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1.
J Cancer ; 14(13): 2552-2561, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37670969

RESUMO

Genes of the homeobox (HOX) family encode transcription factors, which play a role in cancer progression. However, their role in gastric cancer has not been adequately evaluated. Herein, we evaluated the genetic changes and mRNA of target genes of the HOX family in gastric cancer patients using publicly available online datasets. We found that HOXC8 was amplified in gastric cancer tissues, and mRNA expression levels were significantly associated with tumor status (P=0.044) and poor overall survival (P<0.01). HOXC8 knockdown significantly reduced the viability of gastric cancer cell lines. HOXC8 modulated the expression of secreted phosphoprotein 1 (SPP1, osteopontin) and phosphorylation of AKT/ERK in gastric cancer cells. Survival analysis demonstrated a decrease in overall survival rates among the high HOXC8/high SPP1 expression group compared with the low HOXC8/low SPP1 expression group. In conclusion, HOXC8 may be an independent prognostic factor and serve as a useful predictive biomarker for gastric cancer.

2.
Asian J Surg ; 46(1): 222-227, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-35370064

RESUMO

BACKGROUND: /Objective: Laparoscopic distal gastrectomy for early gastric cancer is described as a treatment option in general practice. However, the oncological efficacy and technical safety of laparoscopic gastrectomy with D2 lymphadenectomy in locally advanced gastric cancer are controversial, and clinical trials are ongoing. This study aimed to evaluate the short-term and surgical outcomes between laparoscopic and open gastrectomy procedures in locally advanced gastric cancer. METHODS: We retrospectively analyzed data from 134 patients who underwent subtotal D2 gastrectomy for locally advanced gastric cancer in our hospital between January 2011 and December 2018. Clinicopathological characteristics, surgical outcome, postoperative recovery, disease-free survival, and overall survival were compared between those who underwent laparoscopic and open gastrectomies. RESULTS: Baseline characteristics were similar between patients who underwent open and laparoscopic surgeries. Less surgical time (250.8 vs. 347.6 min in laparoscopic vs. open surgery, respectively; P < 0.05) and lower blood loss (83.7 vs. 333 mL in laparoscopic vs. open surgery, respectively; P < 0.05) were noted in patients who underwent laparoscopic surgery than in those who underwent open gastrectomy. The time of starting oral intake was earlier and the length of postoperative hospital stay was shorter in the laparoscopic group than in the open group. Surgical morbidity and mortality rates, as well as disease-free survival and overall survival rates, did not differ between the two groups. CONCLUSION: Laparoscopic gastrectomy is feasible and safe for locally advanced gastric cancer. Based on the perioperative results and short-term outcomes, laparoscopic gastrectomy is non-inferior to open gastrectomy.


Assuntos
Laparoscopia , Neoplasias Gástricas , Humanos , Estudos Retrospectivos , Neoplasias Gástricas/patologia , Gastrectomia/métodos , Laparoscopia/métodos , Excisão de Linfonodo/métodos , Resultado do Tratamento
3.
World J Surg ; 45(6): 1779-1784, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33641001

RESUMO

BACKGROUND: The transoral approach and the bilateral axillo-breast approach (BABA) are remote access approaches for endoscopic thyroidectomy. Both follow a symmetric design and use CO2 insufflation to maintain the working space. The outcome differences between the techniques are rarely compared in the literature. METHODS: All patients who underwent endoscopic transoral (n = 72) and BABA (n = 63) thyroidectomy between October 2018 and August 2020 by a single surgeon were retrospectively reviewed. The following peri-operative data were collected and compared: operative time, blood loss, postoperative drainage amount, hospital stay, pain score, number of retrieved lymph nodes, and complications. RESULTS: Patients in the transoral group were younger (44.7 vs. 49.3 years, p = 0.022) and had smaller tumors (2.4 vs. 2.8 cm, p = 0.020) than those in the BABA group. The operative times were significantly longer in the transoral group than in the BABA group (lobectomy, 194.1 vs. 177.0 min, p = 0.026; total thyroidectomy, 246.0 vs. 214.3 min, p = 0.042). Nevertheless, the time difference became insignificant after completing the initial 20 cases of transoral thyroidectomy. The drainage fluid collected after the surgery was serosanguinous, and a lower drainage volume was observed in the transoral group than that in the BABA group (64.9 vs. 78.5 ml, p = 0.017). However, there was no significant difference regarding the blood loss, hospital stay, postoperative pain score, and lymph nodes retrieved. The rate of postoperative complications, such as hypoparathyroidism and vocal cord palsy was comparable between the two groups. CONCLUSIONS: Transoral approach and BABA are comparable with regard to surgical outcomes. Selected patients may choose either technique based on their preferences.


