Abstract:
The invention relates to a procedure for determining an identification of a sample of material, or its properties. Electromagnetic radiation from a radiation source (1) is reflected or transmitted through the sample. The radiation from the sample is collected and analyzed over several channels (7, 7', 7"), which modulate the radiation with a spectral transmission function which is unique for each channel. The modulated radiation is transmitted to one or several detectors (9, 9', 9") which produce output signals which are further electronically processed. The spectral range of each of the individual channels is common to all of the channels. Within the common range the channels are provided with different spectral transmission functions (7, 7',7") which are optimally chosen for a given application.
Abstract:
The polarization interferometer comprises a source of light (1), a collimator (2), a first polarizing means (3), a double-refractive means (4,5,6) and a second polarizing means (7) which polarizes the light emerging from the double-refractive means (4,5,6) and directs it to a photon detector (8). The double-refractive means (4,5,6) consists of two optical wedges (5,6) displaceable along those lateral surfaces which face each other, said wedges complementing each other to a right parallelepiped, and of a double-refractive, plane-parallel plate (4) serving as a compensator. The optical axis of the compensator (4) is twisted in a plane perpendicular to the light beam by a finite angle relative to that of the two wedges (5,6), the optical axes of the two wedges (5,6) coinciding with each other. The optical axes of the two polarizing means (3,7) are arranged perpendicularly or parallely to each other and are aligned non-parallely to the axes of the two wedges (5,6) of the double-refractive means (4,5,6).
Abstract:
In a photoelectric smoke detector, a radiation source is driven intermittently by a control circuit and the radiation influenced by smoke particles, for instance scattered radiation, is picked up by a radiation receiver. The signal of the radiation receiver is transmitted to a signal processing circuit which is transmitted to a signal processing circuit which is simultaneously regulated by the control circuit. The signal processing circuit comprises a phase sensitive circuit which reverses or inverts the received signal according to the phase of the signal of the control circuit and transmits the thus modified signal to an integrating circuit. The integrating circuit controls a display circuit by means of its integrated output signal. The display circuit can, for instance, output an alarm signal when the integrated signal, i.e. the smoke intensity, exceeds a prescribed threshold value or can display the smoke intensity. In this manner, even weak smoke signals can be surely and reliably detected even when they are fully masked by noise. Such a smoke detector can be advantageously employed as an especially sensitive and interference-resistant fire alarm.
Abstract:
In a line extinction detector using a pulse-operated radiation source, a radiation receiver is connected to an input amplifier of an evaluation circuit. The output pulses generated by the input amplifier are compared to a reference voltage. Circuit elements having a time constant above one minute are provided to adjust either one of the voltage of the output pulses or the reference voltage such that their difference practically becomes zero. The output pulses of the input amplifier are further compared to an alarm threshold derived from the reference voltage and an alarm is triggered when the output signal falls below the alarm threshold value. The output pulses of the input amplifier are also compared to a disturbance threshold value and a disturbance signal is generated when the output signal drops below the disturbance threshold value. A further disturbance signal value is also triggered at preset limits for the compensating adjustment between the output signal of the input amplifier and the reference voltage. A device permits to change the ratio of the alarm threshold value and the reference voltage in order to adapt the sensitivity of the smoke detector to different distances between the radiation source and the radiation receiver.
Abstract:
A smoke detector contains two radiation transmitters and two radiation receivers. Each of the radiation transmitters emits in a different spectral region, for instance, one emits above and the other one below 600 nm. One part of the radiation of both radiation transmitters is conducted via a measuring path, which is accessible to smoke, to one of the receivers constituting a measuring radiation receiver, and another part of such radiation is conducted via a comparison path, which is not accessible to smoke, to the other of the receivers constituting a comparison radiation receiver. Connected to both radiation receivers is an evaluation circuit which forms from the measuring radiation intensities prevailing in the two spectral regions and from the comparison radiation intensities prevailing in the same spectral regions a function of the type: ##EQU1## By suitably adjusting or selecting the components of the evaluation circuit, the coefficients a and b are selected such that in the absence of smoke in the measuring path, A becomes zero and in the presence of smoke such is proportional to the smoke density.