WO2020231331A1 - Colorimeter and method of measuring colour of a sample in a container having an aperture - Google Patents
Colorimeter and method of measuring colour of a sample in a container having an aperture Download PDFInfo
- Publication number
- WO2020231331A1 WO2020231331A1 PCT/SG2020/050268 SG2020050268W WO2020231331A1 WO 2020231331 A1 WO2020231331 A1 WO 2020231331A1 SG 2020050268 W SG2020050268 W SG 2020050268W WO 2020231331 A1 WO2020231331 A1 WO 2020231331A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- sample
- light
- colorimeter
- photodetector
- leds
- Prior art date
Links
- 238000000034 method Methods 0.000 title claims description 24
- 230000001360 synchronised effect Effects 0.000 claims description 16
- 238000005286 illumination Methods 0.000 description 8
- 241000894006 Bacteria Species 0.000 description 7
- 230000003287 optical effect Effects 0.000 description 7
- 238000001514 detection method Methods 0.000 description 5
- 239000012528 membrane Substances 0.000 description 4
- 238000005259 measurement Methods 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000011800 void material Substances 0.000 description 2
- ORWQBKPSGDRPPA-UHFFFAOYSA-N 3-[2-[ethyl(methyl)amino]ethyl]-1h-indol-4-ol Chemical compound C1=CC(O)=C2C(CCN(C)CC)=CNC2=C1 ORWQBKPSGDRPPA-UHFFFAOYSA-N 0.000 description 1
- 206010047513 Vision blurred Diseases 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/46—Measurement of colour; Colour measuring devices, e.g. colorimeters
- G01J3/50—Measurement of colour; Colour measuring devices, e.g. colorimeters using electric radiation detectors
- G01J3/501—Colorimeters using spectrally-selective light sources, e.g. LEDs
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/02—Details
- G01J3/0205—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
- G01J3/021—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows using plane or convex mirrors, parallel phase plates, or particular reflectors
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/02—Details
- G01J3/0256—Compact construction
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/02—Details
- G01J3/0283—Details using a charging unit
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/02—Details
- G01J3/10—Arrangements of light sources specially adapted for spectrometry or colorimetry
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/251—Colorimeters; Construction thereof
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J1/00—Photometry, e.g. photographic exposure meter
- G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
- G01J2001/4242—Modulated light, e.g. for synchronizing source and detector circuit
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2201/00—Features of devices classified in G01N21/00
- G01N2201/06—Illumination; Optics
- G01N2201/062—LED's
- G01N2201/0627—Use of several LED's for spectral resolution
Definitions
- This invention relates to a colorimeter and a method of measuring colour of a sample in a container having an aperture.
- the sample When a sample is located in a relatively deep well, the sample is provided in a container where the numerical aperture of observable area of the sample is low (e.g. 1 :5).
- the numerical aperture of observable area of the sample is low (e.g. 1 :5).
- a substrate such as a fdter, located in a deep well, where precursors or products change colour and it is desirable to monitor the process by optical means, such as by measuring the colour of the sample as the reaction progresses.
- optical means such as by measuring the colour of the sample as the reaction progresses.
- currently available colorimeters are unable to measure the colour of such samples due to the narrow aperture of the container in which the sample is deeply set.
- a colorimeter to measure colour of a sample in a container having an aperture, the colorimeter comprising a receptacle to hold therein the sample in the container; a plurality of spatially separated light emitting diodes (LEDs) each configured to emit light of a different colour; a photodetector; a semi-transparent mirror positioned to reflect unfocused light from each of the plurality of LEDs through the aperture onto the sample and to allow passage of the scattered light from the sample through the semi transparent mirror to the photodetector, wherein the unfocused light reflected by the semi transparent mirror onto the sample and the scattered light from the sample to the photodetector pass through the aperture in opposite directions; a lens provided between the semi-transparent mirror and the photodetector to focus the scattered light from the sample onto the photodetector, wherein no light from the plurality of LEDs passes through the lens; a controller to control switching of light emission from each of the plurality of LEDs; and a digitizer
- the numerical aperture of observation of the sample may be at least 1 :5.
- the colorimeter may comprise a synchronous amplifier to amplify output from the photodetector in synchronization with light emission from the plurality of LEDs.
- the colorimeter may comprise a software module provided in the controller to synchronize digitizing of output from the photodetector with switching of light emission from each of the plurality of LEDs by the controller.
- the software module, the controller and the digitizer may be provided on an Engineering platform.
- the controller, the digitizer and the synchronous amplifier may be provided on an chicken platform
- the colorimeter may be configured to be powered by a 5 Volt power source.
- a method of measuring colour of a sample in a container having an aperture comprising the steps of:
- step (c) controlling step (b) via a controller
- the method may comprise amplifying output from the photodetector via a synchronous amplifier in synchronization with step (a) prior to digitizing output from the synchronous amplifier by the digitizer.
- the method may comprise providing the synchronous amplifier, the controller and the digitizer on an chicken platform.
- the method may comprise a software module synchronizing step (g) with step (b).
- the method may comprise providing the software module, the controller and the digitizer on an Engineering platform.
- the plurality of LEDs may be exchangeable.
