Photon FAQs - Environmental

1. Is a protective enclosure available for Photon?

FLIR's PathFindIR product is one option. PathFindIR comprises a Photon/19mm lens in an aluminum housing that is completely sealed. The field of view is 36 degrees horizontal. A hermetic connector provides the electrical interface for input power and output video. For more information, refer to http://www.corebyindigo.com/products/core_pathFindIR.cfm. There are no PathFindIR lens options offered other than the 19mm (36-degree FOV).

There are also several FLIR Security & Surveillance products available that incorporate Photon cores into environmentally sealed systems, including the ThermoVision Integration Series (TVIS), Wide Eye, Security HD, and Sentinel. Please refer to http://www.flir.com/imaging/Security/Products/index.aspx for more information about these products.

2. Does Photon have requirements for electromagnetic interference (EMI) attenuation?

FLIR / Indigo does not make any specific claims about EMI with respect to the Photon 320 or lower resolution versions of Photon. Photon exhibits an EMI "spike" at about 290 MHz. The standard rear cover does not mitigate Photon's EMI emission.

There is an optional rear cover available for Photon 320 and lower resolution versions of Photon that, with appropriate grounding, cable shielding, and power considerations, mitigates the resulting radiated EMI emissions to near-CE class A performance levels (~0dB margin). The Photon 320 EMI Rear Enclosure Assembly part number is 500-0312-00. This accessory includes a circuit board that must be installed onto the power conditioning board, resulting in an increase to the overall camera length of about 3/8". The power dissipation of the camera increases by a negligible amount, approximately 0.05W when the EMI rear cover is installed.

Photon 640 implements EMI reduction by way of an adapter board that includes an embedded 26-pin adapter and rear cover. The Photon 640 EMI Rear Enclosure Assembly part number is 421-0028-00. This accessory includes a circuit board that is installed onto the power conditioning board, resulting in an increase to the overall camera length of about 11/32” or 1.5 cm. The power consumption of the camera with or without the EMI board depends on input voltage. As a general estimate, the EMI board uses about 50mW additional power.

The Photon 640 EMI Rear Enclosure is also required for compatibility with the Photon 640 Ethernet Module accessory.

3. Is there a good reflector for IR? Can a standard front surface mirror be used or are there other materials available?

The best choice for a reflector is a front surface gold coated mirror. The next best choice is aluminum – a common material for front surface mirrors. Other polished metals would also work, but they tend to be slightly less reflective or are prone to oxidation.

4. How do water droplets on the camera lens affect the image? Do they affect the image as much as a on a visible light range camera?

Water droplets are entirely opaque in the thermal IR. How they affect the image will depend on several factors. Lens focal length and focus position are two of the important ones after total percent of coverage. If the lens is focused at infinity, rain or water drops will be more out of focus than if the lens is focused up close. A longer focal length lens will also generally cause the droplets to be more out of focus. If the droplets are sufficiently out of focus (they should be if the lens is focused at infinity) then water drops on the lens will reduce the image contrast in proportion to the ratio of obscured area to total lens front surface area.

5. What is the mean time between failure (MTBF) for Photon?

The most recent estimate for Photon's MTBF is > 4.5 years. Specific configurations can be made that more than double the MTBF – email oem@indigosystems.com.

6. What are the detection ranges for the various Photon/lens versions?

This question has many variables that must be considered, and some of those variables are inter-related. We make some assumptions to simplify the problem, but it is important to note that this type of question (what can be seen at what distance with an particular IR camera system) is typically approached in terms of target detection, recognition & identification ranges, along with an associated probability of success. Typically the result will be communicated in terms of a percentage probability of a particular target being detected, recognized and identified and certain ranges. There is a standard set of conditions regarding targets and defined meaning for the results that allows some simple test measurements to be fed into models that provide range outputs. Where applicable, our assumptions are consistent with standard range modeling.

We have compiled two charts that provide the nominal detection, recognition, and identification ranges for the different Photon versions. One chart is based on a person-sized object the other on a 2.3 meter vehicle-sized object.

1) Detection, Recognition, & ID of Human Target
2) Detection, Recognition, ID of 2.3m Vehicle

7. What is the Digital Detail Enhancement (DDE) filter?

DDE is basically a spatial filter designed to enhance the high spatial frequencies (edges etc.) and appears as boosted lens MTF. The DDE filter attenuates high amplitude signals, making more of the total dynamic range available to display faint objects and details. The amount of attenuation is automatically determined by analyzing scene statistics.

Enabling, disabling, and adjusting DDE can be accomplished by the user via the Photon GUI or by serial command to the camera. Experimentation may be necessary to see if or how much DDE is beneficial to a particular application.

Photon cameras with software versions prior to 2.2 (i.e., most cameras delivered prior to 2008) have factory-set DDE values that may not be optimal. Specifically, if the DDE values are too high in certain scene situations, the image may appear to exhibit a noticeable amount of fixed-pattern noise. We recommend resetting the Filter Gain value to 16 (not higher) and the Spatial Control value to 4, then save the changed values by clicking the "Set" button. Next, save the camera settings by clicking the Save settings button under the Camera tab. Try these new settings for awhile and adjust them as necessary to see if any improvement results.

