HU186197B - Equipment for calibration of light-sensor - Google Patents

Abstract

The apparatus of the present invention for calibrating a light sensor is a monochromatic light source, its light beam on a first light reference light sensor, a light detector for transmitting light to a light sensor to be calibrated on a second light, a further light sensor reflecting light reflected from the light sensor to be calibrated, and a quotient comprising a quotient connected to the light sensor. According to the invention, the apparatus has an optical box in which a light trap is illuminated by a monochromatic light beam through a polarization filter, and mechanical couplings are provided on the optical box in the direction of the first and second light paths and for measuring heads incorporating a light sensor in a direction opposite the second light path. . The mechanical connectors are designed to be interchangeable for the interchangeability of the measuring heads. 5 feet -1-

Description

(57) EXTRAS

The apparatus of the invention for calibrating a light sensor has a monochromatic light source, a light coupler for transmitting light beam to a reference light sensor at a first light path, an additional light sensor for detecting reflected light from the light sensor to be calibrated, and a light sensor coupled to said light sensor. According to the invention, the apparatus has an optical box having a light coupler illuminated by a monochromatic beam through a polarization filter, mechanical connectors are provided on the optical box in the direction of the first and second light paths and in the opposite direction of the second light path. The mechanical connectors have the same design for exchanging the probes.

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186,197

The present invention relates to an apparatus for calibrating a light sensor, in particular a photocell, in order to provide a radiometric standard.

Until now, black body emitters, electrically substituted thermal radiometers and lamp light sources have been used as radiometric standards. These devices are very complicated, expensive, difficult to obtain, difficult to use and require special equipment and training. The device according to the invention is much simpler compared to the known prior art standards, and its application is possible not only in large national laboratories, but also in factory workshops. The device of the present invention provides a new radiometric standard based on a semiconductor light sensor. The radiometric standard so created compares with the aforementioned conventional radiometric standards and the measurement error of the standard produced by the apparatus is the same as that of the known primary radiometric standards. However, the cost of the equipment is a fraction of the cost of said known equipment. One of the great advantages of the radiometric standard created according to the invention over known radiometric standards is that its sensitivity is several orders of magnitude higher.

A solution for calibrating light sensors is known, where the light source and the output light intensity of the light source are stabilized by means of a control loop. In this case, the light emitted from the light source is split by a dimmer and the coupled light is controlled through a control loop so that the polarization angle of the voltage-dependent light polarizer placed in the output light path of the laser light is changed until the intensity of the emitted light remains constant. Such a solution is described in Technical Note No. 987 of the US National Bureau of Standards. (Servo Controlled Electro-Optic Modulator Forum cw Laser Power Stabilization and Control.) This solution is used in "Silicon photodiode absolute spectral response self-calibration", Applied Optics Vol. Also in their article published in 1980 in the journal 1214. The disadvantage of this solution is that it can only be applied to laser light sources, so that calibration can only be performed at specific wavelengths, and it is very expensive and complicated. A further disadvantage of this solution is that the optical system built up contains a large number of discrete optical elements which are assembled on a general-purpose optical table. The disadvantage of such an assembly is that it is very difficult to assemble or calibrate the apparatus during each calibration. which makes the measurement slow, cumbersome and very expensive.

An advantage of the device according to the invention is that not only a laser light source, but also a monochromator and a conventional light source adapted thereto can be used, thus providing an optical arrangement for light sensor calibration in a compact form, which has the advantage of maintaining the system before and after calibration. Both the light sensor to be calibrated and the reference light2 sensor can be detachably connected to this compact optical unit with high-sensitivity probes.

High sensitivity is also required so that not only a high intensity laser light source can be used as a monochromatic illumination source, but also a conventional light source combined with a monochromator. In this way, calibration can be performed at any wavelength. The advantage of the compact optical unit is that it is easy, easy to move and transport, and allows light sensors mounted on probes to be calibrated simply, quickly and reliably. A large number of light sensors can be calibrated with the aid of an optical unit and the associated electronic unit, also in a compact form. Thus, the present invention provides not only a one-off, rare-time calibration capability, but also the ability to standardize and calibrate the light sensor between operational requirements.

It is also an advantage of the invention that the light sensors can be used in the same probes after calibration, in which they were placed during calibration. Calibration eliminates the need to modify the probe design.

