Portable light source device for luminometer calibration

Abstract

The present application relates to a portable light source device for luminometer calibration.

Description

[0001] P24-248

[0002] - 1 -

[0003] PORTABLE LIGHT SOURCE DEVICE FOR LUMINOMETER CALIBRATION

[0004] Technical Field

[0005] 5

[0006] The present application relates to a portable light source device for luminometer calibration.

[0007] Background

[0008] 10

[0009] Luminometers are used in many fields to control the presence of microbial contamination by detection of adenosine triphosphate (ATP) through bioluminescence. ATP detection with luminometers can provide results within a few seconds. The bioluminescence results from a reaction between ATP and an enzyme complex (luciferin / luciferase), generally contained within a sampling device, which may also serve the purpose of taking samples from an area, such as a working surface.

[0010] The light generated through the bioluminescence is measured by a photosensor SIPM (silicon photomultiplier) or PMT (photomultiplier) of the luminometer, and photons collected are converted into results, which are then displayed on a system interface according to a calibration factor.

[0011] In order to ensure that the system displays consistent and accurate results according to the quantity of photons collected from a bioluminescence reaction, the system needs

[0012] 25 regular verification and adjustment (calibration). This verification / adjustment of ATP measuring consists of using a calibrated light source with a known light output intensity (converted into luminometer scale) to ensure that the luminometer reports results with the expected relative light unit scale.

[0013] The challenge for such calibration source is the ultralow light intensity that needs to be reached (< 1 pW) requiring specific technics and / or methods to reach a low enough light output in a controlled and reproducible manner.

[0014] The calibration of a luminometer can be performed essentially in three different ways:

[0015] 35 (1) By chemical calibration requiring solutions of very accurately known concentration, which is difficult to achieve due to the accurate concentration for a reliable P24-248

[0016] - 2 - reference being highly dependent on environmental and human factors during solution preparation;

[0017] (2) calibration based on Carbon-14 using a scintillator to convert the emitted betaradiation into photons; or

[0018] 5 (3) using a light source, mainly based on LEDs (light emitting diodes), using different means to decrease the light output to reach the low light level required:

[0019] (3a) Driving the LED with an ultralow current (few nA / pA);

[0020] (3b) using a pinhole, optionally in combination with an optical filter or diffuser to guide the light to the emitting area; and / or

[0021] 10 (3c) using neutral density filters.

[0022] While these technics provide a reasonably good control of the low light level required, a user cannot change these parameters to get different light output levels as they are built into the characteristics of the respective process / device.

[0023] JP 2009 / 287976 A2 discloses a light source device for sensitivity calibration emitting light from a semiconductor light emitting element (for example, an LED or LD) placed in a case / housing, and guiding the light through an outer end surface of a light guide and then into a hemi-spherical light transmission cover. In the light transmission cover, an effective section of the light guide has a plurality of light emitting sections in the direction of the central axis. In consideration of the material and length of the light transmission cover, by changing the position of each of light emitting sections during designing, a vertically long light is generated uniformly from the light transmission cover in the direction of the central axis. The light emission in this device, however, cannot be changed by a user.

[0024] 25

[0025] US 2021 / 0231573 Al discloses a calibration device for an optical detector comprising a light emitting diode, and an electronic circuit for driving the light emitting diode, wherein the electronic circuit is a constant current generator configured to supply a constant driving current to the light emitting diode in the reange of 0.5 to 25 pA.

[0026] K. Marks et al., "A Portable Silicon Photodiode Luminometer", Journal of Bioluminescence and Chemiluminescence, Vol. 1, 173-179 (1987) discloses a simple, inexpensive, battery- powered, portable luminometer based on a silicon photodiode.

[0027] 35 Several further reference light sources have been proposed but each has a preset light output defined by its architecture that cannot be adjusted by the user if he / she needs to P24-248

[0028] - 3 - use a calibrator with a luminometer having a different setpoint or needs to have several light intensities for his / her application.

[0029] The ability to adjust to several light intensities could be used for multi-points calibration

[0030] 5 (to allow linearity for low and high end of the desired measurement ranges) or to use the same light reference device for calibrating different systems or applications.

[0031] 10 Summary

[0032] The present application aims at providing a portable light source device for luminometer calibration that solves at least some of the problems associated with existing solutions and that can in particular expand the possibilities of adjusting the light output by a user.

[0033] To solve the problem, the present application provides a portable light source device for luminometer calibration as defined by claim 1. Preferred embodiments of the portable light source device are defined in the dependent claims.

