| Glass lens |
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| Substrates: |
all types of optical glasses, fused silica and quartz crystals. |
| Diameter: |
typical range is 5mm to 250mm; special case is 2mm to 5mm and 250mm to 350mm. |
Form accuracy
(Irregularity): |
typical error is 0.5 Fringe to 1 Fringe (within any 50mm diameter); special case is 0.2 Fringe to 0.5Fringe (within any 30mm diameter). |
Centering
(transmission method): |
typical error is between 0.5 arc minute to 1 arc minute; special case is between 15 arc second to 30 arc second. Measurement by reflection method (wedge angle) is available too. |
| Special form: |
irregular profile on rim edge could be done accurately through Computer-Numerical-Control (CNC) machine. |
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| Silicon lens |
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| Substrates: |
optical grade, mono crystalline silicon material. |
| Diameter range: |
between 5mm to 100mm. |
Form accuracy
(Irregularity): |
typical error is 0.5 Fringe to 1 Fringe (within any 30mm diameter). |
Centering
(reflection method): |
typical error is between 1 arc minute to 1.5 arc minutes. |
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| Germanium lens |
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| Substrates: |
optical grade germanium material, both mono and poly crystalline. |
| Diameter range: |
between 5mm to 100mm. |
Form accuracy
(Irregularity): |
typical is 0.5 Fringe to 1 Fringe (within any 30mm diameter). |
Centering
(reflection method): |
typical error is between 1 arc minute to 1.5 arc minutes. |
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| Aspheric lens |
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| Substrates: |
all types of optical glasses. |
| Diameter range: |
between for 20mm to 80mm. |
| Profile error: |
typical is 1 µm to typical is 1 arc minute to 3 arc minute; special case is 0.5 arc minute to 1 arc minute.2 µm; special case is 0.5 µm to 1 µm.
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| Slope error: |
typical is 1 arc minute to 3 arc minute; special case is 0.5 arc minute to 1 arc minute. |
Centration
(Runout): |
typical error is between 1 µm to 2 µm (diameter 40mm). |
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| Glass prism |
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| Substrates: |
all types of optical glasses, fused silica and quartz crystals. |
Size
(length or width): |
typical range is 5mm to 100mm; special case is 1mm to 5mm and 100mm to 200mm. |
| Flatness: |
typical range is 0.3 Fringe to 1 Fringe (within any 50mm diameter); special case is 0.1 Fringe to 0.3 Fringe (within any 50mm diameter). |
| Wavefront deformation: |
typical range is 1 Fringe to 2 Fringes (within any 50mm diameter); special case is 0.35 Fringe to 1 Fringe (within any 50mm diameter). |
| Angle accuracy: |
typical range is 0.5 arc minute to 3 arc minutes; precision case is 5 arc seconds to 30 arc seconds; special case is 1 arc seconds to 5 arc seconds. |
| Pyramidal error: |
typical range is 1 arc minute to 3 arc minutes; special case is 15 arc seconds to 1 minute. |
Light deviation
(through prism): |
typical range is 0.5 minute to 3 minute; special case is 10 arc seconds to 30 arc seconds. |
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| Glass window |
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| Substrates: |
all types of optical glasses, fused silica and quartz crystals. |
Size
(diameter, length or width): |
typical range is 5mm to 100mm; special case is 2mm to 5mm and 100mm to 200mm. |
| Flatness: |
typical range is 0.3 Fringe to 1 Fringe (within any 50mm diameter); special case is 0.1 Fringe to 0.3Fringe (within any 50mm diameter). It applies to aspect ratio of < 20. |
| Wavefront deformation: |
typical range is 0.5 Fringe to 0.8 Fringe (within any 50mm diameter); special case is 0.2 Fringe to 0.3 Fringe (within any 50mm diameter). It applies to aspect ratio of <20. |
| Parallelism: |
typical range is 0.25 arc minute to 2 arc minute; special case is 1 arc seconds to 15 arc seconds. |
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| Sapphire window |
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| Substrates: |
optical grade sapphire material |
| Size: |
diameter range between 5mm to 25mm; the range for square or rectangular shape is between 5mm to 20mm. |
| Flatness: |
typical is 1Fringe to 2 Fringe (within any 25mm diameter); special case is 0.5 Fringe to 1 Fringe (within any 25mm diameter). |
| Parallelism: |
typical range is 1 arc minute to 2 arc minute. |
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| Germanium window |
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| Substrates: |
optical grade germanium material, both mono and poly crystalline. |