In fact, during calibration, measurements are made to determine the relative losses of the light sensor. During these measurements, we measure the quantum efficiency of the light sensor from the unit and also measure to what extent the optical sensitivity of the light sensor is reduced due to the reflection of the light sensor surface. Thus, when measuring the relative losses, we first make a reflection reflection, and then make measurements to determine the decrease in the quantum efficiency of the semiconductor light sensor. For this purpose, the light sensor, e.g. the light element, various so-called. undergoes biasing measurements, the effect of which is that the voltage applied to the photocell eliminates recombination losses in the photocell and the quantum efficiency of the photodetector device becomes unit. If this measurement is repeated by disconnecting the biasing voltage from the device, the recombination losses will reappear and the quantum efficiency of the device will drop below the unit value. Thus, when performing relative loss measurements that explain how the device's quantum efficiency has declined, we make relative measurements when the device is first measured without preload and then preloaded. Then we divide the two values. With the device according to the invention, prestressing measurements can be carried out very simply and reliably by attaching the light sensor to the probe by means of a self-calibrating adapter. This attachment allows you to connect the light sensor connectors or the required prestressing voltage can be applied to its surface. All relative loss measurements are made with a two-light design, with both the light sensor to be calibrated and the reference light sensor each being a thermostatically

186 ί 97 is plugged into a moderately controlled probe and both probes have a high resolution and high precision quotient counter for simultaneous division. is connected to the signal input. The advantage of using a simultaneous divisor quotient is that changes in the intensity of the light source, since they are present in both light paths to the same extent, do not interfere with the measurement result due to the quotient formation.

With the apparatus of the invention, the aforementioned relative loss measurements can be made with a resolution of 10,000 points, thus ensuring a very high calibration accuracy. After the relative loss measurements, there is only one simple calculation left, whereby from our measurement results the wavelength dependence of the light sensor to be calibrated depends on the absolute light sensitivity, or. light-electric transmission can be determined in Amper / Watt.

The invention thus provides an apparatus for calibrating a light sensor having a monochromatic light source, a light coupler transmitting its beam at a first light path to a reference light sensor, a second light path to a light sensor to be calibrated, an additional light sensor detecting reflected light from the light sensor to be calibrated. The apparatus according to the invention is characterized in that it has an optical box having a light coupler illuminated by a monochromatic beam through a polarization filter, the optical box having mechanical connectors for measuring heads comprising light sensors in the direction of the first and second light paths. formed.

Preferably, the mechanical connectors are uniform in design for the interchangeability of the probes. Preferably, the light sensor to be calibrated is attached to a mechanical connector in the direction of the second light path to reflect the loss of reflection.

Preferably, the light sensor to be calibrated is inserted into the first probe by inserting an electrical prestressing device for the light sensor to be calibrated, which is electrically connected to both the first probe and the self-calibrating electrical unit.

Another advantage is that the first probe is thermostated and the attachment is connected to a surface with good heat conductivity.

It is also an advantage that the attachment has an electrically shielded cavity for receiving electrical connections.

Preferably, the self-calibrating attachment is provided with a heat insulating sleeve. It is also advantageous that the self-calibrating attachment is provided with a prestressing voltage electrode to the surface of the light sensor to be calibrated.

Usability and acceleration of the calibration measurement are facilitated by the fact that the self-calibrating electrical unit has a switching system for supplying bias voltage to the light sensor to be calibrated and a zero compensation signal, and that the self-calibrating electrical unit includes a potentiometer for setting the zero compensation signal. Preferably, the reference light sensor thermostat is located in a second probe.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described with reference to the embodiments illustrated in the drawings, in which: Figure 1 is an optical diagram of an exemplary embodiment of the apparatus of the invention;

Fig. 2 is a mechanical connection of an exemplary attachment of the apparatus according to the invention, a

Figure 3 is an exemplary embodiment of the apparatus of the invention, a

Fig. 4 is an exemplary reflection cap of the apparatus of the present invention

Fig. 5 shows a circuit diagram of an exemplary attachment and self-calibrating electrical unit of the apparatus of the invention,

6 is a block diagram of an exemplary embodiment of the apparatus of the invention.

In Figure 1, the light 60 of a conventional light source is transmitted through a slit 12 through a polarization filter 8 in the optical box 14 via a collimator mirror 13 located on a monochromator 11 to the incoming light via the light coupler 10 in the reference light sensor 26. , respectively. the coupled light is imaged on a light sensor 1 to be calibrated, or after a reflection on a standard mirror 2, which can be fitted to the lower mechanical connector of the optical box 14, on a further light sensor 5 located in the first probe.