[0034] The present application in particular provides a portable light source device for luminometer calibration, comprising

[0035] (i) a light source element, in particular an LED, for emitting light in a defined wavelength spectrum;

[0036] (ii) a driver circuit for driving the light source element;

[0037] 25 (iii) a light attenuator comprising a neutral density (ND) filter and / or a pinhole element comprising a pinhole of well-defined diameter arranged downstream, in a light path, of the light source element, wherein the light attenuator is arranged so as to be exchangeable by a user against another light attenuator with a neutral density filter of different predetermined optical density or a pinhole element comprising a pinhole of a different well-defined diameter (for multiple points calibration or calibration of systems using different setpoints).

[0038] The present portable light source device for luminometer calibration provides a possibility for the user to adapt the device, in a simple manner, for multiple points calibration or

[0039] 35 calibration of systems using different setpoints by designing the light attenuator so as to be exchangeable by the user against another light attenuator with a neutral density filter of different predetermined optical density or a pinhole element comprising a pinhole of a P24-248

[0040] - 4 - well-defined diameter. It is noted that the exchange of light attenuator may also include a change in the type of light attenuator, e.g. a neutral density filter may be exchanged with a pinhole element and vice-versa. Alternatively, a light attenuator of a single type of attenuator may be exchanged with a combination of types of light attenuator, e.g. a

[0041] 5 neutral density filter may be exchanged with a combination of neutral density filter and pinhole element or with a combination of neutral density filters or with a combination of pinhole elements.

[0042] Whereas the present portable light source device may make use of a driver circuit for

[0043] 10 driving the light source element (which may comprise an LED with emission of light having a preferred wavelength in the range from 510 to 570 nm) that is configured to supply a current to set the luminous intensity of the light emission of the light source element to a value of at most 1 pW (< 1 pW), to produce a stabilized ultralow light output, it additionally allows the user to adjust the light output to known values that are not fixedly preset on the system electronics by allowing the user himself / herself to change the light attenuation element(s) to decrease (or - depending on the situation - increase) the light output in defined steps.

[0044] Preferably, the driver circuit for driving the light source element is configured to supply the current in two or more user-selectable level settings, to set the luminous intensity of the light emission of the light source element to plural values along a curve plotting light output versus injection current of the particular light source element used. This aspect multiplies the setting options for the light output by combining electronic settings with the possibility of exchanging the light attenuator.

[0045] 25

[0046] The portable light source device may further comprise a diffuser, preferably a Lambertian diffuser, that is arranged downstream of the light attenuator in the light path. The provision of the diffuser makes the light intensity homogeneous across the entire emitting surface / area so that the light measured by the luminometer is - at least within a larger moving range - independent from the positioning of the device.

[0047] The portable light source device may further comprise a housing, preferably a rod- or penshaped housing, that accommodates the functional components (and its subcomponents) including the light source element, the driver circuit, the light attenuator,

[0048] 35 and, if provided, the diffuser. The rod- or pen-shaped housing can be easily stored and intuitively handled. P24-248

[0049] - 5 -

[0050] Preferably, the light attenuator is arranged at an end portion of the rod- or pen-shaped housing and a light output opening downstream of the light attenuator (or the diffuser, if provided) is provided to emit light in an axial (longitudinal direction of the rod- or penshaped housing) and / or radial direction at the end portion of the rod- or pen-shaped

[0051] 5 housing. Generally, it is the end portion where the attenuator is arranged that is inserted into the luminometer.

[0052] Axial emission may be from a most distal end from one side of the device or a single position in a radial direction or may be in a radial direction over a larger peripheral range

[0053] 10 up to 360°.

[0054] The driver circuit may comprise a light output stabilization function including a photodiode arranged to preferably directly receive the light emission from the light source element to measure the light intensity upstream of the light attenuator in the light path and a feedback loop feeding back the measuring result to the driver circuit to prompt an adjustment of a driver output for the light source element (either to increase or to reduce the driving current) to reach a predetermined nominal value of the light intensity.

[0055] Preferably, the neutral density (ND) filter of the user-exchangeable light attenuator is composed of a stack of serially arranged filters with predetermined optical density. Thus, the overall light attenuation can be built up in stages. For example, if a first ND filter has a transmittance of 10% and a second ND filter has a transmittance of 1%, each of these filters can be used alone. If the first and second filters are serially arranged and combined, the resulting total transmittance will be 0,1%, and, if two of the second filters are serially

[0056] 25 arranged and combined, the resulting total transmittance will be 0,01%. Further combinations are possible according to this concept.

