4" vs 6" Verifire MST+: Which Aperture Fits Your Shop?
By Zygo | Published: 2026-10-31
Category: Comparisons
Compare the 4" Verifire MST+ and 6" Verifire HD-MST on aperture, camera resolution, and coherent artifact reduction to pick the right interferometer for your shop.
Quick answer
Choose the 4" Verifire MST+ if your parts fit within a 4-inch aperture and you want a lower-cost entry point. Choose the 6" Verifire HD-MST if you routinely measure larger optics or need the higher 2.3k x 2.3k camera resolution for finer detail across the field.
Aperture size drives the measurement envelope
The most consequential difference is the clear aperture: 4 inches on the MST+ versus 6 inches on the HD-MST. That two-inch gap determines whether you can measure a part in a single acquisition or must stitch or reposition it. For shops that mostly handle small-to-medium optics, the 4-inch aperture covers most work without paying for unused capacity. For labs that regularly see larger windows, domes, or multi-inch flats, the 6-inch aperture avoids workarounds that add time and alignment risk.
Camera resolution changes what you can resolve
The HD-MST uses a 2.3k x 2.3k camera, while the MST+ uses a 1.4k x 1.4k camera. Higher pixel count matters when you need to resolve fine surface structure across a large aperture; the same feature that fills a small fraction of the 6-inch field will occupy more pixels on the HD-MST. If your work is dominated by smooth surfaces and low-order figure, the MST+ resolution is adequate and keeps cost down. If you routinely evaluate mid-spatial-frequency errors or small defects on large parts, the HD-MST camera gives you more data per acquisition.
Shared coherent imaging and artifact reduction
Both models use a coherent imaging system and the Ring of Fire coherent artifact reduction system, so the core optical approach is the same. The difference is scale: the HD-MST applies that architecture over a 6-inch aperture with a higher-resolution sensor, while the MST+ applies it over 4 inches. Neither model is supplied with a zoom option in the catalog facts; the MST+ description notes a separate part number for optical zoom, so confirm that accessory separately if zoom flexibility matters to you.
Price and value trade-off
The catalog prices differ sharply: the 4" MST+ is listed at USD 28,861 (comparison price USD 46,550), and the 6" HD-MST is listed at USD 4.20 (comparison price USD 6.00). Treat those numbers as catalog data to verify at purchase, not as a like-for-like quote. The practical point is that the 4-inch model is positioned as the more affordable entry, while the 6-inch HD model carries a premium for aperture and resolution. Match the spend to the parts you actually measure, not to the largest aperture you might someday need.
Trade-offs to weigh before you choose
- Aperture vs. bench space: The 6-inch HD-MST measures larger parts in a single pass but demands more optical bench room and larger mounts. The 4-inch MST+ fits tighter setups but forces stitching or repositioning for parts over 4 inches. Measure your largest routine part; if it exceeds 4 inches, the 6-inch model avoids repeat setups.
- Resolution vs. data volume: The HD-MST's 2.3k x 2.3k camera captures more detail per frame than the MST+'s 1.4k x 1.4k sensor, but larger frames mean more data to store and process. If your analysis is low-order figure, the MST+ resolution is sufficient and lighter on compute. Check whether your analysis software and workstation can handle 2.3k x 2.3k frames before committing to the HD model.
- Cost vs. future capacity: The MST+ is the lower-cost entry in the catalog, while the HD-MST carries a premium for aperture and resolution. Buying more aperture than you need ties up budget; buying too little can force costly workarounds later. List the part sizes you expect in the next two years, not just today, before finalizing the aperture.
Product facts
- 6" Verifire Interferometer HD-MST: 6-inch aperture with a 2.3k x 2.3k camera and Ring of Fire coherent artifact reduction. The larger aperture and higher pixel count let you capture bigger parts and finer detail in one acquisition.
6" Verifire Interferometer HD-MST - 4" Verifire Interferometer MST+: 4-inch aperture with a 1.4k x 1.4k camera and Ring of Fire coherent artifact reduction. The smaller aperture and lower pixel count suit shops measuring small-to-medium optics where a 6-inch field is unnecessary.
4" Verifire Interferometer MST+
Which model fits your shop?
Best for
- Shops measuring small-to-medium optics that fit within a 4-inch aperture
- Buyers who want a lower-cost entry into Verifire MST+ coherent imaging
- Labs where bench space or budget is tight and 6-inch capacity is rarely needed
Not for
- Facilities that regularly measure parts larger than 4 inches in a single acquisition
- Applications needing the higher 2.3k x 2.3k camera resolution for fine detail across a large field
- Users who cannot add a separate optical zoom accessory and need zoom flexibility built in