The reflection accessory 7 and the light sensor 1 to be calibrated in the first probe 5 are alternatively and removably connected to the optical box 14. There are two ways to measure mirror reflection. In the first case, the light sensor 1 to be calibrated is measured relative to the reference mirror 2. In the second case, without the reference mirror, the optical box 14 and the second and third optical boxes 3 are respectively. Measure the mirror reflection loss using the first 5 probes. In both cases, the light sensor to be calibrated is secured to the lower mechanical connector of the optical box 14 by means of a reflection accessory 7. In all cases, the reflected light from the surface to be measured is forced through the light deflector plate 10. When the reflection of the mirror 2 is measured relative to the reference mirror 2, further reflection caused by the light coupler 10 also occurs in the standard and comparative measurement, so that the reflection error caused by the light coupler 10 is eliminated by comparison. However, in the second case, when no reference mirror is used, the reflection of the light emitter 10 causes an error when measuring the light reflected from the surface to be measured. This error can be determined by the following two additional measurements. First, the first probe 5, together with the additional light sensor 4 attached thereto, is secured to the lower mechanical connector of the optical box 14, while the second probe 3, with the reference light sensor 26 inserted therein, is secured to the lateral mechanical connector 3 the ratio of the output signals of the second probes. Subsequently, the first and second probes 5 are exchanged and the ratio of their output signals is measured again, without changing the electrical connections. The last two m3

From the results of the 186 slit, we can calculate the reflection of the reflector 10. Knowing this, the reflection loss of the light sensor 1 to be calibrated can also be calculated.

During the prestressing measurements, the first probe 5 with self-calibrating attachment 6 is placed in place of the reflection accessory 7. The self-calibrating electrical unit 15 in the optical box 14 is also used to perform the prestressing measurements.

Figure 2 shows a mechanical connection of an exemplary embodiment of the attachment 6 to the first probe 5. The light sensor 1 to be calibrated is connected to the mount 6 by means of the socket 21. The upper part 27 and the lower part 28 of the attachment 6 surround the cavity 23 in which the electronic components necessary for the prestressing measurement are located. In the lower part 28 there are further 2 connecting plugs 22 which allow detachable attachment of the attachment 6 to the first probe 5. The attachment 6 is also thermostated, since the temperature of the inner metal housing 61 of the first probe 5 is taken over by the attachment by means of a heat transfer plate 18. The attachment 6 can be secured to the inner metal housing 61 of the first probe 5 by means of a clamping screw 20. Attachment 6 allows for a drop of water to be placed on the surface of the light sensor to be calibrated during prestressing measurements and to prestress the coating layer of the light sensor 1 to be calibrated using the metal wire 24 using this water drop. Also, the condition makes it possible for the light sensor to be calibrated to be tensioned in the opposite direction during the other biasing measurement, i.e. the reverse biasing of the light sensor, without having to reach into the first probe 5 without making any structural changes.

The first probe 5 with its attachment can be connected to the optical box 14 by means of the probe guide pin 17. This connection is effected by means of the ring 16 of the optical box and the ring 19 of the probe. During the light sensor calibration measurements, the heat sealing casing 25 enclosing the insert ensures that the temperature stabilized die 6 does not release more heat than required and thus maintains a constant temperature during the calibration.

FIG. 3 is a schematic drawing of an exemplary embodiment of the apparatus 6 of the present invention. The symbols in the figure are the same as in the figure 2. The light sensor to be calibrated 1 is plugged into the socket 21 with its feet 30. To measure the oxide preloader, for example by placing a distilled water droplet on the light sensor surface to prestress the oxide layer, the light sensor cover to be calibrated 1 is removed and the distilled water dropper is placed on the light sensor surface so that it does not hang into the anode ring. attached to the 38 buckets, dripping into the distilled water droplet. The metal wire 24 can only hang in the distilled water droplet to such an extent that it does not obscure any light from the surface of the light sensor. In this case, the prestressing voltage is applied by the metal wire 24 to the surface of the light sensor by means of a distilled water droplet. For this reason, it was essential that the attachments 6 be placed horizontally. For the sake of simplicity, the first probe 5 containing the light sensor 1 to be calibrated is held in a horizontal position during each measurement. The inlets of the electrical components housed in the cavity 23 of the attachment 6 are guided through the hole series 29 and the connector 39 to the self-calibrating electrical unit 15 in the optical box 14. The breakability of the connector 39 greatly simplifies the conduct of the measurements, since the cradle 6 can be detached from the probe very quickly and can be detached from the optical box 14.