| Size: |
diameter range between 5mm to 100mm; the range for square or rectangular shape is between 5mm to 70mm. |
| Flatness: |
typical range is 1 Fringe to 2 Fringe (within any 50mm diameter). It applies to aspect ratio of < 20. |
| Parallelism: |
typical range is 1 arc minute to 2 arc minute. |
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| Toroid |
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| Substrates: |
all types of optical glasses. |
Size
(length or width): |
typical range is between 20 to 80mm; special case is between 80mm to 130mm. |
Form accuracy
(Irregularity): |
typical range is 3 Fringes to 6 Fringes (within any 50mm. diameter); special case is 1 Fringe to 2 Fringes (within any 30mm diameter). |
| Type: |
typical type is concave surface on one side and flat on the other side. |
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| Graticule (Recticule) |
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| Substrates: |
optical glasses with high acid resistance. |
| Size: |
Maximum 50 mm diameter. |
| Types: |
edge illuminated (day grats) and back illuminated (night grats). |
| Line resolution: |
typical size is 15 microns for day grats; 13 microns for night grats. |
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| Optical coatings |
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| Techniques used: |
Physical Vapor Deposition (PVD), Ion-assisted Deposition (IAD) and Advanced Plasma IAD (APSIAD). |
| Coating types: |
Anti-reflection (AR) coatings
• Single layer MgF2 AR
• V-coat AR
• High efficient broad band AR (HEBBAR)
• Dual band AR (DUAR) and multiple band AR
• Ultra durable AR (UDC)
• Infrared AR at 2.5 - 5.5 micrometer (mainly silicon substrate)
• Far infrared AR at 7.5 – 12 micrometer (mainly germanium substrate)
• High laser damage resistance AR
• AR coatings in near UV
• Special AR coatings for TIR prisms
Reflection coatings
• Standard protected front /rear surface metallic mirrors
• Highly durable front surface metallic mirrors
• UV-enhanced metallic mirrors
• Dielectric high reflectance mirror
Beam splitter coatings
• Neutral density beam splitter
• High extinction, low f number polarizing beam splitter (PBS)
• Hybrid PBS
• Dielectric non-polarizing beam splitter (NPBS)
Dichroic interference coatings
• Colour-trim (R, G, B) filter
• Cold mirror used at 0° or 45°
• Infrared (IR) filter
• Hot mirror (Infrared cut-off)
Other coatings
• Laser protection filters with high optical density (OD~3 to 6)
• Band-pass filters (BPF)
• Band-stop (minus) filter
• Narrow band filter
• Index-matched
• Highly transparent conductive Indium-Tin-Oxide (ITO) film
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| Edge blackening |
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| Types: |
black ink or epoxy paint could be applied on ground glass surface or sprayed on polished glass surface. |
| Durability: |
epoxy paint could withstand stringent environmental tests. |
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| Bonded components |
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| Types: |
doublet lens, triplet lens, lens and prism assembly, TIR (Total Internal Reflection) prism (typical air gap size is 5 to 10 micron), X-cube, PCA (Polarising Converter Assembly). |
Centering
(transmission method): |
typical error is between 0.5 arc minute to 1 arc minute; special case is between 15 arc second to 30 arc second. Measurement by reflection method (wedge angle) and light deviation are available too. |
| Adhesives used: |
ultraviolet cured or heat cured. |
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| Metrology and tests |
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| Surface form & wavefront deformation: |
interferometers are used for measurement of surface form error and wavefront deformation. Precision level for transmission sphere is λ/10; transmission flat is λ/20 and λ/40 (with vibration- control).
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| Form tracing: |
profilometer (surface contact method) is used for measuring aspheric surface profile. |
| Reflectance and transmittance: |
spectrophotometers are used. The measuring wavelength range covers full spectrum range from deep UV (190 nanometer), visible, near infrared, to far infrared (20 micrometer). High optical density (OD) up to 6 can be accurately measured.
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| Environmental tests: |
high/low temperature and humidity test chambers are used for testing on coating film and epoxy paint durability. Coating film adhesion and hardness are tested on samples after environmental tests are conducted. Salt spray/solubility test chamber is used for testing on stringent environmental conditions. |
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