Pulsed illumination projector

• US 4,717,862 A
• Filed: 11/19/1984
• Issued: 01/05/1988
• Est. Priority Date: 11/19/1984
• Status: Expired due to Fees

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: Department of Health and Human Services (State of Victoria)
• Inventors: Anderson, William B.
• Primary Examiner(s): Boudreau, Leo H.
• Assistant Examiner(s): Razavi, Michael
• Application Number:
  US06/672,728
• Time in Patent Office: 1,142 Days
• Field of Search: 315/307, 315/241 S, 315/149, 315/150, 315/271, 315/247, 315/246, 315/287, 356/438, 367/13
• US Class Current: 315/246
• CPC Class Codes: H05B 39/09 in which the lamp is fed by pulses automatic circuit devices built into or on the incandescent lamp H01K1/625; vehicle winking devices B60Q1/38

Abstract

A pulsed illuminator projector for reducing the reverberation levels of rected ligh by illuminating a lamp that is pulsed on and off at a specified rate and for a specified time duration. The critical factor is controlling the amount of time the light is on versus amount of time it is off, and the frequency at which the lamp is pulsed on. The pulsed illumination projector device reduces the amount of backscatter from particulate matter such as water, zooplankton, dust, fog and the like which causes a significant amount of light to reflect back toward the source thereby reducing visibility. Backscatter is reduced through the reduction of direct incident light. As the backscatter is reduced, the distance which objects can be detected is increased. Illumination is controlled directly by pulse length and repetition rate. The device is completely portable and can be hand held item as well as mounted on a vehicle and operable in gaseous or liquid atmospheres.

Claims

1. A method for providing improved illumination visibility in an illuminated medium having particulate matter suspended therein by reducing luminous reverberation backscatter from said particulate matter which comprises:

(a) providing illumination in a series of light pulses; and

(b) adjusting the pulse length and pulse repetition rate of said light pulses during operation to minimize the luminous reverbation backscatter.

2. A method as recited in claim 1 wherein said step of providing illumination in a series of light pulses includes providing illumination in a series of light pulses having an adjustable pulse repetition rate of between 0.5 pulses per second and 5 pulses per second and an adjustable pulse length of between 1000 microseconds and 1 second.

3. Apparatus for providing improved illumination visibility in an illuminated medium having particulate matter suspended therein by reducing luminous reverberation backscatter from said particulate matter, which comprises:

(a) a lamp for providing illumination; and

(b) control means for energizing said lamp to provide illumination in a series of light pulses,

(c) said control means having means for selecting the pulse repetition rate of said light pulses,

(d) said control means having means for selecting the pulse length of said light pulses, said pulse repetition rate and pulse length being adjustable during operation to reduce reverberation backscatter.

4. Apparatus as recited in claim 3 wherein said control means for energizing said lamp to provide illumination in a series of light pulses includes means of energizing said lamp to provide illumination in a series of light pulses having a pulse repetition rate range of between 0.5 pulses per second and 5 pulses per second and a pulse length range of between 1000 microseconds and 1 second.

5. Apparatus as recited in claim 4 wherein said control means includes:

(a) a pulse repetition rate generator for providing a series of first pulses at the desired pulse repetition rate;

(b) a differentiator coupled to receive said series of first pulses, said differentiator generating a second pulse at the beginning of each first pulse to provide a series of second pulses;

(c) a pulse length generator coupled to receive said second pulses from said differentiator, said pulse length generator producing a series of third pulses having the desired pulse length;

(d) an AND circuit coupled to receive said first pulses from said pulse repetition rate generator and said second pulses from said pulse length generator, said AND circuit providing a series of fourth pulses having the desired pulse repetition rate and the desired pulse length, said series of fourth pulses being coupled to drive said lamp to provide illumination in a series of light pulses at the desired pulse repetition rate and pulse length.

6. Apparatus as recited in claim 5 wherein said control means further includes means for adjusting the pulse repetition rate of said first pulses from said pulse repetition rate generator and means for adjusting the pulse length of said third pulses from said pulse length generator.