Portable laser diode scanning head having a focusing lens and an aperture

• US 5,247,162 A
• Filed: 04/24/1991
• Issued: 09/21/1993
• Est. Priority Date: 02/28/1985
• Status: Expired due to Term

• Current Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Adelson, Alexander M., Barkan, Edward, Swartz, Jerome, Metlitsky, Boris, Barkan, Eric F., Shepard, Howard M., Krichever, Mark J.
• Primary Examiner(s): SHEPPERD, JOHN W
• Application Number:
  US07/690,705
• Time in Patent Office: 881 Days
• Field of Search: 235/467, 235/472, 359/214
• US Class Current: 235/462.35
• CPC Class Codes: G06K 2207/1011 Aiming
• CPC Class Codes: G06K 7/10633 by oscillation
• CPC Class Codes: G06K 7/10881 constructional details of hand-held scanners

Abstract

A portable laser diode scanning head, aimable at each symbol to be read, emits and receives non-readily-visible laser light, and is equipped with a trigger-actuated aiming light arrangement for visually locating and tracking each symbol. A compact laser diode optical train and an optical folded path assembly, as well as an interchangeable component design and an integral window construction for the head also are disclosed. Also disclosed is an optic means mounted in the laser diode scanning head including a focusing lens and an aperture stop for forming the emitted laser light to have a beam cross-section of an altered size within a working distance range.

Claims

1. A laser scanning head for reading bar-coded symbols, comprising:

(a) an actuatable laser diode mounted in the head for generating an incident laser beam of relatively low power, the laser diode having a p-n junction as the emitter of the laser beam;

(b) optic means mounted in the head for forming and directing the incident laser beam along a first optical path toward a reference plane located exteriorly of the head and to a symbol located in a working range in the vicinity of the reference plane, the laser beam reflecting off the symbol and returning along a second optical path back towards the head;

the optic means including a focusing lens and an aperture stop both located in the first optical path in the immediate vicinity of the laser light source for forming the incident laser beam to have a beam cross-section of an altered size and shape within the working range, the focusing lens being located between the aperture stop and the laser light source;

the aperture stop defining a shaped opening which in cross-section is smaller than the beam cross-section at the aperture stop to permit a portion of the incident light beam to pass through the aperture stop and to directly determine the beam'"'"'s size and shape within the working range, such cross-section being measured in the direction perpendicular to said p-n junction;

(c) a scanner mounted in the head for scanning the laser beam across the symbol, the returning portion of the laser light having a variable intensity over the scan;

(d) a sensor mounted in the head for detecting the variable intensity of the returning portion of the laser light, and for generating a sensor signal representative of the detected variable light intensity;

(e) a signal processor mounted in the head for processing the sensor signal and for generating a processed signal indicative of characteristics of the symbol; and

(f) an actuator mounted in the head for actuating the laser light source.

2. The head as recited in claim 1 wherein the actuator comprises a manually-actuatable trigger.

3. The head as recited in claim 1 and including a housing for integrally supporting the aperture stop, the focusing lens, and the laser light source.

4. The head as recited in claim 1 wherein the scanner includes an electrically driven motor.

5. The head as recited in claim 1 wherein the scanner includes at least one mirrored surface and an electrically driven motor coupled to move the mirrored surface.

6. The head as recited in claim 5 wherein the motor is driven to reciprocally oscillate the mirrored surface.

7. The head as recited in claim 6 wherein the mirrored surface is flat.

8. The head as recited in claim 6 wherein the mirrored surface is curved.

9. The head as recited in claim 1 and including a decoder for decoding the processed signal.

10. The head as recited in claim 1 wherein the decoder is mounted within said head.

11. The head as recited in claim 1 wherein the head includes a housing adapted to be held in the hand.

12. The head as recited in claim 1 wherein the incident laser beam has a non-radially symmetric cross-section, and wherein the aperture stop has a radially symmetrical cross-section and modifies the non-radially symmetrical beam cross-section to one which is radially symmetrical at the reference plane.

13. The head as recited in claim 1 wherein the incident laser beam has a non-radially symmetric cross-section, and wherein the aperture stop has a non-radially symmetrical cross-section and modifies the non-radially symmetrical beam cross-section to one which is of a predetermined non-symmetry at the reference plane.

14. The head according to claim 1 wherein the laser light source includes a laser diode which produces a beam having a first cross-sectional size and shape at a place in the region of the aperture stop and wherein the aperture stop is configured to modify the first shaped beam to have a different size and shape at the reference plane.

15. The head according to claim 1 wherein the laser light source includes a solid state laser diode.

16. The head as recited in claim 15 wherein the optical means includes means for adjustably and jointly positioning the lens and the aperture stop at a predetermined spacing from the diode.

17. The head as recited in claim 1 wherein said aperture stop and said focusing means cooperate to provide a numeric aperture on the order of 0.05.