Figure 4 is a schematic drawing of an exemplary reflection cap of the apparatus of the invention. As the light sensor to be calibrated is to be calibrated and the reference mirror to be calibrated, it is advisable to make 2 of these reflectors and fix the light sensor to be calibrated and the reference mirror fixed. The figure shows the attachment of the light sensor 1 to be calibrated, which is released from its cover and secured by the light sensor base 31 by means of the clamping ring 35. The adjustable cylinder 36 can be adjusted with the adjusting bolts 34 relative to the disk 32 using the ball 37 as a bearing. The guide pins 33 allow for positioning in the optical box 14.

Fig. 5 shows a switching arrangement of the self-calibrating electrical unit 15 of the attachment 6 and the optical box 14. The electrically shielded attachment 6 is provided by being directly connected to the first probe 5 by means of a metallic contact. A protective diode 50, 51 is located in the cavity 23 of the cap 6, which protects the operational amplifier input 47 against overvoltage. This is required for prestressing measurements. Also located in cavity 23 is the resistor 48, which serves to reset the output voltage of the operational amplifier 47 by means of the reset potentiometer 49 during biasing measurements. The reset potentiometer 49, together with the biasing mode switching system 41, is located in the self-calibrating electrical unit 15 in the optical box 14. The switching system 41 has three positions that can be selected with the 41A button. In the first position 42, an oxide biasing measurement is made, in the second position the biasing voltages are disconnected from the light sensor, and in the third position 44, the light sensor is reversed biasing. An external power supply unit 45 and 46 can be connected to the self-calibrating electrical unit 15. The two power supplies are floating, ie unearthed. The common point of the power supply unit receives the ground potential from the grounded, non-inverting input point of the operational amplifier 47 in the first probe 5 via the shield 6 and the shield cable connecting the shunt 6 to the self-calibrating electrical unit 15. By placing the attachment 6 directly on the first probe 5, it is possible not to reduce the photo-sensitivity of the first probe 5 during calibration, i.e., the very high sensitivity of the photo-probe provided by the probes can be fully utilized during light sensor calibration. This solution made it possible to minimize the length of the wires measuring very small luminous fluxes

186 197 and the aforementioned shading! By designing the system, the interference from external electrical signals has also been completely eliminated. The very advantage of the attachment 6 and the self-calibrating electrical unit 15 in the present invention is that it does not require any special central electronic unit configuration. i

For all light sensor calibration measurements, it is possible to use a standard dual channel radiometer quadrant central electronic unit. This also has the advantage that the apparatus for calibrating the light sensor without the optical box 14 is capable of a wide variety of photometric and radiometric applications using the same probes as used for calibrating the light sensor. By applying different optical conditions to the first 5 probes, we can measure different amounts of photo and radiometry with high accuracy and high resolution. The symbols in Figure 5 are otherwise identical to those used in Figures 1, 2 and 3. The resistor 52 forms a voltage divider with the reset potentiometer 49, and the resistor 53 is connected in series with the droplet electrode and serves protection purposes.

FIG. 6 is a block diagram of an exemplary embodiment of the apparatus of the invention. 58 light traps were placed in front of the monochromator 11. This light shutter 58 is preferably remotely controlled from the electronic measuring unit 59. Alternatively, the light shutter 58 is preceded by an array of beam 56 extending the beam 54 of the laser and an assembly of conventional light sources 55 and 57 optical units. Preferably, the transmission of the wavelength of the monochromator 11 can be remotely controlled from the electronic measuring unit 59. In an advantageous embodiment, the external power supply unit 45, 46 can also be remote controlled from the electronic measuring unit 59. In the case of light sensor calibration, the first probe 5 is first placed in the upper position shown in the figure, that is, as shown in the figure, secured to the upper mechanical connector of the optical box 14. The first probe 5 is then fitted with any light sensor, preferably a light element, not the light sensor to be calibrated. A standard mirror 2 is then mounted on the lower mechanical connector of the optical box 14, mounted on the reflection accessory 7. Subsequently, with the help of the electronic measuring unit 59 containing the quotient, the reflection is measured step by step at each wavelength. Thereafter, the light sensor 1 to be calibrated is mounted on the reflection accessory 7 or a second reflection accessory containing the light sensor to be calibrated is taken and the previous measurement is carried out with its attachment. During the measurement, a second probe 3 comprising a reference light sensor 26 is connected to the denominator input of the electronic measuring unit 59. If the mirror reflection loss of the light sensor 1 to be calibrated is not measured relative to the reference mirror 2, the reflection factor of the light emitter 10 is determined by the two additional measurements described above. In this case, the two probes are mounted on the lower and lateral mechanical connectors of the optical box 14, and in both mounting versions of the probes, a quadratic measurement is performed such that the second probe 3 is always connected to the denominator of the quotient. Next, attach the attachment 6 to the first probe 5 and insert the light sensor to be calibrated into the attachment 6 and screw the resulting calibration assembly onto the lower mechanical connector of the optical box 14. The measuring line of the first probe 5, i.e. the probe output, is still connected to the signal input of the counter 59 of the electronic measuring unit. In the subsequent measurements, the self-calibrating electrical unit 15 will also be used. As a first step, the button 41A is moved to the third position 44, i.e. the reverse bias position. In the first phase of this measurement, the shutter 58 is set to a dark position. In this position, the zero potentiometer 49 is used for zero compensation, in which case the light sensor 1 to be calibrated as shown in FIG. The next step in the measurement is opening the shutter 58 and measuring with the electronic measuring unit 59 at all wavelengths without biasing, by pressing the button 41A in the middle position 43, i.e. without prestressing, and again measuring the electronic measuring unit 59 at each wavelength. button 44 is moved to the third position, which is the reverse bias position.

