摘要:
The present invention refers to a method of operating a self-mixing interference sensor and a corresponding self-mixing interference sensor device. In the method the laser (1) of the device is controlled to periodically emit a laser pulse followed by an emission period of laser radiation having a lower amplitude. The pulse width of the laser pulse is selected such that the pulse after reflection at the object (3) re-enters the laser (1) during the emission period of laser radiation with lower amplitude. The corresponding SMI signal has an increased signal to noise ratio.
摘要:
A security system is described, comprising a sensor module (15) which accommodates a laser sensor (10) working with self-mixing interference. The laser sensor (10) generates measurement data which are related to the velocity of an object such as the body of a human being and, optionally, the distance between the laser sensor (10) and the object. Dependent on the measurement data assembled by the laser sensor (10) and supplied to a control circuit (30) such as an airbag computer, the airbag computer activate security means such as an airbag (35)in order to prevent injuries of the human body. Furthermore, a method of driving such a security system is described.
摘要:
A sensor system is described, using self-mixing laser sensors (10) and an analyzer circuit (30) in order to determine the velocity of a vehicle, such as a car, and the rotational velocity of a wheel (20) of the car. Deviations between the velocity of the vehicle and the rotational velocity of the wheel (20) can be used to determine sliding of the wheel (20) and, finally, the traction or, more specifically, the coefficient of driving friction between the wheel (20) and the surface the car is driving on. Furthermore, a vehicle control system is described, initiating test accelerations of a wheel (20) by means of a control circuit (50) and control means (300, 400) in order to determine the coefficient of driving friction during driving. The test accelerations initiate short periods of sliding of the wheel (20) and the sliding is detected by means of the sensor system.
摘要:
A sensor module (1) for measuring the distance to a target and/or the velocity of the target (50), the sensor module (1) comprising at least one laser source (100), at least one detector (200) being adapted to detect modulated laser light and at least one control element the control element (400) being adapted to vary the focus point of the laser light and/or the intensity of the laser light and/or the direction of the laser light. The control of the laser light emitted by the laser source (100) either by active optical devices as variable focus lenses or controllable attenuators or passive optical elements in combination with arrays of laser sources (100) and detectors (200) enable flexible and robust sensor modules.
摘要:
The present invention relates to an optical element for VEC-SELs or VECSEL arrays. The optical element is formed of a substrate (200) which is transparent at least in a wavelength region of optical radiation. A first interface of the- substrate (200) comprises one or several curved regions forming part of an optical lens or of an array of optical lenses (220) integrated in the substrate (200). The substrate (200) further comprises one or several optical mirrors (210) formed on a second interface of the substrate (200) opposing the first interface or embedded in the substrate (200). The optical mirrors (210) are arranged and designed to back reflect a fraction of optical radiation incident on the first or second interface. The optical mirrors (210) are flat mirrors or curved mirrors having a radius of curvature different from the radius of curvature of the curved region (220). The optical element allows the fabrication of a VECSEL or VECSEL array having a high brightness without the requirement of additional adjustments during fabrication. The VECSEL are arranged at a distance (L) to the optical mirrors (210) and this equals the length of the external cavity. The ROC of the optical lens may be chosen to ROC=L/2 and for the optical mirror ROC>L. The cavity length may be adjusted by a monolithic spacer (120)
摘要:
The present invention relates to a switchable dual wavelength solid state laser with a solid state gain medium (1) which is selected to emit optical radiation at a first wavelength with a first polarization and of at least a second wavelength with a second polarization different from said first polarization when optically or electrically pumped. A polarizing device (7) is arranged within the laser cavity, said polarizing device (7) being adjustable at least between said first and said second polarization. The two end mirrors (2, 3) of the laser cavity are designed to allow lasing of the solid state laser at the first wavelength when the polarizing device (7) is adjusted to the first polarization, and to allow lasing of the solid state laser at the second wavelength when the polarizing device (7) is adjusted to the second polarization. The proposed solid state laser allows an easy switching between two emission wavelengths.
摘要:
An optical sensor (600) for detecting the movement of an object relative to the position of the optical sensor (600), using self-mixing interference, is described. The optical sensor (600) comprises a laser (100), a detector (200) and a filter device (500). The filter device (500) suppresses measurement signals generated by means of the detector (200) when movements of the object at a velocity below a defined threshold value cause the measurement signals. The optical sensor (600) may be used in a switch in order to enable selective switching depending on the velocity of the movement of the object.
摘要:
The present invention relates to a method of manufacturing the light emitting component of a VECSEL and the corresponding VECSEL. In the method a layer stack (2) is epitaxially grown on a semiconductor substrate (1). The layer stack comprises an active region (4), an upper distributed Bragg reflector (5) and a n- or p-doped current injection layer (13) arranged between the active region (4) and the semiconductor substrate (1). A mechanical support (6) or submount is bonded to an upper side of the layer stack (2) and the semiconductor substrate (1) is subsequently removed. A metallization layer (7) is optionally deposited on the lower side of the layer stack (2) and an optically transparent substrate (8) is bonded to this lower side. The proposed method allows the manufacturing of such a component in a standard manner and results in a VECSEL with a homogenous current injection and high efficiency of heat dissipation.
摘要:
The present invention is directed to a laser resonator emitting visible radiation with reduced speckle noise, wherein said optical resonator is formed by at least two mirrors at both ends of a visible radiation emitting lasing material, wherein that optical resonator enhances multimode operation, so that said visible radiation emitting lasing material emits a spectrally broadened visible radiation, wherein the enveloping function of said spectrally broadened visible radiation has a full width at half maximum (FWHW) within 1 nm to 15 nm.
摘要:
A method and a circuit arrangement for operating a discharge lamp, in particular during the first hours of operation after lamp manufacture, are described. The method and the circuit arrangement are provided in particular for high-pressure gas discharge lamps (HID or high intensity discharge lamps or UHP or ultra high performance lamps). Furthermore, a lighting unit with a discharge lamp and such a circuit arrangement and a projection system with a projection display and such a lighting unit are described. Switching-over between various modes of operation with different operating frequencies serves to avoid that the burning voltage of the lamp drops into a region of a minimum voltage of a lamp driver unit below which the latter can no longer drive the lamp with its rated power or a desired power.