18. The head as recited in claim 1 wherein the beam-passing cross-sectional area of the aperture stop is on the order of 1-2 square millimeters.

19. The head as recited in claim 1 wherein the focal distance of the focusing lens is on the order of 9.5 to 9.7 millimeters.

20. The laser scanning head according to claim 1 wherein said cross-section is measured in both parallel and perpendicular directions with respect to said p-n junction.

22. The optical system as recited in claim 1 wherein the laser beam has a non-radially symmetrical cross-section, and wherein the aperture stop has a radially symmetrical cross-section and modifies the non-radially symmetrical beam cross-section to one which is radially symmetrical at the reference plane.

23. The optical system as recited in claim 1 wherein the laser beam has a non-radially symmetrical cross-section, and wherein the aperture stop has a non-radially symmetrical cross-section and modifies the non-radially symmetrical beam cross-section to one which is of a predetermined non-symmetry at the reference plane.

21. An optical system for reading coded symbols, comprising:

(a) means including a solid state laser diode for generating a wide-angle, low power laser beam, the laser diode having a p-n junction as the emitter of the laser beam; and

(b) optical means for optically forming and directing the laser beam along an optical path to different light-reflective indicia portions of a coded symbol for reflection therefrom, said optic means including a single focusing lens and an aperture stop located in the optical path in the immediate vicinity of the focusing lens between the laser light source and the light-reflective indicia portions, for focusing the laser beam to have a beam cross-section of a predetermined size within a working distance range, said aperture stop being located downstream of the lens and having a shaped cross-section which is smaller than the beam cross-section at the aperture stop to permit a part of the beam to pass through the aperture stop en route to the indicia portions, said cross-section of the aperture stop directly determining said pre-determined size of the beam cross-section, said aperture stop being bounded by a blocking wall for obstructing the remaining part of the beam from passing through the aperture stop en route to the indicia portions, such cross-section being measured in the direction perpendicular to said p-n junction.

24. The optical system of claim 21 wherein the laser light source is a semiconductor diode and the optical means further includes a means for adjustability and jointly positioning the lens and the aperture stop at a predetermined spacing from the diode.

25. The optical system of claim 21 wherein the focusing means includes a single focusing lens having a curved surface.

26. The optical system of claim 21 wherein the focusing means includes a single focusing lens having a plano-convex configuration.

27. The optical system of claim 21 wherein the focusing means includes a single focusing lens having a flat surface.

28. The optical system of claim 21 wherein the cross-section of the aperture stop is circular.

29. The optical system of claim 21 wherein the cross-section of the aperture stop is rectangular.

30. The optical system of claim 21 wherein the cross-section of the aperture stop is oval.

31. The optical system according to claim 21 wherein said laser beam from the laser light source to the focusing means and aperture stop is substantially uncollimated.

32. The optical system according to claim 21 wherein said aperture stop and said focusing means cooperate to provide a numeric aperture on the order of 0.05.

33. The optical system according to claim 21 wherein the laser light source comprises a semiconductor laser diode.

34. The optical system according to claim 21 wherein the laser light source includes a laser diode which produces a beam having a first cross-sectional size and shape, and wherein the aperture stop is configured to modify such first shaped beam to have a different size and shape at the reference plane.

35. The optical system according to claim 21 wherein the laser light source includes a laser diode which produces a beam having a non-circular shape in cross-section, and wherein the aperture stop is configured to modify such non-circular shaped beam to have a substantially circular shape of reduced size at the reference plane.

36. The optical system according to claim 21 wherein the beam-passing cross-section of said aperture stop is on the order of about 1 mm to 2 mm.

37. The optical system according to claim 21 wherein the beam-passing cross-sectional area of the aperture stop is approximately 1 square millimeter to 2 square millimeters.

38. The optical system according to claim 37 wherein the aperture stop is about 9.7 mm to about 9.9 mm from the laser light source.

39. The optical system of claim 21 wherein the focusing means defines a numeric aperture of less than 0.05.

40. The optical system of claim 21 wherein the laser beam is substantially uncollimated when it strikes the focusing lens.

41. The optical system of claim 21 wherein the focal distance of the focusing lens is about 9.5 to 9.7 mm.

42. The optical system of claim 21 wherein the aperture stop is about 9.7 mm to about 9.9 mm from the laser light source.

43. The optical system according to claim 21 wherein said cross-section is measured in both parallel and perpendicular directions with respect to said p-n junction.