The next measurement is the oxide bias measurement, in which case the liquid droplet, preferably a distilled water droplet, is placed on the light sensor to be calibrated and the metal wire 24 is contacted with the distilled water droplet. The AT button 41 is moved to the first position 42, which is the oxide biasing position. The light shutter 58 is then darkened and reset with the reset potentiometer 49. Then, similarly to the previous measurement, the two-path device is measured again by reading the numerical display of the electronic measuring unit 59 at all wavelengths without biasing, and thereafter at each wavelength with biasing. The non-pretensioned position is again the second position of the button 41 A, while the pretensioned position is 4! The first 42 positions of the button correspond to. At the end of this measurement, the drop of liquid applied to the light sensor 1 to be calibrated, e.g. distilled water droplet is removed. Following the measurement, a brief calculation is performed, the first step of which is to determine the quantum efficiency components, which, together with their reflection, can calculate the absolute spectral sensitivity of the light sensor to be calibrated at all measured wavelengths in A / W.

At the lower mechanical connector of the optical box 14, the incident light power was determined at each wavelength. The light sensor to be calibrated is then placed on the lower mechanical connector of the optical box 14 to determine its output signal / incident power sensitivity per wavelength.

Claims (11)

Patent claims 1 Apparatus for calibrating a light sensor having a monochromatic light source having a beam at first light path to a reference light sensor, other5 186,197 th light path for transmitting the calibrated light sensor fénykicsatolója, reflected light detector to be calibrated light sensor further light sensor, and the measuring range comprising hányadosmérőt connected to the light detectors is characterized in ⁵ that the optical box (14), wherein the polarization of the monochromatic light beam filter (8) a light coupling (10) illuminated through said optical box (14) is provided with mechanical connectors for probes incorporating a light sensor in the direction of the first and second light paths and in the opposite direction of the second light path. Apparatus according to claim 1, characterized in that the mechanical connectors are uniform in design for the interchangeability of the probes. Apparatus according to claim 1 or 2, characterized in that the light sensor (1) to be calibrated is attached to a mechanical connector 29 in the direction of the second light path by means of a reflection accessory (7). 4. Apparatus according to any one of claims 1 to 4, characterized in that the light sensor (1) to be calibrated is inserted in the first probe (5) by inserting a prestress (6) for electrically prestressing the light sensor (1) to be calibrated. 5) on the other hand, it is electrically connected to a self-calibrating electrical unit (15). Apparatus according to claim 4, characterized in that the first probe (5) is thermostated and connected to it by a surface (6) which provides good thermal conductivity. Apparatus according to claim 4 or 5, characterized in that the attachment (6) has an electrically shielded cavity (23) receiving the electrical connections. 7. Apparatus according to any one of claims 1 to 3, characterized in that the top (6) is provided with a heat-insulating sleeve (25). 8. Apparatus according to any one of claims 1 to 4, characterized in that the attachment (6) is provided with a metal wire (24) which prestresses the surface of the light sensor (1) to be calibrated. Apparatus according to claim 4, characterized in that the self-calibrating electrical unit (15) has a switching system (41) for supplying a bias voltage and a zero compensation signal to the light sensor (1) to be calibrated, Apparatus according to claim 9, characterized in that the self-calibrating electrical unit (15) comprises a potentiometer (49) for adjusting the zero compensation signal. 11. Apparatus according to any one of claims 1 to 4, characterized in that the reference light sensor (26) is located in a thermostated second probe (3). 6 pieces of figure Published by the National Office of Inventions Λ for publication Telel: Zoltán Himer, Head of Department Published by Technical Publisher Collected by the Printing Light Factory (868720/09) COPV LUX Printing and Duplication Cooperative