2.3.3.3.49. NXbeam_path

Status:

base class, extends NXobject

Description:

A beam path consisting of one or more optical elements. ...

A beam path consisting of one or more optical elements.

NXbeam_path is used in NXopt to describe the beam path, i.e. the arrangement of optical elements between the excitation source and the sample, or between the sample and the detector unit.

To describe the order of the elements, use ‘order(NXtransformations)’, where each element’s position points to the preceding element via ‘@depends_on’. Special case beam splitter: A beam splitter is a device which separates the beam into two or more beams. If such a device is part of the beam path use two or more NXbeam_paths to describe the beam paths after the beam splitter. In this case, in the dependency chain of the new beam paths, the first elements each point to the beam splitter, as this is the previous element.

Describe the relevant optical elements in the beam path by using the appropriate base classes. You may use as many elements as needed, also several elements of the same type as long as each element has its own name.

Symbols:

No symbol table

Groups cited:

NXaperture, NXattenuator, NXbeam_splitter, NXdisk_chopper, NXfiber, NXfilter, NXgeometry, NXgrating, NXlens_opt, NXmirror, NXmonochromator, NXpinhole, NXpolarizer_opt, NXslit, NXsource, NXtransformations, NXwaveplate, NXxraylens

Structure:

depends_on: (optional) NX_CHAR

Entry point of the dependency chain defined by the NXtransformations ...

Entry point of the dependency chain defined by the NXtransformations field, i.e. a link to the last element in the beam path. Example: /entry/instrument/beam_path/detector.

TRANSFORMATIONS: (optional) NXtransformations

Specify the order of the optical elements by defining a dependency chain. ...

Specify the order of the optical elements by defining a dependency chain. For each element, a ‘@depends_on’ attribute should be used to state the position of the element in the beam path by pointing to the previous element. For the very first element, use the string “.” instead.

AXISNAME: (optional) NX_NUMBER {units=NX_TRANSFORMATION} ⤆

For each element in the beam path, one such field must exist with a ...

For each element in the beam path, one such field must exist with a ‘@depends_on’ attribute defined to specify its position in the beam path. Note that also ‘NXopt/ENTRY/INSTRUMENT/sample_stage’ and windows (‘NXopt/ENTRY/INSTRUMENT/sample_stage/entry_window’ and ‘NXopt/ENTRY/INSTRUMENT/sample_stage/exit_window’) may be added to the dependency chain, i.e. may have an entry in this class even if they are not described in the beam path. ELEMENT is a place holder for the name of an optical beam path element. Note that the name of this field must be exactly the same as the element’s field name.

@depends_on: (optional) NX_CHAR ⤆

Add a link to the previous beam path element.

SOURCE: (optional) NXsource

Excitation source. One or more may be needed (e.g. two for a pump-probe ...

Excitation source. One or more may be needed (e.g. two for a pump-probe setup with one pump and one probe beam). Depending on the source type, different properties are relevant, which are provided through the respective base class (e.g. use NXopt_source for lamps or lasers, NXchem_source for chemical reaction etc.). Some base classes are incomplete (NXchem_source, NXbio_source); the expertise of the respective communities is needed.

depends_on: (optional) NX_CHAR ⤆

Use this field to point to the previous optical element.

type: (optional) NX_CHAR ⤆

Type of excitation source. ...

Type of excitation source.

Any of these values:

  • semiconductor laser

  • gas laser

  • other laser

  • lamp

  • X-rays

  • silicon carbide globar

  • super continuum

  • chemical reaction

  • ultrasound

  • sound

  • living organism

  • power supply

  • electron source

  • other

lifespan: (optional) NX_NUMBER {units=NX_TIME}

Lifespan of the excitation (typically provided in hours).

measure_time: (optional) NX_NUMBER {units=NX_TIME}

How many hours has the lamp been used?

excitation_wavelength: (optional) NX_FLOAT {units=NX_ANY}

Wavelengths or energy vector of the excitation source. This can be a ...

Wavelengths or energy vector of the excitation source. This can be a single value or a spectrum, depending on the type of experiment.

@units: (optional) NX_CHAR

Unit of wavelength or energy.

beam_profile: (optional) NX_CHAR (Rank: 2, Dimensions: [N_beam_profile_dim, N_beam_profile_points])

Two- or three-dimensional beam profile.

peak_power: (optional) NX_FLOAT {units=NX_POWER} ⤆

Power of one light pulse if the source is a pulsed source.

cw: (optional) NX_BOOLEAN

Is the excitation source continuous wave (CW)?

cw_power: (optional) NX_FLOAT

Power of CW beam.

bandwidth: (optional) NX_FLOAT {units=NX_WAVELENGTH}

FWHM bandwidth of the excitation source.

coherence_length: (optional) NX_FLOAT {units=NX_LENGTH}

Coherence length.

divergence: (optional) NX_FLOAT {units=NX_ANGLE}

Divergence of the excitation beam.

PINHOLE: (optional) NXpinhole

Use this field to describe a simple pinhole (round geometry). Define its ...

Use this field to describe a simple pinhole (round geometry). Define its dimension using ‘diameter’. For more complex geometries, ‘NXaperture’ should be used.

SLIT: (optional) NXslit

Use this field to describe a simple slit (rectangular geometry). Define ...

Use this field to describe a simple slit (rectangular geometry). Define its dimensions using ‘x_gap’ and ‘y_gap’. For more complex geometries, ‘NXaperture’ should be used.

aperture_NUMBER: (optional) NXaperture

Use this field to describe an aperture. To specify a window, use the ...

Use this field to describe an aperture. To specify a window, use the field ‘window_NUMBER(NXaperture)’.

window_NUMBER: (optional) NXaperture

A window, e.g. an entry or exit window of a cryostat.

depends_on: (optional) NX_CHAR ⤆

Use this field to point to the previous optical element.

material: (optional) NX_CHAR ⤆

The material of the window. ...