- the plurality of LEDs may comprise a first LED configured to emit light having a wavelength of 512nm, a second LED configured to emit light having a wavelength of 640nm, and a third LED configured to emit light having a wavelength of 850nm.
- FIG. l is a schematic illustration of a first exemplary embodiment of a colorimeter.
- FIG. 2 is a schematic illustration of a second exemplary embodiment of a colorimeter.
- FIG. 3 is a photograph of samples of metallic nanostain on filters with different concentrations of bacteria.
- FIG. 4 is a graph of colorimeter measurement of darkness of metallic nanostain on filters with different concentrations of bacteria.
- FIG. 5 is a zoomed in section of higher intensity values of the graph of FIG. 4.
- FIG. 6 is a flowchart of an exemplary method of measuring colour of a sample in a container having an aperture.
- FIGS. 1 to 6 Exemplary embodiments of a colorimeter 100 and method 200 of measuring colour of a sample 10 in a container 12 having an aperture 16 will be described below with reference to FIGS. 1 to 6, where the same reference numerals refer to the same or similar parts.
- the colorimeter 100 comprises a receptacle 20 to hold therein the sample 10 in its container 12.
- the container 12 has an aperture 16 that may be narrow (for example 4 mm in diameter or 2 mm in radius), while the sample 10 may be set rather deeply within the container 12 (for example 10 mm away from the aperture 16).
- the numerical aperture of observation or viewing angle is defined as the ratio of radius of the aperture 16 to the distance between the aperture 16 and the sample 10 in the container 12.
- An advantage of coloured illumination of the sample 12 by unfocused light 39 is that the unfocused light 39 is more tolerant of alignment errors such that misalignment of the sample 10 in its container 12 in the receptacle 20 does not change light intensity on the sample 10.
- a further advantage lies in the simplicity and lower cost of using a semi-transparent mirror to direct light onto the sample 10 as opposed to using a focusing system that requires use of one or more lenses
- the plurality of LEDs 30 may comprise a first LED configured to emit light having a wavelength of 512nm, a second LED configured to emit light having a wavelength of 640nm, and a third LED configured to emit light having a wavelength of 850nm.
- the plurality of LEDs 30 is preferably exchangeable so that desired colours of light can be used for desired purposes.
- Emission of the unfocused light 39 is controlled by a controller 52 that controls switching of light emission from each of the plurality of LEDs 30.
- sequential switching of the plurality of LEDs 30 may be controlled at a frequency of 22 Hz.
- unfocused light 39 from the plurality of LEDs 30 does not pass through the sample 10 to another side of the sample 10 for detection, but is instead absorbed and re-emitted by the sample 10 as scattered light 19 in a direction opposite to the direction of incidence of the unfocused light 39 on the sample 10.
- the scattered light 19 from the sample 10 passes through the aperture 16 and also passes through the semi-transparent mirror 40 to be focused by a lens 70 onto a photodetector 60 comprised in the colorimeter 100.
- the semi-transparent mirror 40 is thus positioned to reflect unfocused light 39 from each of the plurality of LEDs 30 through the aperture 16 onto the sample 10 and allow passage of the scattered light 19 from the sample 10 through the semi-transparent mirror 40 and the lens 70 onto the photodetector 60.
- the unfocused light 39 reflected by the semi-transparent mirror 40 onto the sample 10 and the scattered light 19 from the sample 10 both pass through the aperture 16 of the container 12 in opposite directions, as can be seen in FIGS. 1 and 2.
- the lens 70 is provided between the semi-transparent mirror 40 and the photodetector 60 to focus the scattered light 19 from the sample 10 onto the photodetector 60.
- no light from the plurality of LEDs 30 passes through the lens 70 as all light provided by the plurality of LEDs 30 and incident on the sample 10 is unfocused light 39.
- the receptacle 20, semi-transparent mirror 40, lens 70 and photodetector 60 may be provided in an optical box 90 in the colorimeter 100.
- numerical aperture of the optical system formed by the components in the optical box 90 may be as low as 1 :5 when the aperture 16 has a radius of 2 mm and the sample 10 is 10 mm away from the aperture 16.
- the colorimeter 100 and method 200 will work with other samples 10 having numerical apertures of observation of at least 1 :5, including ratios such as 1 :4, 1 :3 and so on.
- the colorimeter 100 further comprises a synchronous amplifier 80 that amplifies output signals from the photodetector 60 in synchronization with light emission from the plurality of LEDs 30.
- the synchronous amplifier 80 may give an output voltage in each channel ranging from 0 to 2 Volts that is proportional to intensity of scattered light 19 from the sample 10.
- a digitizer 54 is provided to digitize the output voltage from the amplifier 80 and transmit the digitized output to a computing device (not shown).
- the digitizer 54 and the synchronous amplifier 80 may be provided on the iOS platform 50 together with the controller 52.
- the colorimeter 100 may comprise a digitizer 54 provided to digitize output from the photodetector 60 and transmit the digitized output to a computing device, as well as a software module (not shown) provided in the controller 52 and configured to synchronize digitizing of output from the photodetector 60 by the digitizer 54 (i.e. synchronous digitizing) with switching of light emission from each of the plurality of LEDs 30 by the controller 52.