Assuntos
Procedimentos Cirúrgicos Robóticos , Cirurgiões , Neoplasias da Glândula Tireoide , Axila , Mama , Humanos , Duração da Cirurgia , Complicações Pós-Operatórias/epidemiologia , Estudos Retrospectivos , Neoplasias da Glândula Tireoide/cirurgia , Tireoidectomia , Resultado do Tratamento
4.
World J Surg ; 45(5): 1446-1456, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33512565

RESUMO

BACKGROUND: Endoscopic thyroidectomy has comparable surgical outcomes and superior cosmetic satisfaction to open thyroidectomy. However, steep learning curve is a concern. This study evaluated the learning curve of endoscopic thyroidectomy using various parameters and statistical methods. METHODS: A total of 90 consecutive patients who underwent endoscopic thyroidectomy using bilateral axillo-breast approach (BABA) between March 2016 and April 2020 were enrolled. Operative time, postoperative drainage amount, and blood loss were assessed by cumulative sum (CUSUM) analysis and moving average to evaluate the learning curve. RESULTS: Using the CUSUM analysis, the peak point of both operative time and drainage amount occurred at the 30th case. No clear single peak was identified in the CUSUM plot for blood loss. The moving average also showed significant reduction in operative time and drainage amount after, approximately, the first 30 cases. The blood loss decreased after the 25th case. We therefore divided the patients into 2 phases: phase 1 (1-30 cases) and phase 2 (31-90 cases). The operative time, drainage amount, and blood loss decreased significantly in the phase 2 compared with phase 1. Lower pain score in first postoperative day and shorter hospital stay were also observed in the phase 2. Although the reduction in transient hypoparathyroidism did not reach statistical significance, no permanent hypoparathyroidism was noted in the phase 2. CONCLUSIONS: The learning curve for endoscopic thyroidectomy is approximately 30 cases. Aside from the operative time, drainage amount may also serve as a surrogate for the learning curve evaluation.


Assuntos
Curva de Aprendizado , Tireoidectomia , Mama , Endoscopia , Humanos , Duração da Cirurgia , Complicações Pós-Operatórias , Estudos Retrospectivos , Tireoidectomia/efeitos adversos
5.
World J Surg ; 44(5): 1514-1517, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-31897697

RESUMO

BACKGROUND: Transoral thyroidectomy via the vestibular approach retains no scars in the body surface and is a good option for patients indicated for thyroidectomy but with cosmetic concerns. However, the working space of this procedure is relatively small and is also difficult to create compared with that of other remote-access thyroidectomy procedures. METHODS: In this study, we first created a tract from the chin to the sternal notch, after which a Foley catheter with stylet was inserted through the middle oral incision. Sequential balloon insufflations were performed to dilate the entire subplatysmal tunnel. RESULTS: After Foley catheter dilatation, the subplatysmal space was larger, and subsequent trocar insertion became much easier. With the help of a balloon compressing the surrounding tissue, hemostasis was secured and a clearer tissue plane could be identified for subsequent sharp dissection. CONCLUSIONS: Foley balloon dilatation is a simple, effective, and low-cost technique that overcomes the difficulty in creation of working space during the initial stage and can be applied to all transoral thyroidectomy procedures.


