Molded dichroic mirror and method of manufacture thereof

• US 9,618,756 B2
• Filed: 10/09/2013
• Issued: 04/11/2017
• Est. Priority Date: 10/01/2010
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Taylor, Byron B., Poisl, W. Howard
• Primary Examiner(s): Wilkes, Zachary
• Assistant Examiner(s): Oestreich, Mitchell
• Application Number:
  US14/049,847
• Publication Number:
  US 20140247479A1
• Time in Patent Office: 1,280 Days
• Field of Search: 359359, 359634
• CPC Class Codes: B29D 11/00596 Mirrors
• CPC Class Codes: B29D 11/00865 Applying coatings; tinting; colouring printing, marking or copying processes B41M; identification in general G09F3/00; producing decorative effects in general B44C; positioning or marking of lenses B24B13/0055
• CPC Class Codes: F41G 7/008 Combinations of different guidance systems
• CPC Class Codes: F41G 7/2246 Active homing systems, i.e. comprising both a transmitter and a receiver
• CPC Class Codes: F41G 7/2253 Passive homing systems, i.e. comprising a receiver and do not requiring an active illumination of the target
• CPC Class Codes: F41G 7/2286 using radio waves
• CPC Class Codes: F41G 7/2293 using electromagnetic waves other than radio waves
• CPC Class Codes: G02B 17/0694 with variable magnification or multiple imaging planes, including multispectral systems systems with only refractive elements G02B15/14
• CPC Class Codes: G02B 23/12 with means for image conversion or intensification
• CPC Class Codes: G02B 27/141 using dichroic mirrors
• CPC Class Codes: G02B 5/08 Mirrors vehicle mirrors involving special optical features B60R1/08
• CPC Class Codes: G02B 5/0825 the reflecting layers comprising dielectric materials only
• CPC Class Codes: G02B 5/208 for use with infrared or ultraviolet radiation, e.g. for separating visible light from infrared and/or ultraviolet radiation

Abstract

A molded dichroic mirror and method of manufacture thereof. The dichroic minor may be molded from polysiloxane or lithia potash borosilicate and may be coated to reflect an infrared signal and configured to transmit a radio frequency signal between 33 GHz and 37 GHz.

Claims

1. A dichroic mirror constructed and arranged to transmit a millimeter-wave (MMW) signal, the dichroic mirror comprising a base mirror consisting of polysiloxane having a dielectric constant in a range of about 3.36 to about 3.41 at millimeter-wave frequencies, and a coating disposed on a surface of the base mirror and configured to reflect an infrared signal.

2. The dichroic mirror of claim 1, wherein the dichroic mirror has a loss tangent less than or equal to 0.01 at millimeter-wave frequencies.

3. The dichroic mirror of claim 1, wherein the dichroic mirror is formed by a process of molding the material of the base mirror.

4. The dichroic mirror of claim 1, wherein a softening temperature of the material of the base mirror is less than or equal to 600°

C.

6. The dichroic mirror of claim 1, wherein the millimeter-wave signal has a frequency in a range of 26.5 GHz to 40 GHz.

7. The dichroic mirror of claim 6, wherein the frequency of the millimeter-wave signal is in a range of 33 GHz to 37 GHz.

5. A method of making a dichroic mirror configured to transmit a millimeter-wave signal and to reflect an infrared signal, the method comprising:

selecting a polysiloxane material that transmits the millimeter-wave signal, the polysiloxane material having a softening temperature of less than or equal to 600°

C., and a dielectric constant in a range of about 3.36 to about 3.41 at millimeter-wave frequencies;

molding the polysiloxane material to form a base mirror consisting of the polysiloxane material; and

coating at least one surface of the base mirror with a dielectric stack that reflects the infrared signal.

8. A dichroic mirror constructed and arranged to transmit a millimeter-wave (MMW) signal and reflect an infrared signal, the dichroic mirror comprising:

a molded base mirror constructed and arranged to transmit the MMW signal, the molded base mirror consisting of polysiloxane having a dielectric constant in a range of about 3.36 to about 3.41 at millimeter-wave frequencies; and

a coating disposed on at least one surface of the molded base mirror, the coating being configured to reflect the infrared signal.

9. The dichroic mirror of claim 8, wherein the molded base mirror has a softening temperature of less than or equal to 600°

C., and a loss tangent of less than or equal to 0.01 at millimeter-wave frequencies.

10. The dichroic mirror of claim 8, wherein the coating includes a dielectric stack.

11. The dichroic mirror of claim 8, wherein the millimeter-wave signal has a frequency in a range of 26.5 GHz to 40 GHz.