Multimode, multispectral scanning and detection

• US 4,794,398 A
• Filed: 10/01/1986
• Issued: 12/27/1988
• Est. Priority Date: 10/01/1986
• Status: Expired due to Fees

• Current Assignee: Siemens Rail Automation Ltd. (Siemens AG)
• Original Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Raber, Peter E., Kosowsky, Lester H.
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Johnson, Doris J.
• Application Number:
  US06/913,890
• Time in Patent Office: 818 Days
• Field of Search: 343/725, 343/753, 343/754, 343/757, 343/815, 343/909, 343/911 R, 343/912
• US Class Current: 343/754
• CPC Class Codes: H01Q 3/14 for varying the relative position of primary active element and a refracting or diffracting device

Abstract

In a multimode or multispectral electromagnetic detection system (11), a pair of rotatable scanning prisms (13'"'"' and 13"), each of said prisms comprising at least a pair of cooperative subprisms (13'"'"'a, 13'"'"'b, 13"a and 13"b), and the cooperative materials of the subprism being selected so as to ensure that electromagnetic radiation passing through the pair of rotatable prisms is equally deviated in a transverse direction.

Claims

1. A multi frequency electromagnetic detection system comprising:

electromagnetic transceiver means responsive to electromagnetic radiation in a radar frequency range about a frequency f1 and an optical frequency range about a frequency f2; and

scanning means including cooperative first and second rotatable scanning prisms, characterized in that each of said scanning prisms comprises at least first and second subprisms each constructed of a material, having frequency-dependent indices of refraction na(f) and nb(f), respectively and having prism angles aa and ab, respectively, with the indices of refraction related by the condition that na(f1)=nb(f1) and the condition that na(f2)<

nb(f2)<

na(f1), and the prism angles having values such that the deviation of electromagnetic radiation passing through said scanning means is the same for frequencies substantially equal to f1 or f2.

2. A system according to claim 1 for deviating electromagnetic radiation through an angle d for each scanning prism, further characterized in that d is determined by the equation:

space="preserve" listing-type="equation">d=sin.sup.-1 {nb(f)sin[ab-sin.sup.-1 {[na(f)/nb(f)]sin(aa+sin.sup.-1) {sin(ab-aa)/na(f)})}]},

where ab is the angle of the prism having index of refraction nb and aa is the angle of the prism having index of refraction na.

3. The arrangement of claim 2, in which at least one of the frequencies scanned is infrared.

4. The arrangement of claim 2, in which at least one of the frequencies used is radio frequency.

5. The arrangement of claim 2, in which at least one of said frequencies is visible.