[0057] Preferably, the pinhole element is composed of an element, preferably an element made of non-transparent material, with a pinhole in its center, the pinhole having a well-defined diameter (for example, of at least 0.5 mm and of a most 1.5 mm) with known light reduction properties proportional to the diameter of the central hole.

[0058] The light attenuator may be arranged so as to be manually exchangeable by the user as a unit or "cartridge", preferably by removing a holder that supports the light attenuator at

[0059] 35 the housing from the housing, i.e. by opening a part of the housing to provide access to the holder or by removing a part of the housing including the holder. Several compatible holders may be prepared which each may include a light attenuator (ND filter or set of ND P24-248

[0060] - 6 - filters as described above or one or more pinhole element as described above) of a different transmittance value. The transmittance value may be indicated on the holder directly or coded, for example by using a color code scheme indicative of different attenuation values.

[0061] 5

[0062] The light attenuator may be exchangeable together with the diffuser, if provided, as a unit or independently from the diffuser. The holder may be in particular removable from the housing as a unit by a mechanical form-locking connection, preferably a threaded connection or bayonet-type connection.

[0063] 10

[0064] The device may include, in the housing, further functional components or subcomponents of functional components, one of them being possibly an integrated energy source, in particular a rechargeable battery, for allowing autonomous mobile operation, and / or an external power supply connector (like USB in the various standards providing a power supply, possibly according to the USB Power Delivery protocol) to recharge the batteries or allow operation without a built-in power supply.

[0065] Brief description of the drawings

[0066] The present portable light source device is in the following described in detail on the basis of a preferred embodiment by reference to the attached exemplary, schematic, and nonlimiting drawings:

[0067] Figure 1 shows a schematic diagram illustrating the exchangeability of the light attenuator

[0068] 25 in the present light source device.

[0069] Figure 2 shows a schematic concept diagram of a light source device in a rod- or penshaped structure according to an embodiment.

[0070] Figure 3 shows a schematic diagram illustrating a light output stabilization function as may be used in the present light source device.

[0071] Detailed description

[0072] 35 The schematic overall concept diagram of a portable or mobile light source device for luminometer calibration in a rod- or pen-shaped structure according to an embodiment is shown in Figure 2. P24-248

[0073] - 7 -

[0074] The portable light source device 1, comprises a light source element 6 for emitting light having a defined wavelength spectrum, in particular one or more LEDs, preferably suitable to emit light having a peak wavelength in the range from 510 nm to 570 nm, and a driver

[0075] 5 circuit 5 on a circuit or control board for driving the light source element 6. A light attenuator 7 comprising a neutral density (ND) filter is arranged downstream, in a light path, of the light source element 6, and upstream in the light path of an optional diffuser 8, preferably a Lambertian diffuser.

[0076] 10 These functional components are integrated and accommodated in an elongated rod- or pen-shaped housing 2, which may accommodate additional components like an integrated energy source 3, here in the form of a rechargeable battery, and / or an external power supply connector (not shown) for charging the battery or operating the device. Further, the housing may include an ON / OFF or start switch 4 and, if desired, further operating elements for selecting built-in functions in a gripping section of the housing 2 at an end portion that is opposite to the end portion where the light source element 6, the light attenuator 7 and the diffuser 8 and a light output opening are provided, for emitting the light to the outside. The light output opening may be formed to emit the light in an axia l / lo ngit udi na I direction and / or in a radial direction at the end portion of the rod- or pen-shaped housing 2.

[0077] Of course, the battery may be chargeable by a wireless inductive charging system (i.e. the housing may include the necessary circuitry) as is known from small portable electronic devices. Further, the operation of the device may be controllable through a wireless

[0078] 25 connection (i.e. through standards like Bluetooth, WIFI, NFC) through an external software providing a user interface and running on a mobile electronic device like a tablet, smartphone or PC in the vicinity of the device. The necessary circuitry may be included in the housing as well, for example on the circuit or control board of the driver circuit 5.

[0079] An essential feature of the present portable light source device is the structure that the light attenuator 7 is arranged in the housing 2 so as to be manually exchangeable by a user against another light attenuator 7 (7a, 7b) with a neutral density filter of different predetermined optical density or a pinhole element comprising a pinhole of well-defined diameter. This concept is illustrated in Figure 1, wherein in this diagram the housing may

[0080] 35 be split or separated into a main housing section 2a and a removable housing section (or cap) 2b to gain access to the light attenuator 7 and diffuser 8. P24-248

[0081] - 8 -

[0082] To achieve a different optical density, the neutral density filter may be composed of serially arranged filters with predetermined optical density as described above.

