कला
सुन्दरता र कल्याण
हस्तकला
संस्कृति र इतिहास
मनोरञ्जन
वातावरण
खाना र पेय
रिभर्स इन्जिनियरिङ
विज्ञान
खेलकुद
प्रविधि
पहिर्न मिल्ने
Cooke Triplet Lens
Nineteenth-century lens makers flattened the image with a stop placed in front of or behind the lens, at the cost of astigmatism at the edges. Harold Dennis Taylor, optical manager at T. Cooke & Sons of York, dropped that trick entirely. He showed that a negative lens images a flat object onto a surface curved exactly as much as a positive lens of equal power, but the other way - so one can cancel the other.
**US 540,122**, "Lens", Taylor, filed 5. February 1894, granted 28. May 1895, puts "a negative lens … between two positive lenses, the focal power of the negative lens being approximately equal to the combined focal powers of the two positive lenses". Three separated elements: the Cooke triplet, still the simplest well-corrected camera lens.
**You build one from stock lenses**, and compare how flat its image is with a single lens.
मध्यम
2 hours
निर्देशनहरू
1
1
Choose three lenses
Choose three lenses
Two convex lenses of about 100 mm focal length (check each on a distant window) and one concave of about -50 mm. Powers: +10 and +10 dioptres against -20.
यस चरणका सामग्री:
उत्तल लेन्सको सेट1 सेट
अवतल लेन्स1 टुक्राचाहिने औजार:
फलामे रुल2
2
Mount the triplet
Mount the triplet
On the bench: convex, 20 mm gap, concave, 20 mm gap, convex. Centre all three on the same height.
चाहिने औजार:
प्रकाशीय बेन्च र पाटो
लेन्स अड्याउने सेट3
3
Light a grid
Light a grid
Tape graph paper to a window or light it from behind with a torch, 1.5 m from the lens. Put a tracing-paper screen behind the triplet and focus the centre of the grid sharply.
यस चरणका सामग्री:
रेखाचित्र कागज1 पाना
नमुना सार्ने कागजको मुठो1 पाना
मास्किङ टेप1 रोलचाहिने औजार:
एलईडी निरीक्षण टर्च
नाप्ने फित्ता4
4
Measure the edge refocus
Measure the edge refocus
Without touching the lenses, move the screen until the grid 15 mm from the image centre is sharpest. Note how far it moved. Replace the triplet with one convex lens, refocus the centre, and measure the refocus again at the same 15 mm image height.
चाहिने औजार:
फलामे रुल5
5
Petzval sum and design
Petzval sum and design
Jupyter नोटबुक लोड हुँदैछ…
6
6
History & Context
History & Context
**What the patent specifies:** a negative lens between two positive lenses, its power about equal to theirs combined, each element free of diaphragm corrections, flattening the field and removing marginal astigmatism. **Modern build (derived):** three stock singlets on a bench.
Taylor's employer declined to make it; Taylor, Taylor & Hobson did, as the Cooke lens. Tessar and many later designs grew from it. Its limits: with only three elements the aperture and angle of view are modest before aberrations return.
सामग्री
5- 1 सेटप्लेसहोल्डर
- 1 टुक्राप्लेसहोल्डर
- 1 पानाप्लेसहोल्डर
- 1 पानाप्लेसहोल्डर
- 1 रोलप्लेसहोल्डर
आवश्यक उपकरणहरू
5- प्लेसहोल्डर
- प्रकाशीय बेन्च र पाटो10% कमिसनप्लेसहोल्डर
- लेन्स अड्याउने सेट10% कमिसनप्लेसहोल्डर
- प्लेसहोल्डर
- 1 vendor sell this, none ship to you yetप्लेसहोल्डर
सम्बन्धित ब्लुप्रिन्ट
यी ब्लुप्रिन्टहरूले ज्ञान साझा गर्छन् — प्रविधि, सामग्री वा सिद्धान्त
CC0 सार्वजनिक डोमेन
यो ब्लुप्रिन्ट CC0 अन्तर्गत जारी गरिएको छ। तपाईं अनुमति नसोधी प्रतिलिपि, परिमार्जन, वितरण र प्रयोग गर्न सक्नुहुन्छ।
ब्लुप्रिन्ट मार्फत उत्पादनहरू किनेर सिर्जनाकर्तालाई सहयोग गर्नुहोस् सिर्जनाकर्ता कमिसन विक्रेताले तोकेको, वा यो ब्लुप्रिन्टको नयाँ संस्करण बनाउनुहोस् र आम्दानी बाँड्न आफ्नो ब्लुप्रिन्टमा जडानको रूपमा समावेश गर्नुहोस्।