slmsuite.hardware.slms.meadowlark.Meadowlark

class Meadowlark(verbose=True, sdk_path='C:\\Program Files\\Meadowlark Optics\\Blink 1920 HDMI\\', lut_path=None, dx_um=8, dy_um=8, **kwargs)

Bases: SLM

Interfaces with Meadowlark SLMs.

slm_lib

Connection to the Meadowlark library.

Type

ctypes.CDLL

sdk_path

Path of the Blink SDK folder.

Type

str

Methods

close	See SLM.close().
get_coverglass_voltage	Read the voltage of the SLM coverglass.
get_temperature	Read the temperature of the SLM.
info	The normal behavior of this function is to discover the names of all the displays to help the user identify the correct display.
load_lut	Loads a voltage lookup table (LUT) to the SLM.
load_vendor_phase_correction	Loads vendor-provided phase correction from file, setting phase_correction.
point_spread_function_knm	Fourier transforms the wavefront calibration's measured amplitude to find the expected diffraction-limited perfomance of the system in "knm" space.
set_measured_amplitude_analytic	Sets measured_amplitude used for hologram generation in the absence of a proper wavefront calibration.
spot_radius_kxy	Approximates the expected radius of farfield spots in the "kxy" basis based on the near-field amplitude distribution measured_amplitude.
write	Checks, cleans, and adds to data, then sends the data to the SLM and potentially waits for settle.

__init__(verbose=True, sdk_path='C:\\Program Files\\Meadowlark Optics\\Blink 1920 HDMI\\', lut_path=None, dx_um=8, dy_um=8, **kwargs)

Initializes an instance of a Meadowlark SLM.

Caution

Meadowlark defaults to 8 micron SLM pixel size (SLM.dx_um = SLM.dy_um = 8). This is valid for most Meadowlark models, but not true for all!

Parameters

• verbose (bool) – Whether to print extra information.

• sdk_path (str) – Path of the Blink SDK folder. Stored in sdk_path.

• lut_path (str OR None) – Passed to load_lut().

• kwargs – See SLM.__init__() for permissible options.

load_lut(lut_path=None)

Loads a voltage lookup table (LUT) to the SLM. This converts requested phase values to physical voltage perturbing the liquid crystals.

Parameters

lut_path (str OR None) – Path to look for an LUT file in. If this is a .lut file, then this file is loaded to the SLM. If this is a directory, then searches all files inside the directory, and loads either the first .lut file, or if possible an .lut file starting with “slm” (which is more likely to correspond to the LUT customized to an SLM, as Meadowlark sends such files prefiexed by “slm” such as “slm5758_at532.lut”).

Raises

RuntimeError – If a .lut file is not found.

Returns

The path which was used to load the LUT.

Return type

str

static info(verbose=True)

The normal behavior of this function is to discover the names of all the displays to help the user identify the correct display. However, Meadowlark software does not currently support multiple SLMs, so this function instead raises an error.

Parameters

verbose (bool) – Whether to print the discovered information.

Raises

NotImplementedError –

close()

See SLM.close().

get_temperature()

Read the temperature of the SLM.

Returns

Temperature in degrees celcius.

Return type

float

get_coverglass_voltage()

Read the voltage of the SLM coverglass.

Returns

Voltage of the SLM coverglass.

Return type

float

load_vendor_phase_correction(file_path)

Loads vendor-provided phase correction from file, setting phase_correction. By default, this is interpreted as an image file and is padded or unpadded to the shape of the SLM. Subclasses should implement vendor-specific routines for loading and interpreting the file (e.g. Santec loads a .csv).

Parameters

file_path (str) – File path for the vendor-provided phase correction.

Returns

phase_correction, the vendor-provided phase correction.

Return type

numpy.ndarray

point_spread_function_knm(padded_shape=None)

Fourier transforms the wavefront calibration’s measured amplitude to find the expected diffraction-limited perfomance of the system in "knm" space.

Parameters

padded_shape ((int, int) OR None) – The point spread function changes in resolution depending on the padding. Use this variable to provide this padding. If None, do not pad.

Returns

The point spread function of shape padded_shape.

