SENI
KECANTIKAN & KESEJAHTERAAN
KRAFTANGAN
BUDAYA & SEJARAH
HIBURAN
ALAM SEKITAR
MAKANAN & MINUMAN
KEJURUTERAAN TERBALIK
SAINS
SUKAN
TEKNOLOGI
BOLEH PAKAI
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.
Pertengahan
2 hours
Arahan
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.
Bahan untuk langkah ini:
Set kanta cembung1 set
Kanta cekung1 kepingAlatan diperlukan:
Pembaris Keluli2
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.
Alatan diperlukan:
Bangku dan rel optik
Set pemegang kanta3
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.
Bahan untuk langkah ini:
Kertas Graf1 helaian
Gulung kertas surih corak1 helaian
Pita pelekat kertas1 gulungAlatan diperlukan:
Lampu suluh LED pemeriksaan
Pita Ukur4
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.
Alatan diperlukan:
Pembaris Keluli5
5
Petzval sum and design
Petzval sum and design
Memuatkan buku nota Jupyter…
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.
Bahan
5- 1 setPemegang Tempat
- 1 kepingPemegang Tempat
- 1 helaianPemegang Tempat
- 1 helaianPemegang Tempat
- 1 gulungPemegang Tempat
Alatan Diperlukan
5- Pemegang Tempat
- Bangku dan rel optik10% komisenPemegang Tempat
- Set pemegang kanta10% komisenPemegang Tempat
- Pemegang Tempat
- 1 vendor sell this, none ship to you yetPemegang Tempat
Blueprint berkaitan
Blueprint ini berkongsi pengetahuan — teknik, bahan atau prinsip
CC0 Domain Awam
Blueprint ini dikeluarkan di bawah CC0. Anda bebas menyalin, mengubah, mengedar, dan menggunakan karya ini untuk sebarang tujuan, tanpa meminta kebenaran.
Sokong Pembuat dengan membeli produk melalui Blueprint mereka di mana mereka memperoleh Komisen Pembuat ditetapkan oleh Penjual, atau cipta iterasi baru Blueprint ini dan sertakan ia sebagai sambungan dalam Blueprint anda sendiri untuk berkongsi hasil.