- the software module, the digitizer 54 and the controller 52 may be provided on an electrician platform 50. Compared to using a synchronous amplifier followed by digitizing the amplifier output, synchronous digitizing simplifies the electronic circuitry and reduces cost of the colorimeter 100.
- pinMode (inputPinl, INPUT); pinMode ( inputPin2 , INPUT); pinMode (inputPin3, INPUT); pinMode ( inputPin4 , INPUT); pinMode ( inputPin5 , INPUT); pinMode (2, OUTPUT);
- ledcount ledcount +1;
- vail (float) dark - ledread[2] / reads [2];
- val2 (float) dark - ledread[3] / reads [3];
- val3 (float) dark - ledread[4] / reads [4];
- val4 (float) dark - ledread[5] / reads [5];) else
- the colorimeter 100 provides digital colour synchronization of illumination and detection of the sample 10.
- the whole colorimeter 100 can be powered using a single 5 V source (e.g. from a USB port or battery) and has a low power consumption of 300 mW.
- the colorimeter 100 is simple and compact, and in an exemplary embodiment, may weigh about 400 grams and have a compact size of 20 cm x 12 cm x 7 cm.
- the colorimeter 100 may also be modified to function as a fluorimeter by proper choice of LEDs and placing an appropriate optical filter before the photodetector 60.
- the colorimeter 100 was applied for quantitative bacteria detection. Specifically, the colorimeter 100 was used to analyse darkness of metallic nanostains on filter membranes, wherein each membrane was located at 10 mm deep in a filter having an aperture 16 with a diameter of 4mm. The filter membrane samples 10 held bacteria at different concentrations. Recording of signals using the colorimeter 100 began without a sample. As outlined in FIG. 6, the filter samples 10 were then inserted or placed, one by one, into the receptacle 20 of the optical box 90 (201) and held there for 60 seconds each to perform the illumination and detection of each sample 10.
- the illumination and detection process comprised sequentially emitting unfocused light 39 onto the semi-transparent mirror 40 from each of the plurality of spatially separated LEDs 30 (202) under the control of the controller 52 (203), and reflecting the unfocused light 39 through the narrow aperture 16 onto the sample 10 via the semi-transparent mirror 40 (204).
- Scattered light 19 from the sample 10 was then passed through the aperture 16 and the semi-transparent mirror 40, wherein the unfocused light 39 reflected by the semi-transparent mirror 16 onto the sample 10 and the scattered light 19 from the sample 10 pass through the narrow aperture 16 in opposite directions (205), and the scattered light 19 from the sample 10 was focused onto the photodetector 60 via the lens 70, wherein no light from the plurality of LEDs 30 passes through the lens 70 (206).
- Output from the photodetector 60 was digitized via the digitizer 54 (207) and transmitted to a computing device (208). It was observed that when a filter sample 10 was inserted into the colorimeter 100, the intensity of scattered light 19 was seen to increase. Darker filter membrane samples 10, such as those having 10 6 and 10 7 bacteria concentration levels, produced lower increase of scattered light 19. Light intensity obtained from the filter samples 10 was normalised against light intensity obtained with a blank filter having 0 bacteria concentration level, and the normalised intensity values are shown in the graph of FIG. 4. The graph in FIG. 5 shows a zoomed in view of the higher normalized intensity values of the graph in FIG. 4, i.e., from 700 and above. From FIG. 5, it can be seen that the noise level of the colorimeter 100 is around 1% of the blank value having a bacteria concentration level of 0.
- the present colorimeter 100 relies on using unfocused light 39 and a semi transparent mirror 40 to direct unfocused light 39 onto the sample 10. This is despite unfocused light 39 and a semi-transparent mirror 40 typically being not the illumination components of choice in optical systems due to the low light intensity provided by unfocused light that is worsened by a drop in light intensity when light is reflected off the semi transparent mirror, resulting in sample measurement being made more difficult.
- the present colorimeter 100 is able to use unfocused light 39 and a semi transparent mirror 40 to illuminate the sample 10, thus overcoming the difficulty of focusing spatially separated colour light sources on a deeply set sample in a container having a narrow aperture, while also providing a simple, cost-effective and compact device to obtain colour measurements of samples 10 without needing a complex illumination system.
Landscapes
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- General Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Spectrometry And Color Measurement (AREA)
Abstract
A colorimeter to measure colour of a sample in a container having an aperture, the colorimeter comprising a receptacle to hold therein the sample in the container; a plurality of spatially separated light emitting diodes (LEDs) each configured to emit light of a different colour; a photodetector; a semi-transparent mirror positioned to reflect unfocused light from each of the plurality of LEDs through the aperture onto the sample and to allow passage of the scattered light from the sample through the semi-transparent mirror to the photodetector, wherein the unfocused light reflected by the semi-transparent mirror onto the sample and the scattered light from the sample to the photodetector pass through the aperture in opposite directions; a lens provided between the semi-transparent mirror and the photodetector to focus the scattered light from the sample onto the photodetector, wherein no light from the plurality of LEDs passes through the lens; a controller to control switching of light emission from each of the plurality of LEDs; and a digitizer to digitize output from the photodetector and transmit the digitized output to a computing device.
