Forensic light using semiconductor light source

• US 7,252,678 B2
• Filed: 04/22/2005
• Issued: 08/07/2007
• Est. Priority Date: 09/24/1999
• Status: Expired due to Term

• Current Assignee: CAO Group, Inc.
• Original Assignee: CAO Group, Inc.
• Inventors: Cao, Densen, Ostler, Calvin D., Lin, Zhaohui, Li, Hongyan
• Primary Examiner(s): Vo; Tuyet
• Assistant Examiner(s): A, MINH D
• Application Number:
  US11/112,721
• Publication Number:
  US 20050231965A1
• Time in Patent Office: 837 Days
• Field of Search: 315/39.59, 315/112, 362/257, 362/259, 362/264, 362/227, 362/230, 362/294, 607/88, 607/89, 607/96, 607/102
• US Class Current: 607/88
• CPC Class Codes: F21V 29/54 using thermoelectric means, e.g. Peltier elements
• CPC Class Codes: F21V 29/67 characterised by the arrangement of fans
• CPC Class Codes: F21V 29/70 characterised by passive heat-dissipating elements, e.g. heat-sinks
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01N 2021/6471 Special filters, filter wheel
• CPC Class Codes: G01N 21/255 Details, e.g. use of specially adapted sources, lighting or optical systems
• CPC Class Codes: G01N 21/29 using visual detection G01N21/31 takes precedence
• CPC Class Codes: G01N 21/6447 by visual observation
• CPC Class Codes: G01N 21/645 Specially adapted constructive features of fluorimeters
• CPC Class Codes: G01N 21/94 Investigating contamination, e.g. dust G01N21/85 takes precedence
• CPC Class Codes: G01N 2201/0221 Portable; cableless; compact; hand-held

Abstract

A semiconductor forensic light is disclosed. The forensic light may use a variety of semiconductor light sources to produce light that contrasts forensic evidence against its background for viewing, photographing and collection. Example semiconductor light sources for the forensic light include light emitting diodes and laser chips. A heat sink, thermoelectric cooler and fan may be included to keep the forensic light cool. A removable light source head may be included on the forensic light to provide for head swapping to give the user access to different wavelengths of light.

Claims

1. A semiconductor forensic light comprising:

a housing having a proximal end, a distal end, a top, a bottom and an interior,

control circuitry located in said housing interior,

said control circuitry being able to control on/off and power intensity selection functions of the forensic light,

a power level selection button located on said housing, said power level selection button accommodating the increase and decrease of light output levels from the forensic light,

said power level selection button being in operable communication with said control circuitry,

a trigger on said housing, said trigger serving to accommodate initiation and terminate of light emission from the forensic light,

said trigger being constructed so that it will automatically terminate light transmission of a human finger engaged in actuating the trigger is removed from the trigger,

said trigger being in operable communication with said control circuitry,

a power pack located at said housing proximal end for providing electrical power to the forensic light, a light head located at said housing distal end,

a light source within said light head,

said light source including

a semiconductor light emitting device that can emit light of a wavelength useful in detecting forensic evidence,

a primary heat sink to which said semiconductor light emitting device is affixed, said primary heat sink serving to draw heat away from said semiconductor light emitting device,

a thermoelectric cooler located adjacent said primary heat sink, said thermoelectric cooler experiencing a drop in temperature when exposed to an electrical voltage,

a secondary heat sink to which said primary heat sink is affixed, said secondary heat sink serving to dissipate heat produced by said semiconductor light emitting device,

a fan serving to move air past at least one of said heat sinks in order to cool the light source,

at least one ventilation aperture on said light head for permitting air to enter and exit the light head to facilitating heat dissipation, and

at least one light exit on said light head, said light exit being sized and shaped to permit light to exit said light head for use in detecting forensic evidence.

2. A forensic light as recited in claim 1 wherein said light head is detachable from said housing distal end.

3. A forensic light as recited in claim 1 wherein said semiconductor light producing device is a light emitting diode.

4. A forensic light as recited in claim 1 wherein said semiconductor light producing device is a diode laser.

5. A forensic light as recited in claim 1 further comprising a focus lens at said light exit.

6. A forensic light as recited in claim 1 wherein said semiconductor light producing device is an LED module that include the primary heat sink, an LED chip located in a well on the primary heat sink, and a dome over said LED chip, the LED chip including a substrate and epitaxial layers.

