July 25, 2025

Night Vision: Tube types

Understanding Image Intensifier Tubes (IITs): A Comparison of 37mm ANVIS vs 43mm non-inverted PVS-7 Style tube and 43 mm G2G Tubes

Image intensifier tubes (IITs) are the heart of night vision technology, amplifying available light to produce a visible image in low-light environments. While all IITs serve the same fundamental function, their form factor and configuration can significantly impact performance, compatibility, and use-case. Let’s compare three commonly encountered designs: 37mm inverted ANVIS tubes, 43mm non-inverted PVS-7 style tubes, and 43mm "glass-in glass-out" (G2G) tubes.

1. 37mm Inverted ANVIS Tubes

Overview:
These compact tubes are primarily used in aviation and military-grade AN/AVS-6 and AN/AVS-9 systems as well as in common PVS-14 units. The term “inverted” refers to the image being flipped inside the tube, eliminating the need for additional optics to correct orientation.

Key Features:
• Inverted image output
• Compact 37mm form factor
• Lightweight and ideal for aviation or dual-tube goggles (e.g., RNVG, BNVD)
• Often used with L3 or Elbit tube assemblies

Pros:
• Smaller and lighter
• Simplifies goggle design (no need for inverting optics)
• Widely available in modern Gen 3+ tubes

Cons:
• Limited to systems designed around 37mm housing
• Typically requires dedicated optics or mounts

2. 43mm Non-Inverted PVS-7 Style Tubes

Overview:
These are the traditional image intensifiers used in legacy systems like the PVS-7 or PVS-22. The image is not inverted, so additional prisms or lenses are often required depending on the optical configuration.

Key Features:
• Non-inverted image
• Standard 43mm format
• Common in Gen 2 and Gen 3 military tubes

Pros:
• Broad compatibility with older and legacy systems
• Easy to replace or upgrade

Cons:
• Heavier and bulkier
• Requires inversion optics in some applications

3. 43mm Glass-in/Glass-out (G2G) Tubes

Overview:
The 43mm G2G IIT (Glass-to-Glass) refers to a traditional 43mm image intensifier tube that features both a glass input window and a glass output window. This style is widely used in military and civilian night vision devices Unlike inverted tubes used in ANVIS-style optics, G2G tubes output a non-inverted image, meaning optical systems may require internal image-flipping elements (prisms or lenses) depending on design.

Key Features:
• Glass input and output windows
• Non-inverted or inverted depending on configuration

Pros:
• Proven design with decades of field use
• Wide compatibility with existing systems
• Cost-effective
• Ideal for custom or high-precision builds
• Compatible with many military and civilian body kits

Cons:
• Bulkier than 37mm
• Less common in newer ultra-light systems

Conclusion
The choice between 37mm inverted, 43mm non-inverted, and 43mm G2G tubes depends largely on your platform, weight tolerance, and system compatibility:

• Go for 37mm ANVIS if you want lightweight, modern goggles or are building aviation-compatible dual-tubes.
• Choose 43mm PVS-7 if you need legacy system compatibility or are working with older housings like the PVS-7 or PVS-22.
• Opt for 43mm G2G for rugged, custom builds or high-end applications requiring modularity and inspection access.

No matter the form factor, a high-quality IIT is the core of reliable night vision performance.