44. A laser scanning head for reading bar-coded symbols, comprising:

(a) an actuatable laser diode mounted in the head for generating an incident laser beam of relatively low power, the laser diode having a p-n junction as the emitter of the laser beam;

(b) optic means mounted in the head for forming and directing the incident laser beam along a first optical path toward a reference plane located exteriorly of the head and to a symbol located in a working range in the vicinity of the reference plane, the laser beam reflecting off the symbol and returning along a second optical path back towards the head;

the optic means including a focusing lens and an aperture stop both located in the first optical path in the immediate vicinity of the laser light source for forming the incident laser beam to have a beam cross-section of an altered size and shape within the working range, the focusing lens being located between the aperture stop and the laser light source;

the aperture stop defining a shaped opening which in cross-section is smaller than the beam cross-section at the aperture stop to permit a portion of the incident light beam to pass through the aperture stop and to directly determine the beam'"'"'s size and shape within the working range, such cross-section being measured in the direction parallel to said p-n junction;

(c) a scanner mounted in the head for scanning the laser beam across the symbol, the returning portion of the laser light having a variable intensity over the scan;

(d) a sensor mounted in the head for detecting the variable intensity of the returning portion of the laser light, and for generating a sensor signal representative of the detected variable light intensity;

(e) a signal processor mounted in the head for processing the sensor signal and for generating a processed signal indicative of characteristics of the symbol; and

(f) an actuator mounted in the head for actuating the laser light source.

45. A laser scanning head for reading bar-coded symbols, comprising:

(a) an actuatable laser light source of low power mounted in the head for generating an incident laser beam of relatively low power;

(b) optic means mounted in the head for forming and directing the incident laser beam along a first optical path toward a reference plane located exteriorly of the head and to a symbol located in a working range in the vicinity of the reference plane, the laser beam reflecting off the symbol and returning along a second optical path back towards the head;

the optic means including a focusing lens and an aperture stop both located in the first optical path in the immediate vicinity of the laser light source for forming the incident laser beam to have a beam cross-section of an altered size and shape within the working range, the focusing lens being located between the aperture stop and the laser light source;

the aperture stop defining a shaped opening which in cross-section is smaller than the beam cross-section at the aperture stop to permit a portion of the incident light beam to pass through the aperture stop and to directly determine the beam'"'"'s size and shape within the working range;

(c) a scanner mounted in the head for scanning the laser beam across the symbol, the returning portion of the laser light having a variable intensity over the scan;

(d) a sensor mounted in the head for detecting the variable intensity of the returning portion of the laser light, and for generating a sensor signal representative of the detected variable light intensity;

(e) a signal processor mounted in the head for processing the sensor signal and for generating a processed signal indicative of characteristics of the symbol; and

(f) an actuator mounted in the head for actuating the laser light source.

46. The laser scanning head according to claim 45 wherein the laser light source is a laser diode having a p-n junction for emitting the laser light, and wherein the cross-section is measured in the direction perpendicular to said p-n junction.

47. The laser scanning head according to claim 45 wherein the laser light source is a laser diode having a p-n junction for emitting the laser light, and wherein the cross-section is measured in both parallel and perpendicular directions with respect to said p-n junction.

48. An optical system for reading coded symbols, comprising:

(a) means including a solid state laser diode for generating a wide-angle, low power laser beam the laser diode having a p-n junction as the emitter of the laser beam; and

(b) optical means for optically forming and directing the laser beam along an optical path to different light-reflective indicia portions of a coded symbol for reflection therefrom, said optic means including a single focusing lens and an aperture stop located in the optical path in the immediate vicinity of the focusing means lens between the laser light source and the light-reflective indicia portions, for focusing the laser beam to have a beam cross-section of a predetermined size within a working distance range, said aperture stop being located downstream of the lens and having a shaped cross-section which is smaller than the beam cross-section at the aperture stop to permit a part of the beam to pass through the aperture stop en route to the indicia portions, said cross-section of the aperture stop directly determining said pre-determined size of the beam cross-section, said aperture stop being bounded by a blocking wall for obstructing the remaining part of the beam from passing through the aperture stop en route to the indicia portions, such cross-section being measured in the direction parallel to said p-n junction.

49. An optical system for reading coded symbols, comprising:

(a) means including a solid state laser light source for generating a wide-angle, low power laser beam; and

(b) optical means for optically forming and directing the laser beam along an optical path to different light-reflective indicia portions of a coded symbol for reflection therefrom, said optic means including a single focusing lens and an aperture stop located in the optical path in the immediate vicinity of the focusing lens between the laser light source and the light-reflective indicia portions, for focusing the laser beam to have a beam cross-section of a predetermined size within a working distance range, said aperture stop being located downstream of the lens and having a shaped cross-section which is smaller than the beam cross-section at the aperture stop to permit a part of the beam to pass through the aperture stop en route to the indicia portions, said cross-section of the aperture stop directly determining said pre-determined size of the beam cross-section, said aperture stop being bounded by a blocking wall for obstructing the remaining part of the beam from passing through the aperture stop en route to the indicia portions.

50. The optical system according to claim 49 wherein the laser light source is a laser diode having a p-n junction for emitting the laser light, and wherein said cross-section is measured in both parallel and perpendicular directions with respect to said p-n junction.

51. The optical system according to claim 49 wherein the laser light source is a laser diode having a p-n junction for emitting the laser light, and wherein said cross-section is measured in the direction perpendicular to said p-n junction.