Attachment_4_-_NVESD_ASP_100_dtd_20_Mar_2014.pdf

Unclassified//For Official Use Only

NVESD ASP 100

20 March 2014

NVESD Test Procedure for Advanced Signal Processing

Materials:

Incremental Gradient Thermal (IGT) Targets (2):

This test requires the use of two (2) thermal targets capable of emitting at least three (3) temperatures simultaneously, in distinct zones. The targets should have equal dimensions.

At least one of the targets should be capable of simultaneously emitting at least three temperatures in increments of no more than 0.5°C, over a range that includes 25°C. Independent closed-loop control of the temperature in each zone is desired. The temperature zones should each have equal dimensions and be arranged to contiguously demonstrate temperature transitions, in order from low to high temperature, throughout the total emitting temperature range of the IGT target. The edges of adjacent temperature zones should be of equal length, aligned, and be perceived as touching by the imaging system under test (SUT).

At least one of the targets should be capable of simultaneously emitting at least three temperatures in increments of no more than 1.0°C, over a range that includes 50°C, using the temperature zone configuration described above.

When placed side-by side, horizontally or vertically, the combined footprint of the two targets should subtend no more than 50% of the SUT’s field of view (FOV) in both dimensions, as observed while the

SUT is being operated in the optical test system. An optical test system implementing a collimating mirror is recommended.

An example of a possible IGT target design, used for feasibility demonstration of this test concept, is included in the appendix.

Low-Profile, High-Temperature (LPHT) source:

A LPTH source is required for this test. The temperature of the source should be in the 150-200°C range.

The source should subtend no more than 5% of the SUT’s FOV in either dimension, as observed in the optical test system. The LPHT source must be operated simultaneously with IGT targets, and be movable throughout the SUT’s FOV. As an example, a soldering iron would be a suitable LPTH source.

Distributed Temperature Monitoring System:

This test will require constant monitoring of all temperature zones of both IGT targets, simultaneously.

During test concept feasibility studies, a thermographic camera was demonstrated to greatly facilitate this task. Another possibility, a system of distributed thermocouples, adds the additional benefit of closed-loop temperature control capability.

Procedure:

1. Place the IGT targets at the focal point of the collimating mirror. The targets should be placed at a height corresponding to the center of the collimating mirror.

2. Designate each IGT target as either the low- or the high-temperature range IGT target.

3. Mount the SUT on the test system platform (a mounting stage with azimuth and elevation adjustment capability is recommended).

4. With SUT operating, center the pair of IGT targets in the SUT’s FOV, with no overlapping regions.

5. Adjust zone temperatures of the low-temperature range IGT target so that at least three zones are arranged in order from low to high temperature, in no larger than 0.5°C increments, with one of the zones set to 27±2°C.

6. Adjust zone temperatures of the high-temperature range IGT target so that at least three zones are arranged in order from low to high temperature, in no larger than 1°C increments, with one of the zones set to 50°C.

7. Monitor temperatures of individual zones of each IGT target for stability. Once stable, record temperatures of all zones of both IGT targets.

Figure 1 – FLIR representation of 2 (4 zone) IGT targets during test with no LPHT in the scene

8. Record 16 frames of compressed image data from the SUT with AGC engaged.

9. Turn on the LPHT source and allow stabilization at a temperature in the 150-200°C range. Once stabilized, record the temperature.

10. Place the LPHT source within the SUT’s FOV, but outside of the target area, as demonstrated in figure 2:

Figure 2 - FLIR representation of 2 (4 zone) IGT targets during test with LPHT in outside of target location

11. Record 16 frames of compressed image data from the SUT with AGC engaged.

12. Place the LPHT source directly in front of the high temperature IGT target, as demonstrated in figure 3.

Figure 3 – FLIR representation of 2 (4 zone) IGT targets during test with LPHT in front of the high temperature target

13. Record 16 frames of compressed image data from the SUT with AGC engaged.

14. Repeat Steps 12-13 for LPHT source placed i) in front of the center of the low-temperature IGT target and ii) within the SUT’s FOV, but outside the outer edge of the low-temperature IGT target.

Analysis:

For all acquired image stacks, select a 10x10 pixel2 sample centered in each temperature zone of the IGT target. The sample should be as close as possible to the center of the temperature zone without including artifacts from reticles and symbology, as in figure 4.

For each 10x10 pixel2 sample:

o Calculate and document the average signal intensity (I) of the sample area through the entire 16-frame stack.

o Determine and document the standard deviation (σ) for signal intensity for each sample area through the entire 16-frame stack.

Calculate the difference in Temperature (ΔT) between samples of adjacent temperature zones, for all neighboring pairs.

Calculate the difference in average signal (ΔI) between samples of adjacent temperature zones, for all neighboring pairs.

For each neighboring pair of temperature zones, calculate and document ΔI/σ and (ΔI/σ)/ ΔT, using the larger value of σ between the two temperature zones.

Record the number of bands resolved for both low and high-temperature IGT targets without the LPHT source in the FOV, where resolved pairs are defined to have a ΔI/σ value >1.

Test Criteria 1: Tabulate (ΔI/σ)/ ΔT values for all resolved temperature zone pairs recorded in the previous step.

o All neighboring temperature zone pairs must be resolved with (ΔI/σ)/ ΔT > 4 for the low-temperature range IGT target, when AGC is activated o All neighboring temperature zone pairs must be resolved with (ΔI/σ)/ ΔT > 2 for the high-temperature range IGT target, when AGC is activated

Repeat previous step for each of the following scenarios:

o LPHT source within the SUT’s FOV, but outside of the outside edge of the high-temperature IGT target o LPHT source in front of the center of the high-temperature IGT target o LPHT source in front of the center of the low-temperature IGT target o LPHT source within FOV, but outside of the outside edge of the low-temperature IGT target

Test Criteria 2: Tabulate (ΔI/σ)/ ΔT values for all resolved temperature zone pairs recorded in the previous step. The (ΔI/σ)/ ΔT values calculated when the LPHT is in the FOV shall not vary by more than 25% from the corresponding baseline values without the LPHT present.

Appendix

Reference Example IGT Material Design (used for test concept feasibility studies):

Two (2) Incremented Gradient Thermal (IGT) targets:

o Each target should have 4” x 4”x 0.25” dimensions.

o Each target should be milled with parallel grooves to form 4 discreet temperature zones:

Grooves should be milled at 1”, 2”, and 3” distances from one edge of the target

The milled side of the target is designated as the back surface of the target

Each groove should have a width of 0.25” at the back surface of the target and taper to a point of no more than 0.0313” width at a depth of no more than

0.0313” from the front surface of the target.

o Each temperature zone should be heated with a pair of resisters wired in series, capable of providing temperatures ranging from ambient to 50-60°C:

The resisters should be affixed to the back side of the target via thermally-conductive adhesive (e.g., Loctite 384 Adhesive/7387 Activator)

Each resistor should be capable of expending 12.0-12.5 W maximum power

(e.g., pair of 25 Ω resistors, connected in series with 35 V DC power supply).

o The front surface should be cleaned and evenly coated with flat black paint.

Optical Test System:

o Collimating mirror (120” focal length proved to be compatible with target dimensions cited above).

o Frame grabber capable of accepting both analog and digital video feed o Dage-MTI monochromatic monitor for off-line control of SUT image contrast and brightness o Thermographic camera for monitoring the IGT targets o SUT mounting stage with both azimuth and elevation adjustment capability