Assuntos
Catéteres , Endoscopia/instrumentação , Tireoidectomia/instrumentação , Tireoidectomia/métodos , Dilatação/instrumentação , Dilatação/métodos , Dissecação , Endoscopia/métodos , Humanos
6.
Anticancer Res ; 39(10): 5381-5391, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31570433

RESUMO

BACKGROUND/AIM: Long noncoding RNAs (lncRNAs) are noncoding transcripts that are >200 nucleotides in length. However, the biological functions and regulation mechanisms of lncRNAs in gastric carcinogenesis remain unknown. MATERIALS AND METHODS: The expression levels of Linc00472 were analyzed by real-time PCR. The DNA methylation status was assessed using Combined Bisulfite Restriction Analysis (COBRA). The biological role of Linc00472 was assessed in AGS cells with Linc00472 overexpression. RESULTS: Using the next-generation sequencing approach, we identified DNA methylation-associated lncRNAs in gastric cancer cells. Among them, the expression level of Linc00472 significantly decreased in gastric cancer tissues compared to adjacent normal tissues. Furthermore, we observed a more frequent hypermethylation of CpG islands upstream of Linc00472 in gastric cancer tissues. Ectopic Linc00472 expression could significantly inhibit gastric cancer cell growth and migration. CONCLUSION: Epigenetically regulated Linc00472 expression plays a crucial role in modulating gastric cancer cell growth and motility.


Assuntos
Metilação de DNA/genética , RNA Longo não Codificante/genética , Neoplasias Gástricas/genética , Carcinogênese/genética , Linhagem Celular Tumoral , Movimento Celular/genética , Proliferação de Células/genética , Ilhas de CpG/genética , Regulação Neoplásica da Expressão Gênica/genética , Humanos
7.
Surg Laparosc Endosc Percutan Tech ; 29(5): e72-e75, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31425451

RESUMO

BACKGROUND: Endoscopic thyroidectomy through the bilateral axillo-breast approach (BABA) is a good option for patients who have been advised thyroid resection but are concerned about the cosmetic results. This technique uses the breast tissue as a pivot to facilitate maneuvering of the surgical instruments. However, it is difficult to use this technique in patients with small breasts or having a flat chest. MATERIALS AND METHODS: The authors developed an "X-shaped breast lift" method using fabric adhesive tape, to push up and augment the breast tissue to facilitate the thyroid dissection procedure. Changes before and after the breast lift were quantified by measuring the angle of breast tilt and the distance between relevant anatomic landmarks. RESULTS: Fifteen consecutive patients underwent this procedure before undergoing BABA thyroidectomy. The mean breast tilt angle increased from 3.2 to 9.8 degrees, which is a >3-fold increase (+6.6 degree, 206%). The mean distance between the cricoid cartilage and nipple was reduced by 1.9 cm (-8%), and the mean distance between the axillary incision and nipple increased by 1.1 cm (9%). No skin trauma or ulceration was observed. CONCLUSIONS: X-shaped breast lift is easy to perform, and it significantly improves the thyroid dissection process with no significant adverse effects. It can be used for all cases of BABA thyroidectomy.


Assuntos
Mama , Endoscopia/métodos , Neoplasias da Glândula Tireoide/cirurgia , Tireoidectomia/métodos , Tração/métodos , Pontos de Referência Anatômicos , Axila/cirurgia , Feminino , Humanos , Tempo de Internação/estatística & dados numéricos , Pessoa de Meia-Idade , Estudos Retrospectivos , Fita Cirúrgica
8.
J Gastric Cancer ; 19(1): 132-137, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30944766

RESUMO

The occurrence of hiatal hernia after total gastrectomy with Roux-en-Y reconstruction is rare. We report the case of a 76-year-old man who presented with dyspnea, vomiting, and fever around 8 days after total gastrectomy with Roux-en-Y reconstruction. Abdominal computed tomography revealed a hiatal hernia containing part of the small intestine in the left thoracic cavity. Emergent reduction and repair of the hiatal hernia were performed later. Operative findings revealed that the Roux limb was incarcerated in the left pleural cavity. Esophagojejunostomy leakage, perforation of the small intestine with transient ischemic change, and pyothorax were also found. Thus, feeding jejunostomy, thoracoscopic decortication, and diversion T-tube esophagostomy were performed. Considering that the main cause of hiatal hernia is blunt dissection with division of the phrenoesophageal membrane, approximating the crus with 1 or 2 figure-8 sutures, according to the size of the defect, to prevent the incidence of hiatal hernia after total gastrectomy may be performed.

