Abstract: A light-extinction-type optical particle detection system comprises a laser producing a beam in response to a drive current amplitude reaching a lasing threshold, a view volume, and a light-extinction detector. The beam is characterized by mode-hopping noise energy produced by spurious switching of laser operating modes. The system comprises a signal generator producing the drive current such that its amplitude transitions across the threshold by a selected amount and at a selected frequency to cause the beam to operate simultaneously in multiple modes. The selected amount and frequency cooperate to spread the mode-hopping noise energy over a spectral range established by the number of modes, such that the detector does not appreciably respond to the mode-hopping noise energy.

Abstract: A self-contained laser module assembly has a diode laser and driver circuit enclosed with a cylindrical metal housing which forms a first electrical contact for inputting a DC voltage to power the circuit and laser. The housing has a first end which includes a lens positioned to emit a collimated laser beam along an axis of the housing and a second end including a second external electrical contact positioned to contact the power supply. One application of the module is in a pen-like pointer. The pointer includes conductive cap and body portions which are threaded together to house a laser module and a battery in end-to-end relationship. An O-ring between the battery and the body or module is axially compressed by tightening the cap on the body to enable turning on the pointer. The cap has a pocket clip through which electrical contact is selectably made between the body and a side contact on the module to cause a beam to be emitted.

Abstract: A method and apparatus are provided for mounting a laser diode in an existing TO-5 structure within a cylindrical heat sink so that the laser beam can be focused, aimed and collimated in a mechanically repeatable manner in about 45 seconds. The basis for so doing lies in the use of an alignment apparatus to align the beam of a laser diode within its TO-5 heat sink structure with a lens that has been placed within a second heat sink, and thereby to form an aimed laser optic system (ALOS). The apparatus is constructed using processes that leave several compressive forces acting within itself, whereby the structure is constrained to adopt configurations that are essentially identical upon each installation of a laser diode. An interference fit of the TO-5 heat sink flange against the second heat sink provides an additional degree of heat sinking, thereby permitting the diode to be operated at temperatures of up to 130 deg. F. without damage.