Anti-reflective launch optics for laser to fiber coupling in a photoplethysmograpic device

• US 8,498,507 B2
• Filed: 05/13/2011
• Issued: 07/30/2013
• Est. Priority Date: 05/13/2011
• Status: Active Grant

• Current Assignee: Kestrel Labs, Inc.
• Original Assignee: Kestrel Labs, Inc.
• Inventors: Pologe, Jonas Alexander, Delianides, Theodore Philip
• Primary Examiner(s): Ullah, Akm Enayet
• Application Number:
  US13/107,004
• Publication Number:
  US 20120289798A1
• Time in Patent Office: 809 Days
• Field of Search: 385/31, 385/33, 385/34, 385/35, 385/49, 385/50, 385/88, 385/93, 600/310, 600/322, 600/309, 600/323, 600/331, 372/6, 372/20, 372/70
• US Class Current: 385/38
• CPC Class Codes: A61B 5/02427 Details of sensor
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: G02B 6/4207 with optical elements reducing the sensitivity to optical feedback anti-reflection devices specially adapted for lasers, see H01S3/0064

Abstract

An embodiment of a light launching portion of a photoplethysmographic device having a laser (20) light source and a light guide (40). The coupled end of the light guide (40) includes an anti-reflection coating (30a) to prevent or minimize the back reflection of light emitted by the laser (20). This minimizes the extent to which back reflected light can re-enter the laser and adversely alter the optical output properties of the laser (20) and additionally minimizes the associated light loss thus helping to maximize the optical coupling efficiency. Other embodiments are described and shown.

Claims

1. A photoplethysmographic device including a light launching apparatus, the light launching apparatus comprising:

a. at least one emitter;

b. the at least one emitter comprising at least one laser;

c. at least one light guide;

d. the at least one light guide having an end coated to minimize back reflection;

e. the coated end of the at least one light guide coupled to the at least one laser;

f. the coated end reducing back reflection towards the coupled laser to less than 0.4% of incident light intensity,

whereby light from the at least one laser is launched into the at least one light guide with a minimum of back reflection from the coated end of the at least one light guide.

2. A photoplethysmographic device including a light launching apparatus, the light launching apparatus comprising:

a. one or more lasers;

b. one or more light guides;

c. a launch-optics configured to couple light emitted by at least one of the one or more lasers into at least one of the one or more light guides;

d. the launch-optics having a coating designed to minimize back reflection;

e. the coating reducing back reflection by a minium of at least one order of magnitude.

3. A method for launching light in a photoplethysmographic measurement system, the method for launching light comprising the steps of:

a. providing a laser;

b. providing a light guide;

c. designing an anti-reflection coating to reduce back reflection by at least one order of magnitude;

d. coating at least one end of the light guide with the anti-reflection coating;

e. coupling the at least one end of the light guide with the anti-reflection coating to the laser.