9.
Surg Laparosc Endosc Percutan Tech ; 29(4): e50-e52, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30629035

RESUMO

BACKGROUND: Endoscopic thyroidectomy using the bilateral axillo-breast approach (BABA) achieves excellent cosmetic results. However, concerns have been raised about the extensive dissection and violation of the breast during working space preparation. MATERIALS AND METHODS: We developed a "single biaxillary tunneling" technique for working space creation in BABA thyroidectomy; this technique was applied in 30 cases. RESULTS: Skin bruise was hardly visible, and only minor and small bruises were observed. The whole process of working space creation typically finished within 20 to 30 minutes. CONCLUSIONS: Limited blunt dissection by a single stroke of biaxillary tunneling is a simple method, which significantly reduces ecchymosis formation and is time-efficient. This method can be used in routine practice and is feasible for beginner surgeons.


Assuntos
Endoscopia/métodos , Hipertireoidismo/cirurgia , Neoplasias da Glândula Tireoide/cirurgia , Tireoidectomia/métodos , Adulto , Axila/cirurgia , Mama/cirurgia , Estudos de Coortes , Estética , Feminino , Humanos , Hipertireoidismo/patologia , Pessoa de Meia-Idade , Procedimentos Cirúrgicos Minimamente Invasivos/métodos , Duração da Cirurgia , Segurança do Paciente , República da Coreia , Estudos Retrospectivos , Medição de Risco , Neoplasias da Glândula Tireoide/patologia , Resultado do Tratamento
10.
Anticancer Res ; 38(6): 3309-3318, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29848678

RESUMO

BACKGROUND/AIM: MicroRNAs (miRNAs) are small non-protein-coding RNAs, that can be generated from the 5p or 3p arm of precursor miRNA (pre-miRNA). Differential miRNA arm selection has been reported between tumor and normal tissue in many cancer types; however, the biological function and mechanism of miRNA arm switching in gastric cancer remain unclear. MATERIALS AND METHODS: Profiles of miRNA expression in gastric cancer were obtained from The Cancer Genome Atlas (TCGA). The biological role of miR-193a-5p/-3p in tumor growth and invasive abilities was assessed through a gain-of-function approach. Target genes of miR-193a-3p were identified using bioinformatics and an experimental approach. RESULTS: The expression levels of miR-193a-5p, and not of miR-193a-3p, were significantly decreased in gastric cancer compared to adjacent normal tissues. Ectopic expressions of miR-193a-5p and miR-193a-3p revealed that they both inhibited gastric cancer cell growth, but only miR-193a-3p significantly suppressed cell invasion ability. Using a bioinformatics approach, we identified 18 putative target genes of miR-193a-3p. Both mRNA and protein levels of cyclin D1 (CCND1) and ETS proto-oncogene 1 (ETS1) were significantly decreased in AGS cells transfected with miR-193a-3p mimics. ETS1 or CCND1 knockdown significantly suppressed gastric cancer cell growth, similar to miR-193a-3p overexpression. CONCLUSION: Our results indicated that miR-193a-3p suppressed gastric growth and motility, at least partly, by directly targeting CCND1 and ETS1 expression.


Assuntos
Proliferação de Células/genética , Ciclina D1/genética , Regulação Neoplásica da Expressão Gênica , MicroRNAs/genética , Proteína Proto-Oncogênica c-ets-1/genética , Linhagem Celular Tumoral , Movimento Celular/genética , Ciclina D1/metabolismo , Perfilação da Expressão Gênica/métodos , Humanos , Proto-Oncogene Mas , Proteína Proto-Oncogênica c-ets-1/metabolismo , Interferência de RNA , Neoplasias Gástricas/genética , Neoplasias Gástricas/metabolismo , Neoplasias Gástricas/patologia
11.
Angew Chem Int Ed Engl ; 57(17): 4622-4626, 2018 04 16.
Artigo em Inglês | MEDLINE | ID: mdl-29461658

RESUMO

The combination of conventional transition-metal-catalyzed coupling (2 e- process) and photoredox catalysis (1 e- process) has emerged as a powerful approach to catalyze difficult cross-coupling reactions under mild reaction conditions. Reported is a palladium carbodicarbene (CDC) complex that mediates both a Suzuki-Miyaura coupling and photoredox catalysis for C-N bond formation upon visible-light irradiation. These two catalytic pathways can be combined to promote both conventional transition-metal-catalyzed coupling and photoredox catalysis to mediate C-H arylation under ambient conditions with a single catalyst in an efficient one-pot process.