Return type

numpy.ndarray

set_measured_amplitude_analytic(radius, units='norm')

Sets measured_amplitude used for hologram generation in the absence of a proper wavefront calibration. FourierSLM includes capabilities for wavefront calibration via wavefront_calibrate(). This process also measures the amplitude of the source on the SLM and stores this in measured_amplitude. measured_amplitude is used for better refinement of holograms during numerical optimization. If one does not have a camera to use for wavefront_calibrate(), this method allows the user to set an approximation of the source amplitude based on an assumed \(1/e\) amplitude (\(1/e^2\) power) Gaussian beam radius.

Parameters

• radius (float) – Radius in normalized units to assume for the source Gaussian beam.

• units (str in {"norm", "nm", "um", "mm", "m"}) – Units for the given radius.

Returns

measured_amplitude.

Return type

numpy.ndarray

spot_radius_kxy()

Approximates the expected radius of farfield spots in the "kxy" basis based on the near-field amplitude distribution measured_amplitude.

Returns

Average radius of the farfield spot.

Return type

float

write(phase, phase_correct=True, settle=False)

Checks, cleans, and adds to data, then sends the data to the SLM and potentially waits for settle. This method calls the SLM-specific private method _write_hw() which transfers the data to the SLM.

Warning

Subclasses implementing vendor-specific software should not overwrite this method. Subclasses should overwrite _write_hw() instead.

Caution

The sign on phase is flipped before converting to integer data. This is to convert between the ‘increasing value ==> increasing voltage (= decreasing phase delay)’ convention in most SLMs and slmsuite’s ‘increasing value ==> increasing phase delay’ convention. As a result, zero phase will appear entirely white (255 for an 8-bit SLM), and increasing phase will darken the displayed pattern. If integer data is passed, this data is displayed directly and the sign is not flipped.

Important

The user does not need to wrap (e.g. numpy.mod(data, 2*numpy.pi)) the passed phase data, unless they are pre-caching data for speed (see below). write() uses optimized routines to wrap the phase (see the private method _phase2gray()). Which routine is used depends on phase_scaling:

• phase_scaling is one.

  Fast bitwise integer modulo is used. Much faster than the other routines which depend on numpy.mod().

• phase_scaling is less than one.

  In this case, the SLM has more phase tuning range than necessary. If the data is within the SLM range [0, 2*pi/phase_scaling], then the data is passed directly. Otherwise, the data is wrapped by \(2\pi\) using the very slow numpy.mod(). Try to avoid this in applications where speed is important.

• phase_scaling is more than one.

  In this case, the SLM has less phase tuning range than necessary. Processed the same way as the phase_scaling is less than one case, with the important exception that phases (after wrapping) between 2*pi/phase_scaling and 2*pi are set to zero. For instance, a sawtooth blaze would be truncated at the tips.

Caution

After scale conversion, data is floor() ed to integers with np.copyto, rather than rounded to the nearest integer (np.around() equivalent). While this is irrelevant for the average user, it may be significant in some cases. If this behavior is undesired consider either: write() integer data directly or modifying the behavior of the private method _phase2gray() in a pull request. We have not been able to find an example of np.copyto producing undesired behavior, but will change this if such behavior is found.

Parameters

• phase (numpy.ndarray or None) –

  Phase data to display in units of \(2\pi\), unless the passed data is of integer type and the data is applied directly.

  • If None is passed to write(), data is zeroed.

  • If the array has a larger shape than the SLM shape, then the data is cropped to size in a centered manner (unpad).

  • If integer data is passed with the same type as display (np.uint8 for <=8-bit SLMs, np.uint16 otherwise), then this data is directly passed to the SLM, without going through the “phase delay to grayscale” conversion defined in the private method _phase2gray(). In this situation, phase_correct is ignored. This is error-checked such that bits with greater significance than the bitdepth of the SLM are zero (e.g. the final 6 bits of 16 bit data for a 10-bit SLM). Integer data with type different from display leads to a TypeError.

  Usually, an exact stored copy of the data passed by the user under phase is stored in the attribute phase. However, in cases where phase_scaling not one, this copy is modified to include how the data was wrapped. If the data was cropped, then the cropped data is stored, etc. If integer data was passed, the equivalent floating point phase is computed and stored in the attribute phase.

• phase_correct (bool) – Whether or not to add phase_correction to phase.

• settle (bool) – Whether to sleep for settle_time_s.

Returns

display, the integer data sent to the SLM.

Return type

numpy.ndarray

Raises

TypeError – If integer data is incompatible with the bitdepth or if the passed phase is otherwise incompatible (not a 2D array or smaller than the SLM shape, etc).