Optical radar system for automotive vehicle

• US 5,541,724 A
• Filed: 09/13/1995
• Issued: 07/30/1996
• Est. Priority Date: 09/09/1992
• Status: Expired due to Fees

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Inventors: Hoashi, Yoshiaki
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US08/527,387
• Time in Patent Office: 321 Days
• Field of Search: 356/5.1, 356/3.03, 356/4.07, 356/4.01
• US Class Current: 356/5.1
• CPC Class Codes: G01S 17/36 with phase comparison between the received signal and the contemporaneously transmitted signal
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 3/784 using a mosaic of detectors

Abstract

An optical radar system for tracking a target object is provided. This radar system includes generally a light emitting unit for emitting light toward the target object and a light receiving unit for intercepting the light reflected from the target object. The light receiving unit includes a condenser lens arranged for capturing the reflected light and a light sensitive element arranged at a position offset from a focal point of the condenser lens by a preselected distance in an image forming space thereof to be exposed to the light propagated from the condenser lens for assuring a narrower detection range for a distant target object and a wider detection range for a close target object.

Claims

1. An optical apparatus comprising:

a light emitting device for emitting light; and

a light receiving device for receiving light reflected from the target object, said light receiving device including;

a first condenser lens arranged at a first position to capture and transmit the reflected light,

a first light sensitive element, wherein said first light sensitive element and said first condenser lens each lie substantially on a first common axis, wherein said first light sensitive element is arranged at a position axially offset from a focal point of said first condenser lens, wherein said first light sensitive element receives the reflected light transmitted by said first condenser lens, wherein an intensity of the transmitted reflected light transmitted to said first light sensitive element is inversely proportional to an angle of incidence of the transmitted reflected light incident on said first common axis,

a second condenser lens arranged at a second position different from said first position to capture the reflected light,

a second light sensitive element, wherein said second light sensitive element and said second condenser lens each lie substantially on a second common axis, wherein said second light sensitive element is arranged at a position axially offset from a focal point of said second condenser lens, wherein said second light sensitive element receives the reflected light transmitted by said second condenser lens, wherein an intensity of the transmitted reflected light transmitted to said second light sensitive element is inversely proportional to an angle of incidence of the transmitted reflected light incident on said second common axis.

2. An apparatus as set forth in claim 1, wherein said first light and second light sensitive elements are arranged at respective positions shifted toward said first and second condenser lenses from focal surfaces of said first and second condenser lens, respectively.

3. An apparatus as set forth in claim 1, wherein said first light sensitive element is arranged such that a center of said first light sensitive element is disposed at a position offset from an optical axis of the first condenser lens and toward said second light sensitive element, said second light sensitive element being arranged such that a center of said second light sensitive element is disposed at a position offset from an optical axis of the second condenser lens and toward said first light sensitive element.

4. An apparatus as set forth in claim 1, wherein said light emitting means comprises a three-array laser diode and a condenser lens provided with an aspherical toric plano-convex lens.

5. An apparatus as set forth in claim 1, wherein said first and second condenser lens are provided with a Fresnel lens.

6. An apparatus as set forth in claim 1, wherein a first position, at which said first condenser lens is located, is opposite a second position, at which said second condenser lens is located, across said light emitting means in a radiation plane of said light emitting means.

7. An optical apparatus for detecting a target object, comprising:

a light emitting device; and

a light receiving device, wherein said light receiving device includes;

a first condenser lens operably arranged to capture and transmit light which is reflected from a target object;

a first light sensitive element operably associated with said first condenser lens, wherein said first light sensitive element receives said reflected light transmitted by said first condenser lens, wherein said first light sensitive element is offset from a focal point of said first condenser lens by a first separation;

a second condenser lens operably arranged to capture light and transmit light which is reflected from a target object;

a second light sensitive element operably associated with said second condenser lens, wherein said second light sensitive element receives said reflected light transmitted by said second condenser lens, wherein said second light sensitive element is offset from a focal point of said second condenser lens by a second separation;

wherein said first separation and said second separation operably define a detection field in which a target object can be detected, wherein said detection field has a first region having a first lateral dimension and a second region which is distal to said first region having a second lateral dimension which is more narrow than said first lateral dimension.

8. An optical apparatus comprising:

a light emitting device; and

a light receiving device arranged to receive light reflected from a target object, wherein said light receiving device includes;

a condenser lens operably arranged to capture and transmit the reflected light; and

a light sensitive element operably associated with said condenser lens, wherein said light sensitive element is offset from a focal point of said condenser lens and is arranged so as to receive the reflected light transmitted from said condenser lens, wherein an intensity of the reflected light received by said light sensitive device is inversely proportional to an angle of incidence of the reflected light incident on said light sensitive device,

wherein a target object is detected according to a phase difference relationship between the light emitted from said light emitting device to the reflected light received by said light sensitive element.