Description
COLORIMETER AND METHOD OF MEASURING COLOUR OF A SAMPLE IN A CONTAINER HAVING AN APERTURE
FIELD
This invention relates to a colorimeter and a method of measuring colour of a sample in a container having an aperture.
BACKGROUND
When a sample is located in a relatively deep well, the sample is provided in a container where the numerical aperture of observable area of the sample is low (e.g. 1 :5). There are situations where reactions are performed on a substrate, such as a fdter, located in a deep well, where precursors or products change colour and it is desirable to monitor the process by optical means, such as by measuring the colour of the sample as the reaction progresses. However, currently available colorimeters are unable to measure the colour of such samples due to the narrow aperture of the container in which the sample is deeply set. This is because in such situations, illumination of the sample and observed light from the sample must both pass through the narrow aperture, and a single focusing system is unable to focus light from spatially separated light sources of different coloured lights onto the sample through the narrow aperture. There is thus a need for a colorimeter that is able to measure colour of a sample located in a container having a narrow aperture.
SUMMARY
According to a first aspect, there is provided a colorimeter to measure colour of a sample in a container having an aperture, the colorimeter comprising a receptacle to hold therein the sample in the container; a plurality of spatially separated light emitting diodes (LEDs) each configured to emit light of a different colour; a photodetector; a semi-transparent mirror positioned to reflect unfocused light from each of the plurality of LEDs through the aperture onto the sample and to allow passage of the scattered light from the sample through the semi transparent mirror to the photodetector, wherein the unfocused light reflected by the semi transparent mirror onto the sample and the scattered light from the sample to the photodetector pass through the aperture in opposite directions; a lens provided between the semi-transparent mirror and the photodetector to focus the scattered light from the sample onto the photodetector, wherein no light from the plurality of LEDs passes through the lens;
a controller to control switching of light emission from each of the plurality of LEDs; and a digitizer to digitize output from the photodetector and transmit the digitized output to a computing device.
The numerical aperture of observation of the sample may be at least 1 :5.
The colorimeter may comprise a synchronous amplifier to amplify output from the photodetector in synchronization with light emission from the plurality of LEDs.
The colorimeter may comprise a software module provided in the controller to synchronize digitizing of output from the photodetector with switching of light emission from each of the plurality of LEDs by the controller.
The software module, the controller and the digitizer may be provided on an Arduino platform.
The controller, the digitizer and the synchronous amplifier may be provided on an Arduino platform
The colorimeter may be configured to be powered by a 5 Volt power source.
According to a second aspect, there is provided a method of measuring colour of a sample in a container having an aperture, the method comprising the steps of:
(a) placing the sample in the container in a receptacle;
(b) sequentially emitting unfocused light onto a semi-transparent mirror from each of a plurality of spatially separated light emitting diodes (LEDs) each configured to emit light of a different colour;
(c) controlling step (b) via a controller;
(d) reflecting the unfocused light through the aperture onto the sample via the semi transparent mirror;
(e) passing scattered light from the sample through the aperture and the semi-transparent mirror, wherein the unfocused light reflected by the semi-transparent mirror onto the sample and the scattered light from the sample pass through the aperture in opposite
directions
(f) focusing the scattered light that has passed through the semi-transparent mirror onto a photodetector via a lens, wherein no light from the plurality of LEDs passes through the lens;
(g) digitizing output from the photodetector via a digitizer; and
(h) transmitting the digitized output to a computing device.
The method may comprise amplifying output from the photodetector via a synchronous amplifier in synchronization with step (a) prior to digitizing output from the synchronous amplifier by the digitizer.
The method may comprise providing the synchronous amplifier, the controller and the digitizer on an Arduino platform.
The method may comprise a software module synchronizing step (g) with step (b).
The method may comprise providing the software module, the controller and the digitizer on an Arduino platform.
For both aspects, the plurality of LEDs may be exchangeable.
The plurality of LEDs may comprise a first LED configured to emit light having a wavelength of 512nm, a second LED configured to emit light having a wavelength of 640nm, and a third LED configured to emit light having a wavelength of 850nm.
BRIEF DESCRIPTION OF FIGURES
In order that the invention may be fully understood and readily put into practical effect, there shall now be described by way of non-limitative example only exemplary embodiments of the present invention, the description being with reference to the accompanying illustrative drawings.
FIG. l is a schematic illustration of a first exemplary embodiment of a colorimeter.
FIG. 2 is a schematic illustration of a second exemplary embodiment of a colorimeter.
FIG. 3 is a photograph of samples of metallic nanostain on filters with different
concentrations of bacteria.
FIG. 4 is a graph of colorimeter measurement of darkness of metallic nanostain on filters with different concentrations of bacteria.
FIG. 5 is a zoomed in section of higher intensity values of the graph of FIG. 4.
FIG. 6 is a flowchart of an exemplary method of measuring colour of a sample in a container having an aperture.
DETAILED DESCRIPTION
Exemplary embodiments of a colorimeter 100 and method 200 of measuring colour of a sample 10 in a container 12 having an aperture 16 will be described below with reference to FIGS. 1 to 6, where the same reference numerals refer to the same or similar parts.
