Inside a Real PVS-14 QC Sheet: A Field by Field Walkthrough

By Bon Zhan, Founder, Night Operators
Published: July 29, 2026 | Last updated: July 29, 2026

What is a night vision QC sheet, and where did this one come from?

A QC sheet is the record a factory produces when a specific tube comes off the test bench: its measured resolution, signal-to-noise ratio, gain, sensitivity, uniformity, and a blemish count by zone, all tied to a serial number. Every real production line measures every tube this way, because tubes are graded and priced by these numbers. The data always exists. What varies is whether the seller passes it to the buyer.

The sheet at the top of this post is not a sample or a mockup. It is the actual sheet from a base-tier unit that shipped to a customer, reproduced exactly as it left the factory. We publish sheets like this because a floor claim like "FOM 1400+" is not a spec, and the only cure for floor claims is a measured document per unit. The case for why every tube deserves one is in why per-tube QC sheets matter; this post is about reading one once it is in your hands.

What does each field on the sheet mean?

Eleven entries do all the work, and the table below maps every one of them to what it measures and what to look for. The values in the second column are the real figures from the shipped sheet above.

Read together, these numbers describe one specific tube: a solid base-tier performer with a strong photocathode, an even image, and a blemish-free screen. That is a very different kind of knowledge than "FOM 1400+", which describes nothing except the worst tube a seller is willing to ship.

Does the FOM math check out?

Yes, and you should always run this check, because FOM is the one field you can audit with the sheet alone. FOM is resolution multiplied by SNR. On this sheet, 65 lp/mm times 20.33 gives about 1321, while the printed FOM reads 1301. That small gap is normal and points in the safe direction: factories compute FOM from the unrounded bench measurements before the resolution figure is rounded for printing, so the printed FOM comes out slightly conservative.

The reverse situation is the red flag. If a sheet prints a FOM higher than the printed resolution times the printed SNR, the numbers were not produced by the same measurement, and you should treat the whole document with suspicion. Thirty seconds with a calculator is the fastest authenticity test a night vision buyer has.

What do gain, sensitivity, uniformity, and cathode diameter tell you?

These four fields describe how the image gets made, while FOM describes how good it is. Luminous sensitivity (519 uA/lm here) is the front of the chain: how efficiently the photocathode turns scarce photons into electrons. It is the field where Gen 3 genuinely pulls away, and a big part of what the threefold Gen 3 price buys. At 519, this tube sits at the strong end of Gen 2+ production.

Luminance gain (8226) is the multiplication itself: how many times brighter the output screen is than the scene entering the objective. Uniformity (2.08) tells you the amplification is even, with no bright or dim patches across the field; on this sheet format, lower is better, and 2.08 is comfortably even. Useful cathode diameter (17.5mm) confirms the full image circle of the 18mm format is usable edge to edge. The resolution behind all of this has its own deeper explainer in night vision resolution in lp/mm explained. The reliability field (10,000 hours here) is the factory's rated life under bench conditions: treat it as a rating rather than a stopwatch, since real-world life depends on how often bright light hits the tube.

What is the blemish map, and which zones matter most?

The blemish map divides the image circle into three concentric zones and counts the dark spots in each, and zone 1, the center, is the one that matters most. A spot in zone 1 sits in the middle of your vision every second the device is on, which is why factory allowances are strictest there. Zone 2 is the middle ring, noticeable but easier to live with. Zone 3 is the outer edge, the most forgiving, because small marks there hide in peripheral vision.

This sheet records zero dark spots in all three zones, which is exactly what you want to see on a new tube. Small zone 3 allowances are normal in this industry and do not make a tube defective, but you deserve to know the count before you pay, not after. What different spots and artifacts actually look like through the eyepiece is covered in reading night vision tube blemishes.

What would a bad QC sheet look like?

A bad sheet announces itself in predictable ways, and most of them take under a minute to spot. The common failures: no serial number tying the sheet to a physical tube; a printed FOM larger than resolution times SNR; suspiciously round numbers in every field (real bench measurements produce values like 20.33 and 2.08, not tidy tens); a missing SNR line; no blemish map at all; or the phrase "typical values", which converts the whole document from a measurement back into marketing.

The deepest failure is the sheet that does not exist. A listing that offers a model-level spec range, or a floor like "1400+", and ships nothing measured with the unit is asking you to pay specification prices for a promise. The full pre-purchase list of what to verify, with the QC sheet as its final item, is in PVS-14: everything to check before you buy.

How do you match the sheet to your unit?

Start with the serial number: the serial printed on the QC sheet must match the serial on the tube or housing of the unit in your hands. Then confirm the basics agree with your order: tube type and phosphor (1803WB is an 18mm white phosphor Gen 2+ tube), and a FOM inside the tier you paid for. On the first dark night, look through the device at an evenly dim scene and check that what you see matches the blemish map: a clean sheet should mean a clean field of view.

That first-night routine, including how to inspect for spots without pointing the unit at bright light, is laid out step by step in how to test night vision on arrival. Five minutes of verification turns the sheet from paperwork into proof.

Frequently asked questions

What is a QC sheet in night vision?

A QC sheet is the factory quality-control record for one specific image-intensifier tube, produced when that tube is measured on a test bench before shipping. It lists the tube's measured FOM, resolution, SNR, gain, sensitivity, uniformity, and blemish counts, tied to a serial number. It documents your tube, not the model in general.

What is a good FOM on a QC sheet?

For Gen 2+ tubes, 1250 to 1400 is a solid base tier that handles most real use, 1400 to 1550 is strong, and 1800+ is top-of-class performance overlapping Gen 3 territory. The sheet in this walkthrough reads FOM 1301, comfortably inside its 1250 to 1400 tier. What matters most is that the printed FOM falls inside the range you paid for.

What does SNR mean on a night vision QC sheet?

SNR is signal-to-noise ratio: how much real image the tube delivers relative to the sparkle and grain it generates on its own. Higher SNR means a cleaner picture as light gets scarcer, and it is the half of FOM you notice most in deep darkness. Gen 2+ tubes commonly measure between 18 and 28; this sheet reads 20.33.

Which blemish zone matters most?

Zone 1, the center of the image, matters most because it sits in the middle of your vision every second the device is on. Zone 3, the outer edge, is the most forgiving since spots there hide in peripheral vision. The sheet in this walkthrough records zero dark spots in all three zones.

Why does the printed FOM not exactly equal resolution times SNR?

Because the factory calculates FOM from unrounded bench measurements before the resolution figure is rounded for printing. On this sheet, 65 lp/mm times 20.33 gives about 1321 while the printed FOM is 1301, so the printed number is the conservative one. Be suspicious of the opposite case, where the printed FOM is higher than the multiplication of the printed figures.

Do all night vision sellers provide QC sheets?

No. Most listings publish a model-level spec range or a floor claim like "FOM 1400+" and ship no per-unit measurement at all. A per-tube QC sheet with a matching serial number is the exception in this market, which is exactly why it is worth demanding before you pay.

How do I check that my QC sheet matches my unit?

Compare the serial number printed on the sheet to the serial on the tube or housing of the unit you received, then confirm the phosphor color and FOM tier match what you ordered. On the first dark night, check that the view matches the blemish map. If the serial does not match, contact the seller before going further.

What is tube type 1803WB?

It is the format designation of the tube on this sheet: an 18mm Gen 2+ image-intensifier tube with a white phosphor screen. The 18 refers to the 18mm image format used by PVS-14 pattern housings, and WB indicates white phosphor. The 17.5mm useful cathode diameter on the sheet is the full standard for this format.