12.
Oncol Lett ; 15(1): 278-284, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29285192

RESUMO

A sixth base, 5-hydroxymethylcytosine (5hmC), is formed by the oxidation of 5-methylcytosine (5mC) via the catalysis of the ten-eleven translocation (TET) protein family in cells. Expression levels of 5hmC are frequently depleted during carcinogenesis. However, the detailed mechanisms underlying the depletion of 5hmC expression in gastric cancer cells remains unclear, and further research is required. The present study examined the expression levels of 5mC and 5hmC and the expression levels of TET1 and TET2 in gastric cancer tissues using immunohistochemistry. The results revealed that 5hmC expression levels were markedly lower in gastric cancer tissues compared with corresponding adjacent normal tissues. Furthermore, a decrease in 5hmC expression levels was associated with a decrease in TET1 protein expression levels in gastric cancer tissues. The ectopic expression level of TET1 may increase the 5hmC expression level in gastric cancer cells. In addition, the results revealed that TET1 protein expression was markedly different in regards to subcellular localization, and mislocalization was significantly associated with the depletion of 5hmC expression levels in gastric cancer. Together, the results of the present study indicated that TET1 dysfunction reduces 5hmC expression levels, and this phenomenon may serve a crucial role in gastric cancer progression.

13.
J Opt Soc Am A Opt Image Sci Vis ; 34(7): 1236-1245, 2017 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-29036134

RESUMO

A refractive laser beam shaper comprising two free-form profiles is presented. The profiles are designed using a free-form profile construction method such that each incident ray is directed in a certain user-specified direction or to a particular point on the target surface so as to achieve the required illumination distribution of the output beam. The validity of the proposed design method is demonstrated by means of ZEMAX simulations. The method is mathematically straightforward and easily implemented in computer code. It thus provides a convenient tool for the design and sensitivity analysis of laser beam shapers and similar optical components.

14.
J Opt Soc Am A Opt Image Sci Vis ; 34(3): 361-369, 2017 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-28248363

RESUMO

Conventional paraxial ray-tracing procedures are widely used for optical systems design and analysis. However, they are not applicable to multiple-dispersion-prism systems. Accordingly, the present study simplifies the equations given by the present group in a previous paper [Optik117, 329 (2006)OTIKAJ0030-402610.1016/j.ijleo.2005.10.004] to the form of 3×3 matrix equations for tracing paraxial rays in optical systems containing triangular prisms. The accuracy and validity of the proposed approach are demonstrated by means of four numerical examples. The results confirm that the proposed equations provide a convenient and practical tool for analyzing paraxial rays traveling through non-axially symmetrical optical systems containing triangular and rectangular prisms.

15.
Anticancer Res ; 36(8): 3983-90, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27466503

RESUMO

The isocitrate dehydrogenase (IDH) family of enzymes comprises of the key functional metabolic enzymes in the Krebs cycle that catalyze the conversion of isocitrate to α-ketoglutarate (α-KG). α-KG acts as a cofactor in the conversion of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC). However, the relationship between 5hmC and IDH in gastric cancer remains unclear. Our study revealed that the 5hmC level was substantially lower and 5mC level was slightly higher in gastric cancer tissues; however, 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC) levels did not change significantly in these tissues. We further examined the expression levels of IDH1 and IDH2 in gastric cancer tissues and observed that IDH2 levels were significantly lower in gastric cancer tissues than in the adjacent normal tissues. The ectopic expression of IDH2 can increase 5hmC levels in gastric cancer cells. In conclusion, our results suggested that IDH2 dysfunction is involved in 5hmC depletion during gastric cancer progression.