As shown in FIGS. 1 and 2, the colorimeter 100 comprises a receptacle 20 to hold therein the sample 10 in its container 12. In certain situations, the container 12 has an aperture 16 that may be narrow (for example 4 mm in diameter or 2 mm in radius), while the sample 10 may be set rather deeply within the container 12 (for example 10 mm away from the aperture 16). The numerical aperture of observation or viewing angle is defined as the ratio of radius of the aperture 16 to the distance between the aperture 16 and the sample 10 in the container 12. In such situations, as a result of the low numerical aperture of observation of the sample 10 within the container 12, it is difficult to focus light through a focusing system onto the sample 10 from each of a plurality of spatially separated light emitting diodes (LEDs) 30 that are each configured to emit light of a different colour. Thus, in the presently disclosed colorimeter 100, the sample 10 is not illuminated through a focusing system. Instead, a semi transparent mirror 40 is provided to reflect unfocused light 39 from each of the spatially separated plurality of LEDs 30 through the aperture 16 onto the sample 10. An advantage of coloured illumination of the sample 12 by unfocused light 39 is that the unfocused light 39 is more tolerant of alignment errors such that misalignment of the sample 10 in its container 12 in the receptacle 20 does not change light intensity on the sample 10. A further advantage lies in the simplicity and lower cost of using a semi-transparent mirror to direct light onto the sample 10 as opposed to using a focusing system that requires use of one or more lenses
In an exemplary embodiment, the plurality of LEDs 30 may comprise a first LED configured to emit light having a wavelength of 512nm, a second LED configured to emit light having
a wavelength of 640nm, and a third LED configured to emit light having a wavelength of 850nm. The plurality of LEDs 30 is preferably exchangeable so that desired colours of light can be used for desired purposes.
Emission of the unfocused light 39 is controlled by a controller 52 that controls switching of light emission from each of the plurality of LEDs 30. In an exemplary embodiment, sequential switching of the plurality of LEDs 30 may be controlled at a frequency of 22 Hz.
Notably, in the presently disclosed colorimeter 100, unfocused light 39 from the plurality of LEDs 30 does not pass through the sample 10 to another side of the sample 10 for detection, but is instead absorbed and re-emitted by the sample 10 as scattered light 19 in a direction opposite to the direction of incidence of the unfocused light 39 on the sample 10. The scattered light 19 from the sample 10 passes through the aperture 16 and also passes through the semi-transparent mirror 40 to be focused by a lens 70 onto a photodetector 60 comprised in the colorimeter 100. The semi-transparent mirror 40 is thus positioned to reflect unfocused light 39 from each of the plurality of LEDs 30 through the aperture 16 onto the sample 10 and allow passage of the scattered light 19 from the sample 10 through the semi-transparent mirror 40 and the lens 70 onto the photodetector 60. Notably, the unfocused light 39 reflected by the semi-transparent mirror 40 onto the sample 10 and the scattered light 19 from the sample 10 both pass through the aperture 16 of the container 12 in opposite directions, as can be seen in FIGS. 1 and 2.
In the colorimeter 100, the lens 70 is provided between the semi-transparent mirror 40 and the photodetector 60 to focus the scattered light 19 from the sample 10 onto the photodetector 60. Notably, no light from the plurality of LEDs 30 passes through the lens 70 as all light provided by the plurality of LEDs 30 and incident on the sample 10 is unfocused light 39. The receptacle 20, semi-transparent mirror 40, lens 70 and photodetector 60 may be provided in an optical box 90 in the colorimeter 100. In an exemplary embodiment, numerical aperture of the optical system formed by the components in the optical box 90 may be as low as 1 :5 when the aperture 16 has a radius of 2 mm and the sample 10 is 10 mm away from the aperture 16. It should be noted that the colorimeter 100 and method 200 will work with other samples 10 having numerical apertures of observation of at least 1 :5, including ratios such as 1 :4, 1 :3 and so on.
In a first exemplary embodiment, as shown in FIG. 1, the colorimeter 100 further comprises a synchronous amplifier 80 that amplifies output signals from the photodetector 60 in synchronization with light emission from the plurality of LEDs 30. The synchronous amplifier 80 may give an output voltage in each channel ranging from 0 to 2 Volts that is proportional to intensity of scattered light 19 from the sample 10. In this embodiment, a digitizer 54 is provided to digitize the output voltage from the amplifier 80 and transmit the digitized output to a computing device (not shown). The digitizer 54 and the synchronous amplifier 80 may be provided on the Arduino platform 50 together with the controller 52.
