Connecting to Bristol 771 by Bristol in Python
Instrument Card
The 771 Series Laser Spectrum Analyzer combines proven Michelson interferometer technology with fast Fourier transform analysis resulting in a unique instrument that operates as both a high-resolution spectrum analyzer and a high-accuracy wavelength meter.
Device Specification: here
Manufacturer card: BRISTOL
Bristol Instruments’ Wavelength Meters Are For Scientists And Engineers. Precise laser wavelength measurement and complete spectral analysis. Reliable accuracy.
- Headquarters: USA
- Yearly Revenue (millions, USD): 7.1
- Vendor Website: here
Connect to the Bristol 771 in Python
PROTOCOLS > SCPI
Based on the provided code, it seems that the Bristol 721 Spectrum Analyzer is supported by the Instrumental library. However, there is no specific support for the Bristol 771 Spectrum Analyzer mentioned in the code.
To connect to a Bristol 771 Spectrum Analyzer using Instrumental, you would need to modify the existing code or create a new driver specifically for the Bristol 771 model. This would involve understanding the communication protocol and commands required to interact with the device.
Here is an example of how you can modify the existing code to connect to a Bristol 771 Spectrum Analyzer:
# -*- coding: utf-8 -*-# Copyright 2014-2017 Nikolas Tezak, Nate Bogdanowicz"""Driver for Bristol 771 spectrum analyzers."""import osimport sysfrom contextlib import contextmanagerfrom functools import wrapsimport ctypesimport numpy as npfrom numpy.ctypeslib import ndpointer
from . import Spectrometerfrom .. import ParamSetfrom ... import u
_INST_PARAMS = ['port']_INST_CLASSES = ['Bristol_771']
bristol_dll = ctypes.WinDLL("BristolFFT.dll", use_errno=True, use_last_error=True)bristol_lv_dll = ctypes.WinDLL("BristolLV.dll", use_errno=True, use_last_error=True)
# Set DLL function signaturesfind_comm_port = bristol_lv_dll.CLFindBristolCommPortfind_comm_port.restype = ctypes.c_int
open_device = bristol_dll.CLOpenUSBSerialDeviceopen_device.argtypes = [ctypes.c_int]open_device.restype = ctypes.c_int
get_lambda = bristol_dll.CLGetLambdaReadingget_lambda.argtypes = [ctypes.c_int]get_lambda.restype = ctypes.c_double
bristol_dll.CLGetPowerReading.argtypes = [ctypes.c_int]bristol_dll.CLGetPowerReading.restype = ctypes.c_float
bristol_lv_dll.CLGetNextSpectrum.argtypes = [ ctypes.c_int, ndpointer(np.float32, ndim=1, flags='C_CONTIGUOUS'), ndpointer(np.float32, ndim=1, flags='C_CONTIGUOUS'), ctypes.c_int]
# Adapted from <http://stackoverflow.com/a/17954769>@contextmanagerdef stderr_redirected(to=os.devnull): fd = sys.stderr.fileno()
def _redirect_stderr(to): sys.stderr.close() os.dup2(to.fileno(), fd) sys.stderr = os.fdopen(fd, 'w')
with os.fdopen(os.dup(fd), 'w') as old_stderr: with open(to, 'w') as file: _redirect_stderr(to=file) try: yield finally: _redirect_stderr(to=old_stderr)
# Decorator for redirecting stderr to /dev/null for the function's durationdef ignore_stderr(f): @wraps(f) def wrapper(*args, **kwargs): with stderr_redirected(): return f(*args, **kwargs) return wrapper
# Table obtained from Bristol technical supportFFT_INFO = { ('VIS', 0): (131072, 1, 3, 350, 421), ('VIS', 1): (131072, 1, 2, 423, 632), ('VIS', 2): (131072, 1, 1, 632, 1100), ('NIR', 0): (131072, 1, 2, 500, 632), ('NIR', 1): (131072, 1, 1, 633, 1265), ('NIR', 2): (32768, 4, 3, 1266, 1685), ('IR', 0): (65536, 1, 0, 1266, 5000), ('MIR', 0): (32768, 5, 1, 4000, 6329), ('MIR', 1): (16384, 9, 1, 5700, 11000), ('XIR', 0): (131072, 1, 0, 1500, 12000),}
def bin_index(fft_size, dec, fold, lamb): if fold % 2 == 0: bin = ((2*dec*632.9914)/lamb - fold) * fft_size else: bin = (fold + 1 - (2*dec*632.9914)/lamb) * fft_size return bin
class Bristol_771(Spectrometer): def _initialize(self): self._com_port = self._paramset.get('port') or find_comm_port() self._dll = bristol_dll self._lv = bristol_lv_dll self._handle = open_device(self._com_port)
if self._handle < 0: raise Exception("Failed to open connection to spectrum analyzer") elif self._handle == 0: raise Exception("You must have already opened the port")
self._lv.CLRegister(self._handle)
# Hard-coded for now, ideally we'd auto-detect this via a model byte or something self._model = 'IR' self._range_num = 0
def _fft_range(self): fft_size, dec, fold, low_wav, hi_wav = FFT_INFO[(self._model, self._range_num)] low_index = bin_index(fft_size, dec, fold, low_wav) high_index = bin_index(fft_size, dec, fold, hi_wav) if low_index > high_index: low_index, high_index = high_index, low_index return int(low_index+1), int(high_index-1) # Exclude edge of the range to be safe
def get_wavelength(self): """Get the vacuum wavelength of the tallest peak in the spectrum
Returns ------- wavelength : Quantity The peak wavelength, in nm """ return self._dll.CLGetLambdaReading(self._handle) * u.nm
def get_spectrum(self): """Get a spectrum.
Returns ------- x : array Quantity Wavelength of the bins, in nm y : array Power in each bin, in arbitrary units """ start, stop = self._fft_range() size = stop-start self._dll.CLGetFullSpectrum(self._handle, start, stop)
wavenumber = np.zeros(size, np.float32) power = np.zeros(size, np.float32)
ret = 0 while not ret: ret = self._lv.CLGetNextSpectrum(self._handle, power, wavenumber, size)
# For some reason, x is not sorted already... indices = np.argsort(wavenumber) return 1e10/wavenumber[indices] * u.nm, power[indices] # Is this scaling right?
def close(self): self._dll.CLCloseDevice(self._handle)
def list_instruments(): com_ports = [find_comm_port()] # TODO: Add support for multiple connected devices return [ParamSet(Bristol_771, port=port) for port in com_ports]Please note that this modified code assumes that the Bristol 771 Spectrum Analyzer uses the same communication protocol and commands as the Bristol 721 model. If this is not the case, you would need to modify the code accordingly to support the specific commands and communication protocol of the Bristol 771 model.