The material of the window.

Any of these values:

  • quartz

  • diamond

  • calcium fluoride

  • zinc selenide

  • thallium bromoiodide

  • alkali halide compound

  • Mylar

  • other

other_material: (optional) NX_CHAR

If you specified ‘other’ as material, decsribe here what it is.

thickness: (optional) NX_FLOAT {units=NX_LENGTH}

Thickness of the window

orientation_angle: (optional) NX_FLOAT {units=NX_ANGLE}

Angle of the window normal (outer) vs. the substrate normal ...

Angle of the window normal (outer) vs. the substrate normal (similar to the angle of incidence).

reference_data_link: (optional) NX_CHAR

If reference data were measured add a link to the NeXus file where they ...

If reference data were measured add a link to the NeXus file where they are described.

MIRROR: (optional) NXmirror

filter_NUMBER: (optional) NXfilter

ATTENUATOR: (optional) NXattenuator

A device that reduces the intensity of a beam by attenuation.

attenuator_transmission: (optional) NX_FLOAT {units=NX_DIMENSIONLESS} ⤆

The transmitted intensity divided by the incident intensity.

attenuation: (optional) NX_FLOAT {units=NX_ANY}

Attenuation of the attenuator in dB.

@units: (optional) NX_CHAR

Unit of the measured data is not covered by NXDL units state ...

Unit of the measured data is not covered by NXDL units state here which unit was used.

APERTURE: (optional) NXaperture

Input and output aperture of the attenuator.

GEOMETRY: (optional) NXgeometry

Geometry (shape, size etc.) of the attenuator.

GRATING: (optional) NXgrating

A diffraction grating. Define relevant parameters in the corresponding ...

A diffraction grating. Define relevant parameters in the corresponding fields, e.g. order of diffration (diffraction_order) or angular dispersion (angular_dispersion).

type: (optional) NX_CHAR

Define the type of the grating.

angular_dispersion: (optional) NX_FLOAT {units=NX_UNITLESS}

Dispersion of the grating in nm/mm (or e.g. nm/mrad).

grooves: (optional) NX_FLOAT {units=NX_PER_LENGTH}

Number of grooves per mm.

blaze_wavelength: (optional) NX_FLOAT {units=NX_WAVELENGTH}

Blaze wavelength of the grating.

efficiency: (optional) NX_FLOAT (Rank: 1, Dimensions: [N_spectrum]) {units=NX_UNITLESS}

Efficiency curve versus wavelength or energy.

spectrum: (optional) NX_FLOAT {units=NX_ANY}

Spectral values, e.g. wavelength or energy. Vector of length ...

Spectral values, e.g. wavelength or energy. Vector of length N_spectrum.

@units: (optional) NX_CHAR

Unit of wavelength array (e.g. nanometer or Angstrom)

DISK_CHOPPER: (optional) NXdisk_chopper

A device blocking the beam in a temporal periodic pattern, e.g. a optical ...

A device blocking the beam in a temporal periodic pattern, e.g. a optical chopper wheel. Specify the frequency range using ‘min_frequency’ and ‘max_frequency’.

min_frequency: (optional) NX_FLOAT {units=NX_FREQUENCY}

Minimum frequency in Hertz.

max_frequency: (optional) NX_FLOAT {units=NX_FREQUENCY}

Maximum frequency in Hertz.

frequency_resolution: (optional) NX_FLOAT {units=NX_FREQUENCY}

Frequency resolution in Hertz.

MONOCHROMATOR: (optional) NXmonochromator

A monochromator or spectrometer.

spectrum: (optional) NX_FLOAT {units=NX_ANY}

Spectral values of the monochromator, e.g. wavelength or energy values ...

Spectral values of the monochromator, e.g. wavelength or energy values used for the measurement.

@units: (optional) NX_CHAR

Unit of wavelength array (e.g. nanometer or Angstrom)

spectral_resolution: (optional) NX_FLOAT {units=NX_WAVENUMBER}

Spectral resolution of the instrument.

GRATING: (optional) NXgrating ⤆

Diffraction grating. If two or more gratings were used, define the ...

Diffraction grating. If two or more gratings were used, define the angular dispersion and the wavelength range (min/max wavelength) for each grating and make sure that the wavelength ranges do not overlap. The dispersion should be defined for the entire wavelength range of the experiment.

angular_dispersion: (optional) NX_FLOAT {units=NX_DIMENSIONLESS}

Dispersion of the grating in nm/mm.

grating_wavelength_min: (optional) NX_FLOAT {units=NX_WAVELENGTH}

Minimum wavelength of the grating.

grating_wavelength_max: (optional) NX_FLOAT {units=NX_WAVELENGTH}

Maximum wavelength of the grating.

SLIT: (optional) NXslit

Define the width of the monochromator slit in the subfield x_gap.

fixed_slit: (optional) NX_BOOLEAN

Was the slit width fixed?

max_gap: (optional) NX_FLOAT {units=NX_LENGTH}

If slit width was not fixed, define the maximum slit width.

XRAYLENS: (optional) NXxraylens

POLARIZER_OPT: (optional) NXpolarizer_opt

BEAM_SPLITTER: (optional) NXbeam_splitter

WAVEPLATE: (optional) NXwaveplate

LENS_OPT: (optional) NXlens_opt

FIBER: (optional) NXfiber

Hypertext Anchors

List of hypertext anchors for all groups, fields, attributes, and links defined in this class.

NXDL Source:

https://github.com/FAIRmat-NFDI/nexus_definitions/tree/fairmat/contributed_definitions/NXbeam_path.nxdl.xml