Patent Application
20230288339
“Not Applicable”
“Not Applicable”
“Not Applicable”
“Not Applicable”
This invention describes a device for the rapid acquisition of data that may be used for the optical analysis of a two-dimensional surface when combined with two-dimensional spatial data transmitted to the device from a coupled apparatus. The ability to generate one or more images from this two-dimensional data is also including in this invention. This device utilizes point detectors to permit rapid data acquisition that may not be possible with other schemes to acquire similar data.
The measurement of optical features on a two-dimensional surface is a well-known technique for the characterization of many materials. Traditionally, this was done by rastering the position of the sample under an optical source that would generate the light used for analysis (Vandenabeele et al.). Each position would generate a full spectrum through the use of a CCD or some other type of multiplexed spectral detection system.
Subsequent work used systems that incorporated an expanded source on the surface, a two-dimensional detector, and other optical components that could be used to provide spectral information at each pixel. For example:
FT-IR spectral imaging incorporating an FTIR as part of the optical system so that a full FTIR spectrum is obtained at each pixel (Lewis et al.),
Raman spectral imaging incorporates an expanded laser beam with two-dimensional detectors and a spectral-resolving component such as a Liquid Crystal Tunable Filter (LCTF) (Stewart et al.).
Other methods have used a source beam to raster on the surface of a sample while spectra are acquired using a device such as a CCD that acquires the full spectrum in a given spectral range (Emetere et al.).
All of these methods provide valuable information on the two-dimensional distribution of chemical and/or physical components on a surface. However, by necessity, the hardware required to perform these measurements simultaneously acquires quite a bit of superfluous information that is not required for the analysis. As a result, these measurements often take more time than are needed for certain analyses.
There are cathodoluminescence methods that use three filters and three detectors to acquire red, green, and blue cathodoluminescence light—this technique is often used for geological samples (e.g., Pagel et al., 2000). While this technique does allow for rapid imaging, it is a general technique and does not incorporate filtering of light based on specific chemical or physical structures in a material being analyzed.
The device proposed here incorporates multiple optics and detectors which are used to detect specific chemical or physical structures in a material. This device, when operated with a coupled apparatus to provide two-dimensional data on the location on a surface where the light is being generated, provides for a novel means of data analysis, allowing for the counting of structures on a two-dimensional surface, or for imaging.
This invention consists of a device with a number of discrete components that are used to generate data from a two-dimensional material of interest. These include:
1. An Optical Engine that includes two or more point detectors,
2. One or more elements within the Optical Engine that allows light to be separated spatially as a function of wavelength such that light of a specific wavelength range is incident on a particular detector and each detector is used to detect light of a separate wavelength range,
3. A data interpretation system that combines data from the point detectors with two-dimensional positional information from a coupled apparatus to count specific chemical and/or physical areas of interest across a two-dimensional surface, through counting these regions and/or by generating an image.
This device would incorporate a lightpipe and specific optical elements to select wavelengths of light for measurement at two or more detectors.
F1-F4: Bandpass filters to transmit certain wavelengths of light and reflect other wavelengths of light. Note: this Figure represents four bandpass filters but there may be more or less optical elements in this embodiment.
Det1, Det2: Point detectors to detect light that falls onto the detector. This invention includes two or more detectors. For simplicity, two detectors are shown in
In combination with the filters shown, Det1 would detect light that falls between IF1 and IF2 and Det2 would detect light that falls between IF3 and IF4.
The first filter (F1) may be positioned before the lightpipe. The final optical element in this device may be a mirror or may be omitted and the detector placed in the path of the incoming light.
The detectors may be any device that converts electromagnetic radiation (light) impingent on a detector element and converting that into an electrical or digital signal.
This alternative embodiment could occur without placing the optics in a lightpipe. The optics could be placed inside another structure or could be present in free space.
In this embodiment, a lightpipe is not used and the optical filters and detectors have a different relative configuration. This embodiment is depicted in
It is envisioned that light may be coupled into the optical engine shown in
Some examples of specific components that are envisioned as part of this invention include:
The source (item 1) may be a laser, a synchrotron, an electron beam, or another stimulus or form of energy that causes an optical signal to emanate from the sample. As part of this measurement, the source is moved along a one- or two-dimensional surface and the coordinates at any moment are transmitted to the device described here. The source could also be the sample itself for cases where the sample is emanating light naturally or as a result of other stimulus (e.g., electrical).
The hardware and firmware/software to move the source on the sample (item 2) may be one or more mirrors, prisms, lenses, liquid crystals, scanning coils, deflector plates, or other elements that may be used to move the position of the source on the sample.
The Optical Engine (item 4) may include a lightpipe or some other device that contains two or more detectors in specific positions so that the light detected at that detector corresponds to a specific range of wavelengths.
The Optical Engine may also be comprised of two or more Optical Sub-engines where each Sub-engine comprises light of a certain wavelength range.
All systems described here will be considered to incorporate direct optical coupling. As mentioned above, these may also be fiber-optically coupled or have some other form of optical coupling.
One implementation of this optical engine can be with a microscope where the source used to generate the optical signal is rastered on the surface of a sample.
Note: RO may be located after (below) the WSO.
The collection device illustrated in either the preferred or alternate embodiment may be used for the detection of Raman scattered light. In one example, this device may be used for measurements on graphene to determine the presence of single layers of graphene. Using 532 nm excitation, the G band of graphene would be observed near 1580 cm−1 and the 2D band would be observed near 2700 cm−1. For measurement of the G and 2D band with this device,
An equivalent set of filters and detectors may be used in the Alternate Embodiment for measurement of the G and 2D bands of graphene.
Other lasers may be used for this measurement—this would result in different filters being used but either the Preferred or the Alternate Embodiment can be used with a different laser.
The same design illustrate for graphene could be used for a system to measure the chemical composition of microplastic particles. As one example, a Raman system can easily be configured to measure polystyrene (PS) and polyethylene (PE). Polystyrene exhibits a very strong Raman band near 1001 cm−1 and polyethylene exhibits a strong Raman band near 1294 cm−1. Using 532 nm excitation, filters in the preferred embodiment could be used as shown below:
Additional optical elements and detectors can be added to this configuration to detect other plastics.
This same design could be used for the Raman detection and characterization of microplastics using 785 nm excitation.
This same design could be used for the Raman detection and characterization of microplastics using 1064 nm excitation.
The design in
The design in
The design in
These two species may be monitored with the device shown in
This type of detection method can also be used for fluorescence detection in a manner similar to the Raman or photoluminescence detection configurations.
Similar to the microscope configuration, the optical engine may be combined with a rastering mechanism for reflectance, scattering, transmission, or other measurements without the use of a microscope.
For reflectance, this may also be configured for measuring the reflectance or scattering off a surface such as a wall, a vehicle surface, or some other sample that is too large to be placed inside a typical scientific instrument.
This measurement configuration may be implemented with an electron microscope where the electron beam is used to generate an optical signal from the sample. The electron beam is rastered along the surface and the Optical Engine represented in
This system may use an X-ray source incident on the sample. Rastering of the X-ray source on the surface combined with the Optical Engine depicted in
This application claims priority to U.S. Provisional Patent Application 63/207,576 filed on Mar. 9, 2021.
