date: 09/23/1976
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Owen, Theodore R.
• Primary Examiner(s): Evans, F. L.
• Application Number:
  US05/724,795
• Time in Patent Office: 390 Days
• Field of Search: 356/99, 356/100, 356/186, 356/189, 250/226, 250/227, 350/166, 350/96 B, 350/311, 350/318
• US Class Current: 356/419
• CPC Class Codes: G01J 3/26 using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
• CPC Class Codes: G01J 3/2803 using photoelectric array detector

Abstract

In a spectrophotometer, light that has passed through, or been reflected from, a sample is carried by a fiberoptic bundle. The output end of the fiberoptic bundle is bonded to one side of a wedge-shaped linear variable interference filter. The other side of the filter is bonded to an array of photodiodes. Because each photodiode receives light that has passed through a different portion of the filter, each photodiode will respond to light of a different wavelength.

Claims

1. For use in a spectrophotometer for analyzing the spectra associated with a beam of light across a wide wave band, the combination of:

a linear variable interference filter covering at least the spectrum of light to be analyzed;

transmission means, comprising a fiberoptic bundle for carrying said beam of light, for causing said beam of light to impinge upon one side of said interference filter;

the output end of said fiberoptic bundle comprising a plurality of fiberoptic strands distributed in a substantially linear manner across said one side of said interference filter, said strands being fixed to said interference filter;

a linear array of photodiodes bonded to the other side of said interference filter for receiving light transmitted through said interference filter, said photodiodes each being operative to produce an electrical signal proportional to the intensity of light received by it; and

means for selectively connecting said photodiodes to apparatus for measuring said electrical signal.

2. For use in a spectrophotometer for analyzing the spectra associated with a beam of light across a wide wave band, the combination of:

a linear variable interference filter covering at least the spectrum of light to be analyzed;

transmission means, comprising a fiberoptic bundle for carrying said beam of light, for causing said beam of light to impinge upon one side of said interference filter;

the output end of said fiberoptic bundle comprising a plurality of fiberoptic strands distributed across said one side of said interference filter, the distribution density of said strands varying from a maximum at the end of said interference filter which passes relatively short wavelengths to a minimum at the end of said interference filter which passes relatively long wavelengths, said strands being fixed to said interference filter;

a linear array of photodiodes bonded to the other side of said interference filter for receiving light transmitted through said interference filter, said photodiodes each being operative to produce an electrical signal proportional to the intensity of light received by it; and

means for selectively connecting said photodiodes to apparatus for measuring said electrical signal.