Model 871A User’s Manual USING THE LASER WAVELENGTH METER
Bristol Instruments, Inc. 25
Due to the time varying incident power on the detector from a pulsed laser,
Adjust Frame Rate can only be used when the Laser Type is set to CW
mode. This function is disabled (grayed out) in Pulsed mode. Click to select.
• Auto Exposure – Adjusts the exposure time of the instrument’s detector for
optimal signal intensity. When Auto Exposure is selected, the NuView
software chooses an exposure time that maintains the current Frame Rate
setting and illuminates the detector at approximately 50-75% saturation.
Auto Exposure can only be used when the Laser Type is set to Pulsed. Auto
Exposure is disabled (grayed out) in CW mode. Auto Exposure is turned on
by clicking the menu item. This places a check mark next to Auto Exposure.
Auto Exposure is turned off by clicking the menu item a second time.
Note: When Auto Exposure is turned off the unit will hold the last set
exposure time. To re-enable the maximum exposure time, enter the desired
frame rate using the Settings dialog.
• Settings – This function controls the settings that the 871 system uses to
capture wavelength measurements.
– Input Laser Type – Determines which wavelength measurements the
NuView software reports. Select the Input Laser Type from the drop-
down menu and click OK.
- Pulsed – When enabled, the NuView software reports and records
all wavelength values that reach the minimum detector intensity
requirement during the measurement window. Any measurement
window that does not receive sufficient intensity is discarded. This
enables the NuView software to report the wavelength of individual
pulses for low repetition lasers.
Note: To ensure that the NuView software captures each laser
pulse, the user should choose a higher Frame Rate than the
repetition rate of the laser under test. The NuView software then
reports and records wavelength values at the repetition rate of the
laser, up to the maximum available Frame Rate.
- CW – When enabled, the NuView software reports and records all
wavelength measurements at the chosen frame rate, for all
measurement windows, regardless of the intensity on the detector.
• Trigger Method – Controls the event that prompts the 871 system to
start recording a measurement. The wavelength values that the NuView
software reports and records depend on the Input Laser Type defined
above.
When set in Internal Trigger mode, the number of measurements per
second will correspond to the Frame Rate. When in External Rising or
External Falling trigger mode, a measurement is initiated at the rising or
falling edges (respectively) of a user-defined input. The External triggers
are explained in greater detail in Chapter 5.
Once a measurement has been triggered, the NuView software reports
and records wavelength values based on the Input Laser Type. When
Pulsed Mode is enabled, the NuView software reports and records all
wavelength values that reach the minimum detector intensity
requirement during the measurement window. Any measurement window
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