In a second exemplary embodiment, as shown in FIG. 2, the colorimeter 100 may comprise a digitizer 54 provided to digitize output from the photodetector 60 and transmit the digitized output to a computing device, as well as a software module (not shown) provided in the controller 52 and configured to synchronize digitizing of output from the photodetector 60 by the digitizer 54 (i.e. synchronous digitizing) with switching of light emission from each of the plurality of LEDs 30 by the controller 52. The software module, the digitizer 54 and the controller 52 may be provided on an Arduino platform 50. Compared to using a synchronous amplifier followed by digitizing the amplifier output, synchronous digitizing simplifies the electronic circuitry and reduces cost of the colorimeter 100. An example of an Arduino software programme code for controlling individual colour illumination from the plurality of LEDs and digitizing output from the photodetector 60 is given below: long inputl = 0;
long input2 = 0 ;
long input3 = 0;
long input4 = 0;
long input5 = 0;
long ledread[7] =
1 0 , 0 , 0 , 0 , 0 , 0 , 0 ) ;
int reads[7] = 10,0,0,0,0,0,0)
int i = 0 ;
Int takes = 0;
int inputPinl = A0;
Int lnputPin2 = A1 ;
int inputPin3 = A2 ;
int inputPin4 = A3 ;
int inputPin5 = A4 ;
int lednow = 2 ;
int ledperiod = 20;
int ledcount = 0;
int inputmode = LOW;
float vail;
float val2;
float val3;
float val4;
float dark;
int inByte = 0 ;
void setup ( ) {
// put your setup code here, to run once:
Serial . begin ( 9600 ) ;
pinMode (inputPinl, INPUT); pinMode ( inputPin2 , INPUT); pinMode (inputPin3, INPUT); pinMode ( inputPin4 , INPUT); pinMode ( inputPin5 , INPUT); pinMode (2, OUTPUT);
pinMode ( 3 , OUTPUT);
pinMode ( 4 , OUTPUT);
pinMode ( 5 , OUTPUT);
pinMode ( 6, OUTPUT);
pinMode (7, INPUT);
digitalWrite (lednow, HIGH);
}
void loop ( ) {
inputl = inputl +
analogRead ( inputPinl ) ;
input2 = input2 +
analogRead ( inputPin2 ) ;
input3 = input3 +
analogRead ( inputPin3 ) ;
input4 = input4 +
analogRead ( inputPin4 ) ;
takes = takes + 1;
if (ledcount > 2)
{ ledread [lednow] =
ledread [ lednow] +
analogRead ( inputPin5 ) ;
reads [lednow] = reads [lednow]
+i; }
ledcount = ledcount +1;
if (ledcount > ledperiod)
{
digitalWrite (lednow, LOW); lednow = lednow + 1;
If (lednow > 6) lednow = 2; digitalWrite ( lednow, HIGH); ledcount = 0;
}
if ( Serial . available ( ) > 0)
{
inByte = Serial . read () ;
inputmode = digitalRead ( 7 ) ; if (inputmode == HIGH)
{dark = (float) ledread[6] / reads [ 6 ] ;
vail = (float) dark - ledread[2] / reads [2];
val2 = (float) dark - ledread[3] / reads [3];
val3 = (float) dark - ledread[4] / reads [4];
val4 = (float) dark - ledread[5] / reads [5];) else
{vail = (float) Inputl/takes ; val2 = (float) input2/takes ; val3 = (float) input3/takes ; val4 = (float)
input4/takes ; }
Serial . print (val 1 ) ;
Serial. printC',") ;
Serial . print (val2 ) ;
Serial. printf',") ;
Serial . print (val3 ) ;
Serial. printf',") ;
Serial .printIn (val4 ) ;
inputl = 0;
input2 = 0;
input3 = 0 ;
input4 = 0 ;
takes = 0;
for (int i=2; i<=7 ; i++)
{ ledread [ i ] =0 ; reads[i]=0;)
}
if (takes > 11000)
{
inputl = 0;
input2 = 0;
input3 = 0 ;
input4 = 0 ;
takes = 0;
for (int i=2 ; i<=6; i++)
{ledread[i] =0; reads[i]=0;)
}
}
In all embodiments, the colorimeter 100 provides digital colour synchronization of illumination and detection of the sample 10. The whole colorimeter 100 can be powered using a single 5 V source (e.g. from a USB port or battery) and has a low power consumption of 300 mW. The colorimeter 100 is simple and compact, and in an exemplary embodiment, may weigh about 400 grams and have a compact size of 20 cm x 12 cm x 7 cm. The colorimeter 100 may also be modified to function as a fluorimeter by proper choice of LEDs and placing an appropriate optical filter before the photodetector 60.
In an example of use, the colorimeter 100 was applied for quantitative bacteria detection. Specifically, the colorimeter 100 was used to analyse darkness of metallic nanostains on filter membranes, wherein each membrane was located at 10 mm deep in a filter having an aperture 16 with a diameter of 4mm. The filter membrane samples 10 held bacteria at different concentrations. Recording of signals using the colorimeter 100 began without a sample. As outlined in FIG. 6, the filter samples 10 were then inserted or placed, one by one, into the receptacle 20 of the optical box 90 (201) and held there for 60 seconds each to perform the illumination and detection of each sample 10. The illumination and detection process comprised sequentially emitting unfocused light 39 onto the semi-transparent mirror 40 from each of the plurality of spatially separated LEDs 30 (202) under the control of the
controller 52 (203), and reflecting the unfocused light 39 through the narrow aperture 16 onto the sample 10 via the semi-transparent mirror 40 (204). Scattered light 19 from the sample 10 was then passed through the aperture 16 and the semi-transparent mirror 40, wherein the unfocused light 39 reflected by the semi-transparent mirror 16 onto the sample 10 and the scattered light 19 from the sample 10 pass through the narrow aperture 16 in opposite directions (205), and the scattered light 19 from the sample 10 was focused onto the photodetector 60 via the lens 70, wherein no light from the plurality of LEDs 30 passes through the lens 70 (206). Output from the photodetector 60 was digitized via the digitizer 54 (207) and transmitted to a computing device (208). It was observed that when a filter sample 10 was inserted into the colorimeter 100, the intensity of scattered light 19 was seen to increase. Darker filter membrane samples 10, such as those having 106 and 107 bacteria concentration levels, produced lower increase of scattered light 19. Light intensity obtained from the filter samples 10 was normalised against light intensity obtained with a blank filter having 0 bacteria concentration level, and the normalised intensity values are shown in the graph of FIG. 4. The graph in FIG. 5 shows a zoomed in view of the higher normalized intensity values of the graph in FIG. 4, i.e., from 700 and above. From FIG. 5, it can be seen that the noise level of the colorimeter 100 is around 1% of the blank value having a bacteria concentration level of 0.