7. A forensic light as recited in claim 1 futher comprising an array of LED modules in said light head.

8. A forensic light as recited in claim 1 further comprising:

a well in said primary heat sink, and

a plurality of semiconductor light producing devices located in said well.

9. A forensic light as recited in claim 1 wherein at least one of said heat sinks includes a material selected from the group consisting of copper, aluminum, silver, magnesium, steel, silicon carbide, boron nitride, tungsten, molybdenum, cobalt, chrome, Si, SiO₂, SiC, AlSi, AlSiC, and diamond.

10. A forensic light as recited in claim 1 wherein said semiconductor light producing device includes epitaxial layers located on a substrate and wherein said substrate is selected from the group consisting of Si, GaAs, GaN, ZnS, ZnSe, InP, Al₂O₃, SiC, GaSb, and InAs.

11. A forensic light as recited in claim 1 wherein said semiconductor light producing device includes epitaxial layers located on a substrate, and at least one of the epitaxial layers is selected from the group consisting of:

a buffer layer to reduce defects in the chip that may arise due to differences in material properties between the epitaxial layers and the substrate,

a contact layer,

a cladding layer serving to confine injected electrons, and

an active layer that emits the light when excited by electrons, the light emitted being useful in forensic detection of evidence.

12. A forensic light as recited in claim 1 wherein said thermoelectric cooler includes a material selected from the group consisting of Bi₂Te₃, PbTe, SiGe, BeO₂, BiTeSe, BiTeSb, AlO₃, AlN, and BaN.

13. A forensic light as recited in claim 1 wherein said light head is capable of emitting light that is selected from the group consisting of blue, green, yellow, red, infrared and ultraviolet.

14. A forensic light as recited in claim 1 wherein said light head is capable of emitting light centered about a wavelength selected from the group consisting of 280 nm, 350 nm, 400 nm, 405 nm, 450 nm, 525 nm, 590 nm, 630 nm, 800 nm, 980 nm, 1064 nm, 1300 nm and 1500 nm.

15. A forensic light as recited in claim 1 wherein light emitted by the forensic light is useful in detecting forensic evidence selected from the group consisting of blood, saliva, other body fluids, hair, flesh, bone fragments, teeth, human skin damage such as bruises, bite marks, cuts, shoe prints, fingerprints, footprints, tire prints, gunpowder residue, bullets and portions thereof, paint, grease, oil, glass fragments, metal rubbings, fibers, dust patterns, alteration of documents, narcotics, and herbal evidence.

16. A semiconductor forensic light comprising:

a housing having a proximal end, a distal end, a top, a bottom and an interior,

a light head located at said housing distal end,

said light head being quickly detachable from said housing in order to accommodate removal of one light head and replacement of it with another light head by a forensic technician working in the field,

a light source within said light head,

said light source including

a semiconductor light emitting device that can emit light of a wavelength useful in detecting forensic evidence,

a primary heat sink to which said semiconductor light emitting device is affixed, said primary heat sink serving to draw heat away from said semiconductor light emitting device, and

at least one light exit on said light head, said light exit being sized and shaped to permit light to exit said light head for use in detecting forensic evidence.

17. A forensic light as recited in claim 16 further comprising:

a secondary heat sink to which said primary heat sink is affixed, said secondary heat sink serving to dissipate heat produced by said semiconductor light emitting device.

18. A forensic light as recited in claim 17 wherein said semiconductor light producing device is an LED module that include the primary heat sink, an LED chip located in a well on the primary heat sink, and a dome over said LED chip, the LED chip including a substrate and epitaxial layers.

19. A semiconductor forensic light comprising:

a handle,

a light head attachable to and removable from said housing,

a light source within said light head,

said light source including

a semiconductor light emitting device that can emit light of a wavelength useful in detecting forensic evidence,

a primary heat sink to which said semiconductor light emitting device is affixed, said primary heat sink serving to draw heat away from said semiconductor light emitting device, and

at least one light exit on said light head, said light exit being sized and shaped to permit light to exit said light head for use in detecting forensic evidence.