8. What is the occasional clicking sound made by the camera? What is FFC?

There is a shutter between the camera lens and the sensor package. This shutter is used to perform a flat-field correction, or FFC. During FFC, the shutter presents a uniform temperature source to each detector element in the array. While imaging the flat-field source, the camera updates the offset correction coefficients, resulting in a more uniform image after the process is complete.

The FFC process takes 0.7 second for all Photon camera versions. While the shutter is in the field of view of the sensor, the image just prior to the shutter moving is frozen and displayed until the FFC process finishes and the shutter moves out of the field of view of the sensor. A faint click is produced when the shutter moves in front of the sensor.

When power is applied to the Photon camera, two mandatory shutter events occur: one within 2 seconds of startup; the other within 6 seconds after the first shutter. Photon cameras are normally configured at the factory to automatically FFC at a specified interval following the initial two shutter events. The FFC interval is based on time and camera temperature. Except for the initial two shutter events, the FFC interval parameters can be modified by the user via the GUI or by serial command to the camera. An FFC can be performed on command by the user, regardless of whether the FFC is in the automatic mode or not.

Photons delivered beginning in 2008 have an option, via the GUI or by serial command to the camera, to allow the user to perform an FFC through the lens, using a uniform source or background. The shutter is disabled when an external FFC is performed. An external FFC can help to reduce the effects of non-uniformities and image artifacts inherent in the lens.

9. Can the Photon camera be pointed at the sun?

We do not recommend intentionally viewing the sun, but looking at the sun will not permanently damage the sensor. It will, however, take some time for the camera to recover. The amount of time needed for recovery will depend on how long the camera was exposed to the sun. The longer the exposure, the longer the recovery time needed.

10. Should I clean the Photon lens, and how?

A light dusting of air should be enough to dislodge any dust particles, although small amounts of dust will not affect image quality noticeably. The antireflection coating on the germanium optics is easily scratched and the lens should only be cleaned according to the following procedure: If it is absolutely necessary to clean the lens surface, use 75% isopropyl alcohol and lens tissue, and use extremely light wiping motions. Use a fresh section of tissue with each swipe so as not to drag a piece of dirt back over the lens surface.

11. Does Photon meet any military environmental specifications or requirements?

Photon is intended as a thermal imaging camera core for integration into higher-level systems. It is not sealed, and therefore not IP-rated. Photon is much better resistant to shock and vibration than its predecessor (Omega / Micron / A10) due to its superior design, which uses two discrete PCBs rather than a flex cable. Many thousands of Photon cores are used in automotive applications as a nighttime driving aid. The environmental requirements imposed by automobile manufacturers are generally far more stringent than for military systems. Many more thousands of Photons are used as thermal imaging payloads in small unmanned vehicles used by the military, which frequently crash-land. We have been told by our customers that Photons experience forces of hundreds and in some cases thousands of G’s, yet in most cases keep on working well beyond the product design specifications. We think these are the best testimonials to the ruggedness and reliability of Photon. FLIR uses the term “commercially-developed, military-qualified” (CDMQ) to define such use. Positioning Photon as a CDMQ product helps FLIR keep Photon prices low, because to MIL-qual any product adds cost which has to be passed on to customers that require it.

12. What Power density will saturate the pixels on the Photon camera?

This question typically comes up in the context of illuminating the Photon camera with a laser source. The answer provided assumes the source is CW, and NOT pulsed. The Photon camera’s pixels will saturate at approximately 1E-7 Watts (0.1 µW) per pixel at the FPA. This is a typical value for room temperature operation in the camera’s default operating mode, and will vary depending on parameters such as sensor operating temperature as well as the responsivity of a specific sensor.

For pulsed laser applications, the amount of energy applied to the pixel over a readout frame period to achieve saturation will be significantly less than 1E-7 Watts (0.1µW) *3.3E-3 seconds = 3.3E-9 joules, assuming that the applied energy arrives over a time period significantly less that the thermal time constant of roughly 2.0E-2 seconds (20ms).

13. What material is used for the Photon 320 sensor window? Does the window have an anti-reflection (A/R) coating? Can I use a Photon 320 to image below 8µ?

The sensor window used in the Photon 320 camera is silicon, and yes, it has an A/R coating. Without an A/R coating, the responsivity (sensitivity) of the sensor would be significantly degraded, as the transmission of a bare silicon window is about 50% across the IR spectrum. The A/R coating we use has an integral Long Pass (Solar Blocking) filter. This filter suppresses transmission below 7µ. For customers that want to image below 8µ, the coating will be an inhibitor.

The microbolometer structure itself is “tuned” for the LWIR (8µ to 14µ) part of the spectrum, so even with a broadband A/R coating the sensor’s sensitivity would be degraded below 8µ.

Photon FAQs - Environmental Questions