Notably, the present colorimeter 100 relies on using unfocused light 39 and a semi transparent mirror 40 to direct unfocused light 39 onto the sample 10. This is despite unfocused light 39 and a semi-transparent mirror 40 typically being not the illumination components of choice in optical systems due to the low light intensity provided by unfocused light that is worsened by a drop in light intensity when light is reflected off the semi transparent mirror, resulting in sample measurement being made more difficult. Nevertheless, the present colorimeter 100 is able to use unfocused light 39 and a semi transparent mirror 40 to illuminate the sample 10, thus overcoming the difficulty of focusing spatially separated colour light sources on a deeply set sample in a container having a narrow aperture, while also providing a simple, cost-effective and compact device to obtain colour measurements of samples 10 without needing a complex illumination system.
Whilst there has been described in the foregoing description exemplary embodiments of the present invention, it will be understood by those skilled in the technology concerned that
many variations and combination in details of design, construction and/or operation may be made without departing from the present invention. For example, while the above disclosed colorimeter and method are particularly able to measure colour of samples that have a small angle of observation, such as deep set samples in containers having narrow apertures, the colorimeter and method may also be used to measure colour of samples of other configurations without being limited to samples in containers having narrow apertures.
Claims
1. A colorimeter to measure colour of a sample in a container having an aperture, the colorimeter comprising:
a receptacle to hold therein the sample in the container;
a plurality of spatially separated light emitting diodes (LEDs) each configured to emit light of a different colour;
a photodetector;
a semi-transparent mirror positioned to reflect unfocused light from each of the plurality of LEDs through the aperture onto the sample and to allow passage of the scattered light from the sample through the semi-transparent mirror to the photodetector, wherein the unfocused light reflected by the semi-transparent mirror onto the sample and the scattered light from the sample to the photodetector pass through the aperture in opposite directions;
a lens provided between the semi-transparent mirror and the photodetector to focus the scattered light from the sample onto the photodetector, wherein no light from the plurality of LEDs passes through the lens;
a controller to control switching of light emission from each of the plurality of LEDs; and
a digitizer to digitize output from the photodetector and transmit the digitized output to a computing device.
2. The colorimeter of claim 1, wherein numerical aperture of observation of the sample is at least 1 :5.
3. The colorimeter of claim 1 or claim 2, wherein the plurality of LEDs are exchangeable.
4. The colorimeter of any one of the preceding claims, wherein the plurality of LEDs comprise a first LED configured to emit light having a wavelength of 512nm, a second LED configured to emit light having a wavelength of 640nm, and a third LED configured to emit light having a wavelength of 850nm.
5. The colorimeter of any one of the preceding claims, further comprising a synchronous
amplifier to amplify output from the photodetector in synchronization with light emission from the plurality of LEDs.
6. The colorimeter of any one claims 1 to 4, further comprising a software module provided in the controller to synchronize digitizing of output from the photodetector with switching of light emission from each of the plurality of LEDs by the controller.
7. The colorimeter of claim 6, wherein the software module, the controller and the digitizer are provided on an Arduino platform.
8. The colorimeter of claim 5, wherein the controller, the digitizer and the synchronous amplifier are provided on an Arduino platform
9. The colorimeter of any one of the preceding claims, wherein the colorimeter is configured to be powered by a 5 Volt power source.
10. A method of measuring colour of a sample in a container having an aperture, the method comprising the steps of:
(a) placing the sample in the container in a receptacle;
(b) sequentially emitting unfocused light onto a semi-transparent mirror from each of a plurality of spatially separated light emitting diodes (LEDs) each configured to emit light of a different colour;
(c) controlling step (b) via a controller;
(d) reflecting the unfocused light through the aperture onto the sample via the semi transparent mirror;
(e) passing scattered light from the sample through the aperture and the semi-transparent mirror, wherein the unfocused light reflected by the semi-transparent mirror onto the sample and the scattered light from the sample pass through the aperture in opposite directions
(f) focusing the scattered light that has passed through the semi-transparent mirror onto a photodetector via a lens, wherein no light from the plurality of LEDs passes through the lens;
(g) digitizing output from the photodetector via a digitizer; and
(h) transmitting the digitized output to a computing device.