[0083] Further, the light attenuator 7 may be manually exchangeable together with the diffuser

[0084] 5 8, if provided, as a unit or independent from the diffuser 8. Such unit may be in the form of a holder or cartridge that supports the light attenuator ? at or in the housing. The holder may be removeable from an outside of the housing by a removable mechanical, form locking connection (threaded connection or bayonet-type connection) or after the housing has been opened as indicated in Figure 1.

[0085] The internal driver circuit 5 may comprise a light output stabilization function that is schematically shown in Figure 3 and that includes a photodiode 9 arranged in the vicinity of the light source element 6 (in the main light path or in a light path split from the main light path) for measuring the light intensity of the light emitted from the light source

[0086] 15 element 6 upstream of the light attenuator 7, and a feedback loop back to the driver circuit 5 to automatically adjust a driver output for the light source element 6 to a nominal value.

[0087] Further, the driver circuit 5 may be configured to supply the driving current to the light

[0088] 20 source element 6 not only at a single value (plus / minus minimal adjustments to implement the light output stabilization function) but in two or more user-selectable level settings (each provided with the light output stabilization function), to set the luminous intensity of the light emission of the light source element 6 to plural values < lpW along a curve plotting light output versus injection current of the particular light source element.

[0089] While the use of a single LED as a light source element 6 is described above, it is possible to use plural LEDs of different emission characteristics as the light source element 6 instead to allow switching between luminous intensities and / or spectra of the light emission of the device by electronic means in addition to the possibility of modifying the

[0090] 30 luminous intensity of the output by the mechanical exchange of the light attenuator 7.

Claims

P24-248- 9 -Claims1. A portable light source device (1) for luminometer calibration, comprising(i) a light source element (6), in particular LED, for emitting light in a defined5 wavelength spectrum;(ii) a driver circuit (5) for driving the light source element (6);(iii) a light attenuator (7) comprising a neutral density (ND) filter or a pinhole element comprising a pinhole of well-defined diameter arranged downstream, in a light path, of the light source element (6),10 wherein the light attenuator (7) is arranged so as to be exchangeable by a user against another light attenuator (7) comprising a neutral density filter of different predetermined optical density and / or a pinhole element comprising a pinhole of well-defined diameter.

2. The portable light source device (1) of claim 1, comprising a diffuser (8), preferably a Lambertian diffuser, arranged downstream of the light attenuator (7) in the light path.

3. The portable light source device (1) of claim 1 or 2, comprising a housing (2), preferably a rod- or pen-shaped housing (2), accommodating the light source element (6), the driver circuit (5), the light attenuator (7), and, if provided, the diffuser (8).

4. The portable light source device (1) of claim 3, wherein the light attenuator (7) is25 arranged at an end portion of the rod- or pen-shaped housing (2).

5. The portable light source device (1) of claim 3 or 4, wherein a light output opening is provided to emit light in an axial and / or radial direction at the end portion of the rod- or pen-shaped housing (2).

6. The portable light source device (1) of any one of claims 1 to 5, wherein the light source element (6) comprises an LED with emission of light with peak wavelength in the range from 510 to 570 nm.35 7. The portable light source device (1) of any one of claims 1 to 6, wherein the driver circuit (5) comprises a light output stabilization function including a photodiode (9)P24-248- 10 - for measuring the light intensity upstream of the light attenuator (7) and a feedback loop to adjust a driver output for the light source element (6) to a nominal value.

8. The portable light source device (1) of any one of claims 1 to 7, wherein the neutral5 density filter is composed of serially arranged filters with predetermined optical density or a pinhole element comprising a pinhole of well-defined diameter.

9. The portable light source device (1) of any one of claims 1 to 8, wherein the light attenuator (7) is exchangeable together with the diffuser (8), if provided, as a unit or independent from the diffuser (8).

10. The portable light source device (1) of any one of claims 1 to 9, wherein the driver circuit (5) is configured to supply a current, preferably in two or more user- selectable level settings, to set the luminous intensity of the light emission of the15 light source element (6) to a value < lpW, preferably to plural values along a curve plotting light output versus injection current.

11. The portable light source device (1) of any one of claims 1 to 10, further comprising an integrated energy source (3), in particular a rechargeable battery, and / or an20 external power supply connector.

12. The portable light source device (1) of any one of claims 1 to 11, wherein the light attenuator (7) is arranged so as to be manually exchangeable by the user as a unit, preferably by removing a holder that supports the light attenuator (7) at a / the housing.

13. The portable light source device (1) of claim 12, wherein the holder is removable from the housing (2) as a unit by a mechanical form-locking connection, preferably a threaded connection or bayonet-type connection.30

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