Apparatus for wavelength resolved angular resolved cathodoluminescence
Apparatuses for collection of wavelength resolved and angular resolved cathodoluminescence (WRARCL) emitted from a sample exposed to an electron beam (e-beam) or other excitation beams are described. Cathodoluminescence light (CL) may be emitted from a sample at specific angles relative to the excitation beam and analyzed with respect to light-emitting and other optical phenomena. The described embodiments allow collection of WRARCL data more efficiently and with significantly fewer aberrations than existing systems.
1. An apparatus for collection and analysis of wavelength-resolved and angle-resolved cathodoluminescence light (CL) comprising:
a spectrograph;
a collection-mirror arranged such that CL light collected by said collection-mirror forms a two-dimensional light-pattern representing light intensity as a function of angles of emission of the CL light;
where said collection-mirror has a symmetric axis and an asymmetric axis; and
a slit onto which said two-dimensional light pattern is projected, said slit being arranged to permit only a narrow range of said two-dimensional light pattern to be coupled into said spectrograph;
where said slit is oriented to pass light along said asymmetric axis; and
wherein said light-pattern is scanned over said slit along said symmetric axis to collect a wavelength-resolved and angle-resolved CL light dataset.
2. The apparatus of claim 1 , further comprising a translating fold-mirror arranged to scan said two-dimensional light pattern over said slit.
3. A method for collection and analysis of wavelength-resolved and angle-resolved cathodoluminescence light (CL) from a specimen comprising:
exposing the specimen to a high energy charged particle beam to produce CL light from the specimen;
collecting said CL light with a collection-mirror to form a two-dimensional light-pattern representing light intensity as a function of angles of emission of the CL light, said collection-mirror having a symmetric axis and an asymmetric axis;
projecting said two-dimensional light pattern is onto a slit, said slit being arranged to permit only a narrow range of said two-dimensional light pattern to be coupled into a spectrograph,
wherein said slit is oriented to pass light along said asymmetric axis; and
scanning said light pattern over said slit along said symmetric axis to collect a wavelength-resolved and angle-resolved CL light dataset.
4. The method of claim 3 , wherein said scanning of said light pattern is performed by translating a fold mirror.
5. A system for collection and analysis of wavelength-resolved and angle-resolved cathodoluminescence light (CL) from a specimen comprising:
a high energy charged particle source arranged to expose the specimen to a high energy charged particle beam to produce CL light from said specimen;
a spectrograph;
a collection-mirror arranged such that CL light collected by said collection-mirror forms a two-dimensional light-pattern representing light intensity as a function of angles of emission of the CL light;
where said collection-mirror has a symmetric axis and an asymmetric axis; and
a slit onto which said two-dimensional light pattern is projected, said slit being arranged to permit only a narrow range of said two-dimensional light pattern to be coupled into said spectrograph;
where said slit is oriented to pass light along said asymmetric axis; and
wherein said light-pattern is scanned over said slit along said symmetric axis to collect a wavelength-resolved and angle-resolved CL light dataset.
6. The system of claim 5 , further comprising a translating fold-mirror arranged to scan said two-dimensional light pattern over said slit.