11. The method of claim 10, further comprising amplifying output from the photodetector via a synchronous amplifier in synchronization with step (a) prior to digitizing output from the synchronous amplifier by the digitizer.
12. The method of claim 11, further comprising providing the synchronous amplifier, the controller and the digitizer on an Arduino platform.
13. The method of claim 10, further comprising a software module synchronizing step (g) with step (b).
14. The method of claim 13, further comprising providing the software module, the controller and the digitizer on an Arduino platform.
15. The method of any one of claims 10 to 14, wherein the plurality of LEDs are exchangeable.
16. The method of any one of claims 10 to 15, wherein the plurality of LEDs comprise a first LED configured to emit light having a wavelength of 512nm, a second LED configured to emit light having a wavelength of 640nm, and a third LED configured to emit light having a wavelength of 850nm.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SG11202112176PA SG11202112176PA (en) | 2019-05-10 | 2020-05-08 | Colorimeter and method of measuring colour of a sample in a container having an aperture |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SG10201904231V | 2019-05-10 | ||
SG10201904231V | 2019-05-10 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2020231331A1 true WO2020231331A1 (en) | 2020-11-19 |
Family
ID=73290347
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/SG2020/050268 WO2020231331A1 (en) | 2019-05-10 | 2020-05-08 | Colorimeter and method of measuring colour of a sample in a container having an aperture |
Country Status (2)
Country | Link |
---|---|
SG (1) | SG11202112176PA (en) |
WO (1) | WO2020231331A1 (en) |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6445451B1 (en) * | 1998-02-12 | 2002-09-03 | Hamilton Thorne Research | Colorimeter and assay device |
US20030048449A1 (en) * | 2001-05-16 | 2003-03-13 | Vander Jagt Peter G. | Color measurement instrument with modulated illumination |
US20090180118A1 (en) * | 2007-07-30 | 2009-07-16 | Ivoclar Vivadent Ag | Method of optically monitoring the progression of a physical and/or chemical process taking place on a surface of a body |
CN101592654A (en) * | 2008-05-26 | 2009-12-02 | 开物科技股份有限公司 | The image analysis method of bio-detector |
-
2020
- 2020-05-08 WO PCT/SG2020/050268 patent/WO2020231331A1/en active Application Filing
- 2020-05-08 SG SG11202112176PA patent/SG11202112176PA/en unknown
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6445451B1 (en) * | 1998-02-12 | 2002-09-03 | Hamilton Thorne Research | Colorimeter and assay device |
US20030048449A1 (en) * | 2001-05-16 | 2003-03-13 | Vander Jagt Peter G. | Color measurement instrument with modulated illumination |
US20090180118A1 (en) * | 2007-07-30 | 2009-07-16 | Ivoclar Vivadent Ag | Method of optically monitoring the progression of a physical and/or chemical process taking place on a surface of a body |
CN101592654A (en) * | 2008-05-26 | 2009-12-02 | 开物科技股份有限公司 | The image analysis method of bio-detector |
Also Published As
Publication number | Publication date |
---|---|
SG11202112176PA (en) | 2021-12-30 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
DK1447658T3 (en) | Multi-wavelength reading head for use in the determination of analytes in body fluids | |
US7102131B2 (en) | Device for photometric measurement of several samples | |
US4755058A (en) | Device and method for measuring light diffusely reflected from a nonuniform specimen | |
US20080116382A1 (en) | Light diffuser used in a testing apparatus | |
US5854680A (en) | Photoelectric densitometer | |
AU7368601A (en) | Scanning system and method for scanning a plurality of samples | |
EP0165535B1 (en) | Device for measuring light diffusely reflected from a nonuniform specimen | |
US7342662B2 (en) | Sample analyzer | |
JP2009526239A (en) | Modular fluorescence and photometric reader | |
KR960038386A (en) | Optical detection device for chemical analysis measurement | |
CA2405802A1 (en) | Method and apparatus for detecting fluorescence of a sample | |
EP1830174A3 (en) | Multi-channel fluorescence measuring optical system and multi-channel fluorescence sample analyzer | |
US20100110415A1 (en) | Analyzer and analytic system | |
US8968658B2 (en) | Luminescence measurement utilizing cartridge with integrated detector | |
JPH07120393A (en) | Fluorescence detection method | |
WO2020231331A1 (en) | Colorimeter and method of measuring colour of a sample in a container having an aperture | |
US20240085395A1 (en) | Water quality detection system | |
DE60205406D1 (en) | OPTICAL TWO-WAVELENGTH FLUORESCENT ANALYZER | |
US20090212235A1 (en) | Scanning fluorescent reader with diffuser system | |
WO2004104532A1 (en) | Arrangement for continuous determination of a substance | |
FR2792725A1 (en) | Detecting variation in optical properties of liquid sample comprises sequentially measuring light transmitted from two different light sources in short time | |
CN216622069U (en) | Multi-wavelength scattering polarization fluorescence measuring device | |
JPH1137930A (en) | Absorptiometer | |
JP2005055199A (en) | Led lighting system | |
CN103278449A (en) | Multi-channel optical detection device |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 20804848 Country of ref document: EP Kind code of ref document: A1 |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 20804848 Country of ref document: EP Kind code of ref document: A1 |