Slew Scan Mode
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DLPU016C – April 2014 – Revised April 2019
Copyright © 2014–2019, Texas Instruments Incorporated
Operating the DLP NIRscan EVM
Figure 3-8. Slew Scan Screen
The Slew Scan screen provides users the ability to divide the 1350-2450nm spectral range into user
defined regions, each region with its own spectral range, exposure (integration) times, and spectral
resolutions. Non-overlapping regions from 1 to 10 can be defined. This provides unique scan methods
which enable the following use cases:
•
Wavelength Skipping:
Sometimes, the entire spectral range need not be scanned for users to identify
specific molecules within a sample. Scanning a subset of defined spectral regions of the spectral range
is all that is needed. In this case, uninteresting regions of the spectrum can be omitted in the scan by
specifying only the spectral regions of interest. Gaps between segments are allowed. Figure 3-8 shows
a Slew Scan configuration example showing how spectral regions of interest are entered in the table -
all other areas of the spectrum not entered are ignored, thereby making the scan much shorter yet still
capable of detecting the presence (or absence) of important molecules.
•
Variable Resolution:
Based on the spectrum expected for a given substance, there may be regions of
the spectrum where high digital resolution is needed, with less interesting areas requiring less
resolution. Each region in the configuration table can be configured to have different resolutions. Lower
resolutions for areas of little (expected) detail help speed up scan times.
•
Variable Integration:
Exposure (Integration) Times for each defined region can be increased or
decreased to meet user specific Signal-to-Noise Ratio (SNR) requirements. In regions which have high
absorbance, longer exposure times (averaging) may be needed to improve SNR, and in regions of low
absorbance and possibly little importance, shorter exposure times are more than adequate for
deterministic results. By decreasing exposure times for these uninteresting regions, it helps to speed