Assuntos
Metilação de DNA/genética , Isocitrato Desidrogenase/biossíntese , Neoplasias Gástricas/genética , 5-Metilcitosina/metabolismo , Citosina/análogos & derivados , Citosina/isolamento & purificação , Citosina/metabolismo , Feminino , Humanos , Isocitrato Desidrogenase/genética , Ácidos Cetoglutáricos/metabolismo , Masculino , Neoplasias Gástricas/patologia
16.
J Opt Soc Am A Opt Image Sci Vis ; 33(4): 785-92, 2016 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-27140792

RESUMO

A free-form (FF) surface design method is proposed for a general axial-symmetrical collimator system consisting of a light source and a total internal reflection lens with two coupled FF boundary surfaces. The profiles of the boundary surfaces are designed using a FF surface construction method such that each incident ray is directed (refracted and reflected) in such a way as to form a specified image pattern on the target plane. The light ray paths within the system are analyzed using an exact analytical model and a skew-ray tracing approach. In addition, the validity of the proposed FF design method is demonstrated by means of ZEMAX simulations. It is shown that the illumination distribution formed on the target plane is in good agreement with that specified by the user. The proposed surface construction method is mathematically straightforward and easily implemented in computer code. As such, it provides a useful tool for the design and analysis of general axial-symmetrical optical systems.

17.
Medicine (Baltimore) ; 95(12): e3159, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27015200

RESUMO

The recurrence rate for acute appendicitis treated nonoperatively varies between studies. Few studies have adequately evaluated the management of these patients when appendicitis recurs. We aimed to explore the recurrence rate and management of patients with acute appendicitis that were first treated nonoperatively.We identified patients in the Taiwan National Health Insurance Research Database who were hospitalized due to acute appendicitis for the first time between 2000 and 2010 and received nonsurgical treatment. The recurrence and its management were recorded. Data were analyzed to access the risk factors for recurrence and factors that influenced the management of recurrent appendicitis.Among the 239,821 patients hospitalized with acute appendicitis for the first time, 12,235 (5.1%) patients were managed nonoperatively. Of these, 864 (7.1%) had a recurrence during a median follow-up of 6.5 years. Appendectomy was performed by an open and laparoscopic approach in 483 (55.9%) and 258 (29.9%) patients, respectively. The remaining 123 (14.2%) patients were again treated nonsurgically. Recurrence was independently associated with young age, male sex, percutaneous abscess drainage, and medical center admission by multivariable analysis. In addition, age <18, a (CCI) <2, medical center admission, and a longer time to recurrence were correlated with using laparoscopy to treat recurrence. Neither type of appendicitis, percutaneous abscess drainage, nor length of first time hospital stay had an influence on the selection of surgical approach.In conclusion, a laparoscopic appendectomy can be performed in recurrent appendicitis cases, and its application may not be related to previous appendicitis severity.


Assuntos
Apendicite/terapia , Abscesso Abdominal/terapia , Doença Aguda , Adolescente , Adulto , Idoso , Apendicectomia , Drenagem , Feminino , Seguimentos , Hospitalização , Humanos , Laparoscopia , Masculino , Pessoa de Meia-Idade , Peritonite/terapia , Recidiva , Fatores de Risco , Taiwan , Resultado do Tratamento , Adulto Jovem
19.
Appl Opt ; 52(22): 5385-92, 2013 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-23913055

RESUMO

The design of a partially optically stable (POS) reflector system, in which the exit ray direction and image pose are unchanged as the reflector system rotates about a specific directional vector, was presented in an earlier study by the current group [Appl. Phys. B100, 883-890 (2010)]. The present study further proposes an optically stable image (OSI) reflector system, in which not only is the optical stability property of the POS system retained, but the image position and total ray path length are also fixed. An analytical method is proposed for the design of OSI reflector systems comprising multiple reflectors. The validity of the proposed approach is demonstrated by means of two illustrative examples.

20.
J Opt Soc Am A Opt Image Sci Vis ; 30(5): 993-1001, 2013 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-23695333

RESUMO

A light-emitting diode (LED) projection system is proposed, composed of an LED chip and a variable-focus-parabolic (VFP) reflector, in which the focal length varies as a function of the vertical displacement of the incidence point relative to the horizontal centerline of the LED chip. The light-ray paths within the projection system are analyzed using an exact analytical model and a skew-ray tracing approach. The profile of the proposed VFP reflector and the position of the LED chip are then optimized in such a way as to enhance the uniformity of the illuminance distribution on the target region of the image plane. The validity of the optimized design is demonstrated by means of ZEMAX simulations. It is shown that the optimized VFP projector system yields a significant improvement in illuminance uniformity compared to conventional spherical and parabolic projectors and therefore minimizes the glare effect.

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