Mitutoyo M Plan Apo 20x Objective (NA 0.42, WD 20mm, Infinity, M26)

The Mitutoyo M Plan Apo 20× Objective is a plan apochromat objective from Mitutoyo’s M Plan Apo series — delivering 20× magnification with an exceptional 20mm working distance and plan apochromat correction optimized for visible light. The apochromatic optical design provides a flat, chromatic-aberration-free image for accurate color rendering, making this objective an ideal choice for metallurgical examination, semiconductor inspection, and any industrial application requiring true-color imaging at intermediate magnification with extended working clearance.

• 📏 Long working distance: 20mm — exceptional clearance for a 20× objective, providing ample room for specimens in environmental chambers, cryostats, vacuum systems, industrial fixtures, and laser processing setups where standard objectives cannot reach
• 🔬 NA 0.42, 0.7µm resolving power — practical numerical aperture for a long working distance 20× objective, delivering sub-micron resolution for detailed surface inspection, grain structure analysis, and feature measurement
• 🌟 Plan apochromat (M Plan Apo) correction — Mitutoyo’s highest level of chromatic and spherical aberration correction for accurate, flat-field imaging with true color rendering across the full visible spectrum — essential for metallographic examination and color-based defect analysis
• 🔍 1.2mm field of view (×24 eyepiece) — practical field coverage for intermediate-magnification survey and inspection, bridging the gap between wide-area 5×/10× overview and high-magnification 50×/100× detail
• 💡 Visible light optimized — the standard visible-light version of the M Plan Apo 20×; for NIR/SWIR applications, see the M Plan Apo NIR 20× (378-824-16)
• ♾️ Infinity-corrected, M26 thread — compatible with Mitutoyo FS series microscopes and other infinity-corrected systems with M26 nosepieces
• 🇯🇵 Mitutoyo quality, made in Japan — precision optical construction for consistent, high-efficiency visible light transmission and long service life
• ✅ Catalog number 378-804-3

🔧 Product Description

The Mitutoyo M Plan Apo 20× (378-804-3) is the intermediate-magnification workhorse of the M Plan Apo visible series — combining 20× magnification with a 20mm working distance and plan apochromat correction for versatile industrial, metallographic, and semiconductor inspection. The 20mm working distance provides clearance for the full range of semiconductor inspection fixtures, environmental chambers, cryostats, vacuum systems, and laser processing setups. The plan apochromat correction delivers a flat, chromatic-aberration-free image with accurate color rendering across the full visible spectrum — critical for metallographic examination where grain structure, phase identification, and surface condition are assessed by color and contrast, and for semiconductor inspection where color-based defect analysis and documentation require accurate chromatic registration. At 20× with a 1.2mm field of view (with ×24 eyepiece), this objective provides a practical balance between field coverage and resolution for intermediate-magnification inspection — the natural step between wide-area 5×/10× survey and high-magnification 50×/100× detail in a multi-magnification M Plan Apo workflow. For NIR or SWIR applications at 20×, see the M Plan Apo NIR 20× (378-824-16). Compatible with Mitutoyo FS series microscopes and other infinity-corrected systems with M26 thread nosepieces. Catalog number 378-804-3.

🔎 Typical Applications

• Metallographic examination of grain structure, phase identification, and surface condition at 20×
• Semiconductor and IC surface inspection at intermediate magnification
• Defect analysis and documentation on polished surfaces, thin films, and coatings
• Intermediate-magnification imaging in environmental chambers, cryostats, or vacuum systems
• Inspection of specimens in industrial fixtures requiring 20mm working clearance
• Intermediate step in a multi-magnification M Plan Apo workflow (10× → 20× → 50× → 100×)

📊 Key Specifications

University and institutional purchase orders are welcome. Please contact us for invoicing and procurement documentation.